BIOL112- cell structure and function Flashcards

Question

descibe prokaryotic cell structures

Answer 1

Plasma membrane very simlar in terms of compositon to eukaryotes Cell wall – peptidoglycan Capsule – protects from attacks from the immune system, aslo can cause an immune response If recognised Flagellum- how they move Pilli- hair like structues, involved in sticking to substrated and in comunication

Answer 2

Nucleoid region: contains circular DNA, no nuclear membrane Plasma membrane: has the same basic structure of all biological membranes. Some prokaryotes have infoldings of the plasma membrane which contain specialized enzymes. The cytoplasm contains ribosomes and little else. Many prokaryotes have a cell wall Some prokaryotes have flagella composed of the protein Flagellin. Pili are composed of the protein Pilin and help bacterial stick to their substrate or to each other Many bacteria also secret a Capsule usually of polysaccharides Bacteria have a diverse range of shapes the most common being Cocci (spherical),bacilli (rod shaped), and spirochetes (helical).

Answer 3

conjugation

Answer 4

protects the cell from osmotic shocks composed of peptidoglyca

Answer 5

gram positive gram negative

Answer 6

think simple single layer no lipopolysaccahrides there are teichoic acids pruple gram stain susceptible to antibiotic resistance so easier to treat

Answer 7

thin, complex double layer no teichoic acids there are lipopolysacchardies pink gram stain resistant to antibiotic resistance

Answer 8

Bacteria can be used to produce large quantities of proteins cheaply for therapeutic use for example Insulin. Drug screening tests and diagnostics.

Answer 9

Introduction of a new gene in plant chromosome Example - purple tomatoes have high anthocyanin

Answer 10

Bioremediation – removes pollutants, industrial by-products, oil spills

Answer 11

Lactic bacteria develop the flavour and colour of foodstuff Improve the storage longevity of wines

Answer 12

prokaryotes

Answer 13

producers – make their own food – plants, algae, bacteria

Answer 14

Consumers – consume producers/consumers – mammals

Answer 15

uses light

Answer 16

uses molecules or compounds

Answer 17

eukaryotes

Answer 18

prokaryotes

Answer 19

Are they alive? They cannot self repair No energy transduction system Only visible with the electron microscope Each complete viral particle is called a virion Protein coat is termed the capsid, which is made up of protein units called capsomers they are not prokaryotes or eukaryotes

Answer 20

The nucleic acid is arranged in a helix, with the protein sub-units surrounding and stabilizing it. An example is Tobacco mosaic virus

Answer 21

The nucleic acid is condensed inside a protein envelope which is usually organized into a multisided geometric shape. An example are adenovirus different types cause illness ranging from Gastroenteritis to keratoconjunctivitis

Answer 22

Have lipid envelopes includes the influenza and coronaviruses viruses

Answer 23

This is basically a spheroid virus with a tail. An example is the lambda phage

Answer 24

The foundations of cell biology were formed in the 17th century. In 1665 Robert Hooke published a collection of essays under the title Micrographica. One essay gave a detailed description of a section of cork, in which Hooke described seeing a honeycomb of chambers- now what we call cells. In 1675 Dutchman Anton Van Leeuwenhoek had improved the art of polishing lenses. Leeuwenhoek's best microscopes were able to resolve to about 1.5 microns. He was able to report what he described as a host of little animals in a drop of rain water, these turned out to be protozoa. Leeuwenhoek was later on to describe the existence of bacteria. In the 19th century the maximum theoretical resolution of the light microscope was attained (approximately 0.25 microns). In the 1930's the electron microscope was developed allowing cell organelles to be seen. The term ultrastructure was coined to describe the level of detail obtainable with the EM.

Answer 25

the ratio of an objects image size to its real size

Answer 26

the measure of the minimum distance of 2 ditinguishable points

Answer 27

visible differences in brightness or colour between parts of the sample

Answer 28

dissecting compound brightfield

Answer 29

see structral features 70x magnification reflect light so you can see sample

Answer 30

in depth features, 40-1000x magnification light passes through stage through a series of objector lenses magnification = ocular x objector

Answer 31

bright field the light passes through the specimen so must be at least pertially transparent

Answer 32

image living cell s

Answer 33

fluorescent, phase/differential contrast and confocal microscopes.

Answer 34

limited resolution ( o.2 microns)

Answer 35

shorter wavelneght of radiation

Answer 36

Whole mounts: small relatively transparent specimens can be mounted directly onto slides Tissue sections: most tissues need to be sectioned before they can be examined Fixation: This involves using chemical fixatives to prevent cell autolysis and to preserve the structure of the tissue. Dehydration and clearing: This removes the water from the tissue in preparation for wax impregnation Embedding: The specimen is infiltrated with molten wax, after which it is transferred to a mould Sectioning: Thin sections approximately 5 microns thick are cut on a microtome, and collected onto a glass slides Staining: The wax is removed and the tissue stained with a coloured dye such as Eosin (cytoplasm) or haematoxylin (nuclei)

Answer 37

enhances contrast in unstained cells by amplifiying variation in density wihtin specimen, especiilay useful for examining living unpigmented cells

Answer 38

like phase contrast microscopy it uses optical modifications to exaggerate differnces in density

Answer 39

shows the locations of specific molecules in the cell. flourescent substances absorb short-wavelengths uv radiation and emit long wavelength , visable light oftern made by tagging the moleucles of interest with flourescent moelcules

Answer 40

uses lasers and special optics for optical sectoning , only those regions within a narrow depth of focus are imaged typically used with flouresemtly names samples 3d image can use fixed or live cells if we use live we can add how it chnages over time, so time can be added as a 4thdimention

Answer 41

Algorithms remove out of focus light and this sharpens the image and improves resolution.

Answer 42

gathers light from individual fluorescent molecules and records their position. Combining information from these individual molecules breaks the resolution limit.

