topic 1 Flashcards

Question

main 6 organelles of paramecium

Answer 1

nucleus cell membrane cytoplasm cilia contractile vacuoles food vacuoles

Answer 2

can divide by mitosis to produce the two nuclei that are needed when the cell reproduces (mostly asexually)

Answer 3

controls movement of substances/chemicals into and out of cell

Answer 4

contains enzymes that catalyse metabolic reactions, including respiration

Answer 5

- beating of the cilia moves cell through water - controlled by cell; moves in response to changes in environment

Answer 6

contain smaller organisms that have been consumed (gradually digested + nutrients absorbed into cytoplasm)

Answer 7

homeostasis: - located at each end of cell - fill up with water from inside the cell then expel excess through plasma membrane.

Answer 8

- unicellular eukaryote - soil, freshwater, oceans, snow

Answer 9

autotroph- can photosynthesise

Answer 10

nucleus cytoplasm cell wall cell membrane chloroplasts flagella eyespot contractile vacuoles

Answer 11

- asexual reproduction: nucleus can divide by mitosis to produce 2 nuclei - sexual reproduction: nuclei can fuse + divide to carry out sexual reproduction

Answer 12

contains enzymes that catalyse metabolic reactions, including respiration

Answer 13

- wall is freely permeable - membrane controls what chemicals enter and leave

Answer 14

- where photosynthesis occurs - contains enzymes - in dark, carbon compounds can be absorbed from other organisms via the cell membrane

Answer 15

the beating of the two flagella moves the chlamydomonas through the water it lives in

Answer 16

light sensitive; allows cell to sense where brightest light is and respond by swimming towards it

Answer 17

homeostasis: - located at base of flagella - fill up with water from inside the cell then expel excess through plasma membrane.

Answer 18

by cell differentiation; allows them to carry out their role more efficiently than if they had many different roles.

Answer 19

differentiation involves the expression of some genes and not others in a cell's genome.

Answer 20

self renewal; can continuously divide and replicate. potency; have the capacity to differentiate into different specialised cell types.

Answer 21

bone marrow, skin, liver

Answer 22

- embryonic - cord blood - adult

Answer 23

almost unlimited growth potential; can differentiate into any cell type in the body.

Answer 24

limited capacity to differentiate into different cell types (only naturally develop into blood cells)

Answer 25

limited capacity to differentiate into different cell types.

Answer 26

less chance of genetic damage due to the accumulation of mutations than with adult stem cells.

Answer 27

- more risk of becoming tumour cells than ASC - likely to be genetically different from patient - removal of cells from embryo kills it

Answer 28

- easily obtained and stored - fully compatible with tissues of adult that grows from the baby (no rejection probs) - umbilical cord discarded either way

Answer 29

- limited quantities of stem cells from one baby's cord

Answer 30

- less chance of malignant tumours developing than from ESC - fully compatible with the adult's tissues (no rejection probs) - removal does not kill adult

Answer 31

- difficult to obtain as there are very few of them/buried deep in tissues. 0

Answer 32

Stargardt's disease Leukaemia

Answer 33

Embryonic cells developed into retina cell and then injected into the eye to improve vision.

Answer 34

1. stem cells extracted from bone marrow 2. chemotherapy given, bone marrow loses ability to produce blood cells. 3. stem cells returned to body and start to reproduce red and white blood cells.

Answer 35

size of image = magnification x actual size

Answer 36

0.2 micrometers (μm)

Answer 37

0.001 micrometers (μm)

Answer 38

beams of electrons have a much shorter wavelength.

Answer 39

light passes through the specimen, which filters out certain wavelengths of light

Answer 40

electrons pass through the specimen and get absorbed.

Answer 41

making the separate parts of an object distinguishable

Answer 42

- prokaryotes have a simple cell structure that is not compartmentalised; eukaryotes have a compartmentalised cell structure - eukaryotes have a nucleus bounded by a nuclear envelope consisting of a double membrane; prokaryotes do not have a nucleus

Answer 43

a cell wall

Answer 44

- protects cell - maintains cell shape - prevents cell from bursting

Answer 45

peptidoglycan

Answer 46

Svedberg units

Answer 47

it is not associated with proteins

Answer 48

- cell wall - cytoplasm - pili - flagella - plasma membrane - 70S ribosomes - nucleoid (with naked DNA)

Answer 49

- flagella are mainly responsible for motility (sensitive to temperature, chemicals and metals) - pili are mainly responsible for attachment during conjugation and motility

Answer 50

- enzymes/substrates for a process can be more concentrated than if they were spread throughout cytoplasm - substances that could cause damage to cell can be kept inside membrane of an organelle (eg digestive enzymes of a lysosome) - conditions such as pH can be maintained at ideal for a particular process (may be different to optimum levels for cells) - organelles with their contents can be moved around within the cell.

Answer 51

- plasma membrane - cytoplasm - 80S ribosomes - nucleus - mitochondria (- rough endoplasmic reticulum) (- Golgi apparatus) (- lysosomes) (- chloroplast) (- vacuoles and vesicles) (- microtubules and centrioles) (- cilia and flagella)

Answer 52

- nuclear envelope: a double membrane with pores - contains nucleolus, where ribosomes are made - contains chromosomes, consisting of DNA associated with histone proteins, and chromatin (uncoiled chromosomes) - where transcription occurs (DNA-> mRNA)

Answer 53

- consists of cisternae (flattened membrane sacs) - 80S ribosomes attached to outside of cisternae - rER synthesises proteins for secretion/cell membrane from the cell

Answer 54

- not surrounded by a membrane - 80S - synthesise proteins and release it to work in the cytoplasm

Answer 55

- consists of cisternae (flattened membrane stacks) - processes proteins brought in vesicles from the rER - most are then carried in vesicles to plasma membrane for secretion

Answer 56

- not as long - often curved - do not have attached ribosomes - many vesicles nearby

Answer 57

- approximately spherical with a single membrane - formed from Golgi vesicles - contain high concentrations of protein and digestive enzymes which are used to break down ingested food/organelles/whole cell

Answer 58

- surrounded by a double membrane - inner membrane invaginated to form structures called cristae - contains matrix (fluid) - produce ATP by aerobic respiration - fat digested here if it is being used as an energy source - contains own DNA

Answer 59

- surrounded by double membrane - contains stacks of thylakoids (flattened stacks of membrane) - produce glucose and other organic compounds by photosynthesis, starch grains present if photosynthesising quickly - contains own DNA

Answer 60

- consist of single membrane with fluid inside - vacuoles; store waste products/food/necessary molecules - vesicles are smaller vacuoles; transport materials

Answer 61

- nucleus - chloroplasts - mitochondria

Answer 62

- microtubules are small cylindrical fibres - move chromosomes during cell division, act as transport routes through cell, hold organelles in place, spindle fibres in mitosis - centrioles consist of two groups of nine triple microtubules - form an anchor point for microtubules during cell division

Answer 63

- both are microtubules covered in membrane - cilia are shorter, flagella are longer - cilia move things along the surface of the cell - flagella move the cell

Answer 64

by binary fission

Answer 65

1. single circular chromosome is replicated 2. the two copies of the chromosome move to opposite ends of the cell 3. the cytoplasm and cell divide 4. each of the daughter cells contains one copy of the chromosome so they are genetically identical

Answer 66

secrete digestive enzymes into a duct that carries them to the small intestine where they digest foods

Answer 67

organelles needed to synthesise proteins in large quantities; process them to make them ready for secretion, transport them to the plasma membrane and release them. - plasma membrane - mitochondrion - nucleus - rER - Golgi - vesicles - lysosomes

Answer 68

photosynthesis- producing organic compounds from CO2 and other inorganic compounds, using light energy.