Answer 43

electrons have a very short wavelength so rosoultion 1000s of times better

Answer 44

electrons have poor penetrating power

Answer 45

magnetic fields

Answer 46

transmission scanning

Answer 47

Electron gun: usually a heated tungsten filament which produces electrons by thermionic emission Electron beam passes through the specimen The image is focused and magnified by magnetic objective and projector lenses The electron image is converted into a visible image by a fluorescent screen, which is viewed through a glass window. Photographs can be taken using a digital camera The whole inside of the microscope is kept at a high vacuum during operation

Answer 48

Whole mounts: Bacteria and viruses can be examined directly Tissue sections Fixation: Usually in Glutaraldehyde (protein crosslinking) followed by a second fixation step in Osmium Tetroxide (lipid crosslinking) Dehydration: In an ethanol series Embedding: Specimens for TEM are embedded in plastic resins such as Epoxy resins. Sectioning: 50nm thick sections are cut using a ultramicrotome. Staining: Biological tissue has little contrast under the electron beam, so heavy metal stains such as lead are used to improve contrast

Answer 49

So called because the electron beam is scanned across the specimen. Used for looking at the surface of specimens The top part to the microscope is similar to a TEM Its called a Scanning Electron Microscope as the electron beam is Scanned across the surface of the specimen. Electrons are reflected from the surface of the specimen, collected by a electron detector and converted into an electronic signal which is displayed on a screen. The image on the SEM represents the topology of the sample. The great depth of focus of the SEM gives images a 3-D appearance

Answer 50

Biological samples must be fixed and dried before being examined in the SEM under vacuum Fixation: The same fixatives are used as with TEM preparation Dehydration: The water is replaced with Ethanol Critical Point Drying: This technique allows all of the ethanol to be removed from the sample in a way that minimises shrinkage Coating Specimens are coated with a thin layer of gold to protect them from electron beam damage

Answer 51

allows major organelles to be individuallt separateed out so they can be studied in isolaton

Answer 52

Cells are first homogenised to release the organelles. Differential centrifugation isolates cell components on the basis of size and density by using increasing durations and g forces.

Answer 53

Protein Enrichment Enrich target proteins and improve detection of low abundance protein Protein Characterization Identify the subcellular localization of a protein Protein Translocation Monitor translocation of cell signalling molecules from the cytoplasm to the nucleus

Answer 54

because of their internal membrane system

Answer 55

more comples genetic material is organized into chromosomes and enclosed in a nuclear envelope plasma membrane specialised organnelles inclusing numerous internal emembranes togther temred the endomemrbane system complex cytoskeleton plants have specialised structures inclusing chloroplasts , vaculose and a cell wall

Answer 56

maintains the cell shape and prevents mechanical damage. this cell wall is composed of cellulose fibres embedded in a protein/polysaccharide matric consisting mainly of hemicellulose and pectin

Answer 57

mostly true plants dont have lysosomes they dont normally have flagella

Answer 58

for comunucation between different plant cells / exchnage

Answer 59

lec 3 slide 10 who knows

Answer 60

double membrane and contains nuclear pores about 100 nm in diameter.

Answer 61

Within the nucleus DNA is organized (along with proteins called histones) into a material called chromatin. The nucleolus is where the components of ribosomes are manufactured.

Answer 62

chromasomes

Answer 63

Controls the entry of nutrients and the exit of waste products. Maintains the electrolyte balance in the cell. Acts as sensor to external signals

Answer 64

lipid bilayrer sandwiched between 2 layers of proteins called the davson-daniellli model fluid mosaic model

Answer 65

surrounds entire cell membrane and allows the immune system to detect self from foreign, this is unique to each person

Answer 66

amphiphatic sponatiously form bilayers

Answer 67

phosphlipids glycolipids cholesterol

Answer 68

PLa cluster togther low fluidity

Answer 69

PLs more distnace high fluidity

Answer 70

increases distance between PLs increases fluidity

Answer 71

decreases distance between PLs decreases fluidity

Answer 72

The polypeptide chain of membrane proteins often crosses the lipid bilayer several times, these are called trans membrane proteins. Transmembrane proteins are amphipathic they have hydrophobic regions and hydrophilic regions

Answer 73

Peripheral membrane proteins are only associated with the membrane by non-covalent linkages and are easily dislodged The shape and distribution of membrane proteins can be observed using freeze fracture electron microscopy.

Answer 74

Specialized preparation technique by flash-freezing the samples which splits the membrane along the middle of the phospholipid bilayer– Cryo Electron Microscopy the membrane breaks at the weakest points, which is right in the middle of the lipid tails so we can sperate it found that the insade was very different from the extracellular

Answer 75

Fixation and preservation with glycerol Rapid Freezing – liquid nitrogen Fracturing – under pressure using a liquid nitrogen cooled microtome Replication Replica cleaning

Answer 76

mouse and human cell were fued to make a hybrid ell after 1 hour the proteins has mixed

Answer 77

transport receptor sites structural roles cell junctions

Answer 78

membrane proteins called integrins, allow cell to attach to the extracellular matrix

Answer 79

tight junctions are present between some cell types. They act to separate the apical and basal membranes which have different functions.

Answer 80

Cystic fibrosis is caused by a defective chloride ion channel (a transmembrane protein). This is an autosomal recessive disease. The failure of the chloride channel results in a build-up of viscous mucus within the lungs making the individual prone to infections. It appears to be an ideal disease to treat with gene therapy, but progress has been much slower than expected.

Answer 81

outer surface 10%

Answer 82

cell-cell and cell to extracellular matrix recognition

Answer 83

carbohydrates on the surface of red blood cell s

Answer 84

HIV must bind to the immune cell surface protein CD4 and a “co-receptor” CCR5 to infect a cell HIV cannot enter the cells of resistant individuals that lack normal CCR5

Answer 85

sheets of tightly packet cells, covers the outside of the body and lines organs and cavities inside the body. eg. inner surface of the digestive track and respiratory track and outer surface of the body.

Answer 86

desmosome junctions and sealed via tight junctions to withstand stresses and strains

Answer 87

protects against mechanical injury and also provides a barrier against mcirobed and fluid loss

Answer 88

f it can be, known as simple, but it also can be stratified ( several layers thivk)

Answer 89

mechanical strength binds and suports other tissues

Answer 90

extracellular matrix , in which cells are sparsely scattered

Answer 91

such as cartilage bone and tendon has great mechanical strength and elasticity. Consists of just extracellular matrix with relatively few cells. Eg Bone Tendon, ligaments, sclera, cornea, cartilage. Dense connective tissue is made up of : 1. Fibrous proteins (mainly collagen and elastin) 2. Ground substance usually proteoglycans

Answer 92

Loose connective tissue holds small glands and epithelia together and includes the basal lamina of cells. Blood and adipose tissue are also considered connective tissues although they don’t really fit very well into this category.

Answer 93

glands and organs to withstand stresses and strains

Answer 94

around bones

Answer 95

supports tissue, function to support other tissue with energy

Answer 96

supprt movement

Answer 97

long excitable cells , large number of actin and myosin filaments each fiber is further divided into myofibrils , which contain 2 types of filament Thin filaments composed of actin Thick filaments composed of myosin These two types of filaments slide past each other during contraction The regular arrangement of the filaments along the myofibrils creates a banding pattern. Each band is termed a sarcomere.

Answer 98

skeletal - volanatry movement smooth - involnatry body acitvities cardiac- contraction of the heart

Answer 99

glial or glia

Answer 100

cell body or soma 2 or ,ore nerve processes ( dendrites are processes, which coduct impulses away from the nerve body) Axons transmit impulses away from the nerve body. Specialised cells called Schwann cells wrap around an axon to form a multi- layered membrane sheath to provided electrical insulation. The signal is transmitted along the nerve cell in the form of ion fluxes across the plasma membrane of the cell

Answer 101

no its unique to eukaryotes

Answer 102

endoplasmic reticulum, golgi aparatus and lysosomes

Answer 103

Most cell types have relatively little smooth ER (SER) Phospholipid, fat and steroid (including sex hormones) manufacturer Carbohydrate metabolism Most cell types have relatively little smooth ER (SER) Phospholipid, fat and steroid (including sex hormones) manufacturer Carbohydrate metabolism

Answer 104

breaks down stored glycogen to release glucose

Answer 105

muscle cells

Answer 106

network of tubular sacs, transmitts electrical signals, sequesters calcium ions from the cytosol

Answer 107

muscle contractions

Answer 108

Muscles consist of myofibrils Myofibrils are surrounded by sarcoplasmic reticulum Myofibrils are composed of a repetitive arrangement of filaments called a sarcomere.

Answer 109

a region where the myosin and actin filaments overlap

Answer 110

salcoplasmic reticulum releases calcium ions, this binds to troponin causing a comformational change in tropomyosin myosin and actin can no interact

Answer 111

Myosin – thick filaments Actin – thin filaments Z line – Sarcomere boundary and junction of actin and myosin filaments H line – Shortens during contraction and contains only myosin A line – region containing length of asingle myosin filament. I line- region containing length of a single actin filament.

Answer 112

myosin head looses ATP, porviding energy for the head to nod puliing the actin across mysoin

Answer 113

secreted glycosylated lysosomal enzymes membrane bound proteins

Answer 114

Only ribosomes synthesizing proteins with a specific signal peptide sequence become attached to the RER

Answer 115

The N-terminus of these proteins contains a signal peptide usually 20- 30 amino acids long. A signal recognition particle (SRP) attaches to the signal peptide and stops translation in the cytosol The SRP docks to a SRP receptor on the ER membrane and translation starts again. The hydrophobic signal peptide passes through the membrane and loops back through the membrane and is cleaved off. The rest of the peptide passes through the membrane and into the ER lumen The signal sequence is cleaved off with the enzyme signal peptidase

Answer 116

the additon of sugars or oligosaccharides

Answer 117

An oligosaccharide is added in the RER. It is composed of N- acetylglucosamine, mannose and glucose residues containing a total of 14 sugar residues is transferred to the proteins in the RER

Answer 118

modifies and sorts the proteins which pass through it The Golgi complex also mediates the flow of proteins from the RER to various destinations within the endomembrane system. The default pathway of proteins synthesized in the RER is through the Golgi and then to the plasma membrane for secretion.

Answer 119

Mannose residues of lysosome enzyme proteins are phosphorylated in the cis Golgi. A mannose 6-phosphate receptor then binds these proteins in the trans Golgi reticulum and directs their transfer to lysosomes

Answer 120

as the protein pass through the golgi

Answer 121

cliated and goblet cells

Answer 122

Lysosomes are vesicular structures, limited by a single smooth membrane containing enzymes active at acid pHs Lysosomes contain about 60 hydrolytic enzymes (manufactured in the RER) which will degrade almost all biomolecules.

Answer 123

trans face of the golgi

Answer 124

hydrogen ions are pumped into this secondary lysosomes to bring down the PH and active the enzyes

Answer 125

Lysosomes carry out autophagy (recycling of worn out organelles) Lysosomes carry out phagocytosis eg destruction of bacteria by lymphocytes or feeding by amoeba Lysosomes carry out autolysis during apoptosi

Answer 126

Partially degraded insoluble metabolites can accumulate within lysosomes if a particular lysosomal enzymes is defective. The resulting material results in enlarged lysosomes that compromise cell function in over 50 different lysosomal storage diseases. For example Tay - Sachs disease In Tay - Sachs disease – Hexosaminidase A enzyme deficiency results in the accumulation of the lipid ganglioside. The clinical symptoms are due to accumulation of ganglioside in nerve cells. Death usually occurs by 2-3 years of age

Answer 127

Material is exported from the cell by Exocytosis Exocytosis involves fusion of vesicles from the interior of the cell with the plasma membrane. The vesicles contents are then expelled into the surrounding medium. Exocytosis is important in the secretion of numerous proteins including hormones, and extracellular structural proteins such as collagen and fluids such as mucus.

Answer 128

uptake of insouble material

Answer 129

cells pinch thier PM to take up extracellular fluid inot small vensicles. non specific

Answer 130

binding of macromolecules to specific cell surface receptros which triggers endocytosis

Answer 131

The macromolecules (such as transferrin which transports iron from the blood into cells) become concentrated in endocytic pits The endocytic pits are coated with a bristle-like protein called clathrin Clathrin polymerises around the vesicle forming a cage like structure

Answer 132

endosymbiotic theory

Answer 133

All mitochondria have an inner and an outer membrane, with the inner membrane formed into cristae. There are two compartments in the mitochondria: the matrix inside the inner membrane and the inter-membrane space between the inner and outer membranes.