Answer 69

- cell wall - plasma membrane - chloroplasts - mitochondrion - vacuole - nucleus

Answer 70

due to the amphipathic properties of phospholipid molecules

Answer 71

contain both hydrophilic (water-loving) and lipophilic (fat-loving) regions

Answer 72

- a polar head (hydrophilic) composed of a glycerol and a phosphate molecule - and two non-polar tails (hydrophobic) composed of fatty acid (hydrocarbon) chains

Answer 73

- hydrophobic tails face inwards and so are shielded from the surrounding polar fluids - the two hydrophilic heads associate with the cytosolic (intracellular) and extracellular fluids

Answer 74

weak hydrophobic interactions between the tails

Answer 75

- hydrophilic / hydrophobic layers restrict the passage of many substances - fluidity and flexibility: individual phospholipids can move within the bilayer

Answer 76

allows for the spontaneous breaking and reforming of membranes (endocytosis / exocytosis)

Answer 77

Junctions Enzymes Transport Recognition And neurotransmitters Transduction

Answer 78

cell adhesion to connect and join groups of cells together in tissues and organs.

Answer 79

for immobilised enzymes with the active site on the outside, fixing to membranes localises metabolic pathways (eg small intestine)

Answer 80

act as channels to allow hydrophilic particles across by facilitated diffusion, and as pumps for active transport which use ATP to move particles across the membrane.

Answer 81

May function as markers for cellular identification

Answer 82

cell-to-cell communication, for example receptors for neurotransmitters at synapses

Answer 83

hormone binding sites (peptide hormone receptors), for example the insulin receptor.

Answer 84

- integral proteins - peripheral proteins

Answer 85

- permanently attached to the membrane - typically transmembrane (span across the bilayer) - hydrophobic on at least part of their surface - embedded in hydrocarbon chains at centre

Answer 86

- temporarily attached by non-covalent interactions - associate with one surface of the membrane, not embedded in the membrane - hydrophilic on surface - may be attached to surface of integral proteins/have a single hydrocarbon chain in the membrane

Answer 87

Cholesterol’s hydroxyl (-OH) group is hydrophilic but the remainder of the molecule (steroid ring and hydrocarbon tail) is hydrophobic

Answer 88

towards the phosphate heads of phospholipids

Answer 89

with the phospholipid tails

Answer 90

- controls membrane fluidity - reduces permeability to some solutes

Answer 91

too fluid-> unable to control what substances pass through not fluid enough-> movement of cell and substances would be restricted

Answer 92

3. reduces permeability to hydrophilic particles such as Na+ ions and H+ ions 4. helps membranes curve into a concave shape, which helps formations of vesicles during endocytosis

Answer 93

refer elsewhere

Answer 94

- model whereby two layers of protein flanked a central phospholipid bilayer - 'lipo-protein sandwich': the lipid layer was sandwiched between two protein layers

Answer 95

dark segments seen under electron microscope were identified (wrongly) as representing the two protein layers

Answer 96

- membrane proteins were discovered to be insoluble in water (indicating hydrophobic surfaces) and varied in size - Fluorescent antibody tagging of membrane proteins showed they were mobile and not fixed in place - Freeze fracturing was used to split open the membrane and revealed irregular rough surfaces within the membrane

Answer 97

Such proteins would not be able to form a uniform and continuous layer around the outer surface of a membrane

Answer 98

showed membrane proteins could move and did not form a static layer

Answer 99

rough surfaces were interpreted as being transmembrane proteins, demonstrating that proteins were not solely localised to the outside of the membrane structure

Answer 100

at high temperatures, cholesterol reduces membrane fluidity through its interactions with the fatty acid tails, which stabilise the membrane . at low temperatures, cholesterol increases membrane fluidity by preventing the phospholipid tails from packing too close together.

Answer 101

- simple diffusion - facilitated diffusion - osmosis - active transport

Answer 102

the net, passive movement of molecules from a region of high concentration to a region of low concentration

Answer 103

easiest->hardest 1. small non-polar molecules 2. small polar molecules 3. large polar molecules polar/charged molecules repel hydrophobic tails of phospholipids

Answer 104

oxygen, CO2, glycerol

Answer 105

the cornea has no blood supply so its cells obtain oxygen by simple diffusion from the air (it passes through the fluid/tears and into the cornea)

Answer 106

the passive movement of molecules across the cell membrane via the aid of a membrane protein

Answer 107

molecules that are unable to freely cross the phospholipid bilayer (e.g. large, polar molecules and ions)

Answer 108

channel proteins and carrier proteins

Answer 109

Integral glycoproteins

Answer 110

bind a solute and undergo a conformational change to translocate the solute across the membrane