Answer 134

mvoed by the microtubules of the cytoskeleton

Answer 135

in regions of high ATP consumption, eg. in ht emyofibirls of muscle cells

Answer 136

similar to most other eukaryotes majore protein component is porin- large aqueous channels

Answer 137

Contains three major types of membrane complexes: 1. Electron transport chain 2. ATP synthase 3. Specific transporters of metabolites which vary according to cell/tissue type

Answer 138

increase membrane surface area energy transducing membrane impermeable to most small ions

Answer 139

enzymes which catalyse Krebs cycle and fatty acid oxidation ribosomes mitochondrial DNA

Answer 140

The reaction of ATP and water yields inorganic phosphate (Pi) and ADP and releases energy. Energy released by breakdown reactions (catabolism) in the cell is used to phosphorylate ADP, regenerating ATP. Chemical potential energy stored in ATP drives most cellular work.

Answer 141

Energy coupling using ATP hydrolysis. The exergonic process of ATP hydrolysis is used to drive an endergonic process.

Answer 142

Mechanical or transport: ATP hydrolysis causes changes in the shapes and binding affinities of proteins. This can occur either directly, by phosphorylation, for example for a membrane protein carrying out active transport of a solute, or indirectly, via noncovalent binding of ATP and its hydrolytic products, as is the case for motor proteins that move vesicles (a type of organelle) along cytoskeletal “tracks” in the cell

Answer 143

high energy electrons higher

Answer 144

During glycolysis, each glucose molecule is broken down into two molecules of the compound pyruvate. In eukaryotic cells, as shown here, the pyruvate enters the mitochondrion. There it is oxidized to acetyl CoA, which is further oxidized to CO2 in the citric acid cycle. NADH and a similar electron carrier, a coenzyme called FADH2, transfer electrons derived from glucose to electron transport chains, which are built into the inner mitochondrial membrane. (In prokaryotes, the electron transport chains are located in the plasma membrane.) During oxidative phosphorylation, electron transport chains convert the chemical energy to a form used for ATP synthesis in the process called chemiosmosis

Answer 145

NAD+ is an electron carrier Accepts high energy electrons from organic molecules Donate them to the electron transport chain Cannot be transported into/out of the mitochondria directly so must be regenerated

Answer 146

nicotinamide adenine dinucleotide, describes its structure—the molecule consists of two nucleotides joined together at their phosphate groups (shown in yellow). (Nicotinamide is a nitrogenous base, although not one that is present in DNA or RNA; see Figure 5.24.) The enzymatic transfer of 2 electrons and 1 proton (H+ ) from an organic molecule in food to NAD+ reduces the NAD+ to NADH: Most of the electrons removed from food are transferred initially to NAD+ , forming NADH

Answer 147

In cellular respiration, the same reaction occurs in stages: An electron transport chain breaks the “fall” of electrons in this reaction into a series of smaller steps and stores some of the released energy in a form that can be used to make ATP. (The rest of the energy is released as heat.)

Answer 148

the cytosol small amout of energy

Answer 149

substrate level phosphorylation

Answer 150

enters the mitrochondria

Answer 151

matrix of mitrochondria

Answer 152

inner membrane of the mitrochondria

Answer 153

Hexokinase transfers a phosphate group from ATP to glucose, making it more chemically reactive. The charge on the phosphate also traps the sugar in the cell. Glucose 6- phosphate is converted to fructose 6-phosphate. Phosphofructokinase transfers a phosphate group from ATP to the opposite end of the sugar, investing a second molecule of ATP. This is a key step for regulation of glycolysis. Aldolase cleaves the sugar molecule into two different three-carbon sugars. Conversion between DHAP and G3P: This reaction never reaches equilibrium; G3P is used in the next step as fast as it forms. Two sequential reactions: (1) The sugar is oxidized by the transfer of electrons to NAD+, forming NADH. (2) Using energy from this exergonic redox reaction, a phosphate group is attached to the oxidized substrate, making a high-energy product. The phosphate group is transferred to ADP (substrate-level phosphorylation) in an exergonic reaction. The carbonyl group of G3P has been oxidized to the carboxyl group (—COO–) of an organic acid (3-phosphoglycerate). This enzyme relocates the remaining phosphate group. Enolase causes a double bond to form in the substrate by extracting a water molecule, yielding phosphoenolpyruvate (PEP), a compound with a very high potential energy. The phosphate group is transferred from PEP to ADP (a second example of substrate-level phosphorylation), forming pyruvate.

Answer 154

pyruvate is charged to must enter mitrochondripn via active transport , with the help of a transport protein

Answer 155

substrate level

Answer 156

Notice that the carbon atoms that enter the cycle from acetyl CoA do not leave the cycle in the same turn. They remain in the cycle, occupying a different location in the molecules on their next turn, after another acetyl group is added. Therefore, the oxaloacetate regenerated at step 8 is made up of different carbon atoms each time around. In eukaryotic cells

Answer 157

This generates energy via redox reactions, which occurs when there is a transfer of one or more electrons from one reactant to another. The reactant which loses an electron is oxidized while the reactant receiving the electron is reduced. This process is associated with the release of energy.

Answer 158

collection of multiprotein complexes embedded u the inner membrane of the mitrochondira Most components of the chain are proteins to which are attached prosthetic groups, these are non protein components essential for the catalytic functions

Answer 159

flavoproteins its prosthetic group is flavin mononucleotide

Answer 160

the first molecule is a flavoprotein, Electrons then pass onto an iron-sulphur protein and then to ubiquinone and then to a series of electron carriers termed cytochromes. The prosthetic groups of cytochromes have four organic rings surrounding an iron atom (like haemoglobin) except the iron of cytochromes transports electrons not oxygen. The last cytochrome in the chain passes its electrons onto oxygen, which picks up a pair of H+ to form water. FADH2 also transfers electrons into the electron transport chain but adds its electrons at a lower energy than that of NADH. FADH2 adds its electrons direct to ubiquinone. At the bottom of the chain is oxygen which is very electronegative. The overall energy drop from NADH to oxygen is 53kcal/mol, but this fall is broken up into a many small steps by the electron transport chain.

Answer 161

ATP synthase is a large multiprotein complex which can be seen under the electron microscope in the inner membrane of the mitochondria and has a mushroom-like appearance.

Answer 162

The ion gradient which drives ATP synthesis is a H+ gradient, which exists between the opposite sides of the inner membrane. It is the electron transport chain which generates and maintains this gradient. The electron transport chain uses the energy from the exergenic flow of electrons to pump H+ from the mitochondrial matrix into the intermembrane space. H+ then pass back thorough the ATP synthase and this exothermic process is used to attach inorganic phosphate to ADP, producing ATP.

Answer 163

NADH and FADH2 shuttle high-energy electrons extracted from food during glycolysis and the citric acid cycle into an electron transport chain built into the inner mitochondrial membrane. The gold arrows trace the transport of electrons, which are finally passed to a terminal acceptor (O2, in the case of aerobic respiration) at the “downhill” end of the chain, forming water. Most of the electron carriers of the chain are grouped into four complexes (I–IV). Two mobile carriers, ubiquinone (Q) and cytochrome c (Cyt c), move rapidly, ferrying electrons between the large complexes. As the complexes shuttle electrons, they pump protons from the mitochondrial matrix into the intermembrane space. FADH2 deposits its electrons via complex II—at a lower energy level than complex I, where NADH deposits its electrons— and so results in fewer protons being pumped into the intermembrane space than occurs with NADH. Chemical energy that was originally harvested from food is transformed into a proton-motive force, a gradient of H+ across the membrane. 2 During chemiosmosis, the protons flow back down their gradient via ATP synthase, which is built into the membrane nearby. The ATP synthase harnesses the proton-motive force to phosphorylate ADP, forming ATP. Together, electron transport and chemiosmosis make up oxidative phosphorylation.

Answer 164

Fo portion is a H+ channel F1 head is site of ATP synthesis Movement of H+ through Fo: causes rotation of the rotor and central stalk, while the stator keeps the enzymatic F1 stationary forces sequential conformational changes in the central stalk and F1 provides the energy for ATP synthesis 10H+ moving back into matrix generates ~3 ATP molecules

Answer 165

cyanide prevents the passage of electrons from one of the cytochromes thereby blocking the ETC DNP, makes the inner membrane leaky to H+ so that the gradient cannot be established, ETC still works but energy is released as heat

Answer 166

specialized type of adipose tissue Function of the mitochondria in brown fat is to produce heat Found in large amounts in newborn babies

Answer 167

Thermogenin is a H+ channel in inner membrane in brown fat mitochondria H+ leak back without passing through ATP synthase  no ATP produced Energy produced by the electron transport chain is released as heat

Answer 168

Mitochondrial genetic disease Mutation in the mitochondrially encoded tRNA Lys gene Affects the translation of mitochondrially encoded proteins assembly of the electron transport chain complexes disrupted reduced mitochondrial respiratory function Abnormal mitochondrial morphology Multisystem disease primarily affecting muscles and nerves  epilepsy and general muscle weakness No cure

Answer 169

only the mother

Answer 170

new IVF technique - the embryo hs 3 genetic parents

Answer 171

organisms that can make theirown energy using ligth and co2 via the process or photosythesis

Answer 172

Chloroplasts are surrounded by an outer and an inner membrane which together are termed the envelope. The envelope encloses an aqueous compartment called the stroma in which starch granules are usually found. The inner most compartment is the thylakoid space which is enclosed by the thylakoid membrane. In some chloroplasts the thylakoid membrane is formed into dense stacks called grana. Chlorophyll is present in the thylakoid membrane. The thylakoid is responsible for the steps of photosynthesis which convert light energy into chemical energy.

Answer 173

thylakoid membrane

Answer 174

uses solar energy to make atp and nadph which suplys chemical energy and reducing power to the calvin cycle

Answer 175

. At least three steps in the light reactions contribute to the H+ gradient by increasing H+ concentration in the thylakoid space: 1 Water is split by photosystem II on the side of the membrane facing the thylakoid space; 2 as plastoquinone (Pq) transfers electrons to the cytochrome complex, four protons are translocated across the membrane into the thylakoid space; and 3 a hydrogen ion is removed from the stroma when it is taken up by NADP+ . Notice that in step 2, hydrogen ions are being pumped from the stroma into the thylakoid space, The diffusion of H+ from the thylakoid space back to the stroma (along the H+ concentration gradient) powers the ATP synthase. These light-driven reactions store chemical energy in NADPH and ATP, which shuttle the energy to the carbohydrate-producing Calvin cycle.

Answer 176

The light reaction converts solar energy to chemical energy Light energy absorbed by chlorophyll in the thylakoid membranes is used to transfer electrons and hydrogen to the electron carrier NADP+ so that it becomes NADPH. Water is split during this process and oxygen given off as a by product. ATP is also generated from ADP and inorganic phosphate The thylakoid membranes of the chloroplast are the site of the light reactions

Answer 177

When pigments absorb light energy as photons, an electron in the pigment is elevated to an orbital of higher energy. There are several pigments in the thylakoid membranes: Chlorophyll a, Chlorophyll b and Carotenoids. Only Chlorophyll a can participate directly in the light reactions but the other pigments absorb light energy at different wavelengths and transfer this energy to Chlorophyll a. This broadens the range of wavelengths that can be used. Generally when pigments absorb light, the electrons quickly drop down to their original energy losing their excess energy as heat. In the thylakoid membrane, a nearby molecule called a primary electron acceptor traps a high-energy electron that has absorbed the photon before it can drop back down. Only one localised pair of Chlorophyll a molecules can actually donate their excited electrons to the primary electron acceptor. This is called the reaction centre. The other pigment molecules function as light-gathering antennae which collect energy from the photons and pass it inwards to the reaction centre. The reaction centre and the primary electron acceptor together are termed a Photosystem.