Answer 111

no; they will only bind a specific molecule via an attachment similar to an enzyme-substrate interaction

Answer 112

no; they will only bind a specific molecule via an attachment similar to an enzyme-substrate interaction

Answer 113

may move molecules against concentration gradients in the presence of ATP (i.e. are used in active transport)

Answer 114

Carrier proteins have a much slower rate of transport than channel proteins

Answer 115

Integral lipoproteins

Answer 116

they contain a pore via which ions may cross from one side of the membrane to the other

Answer 117

no; they are ion-selective and may be gated to regulate the passage of ions in response to certain stimuli

Answer 118

no; they can only move molecules along a concentration gradient (i.e. are not used in active transport)

Answer 119

- a part of a neuron which consists of a tubular membrane with cytoplasm inside - used to convey messages rapidly in the form of an electrical impulse

Answer 120

rapid movements of Na ions into and K ions out of the axon membrane via facilitated diffusion (through Na and K channels)

Answer 121

1. the interior of the pump is open to the inside of the axon; three sodium ions enter the pump and attach to their binding sites 2. ATP transfers a phosphate group from itself to the pump; this causes the pump to change shape and the interior is then closed 3. the interior of the pump opens to the outside of the axon and the 3 Na ions are released

Answer 122

active transport, done by a sodium-potassium pump protein

Answer 123

4. 2 K ions from outside can then enter and attach to their binding sites 5. binding of K causes release of the phosphate group; this causes the pump to change shape again 6. the interior of the pump opens to the inside of the axon and the 2 K ions are released

Answer 124

the use of energy to move molecules against a concentration gradient

Answer 125

- The direct hydrolysis of ATP (primary active transport) - Indirectly coupling transport with another molecule that is moving along its gradient (secondary active transport)

Answer 126

carrier proteins (called protein pumps due to their use of energy)

Answer 127

- A specific solute binds to the protein pump on one side of the membrane - The hydrolysis of ATP (to ADP + Pi) causes a conformational change in the protein pump - The solute molecule is consequently translocated across the membrane (against the gradient) and released

Answer 128

voltage gated

Answer 129

- an imbalance of positive and negative charges across the membrane - more +ve outside axon than inside= K channel closed - more +ve inside axon than outside = K channel open, so ions diffuse through

Answer 130

1. channel closed; there is a net -ve charge inside the axon and a net +ve charge outside 2. channel briefly opens; net +ve charge inside and net -ve charge inside; K ions rush outside by translocating ions to create a voltage difference across the membrane 3. channel closed by 'ball and chain' within milliseconds

Answer 131

the net movement of water molecules across a semi-permeable membrane from a region of low solute concentration/high water potential to a region of high solute concentration/low water potential

Answer 132

water molecules, despite being hydrophilic, are small enough to pass through the phospholipid bilayer

Answer 133

aquaporins

Answer 134

they greatly increase membrane permeability to water- eg kidney cells that reabsorb water and root hair cells in plants

Answer 135

materials to be taken into cells by endocytosis or released by exocytosis

Answer 136

The process by which large substances (or bulk amounts of smaller substances) enter the cell without crossing the membrane

Answer 137

- An invagination of the membrane forms a flask-like depression which envelopes the extracellular material - The invagination is then sealed off to form an intracellular vesicle containing the material

Answer 138

no, the proteins in the membrane that carry out this process requires energy from ATP

Answer 139

- phagocytosis to ingest/kill pathogens - in the placenta, proteins from the mother's blood, including antibodies are absorbed into the foetus

Answer 140

1. endocytosis; vesicles can then move through the cytoplasm 2. proteins are synthesised by ribosomes 3. vesicles enter the rough endoplasmic reticulum and accumulate there 4. vesicles bud off from the rER 5. the Golgi apparatus modifies the proteins 6. vesicles bud off from the Golgi and carry the modified proteins to the plasma membrane 7. endocytosis

Answer 141

- vesicles fuse with the plasma membrane - the contents of the vesicle are expelled and the membrane flattens out again

Answer 142

Digestive enzymes released from gland cells by exocytosis (secretion) expulsion of waste products or unwanted materials (eg water in unicellular organisms through contractile vacuoles)