Answer 178

spectrophotometer measures the relative amounts of light of different wavelengths absorbed and transmitted by a pigment solution. 1 White light is separated into colors (wavelengths) by a prism. 2 One by one, the different colors of light are passed through the sample (chlorophyll in this example). Green light and blue light are shown here. 3 The transmitted light strikes a photoelectric tube, which converts the light energy to electricity. 4 The electric current is measured by a galvanometer. The meter indicates the fraction of light transmitted through the sample, from which we can determine the amount of light absorbed.

Answer 179

Exposed algae filament to different wavelengths of light. Placed aerobic bacteria with the algae. Higher concentration of oxygen allowed the aerobic bacteria to proliferate more. Accumulated near the parts of the algae illuminated with red and blue light = the wavelengths that work most efficiently for photosynthesis.

Answer 180

only in one functional group bonded to the porphyrin ring

Answer 181

Photosystems have antennae pigment molecules which absorb photons Energy transferred between pigments to the central pair chlorophyll Electrons elevated to higher energy state and taken by primary electron acceptor

Answer 182

Photosystem I absorbs light energy best at 700nm so the reaction centre is called P700. Photosystem II absorbs light energy best at 680nm so the reaction centre is called P680.

Answer 183

produce a non cyclcic electron flow to genertae nadph and atp and to spllit water

Answer 184

Light excites electrons from P700 which pass to the electron acceptor, but are then passed to NADP+ to produce NADPH. So P700 is now in a very oxidised state In photosystem II, P680 also becomes excited and donates an electron to its primary acceptor. This electron then passes down an electron transport chain until it is eventually accepted by the oxidised P700. The energy generated by this process is used pump hydrogen ions out of thylakoid membrane and generate a hydrogen gradient which is used to ATP synthase to produce ATP . The P680 is now in an oxidised state and P680 gets its electrons from a water molecule, thus splitting it, and generating oxygen.

Answer 185

Photosystem I can operate alone to produce ATP. This is termed cyclic electron flow. Electrons are passed from the primary electron acceptor through a chain which includes ferredoxin, the cytochromes and a copper containing protein called plastocyanin. The electron is eventually passed back to P700. At each step the electron lose energy and this energy is used to pump hydrogen ions across the thylakoid membrane. This generates a hydrogen gradient across the membrane which is used to drive an ATP synthase molecule which generates ATP (just like in mitochondria). Cyclic electron flow uses a single photosystem to make ATP and does not produce NADPH or oxyge

Answer 186

carbon enters n the from of co2 and leaves in the from of sugar requires ATP as an energy soryce abd consumes NADPH as a source of higher enegry electrons Generates hexose phosphates for starch (storage), cellulose (cell walls) and sucrose (translocation), lipids (cell membranes) and amino acids (protein synthesis).

Answer 187

both chloroplasts and mitochondria use the same basic mechanism to generate ATP. In both cases, an electron transport chain located in a membrane pumps hydrogen ions across the membrane. The energy for this process is generated by passing electron through a series of progressively more electro-negative carriers. The membrane also contains an ATP synthase complex which uses gradient of hydrogen ions for the phosphorylation of ADP to ATP. both have a similar endosymbiotic origin Some of the electron carriers including the quinones and cytochromes are very similar in mitochondria and chloroplasts.

Answer 188

In mitochondria, the electron transport chain pumps hydrogen ions out of the matrix. In chloroplasts, the electron transport chain pumps into the thylakoid compartment. In mitochondria, the high energy electrons fed into the electron transport chain come from the oxidation of food molecules. In chloroplasts, the high energy electrons are generated in the photosystems by the absorption of photons.

Answer 189

3D system of fibers running through the cytosol. disscovered with electron microscopy. its important in cell mobility , cell division, cell shape and movement of organelles in chromasomes

Answer 190

microfilaments microtubules intermediate filaments

Answer 191

About 7-8 nm in diameter and are composed of two actin chains twisted around each other. They have a variety of structural and locomotor functions

Answer 192

Straight hollow rods 25nm in diameter and up to 20 microns long, and are constructed from globular proteins called Tubulins

Answer 193

8-12nm in diameter and are made up of a diverse group of proteins. Tend to be permanent fixtures, and are important in maintaining the shape of the cell, as well as maintaining the position of certain organelles

Answer 194

maintenece of cell shape changes in cell shape muscle contractions cytoplasmi streaming cell mobility ( pseudopodia) cell division (cleavage furrow formation)

Answer 195

G actin F actin

Answer 196

g actin assembles into long, helical f actin polymers

Answer 197

white blood cell transmigration cellular extensions- eg. the acrosome reaction in echinoderm sperm

Answer 198

Most animal cells have a network of actin filaments just below the cell surface termed the Cell Cortex; this cortex supports the plasma membrane and facilitates cell movement. Composed of actin which is a globular protein (termed G actin, molecular weight 42,000 kilodaltons) Soluble actin monomers polymerize to form insoluble filamentous actin (F actin), a double right-handed helical molecule.

Answer 199

Muscle contraction where they interact with myosin filaments. Cell movement and migration Cell separation during cytokinesis Cell shape Structural roles – formation of microvilli

Answer 200

myosin use energy from atp hydrolysis to walk along actin filaments.c omtraction or transportation roles

Answer 201

toxins such as phallodini bind to f actin preventing disassemble- attached to a flourescent tag can be used to stain actin q

Answer 202

hollow tubes, wall consists of 13 column sof tublin mlecules

Answer 203

25nm with 15 nm lumen

Answer 204

tubulin, a dimer consisting of alpha- tubulin and beta tubulin

Answer 205

maintenance of cell shape cell mobility ( as in cilia or flagella ) chromasome movements in cell division organelle movement

Answer 206

alpha tubulin

Answer 207

beta- tubulin

Answer 208

beta-tubules

Answer 209

Microtubule/tubulin-binding drugs are used to treat a variety of diseases, including cancer. For example the cancer drug taxol used for ovarian cancer, breast cancer and lung cancer which prevents microtubule disassembly and therefore cell division in cancer cells.

Answer 210

consist of a core of axonemal microtubules ensheathed in an extension of the plasma membrane 9 doublets of microtubules are arranged in a ring an dconnected to 2 central icrotubules by radial spokes- 9+2 qrrangement

Answer 211

Each doublet is connected to its neighbour by sidearms composed of Dynein, which contracts at the expense of ATP forcing the doublets to move relative to each other. Crosslinks prevent the doublets sliding past each other, so that the flagella or cilia bend.