Answer 143

a solution that has the same osmolarity as a tissue

Answer 144

a solution that has a higher osmolarity than a tissue

Answer 145

a solution that has a lower osmolarity than a tissue

Answer 146

hypertonic solutions; water will leave the cell causing it to shrivel (crenation) hypotonic solutions; water will enter the cell causing it to swell and potentially burst (lysis)

Answer 147

hypertonic solutions; the cytoplasm will shrink (plasmolysis) but the cell wall will maintain a structured shape hypotonic solutions; the cytoplasm will expand but be unable to rupture within the constraints of the cell wall (turgor)

Answer 148

it is important for any human tissues or organs to be bathed in an isotonic solution during medical procedures. usually, NaCl solution is used (normal saline)- osmolarity= 300mOsm= cytoplasm osmolarity

Answer 149

bathe it in a salt solution for a short time and measure the increase/decrease in mass- when mass change=0, that is the same conc

Answer 150

by division of pre-existing cells

Answer 151

from non-living material

Answer 152

1. production of carbon compounds such as sugars and amino acids 2. assembly of carbon compounds into polymers 3. formation of membranes 4. development of a mechanism for inheritance

Answer 153

Miller and Urey passed steam through a mixture of methane, hydrogen and ammonia- a mixture representative of the atmosphere of the early earth. when electrical discharges (= lightning) were used, amino acids/other C carbons were formed

Answer 154

deep sea vents: - cracks characterised by gushing hot water carrying reduced inorganic chemicals such as iron sulphide - these could be sources of energy for the assembly of C compounds into polymers

Answer 155

if phospholipids/other amphipathic C compounds existed, they would have naturally assembled into bilayers. experiments have sown these bilayers readily formed vesicles, resembling membranes which would have allowed different internal chemistry from the surroundings to develop

Answer 156

enzymes needed to replicate DNA- but genes needed for enzymes to be made - RNA was original genetic material

Answer 157

as it stores information the same as DNA but is self replicating and can act as a catalyst

Answer 158

the idea that some organelles in eukaryotes were formed by the taking in of prokaryotes

Answer 159

1. prokaryotic organism that had developed the process of aerobic cell respiration were taken in by larger prokaryotes that could only respire anaerobically via endocytosis 2. smaller prokaryotes were not killed but continued to live in the cytoplasm, growing and dividing as fast as the larger ones 3. smaller prokaryotes lost unnecessary functions and persisted over millions of years of evolution to become mitochondria

Answer 160

as they were in a symbiotic/mutualistic relationship in which both of them benefited- larger supplied with energy, smaller supplied with food

Answer 161

prokaryotes that had developed photosynthesis taken in my larger cell

Answer 162

1. mitochondria and chloroplasts have their own genes, on a circular DNA molecule (=prokaryotes) 2. they have their own 70S ribosomes of a size and shape typical of some prokaryotes 3. they transcribe their DNA and use the mRNA to synthesise some of their own proteins 4. they can only be produced by division of pre-existing m/c.

Answer 163

the division of the nucleus into two genetically identical daughter nuclei

Answer 164

all of the DNA in the nucleus must be replicated

Answer 165

during interphase

Answer 166

the period before mitosis

Answer 167

each chromosome is converted from a single DNA molecule into two identical DNA molecules (chromatids)

Answer 168

- embryonic development - growth - tissue repair - asexual reproduction

Answer 169

1. prophase 2. metaphase 3. anaphase 4. telophase

Answer 170

continuous

Answer 171

very active phase in the life of the cell when many metabolic reactions occur

Answer 172

DNA replication in the nucleus and protein synthesis in the cytoplasm

Answer 173

due to the growth and division of these organelles

Answer 174

they synthesise cellulose and use vesicles to add it to their cell walls

Answer 175

- G1 phase - S phase - G2 phase

Answer 176

cell grows physically larger and copies organelles/cellular components except the chromosomes

Answer 177

cell replicates all genetic material in its nucleus

Answer 178

cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis

Answer 179

they enter a phase called G0

Answer 180

by supercoiling during mitosis

Answer 181

a chromatid

Answer 182

by repeatedly coiling the DNA molecule to make the chromosome shorter and wider

Answer 183

histones (proteins) associated with DNA and enzymes

Answer 184

- chromosomes become shorter and fatter by supercoiling - nucleolus breaks down - microtubules grow from MTOCs to form spindle-shaped array that links poles of the cell - end; nuclear membrane breaks down

Answer 185

area inside the nucleus of a cell that is made up of RNA and proteins and is where ribosomes are made.

Answer 186

- microtubules continue to grow and attach to the centromeres on each chromosome - microtubules put under tension to test whether attachment is correct (by shortening of the microtubules at the centromere) - attachment=correct, microtubules remain on equator of cell

Answer 187

the two attachment points on opposite sides of each centromere

Answer 188

- each centromere divides, allowing the pairs of sister chromatids to separate - spindle microtubules pull them rapidly towards the poles of the cell

Answer 189

- at each pole the chromosomes are pulled into a tight group by the MTOC and a nuclear membrane reforms around them - chromosomes uncoil and nucleolus is formed

Answer 190

structures found at the ends of chromosomes. They cap and protect the end of a chromosome

Answer 191

links a pair of sister chromatids together during cell division.

Answer 192

no of cells in mitosis/total no of cells

Answer 193

microtubule-organizing center; a structure found in eukaryotic cells from which microtubules emerge.

Answer 194

after mitosis

Answer 195

process of cell division

Answer 196

- vesicles are moved to the equator, where they fuse to form tubular structures - these merge into two layers of membrane across the whole of the equator

Answer 197

- pectins and other substances brought by vesicles and deposited by exocytosis between the two new membranes, forming the middle lamella that links new cell walls. - both dcs then bring cellulose to the equator and deposit it adjacent to the middle lamella via exocytosis. this forms a cell wall adjacent to the equator

Answer 198

1. cleavage furrow formed (plasma membrane pulled inwards around equator). - this is accomplished by using a ring of contractile protein (actin and myosin) 2. when cleavage furrow reaches centre, the cell is pinched apart into 2 cells

Answer 199

the control of the cell cycle

Answer 200

proteins: - control the cell cycle and ensure that cells divide only when new cells are needed

Answer 201

- bind to enzymes called cyclin-dependent kinases, causing them to become active and attach phosphate groups to other proteins in the cell - this triggers the other proteins to become active and carry out tasks specific to one of the cell cycle phases

Answer 202

triggers cells to move from G0 to G1 and from G1 to S

Answer 203

prepares cell for DNA replication in the S phase

Answer 204

actives DNA replication inside the nucleus in the S phase

Answer 205

promotes the assembly of the mitotic spindle and other tasks in the cytoplasm to prepare for mitosis

Answer 206

when their target protein is required for function

Answer 207

- mutagens - oncogenes - metastasis

Answer 208

abnormal groups of cells that develop at any stage of life in any part of the body

Answer 209

when the cells adhere to each other and do not invade nearby tissues or move to other parts of the body

Answer 210

when the cells become detached and move elsewhere in the body and develop secondary tutors

Answer 211

diseases due to malignant tumours

Answer 212

malignant tumours

Answer 213

an agent that changes the genetic material of an organism (either acts on the DNA or the replicative machinery)

Answer 214

- Physical – Sources of radiation including X-rays (ionising), ultraviolet (UV) light and radioactive decay - Chemical – DNA interacting substances including reactive oxygen species (ROS) and metals (e.g. arsenic) - Biological – Viruses, certain bacteria and mobile genetic elements (transposons)

Answer 215

Mutagens that lead to the formation of cancer

Answer 216

random changes to the base sequences of genes

Answer 217

do not cause cancer

Answer 218

genes that become cancer-causing after mutating

Answer 219

in a normal cell, oncogenes are involved in the control of the cell cycle and cell division, so mutations in them will result in uncontrolled cell division = tumour formation

Answer 220

the movement of cells from a primary tumour to set up secondary tumours in other parts of the body

Answer 221

there is a positive correlation between smoking and incidence of cancer; - cancer of mouth, pharynx, larynx and lungs - esophagus, stomach, kidney, bladder, pancreas cervix - Cigarette smoke contains over 4,000 chemical compounds, over 60 of which are known to be carcinogenic

topic 1 Flashcards

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