Answer 212

in isolated cili, without nexin crosslimks movement of dynein motor proteins causes microtubule doubles to dlife past one another when nexin is present to cross link the doublets. they cannot slide and the force gernated by dyein movement cuases the cilium to blend

Answer 213

Cilia are shorter (2-20µm) and more numerous than flagella (10-200µm), but both have the same structure.

Answer 214

made of protein subunits protrudes through cell wall and cell membrane stiff , twirl like a propella

Answer 215

a bundle (9+2) of microtubules covered by cell membrane whippy action

Answer 216

transport membrane bound vesicles, proteins and organelles along microtubules at the expense of ATP kinesis move cargo towards the + end of the micrptubules ( anterograde) whilst most dyneins transport cargo towards the 0 end of the microtubules ( retrograde )

Answer 217

cytoplasmic - more dynamic and loosely organized found in the cytoplasm. axonemal - highly organized and stable found in cilia flagella and basal bodies

Answer 218

from the polymerization of tubulin dimers

Answer 219

maintenanceof cell shape, cell movement , transport of vesicles within the cell and the separateion of chromosomes during cell division

Answer 220

tracks on which the vesicles and small particles can move . this occurs via kinesin dynein. these are motor proteins one end binds to a microtubule while the other end of attached to a vesicle

Answer 221

fibourous proteins supercoiled into thicker cables

Answer 222

one of severale different proteins such as keratin, depedning on cell type

Answer 223

maintenance of cell shape, tneison bearing elements anchorage of nucleus and certain other organelles formation of nucelar lamina cell junctions

Answer 224

a defect in the keratin 14 gene

Answer 225

impermeable junctions adhesive junctions communicating junctions

Answer 226

prevents the passage of molecules between cells. tight junctions

Answer 227

these emchanically hold cells togther. adherens junctions and adhesive desmosomes

Answer 228

passage of small molecules between cells. gap junctions ro chemical synapses

Answer 229

: Separate the apical plasma membrane from the basal plasma membrane, thus allowing them to have different compositions. This also gives rise to cellular polarity.

Answer 230

prevent molecules from leaking between adjacent cells

Answer 231

The apical surface contains proton and chloride ion pumps which generate HCl Tight junctions keep the apical membrane components separate from the basal membrane components. In the gut, this stops acid being pumped into the blood stream.

Answer 232

adherens junctions desmosomes focal adhesions 'hemi-desmosomes

Answer 233

transmembrane and cytosolic

Answer 234

span the plasma membrane form actual physical barrier

Answer 235

connect each cell to each cell physicalt regulates permeability

Answer 236

cytosolic proteins

Answer 237

signalling polarity

Answer 238

microfilaments

Answer 239

adherens, desmosmes, focal adhesions, hemidesmosomes

Answer 240

directly below the tight junctionsf

Answer 241

resist streach and abresion, keep the cell together, keep the barrier intact, extremely strong

Answer 242

cells need to accommodate streaching stomach cells when eatchung lungs in inhalation bladder when filling with urine vasodilation

Answer 243

cadherins, connect cells to microfilamant actin

Answer 244

intracellular signalling regulation

Answer 245

transmembrane and cytosolic proteins

Answer 246

E- cadherins ( E is epithelium )

Answer 247

within the paracellular spcae, this is the transmembrane proteins that crosses the plasma membrane,

Answer 248

bind each cellular E cadherin to another E cadherin, they form a phsycial barrier brtweenn cells

Answer 249

calcium they are calcium dependent proteins if calcium is not present the e-cadherins cant bind to another e cadherin

Answer 250

beta-catenin

Answer 251

cytosolic protein'

Answer 252

cadherins-catenin complex `

Answer 253

anchor the adherence junction to the cytoskeleton via actin or micro filaments

Answer 254

regulation of wnt signalling during embryonic developement. if certain e-cadherins link break between cells such as if there isnt any calcium. this triggers the depolarisation or dedifferentiation of cells. you then loose the apical basal composition of cells - the cell is depolarised. the beta catenin will translocate into the nucelu,this then leads to cell tissue morphogenesis and fibrosis and the development of epithelium-mesenchyl transition. this change allows the cell to migrate. Eg. Duting a wound

Answer 255

cancer- altering protein structures such as e-cadherins. prevents cells binding togther. causes cells to clump togther and migrate away

Answer 256

desmosomes

Answer 257

link cells together , they interlock with extracellular spcae with adjacent cells involved in stuctural integrity and can withstand mechnaical stress

Answer 258

cadheins - desmoglein, desmocolin

Answer 259

so strong they can spread the force recived by any sort of signal across the whole tissue

Answer 260

intermediate filaments

Answer 261

they don't connect cells to cells they connect to the substrate or extracellular matric to the cytoskeleton.

Answer 262

microfilament

Answer 263

intermediate filament

Answer 264

intergrins

Answer 265

basal lamina

Answer 266

gap junctions

Answer 267

all animals

Answer 268

tiny pores composed of proteins called connexins. 6 connexins on each cell from a gap junction.

Answer 269

share ions, signalling molecules, can pass eletrical siganls . can also signal if there is a problem - called paraci=rine signalling - this is important during infections and leads to programmed cell death

Answer 270

intercellular PH and intracellular calcium levels

Answer 271

cylindrical channels

Answer 272

propagation of the precisley orchestrated pattern of current flow that givern the regular rythm of the health heart

Answer 273

1- mediate electrical communicatino to effect contraction and motility 2- allow passage of molecules and ions between cells 3- modulate cell polarity and directional migration

Answer 274

inflamoratory bowel disease gastrointestinal infection autism spectrum disorder

Answer 275

1- new organisims 2- growth 3- cell replacemnt ( wear and tear, programmed cell death )

Answer 276

1- the DNA of the parent cell must be duplicated 2- the chromosmes conatining the replicated dna must then be physically segregated into the two daughter cells 3- the daugter cells must physically divide from each other

Answer 277

Relatively simple process by which bacteria duplicate their DNA and segregate their chromosome into two daughter cells

Answer 278

1- chromosomes replication beings. them one copy of the origin moves rapidly towards the other end of the cell 2- replication continues. one copy of the origion is now at each end of the cell 3- replication finishes. the plasma membrane grows inwards and a new cell wall is deposited, two daughter cell result

Answer 279

G1= gap cell grows prepares to replicate DNA S= sythesis cell grows synthesis of duplicate DNA ready for mitosis G2 = gap cell grows prepares for mitosis

Answer 280

the physical process of segregating chromosomes inot daugher cells

Answer 281

the chromoeomes constist of two sister chromatids linked at the centromere

Answer 282

intact nuclar envelope chromosomes replicated - remain indistinct as loosley packed chromatin ( DNA and protein ) fibres centrosome replicated microtubules extend radically forming asters

Answer 283

chromatin fibers condense forming discrete chromosomes nuceoli disappear centrosomes moves away from each other mitotic spindle begins to form

Answer 284

breakdown of nuclear envelope some microtubules attach to chromosomes at they kinetochores other microtubules interact with those from opposite poles

Answer 285

centrosomes at opposite poles chromosmes align on the metaphase plate sister kinetchores attached to microtubules coming from opposotes poles

Answer 286

begins with separation of centrosomes sister chromatids move towards opposite poles of the cell each chromatid becomes a new chromasomes poles move futher apart

Answer 287

elongation of cell by polar microtubules daugter nucleoli begin to form at poles of cell nucelar envelopes from chromatin beind to condence

Answer 288

to organise chromatids along the metaphase plate and then to pull sister chromatids apart

Answer 289

astral motors kinetochore motors mom-kinetochroe/ polar motors

Answer 290

pull astral microtubules towards poles during prophase microtubules de polymerise and shorten hold astral microtubules in place during metaphase and later

Answer 291

attach chromsomes to microtubules pull on microtubules during anaphase - chromsomes move towards centrosomes microtubules de polymerise and get shorten

Answer 292

motors are attached to a microtubule from either side where the polar microtubules overlap motors push the microtubules away in opposite directions during metaphase and anaphase microtubules polymerise and get longer cell elongates

Answer 293

separate sister chromatids during anaphase

Answer 294

kintochore kintochores

Answer 295

interpolar interpolar the polaes to move them apart

Answer 296

pulling ( dynein) - kintochore motors pull chromosomes towards the centrosome/ pole - astral motors pull centrosomes towards inner face of the plasma membrane - both shorten depolymerise microtubules pushing ( kinesin ) - non-kinetochores / polar motors add subunits ( polymerises ) microtubules to druve the poles of the spindle apart. this elongates the cell to aid telophase / cytokensis

Answer 297

1. Proteins holding sister chromatids together are inactivated 2. Chromatids separate 3. Kinetochore microtubules have motor proteins (dynein) which ‘walk’ a chromosome to the nearest pole 4. Microtubules shorten by depolymerisation at their kinetochore ends 5-Non-kinetochore microtubules elongate whole cell during anaphase Motor proteins (kinesin) attach to microtubules and lengthen them by addition of subunits

Answer 298

microfilaments form a ring at the furrow ring contracts- owing to interaction between actin and mysoin filaments furrow deepens until cell is piched in two

Answer 299

cell plates froms at equoritoral plane of cell cell wall froms - from plate contents

Answer 300

1) development: organs and body parts need to be correct size/ shape 2) injury: cells need to divide followinf injury but stoop when damage is prepared 3) adaptive responses:

Answer 301

cells in bone marrow resond to low O2- produce more red blood cells - need to stop when O2 return to normal lymphocytes- division triggered in response to antigen - needs to be cotorlled

Answer 302

external and internal signal s

Answer 303

diffusable chemical signals produces by other cells which tell the cell in question how to behave wg. growth factors ( mitogens )

Answer 304

chemical signals produced internally by the cell itself in order to regulate its own division - pesent in the cytoplasm of cells eg. cyclin dependent kinases

Answer 305

f they can also inhibit ot

Answer 306

mitogens or anti-mitogens

Answer 307

s phase cyclins ( i.e those cyclins which drive the cell inot S phase ) are not made

Answer 308

G1 checkpoint

Answer 309

G0 - quite phase or quiescence

Answer 310

receptors in plasma membrane and promote cell growth

Answer 311

platelet derived growth factors an axample of an external growth factor

Answer 312

platelets in response to injury

Answer 313

receptors on surface of skin cells and causes them to strat dividing

Answer 314

by fusing cells from different stanges of the cell cycle

Answer 315

M phase + G2 = M phase conclsion : there is a mitosis promtoing factor in M phase cells M phase + G1 or G2 or S = M phase conclusion: cells at any stage of the cell cycle can be stimulted by M phase cells to enter mitsosis - resonse is not unique to G2 cells S + G2 = S conclusion : there is an s phase promoting factor in s phase cells S + G2 = conclusion: although there is an S phase promoting factor in s phase cells, only G1 cells respond t othis factpr

Answer 316

uncontrolled cell division is a hall mark of cancer checkpoints enable cells to stop dividing if the correct signals are not present checkpoints allow cells to review current circumstances and prevent untimely exit from each cell cycle phase if cell proceeds from one phase of the cycle to the next inappropriately, this can cause genetic instability genetic instability can cause cancer

Answer 317

G1 G2 metaphase or SAC

Answer 318

commits cell to dna replication and cell division it check if the cell is a suitible size, has it recicved the appropriate external signals

Answer 319

cells make a decision whether or not to enter mitosis is the cell a suitbale size, is dna replicated , is environemnt favourable

Answer 320

sir tim hunt in 1982 Observed that, following fertilisation, cells in sea urchin early embryos divided SYNCHRONOUSLY Whole population of cells at same stage of cell cycle as opposed to a mixed population at different stages Found a group of proteins levels of which increased and decreased (cycled) between INTERPHASE and MITOTIC PHASE - CYCLINSv

Answer 321

cyclin-dependent kinases cyclins

Answer 322

at the end of interphase / start of mitosis

Answer 323

promoting factor

Answer 324

contol progression of the cell inot the next phase of the cell cyle

BIOL112- cell structure and function Flashcards

(365 cards)