1
Q
all organisms possess 7 properties. what are they?
A
- cellular organization
- energy & metabolism
- reproduction
- heredity and evolution
- growth and development
6.regulation and homeostasis
7.response to stimuli
2
Q
what is cell theory
A
a cell is the basic structural, functional, and biological unit of organisms. It is the smallest unit of life. All cells derive from pre-existing cells. All organisms are made of cells (one or more)
3
Q
Which 3 things are not considered organisms
A
- virus
- prions
- viroids
4
Q
why are virus, prions, viroids not considered organisms?
A
- No cellular organization
- no internal metabolism
- no growth or development
5
Q
What are viruses?
A
- infectious particle.
cannot replicate outside of a cell - Some viruses have a membranous envelope.
6
Q
What are prions?
A
- infectious agents (misfolded version of a normal cellular protein).
- increase in number by converting correctly folded versions to more prions
7
Q
What are viroids?
A
- small infectious circular RNA molecules. Can replicate using the replication machinery of their plant host cell.
- Don’t code for any protein and can be transmitted between cells/individual plants.
8
Q
What is the importance of carbon on earth? and why?
A
Life on earth uses carbon because :
* Highly abundant on earth and in the atmosphere
* Small molecular weight and size
* Can bind 4 other atoms to form reactive and stable molecules (organic)
* Can bind to other carbon atoms: polymerisation
9
Q
Which elements constitute the majority of biological molecules?
A
Carbon; oxygen; hydrogen; nitrogen
COHN!!
10
Q
What is the Origin of life hypothesis?
A
- origin of life ~3,500 my ago
- prokaryotes were the first cell
- Organic molecules necessary for the first step in the origin of life may have been synthesized from abiotic molecules on the early Earth.
- first cells had RNA
11
Q
What did early atmosphere consist of?
A
methane, ammonia, hydrogen and some energy
12
Q
What is the significance of clay in the origin of life?
A
Clay is mineral catalyst for the polymerization of RNA (RNA world). RNA can also self-replicate.
13
Q
Describe the diversity of cellular functions:
A
- Contain and transmit the genetic material
- Acquisition and conversion of energy
- Feeding and absorption of nutrients
- Structure and support
- Communication and response to environmental stimuli
- Barrier and defense mechanisms (environmental stresses: biotic and abiotic)
- Transport of molecules (osmoregulation, gas exchange)
- Reproduction (gametes)
Cells are like busy cities with different functions: they store and pass on information, get energy, eat and absorb nutrients, provide structure, communicate and respond to the environment, defend against threats, transport molecules, and reproduce.
14
Q
Describe the organization of cells in multicellular organisms:
A
In multicellular organisms, cells are organized in tissues and tissues are organized in organs.
15
Q
What is the central dogma?
A
DNA -> RNA -> Protein:
The central dogma is like a recipe book where DNA provides the instructions (recipe) to make RNA, which then serves as a template to make proteins, but proteins cannot give instructions to make DNA or RNA.
16
Q
What is the relationship between DNA and RNA
A
The genetic information encoded in DNA can be transferred to other DNA molecules. New RNA molecules that have been discovered can transfer their information into DNA.
17
Q
What are the three domains?
A
Bacteria, Archaea, Eukarya
18
Q
What are archaea?
A
Prokaryotes that are not bacteria but can thrive in extreme conditions like highly acidic, hot, and high-salinity environments, and some even produce methane.
19
Q
How do ribosomes reflect the common ancestor of all life?
A
ribosomes are found in all components of life
20
Q
What is the importance of ribosomes for proteins synthesis?
A
ribosomal proteins are highly critical for protein synthesis, as they and are under very strong selection (mutations that disrupt their amino-acid sequence are selected out), they undergo slow evolution and accumulate more mutations among distant lineages; them being highly conserved aids in resolving the root of the tree of life.
21
Q
What are the advantages of multicellularity?
A
Multicellularity is crucial as:
- it enhances surface area for efficient diffusion
- extends lifespan
- allows for the specialization of cells into various types, tissues, and organs
- ultimately enabling organisms to excel in vital functions like protection, feeding, locomotion, and reproduction.
22
Q
What is the colonial hypothesis?
A
single-celled organisms from the same species started working together by either sticking together after they split or by joining up again after separating. They kept dividing, but some of them started to do specific jobs better, like protection or feeding, gradually evolving into multicellular organisms with specialized cells, enabling the development of complex life forms.
23
Q
What are protists?
A
all of the eukaryote organisms that are neither fungi, plants or animals
24
Q
Describe how light microscopes work.
A
The light goes through the specimen and the image is magnified by refraction through a lens.
25
Describe how a transmission electron microscope (TEM) works.
A beam of electrons goes through the specimen and can reveal internal structures. Requires very thin slices of the specimen hardened in resin or frozen, stained with heavy metal and cut using a microtome.
26
Describe how a scanning electron microscope (SEM) works
In a scanning electron microscope, a beam of electrons is directed onto the surface of a specimen that has been coated with a thin layer of gold (a good conductor of electricity). When these high-energy electrons strike the sample's surface, they knock off secondary electrons from the specimen. These secondary electrons are then detected and converted into an electric signal for imaging. This technique allows scientists to create detailed 3D images of the specimen's surface, providing valuable insights into its structure and morphology at a very small scale.
27
Describe how a fluorescence microscope works
In a fluorescence microscope, the specimen is labeled with a fluorescent marker like GFP or a fluorescent chemical. When exposed to specific light, these markers emit a different colored light, creating a vivid image that helps scientists see specific structures or molecules in the specimen.
28
What is the relationship between surface area and volume in cells?
as cells grow, volume increases faster than surface area, leading to a decreased surface area-to-volume ratio.
29
why is surface area important to cells?
because the surface area of a cell's membrane determines the cell's ability to exchange materials with its surroundings (like taking in nutrients and getting rid of waste). When the surface area doesn't grow as fast as the volume, it can become less efficient at these exchanges, which can have biological consequences.
30
How do larger cells compensate for a low SA:Vol ratio?
- Foldings (like villi in intestine) may be formed to maximize absorption and to increase the surface area of the inner lining
31
How do smaller cells compensate for a high S:V ratio?
How do smaller cells compensate for a high S:V ratio?
32
What similarities exist between prokaryotes and eukaryotes?
1. Genetic information encoded in DNA
2. Plasma membrane
3. Similar mechanisms for transcription & translation, photosynthesis, synthesizing and inserting membrane proteins
4. presence of a cytoskeleton
5. Similar processes for the conversion of chemical energy into ATP
6. Shared metabolic pathways
33
Prokaryotes & Eukaryotes genetic information is encoded in:
DNA;
The genetic code is not universal. Variations between species. Mitochondria have a different code.
34
Prokaryotes & Eukaryotes plasma membrane is made of:
a bilayer of phospholipid
35
What is the role of the plasma membrane?
selective barrier
communication
adhesion
cell structure
36
Prokaryotes & Eukaryotes share what similar mechanisms regarding genetic info?
- transcription and translation of genetic information, including similar ribosomes
- photosynthesis (cyanobacteria and plants)
- synthesizing and inserting membrane proteins
37
Explain the presence of cytoskeleton in both Prokaryotes and Eukaryotes
It provides shape, support, and aids in various cellular processes like cell division and movement. but the proteins differ between
prokaryotes :FtsZ and MreB eukaryotes : actin, tubulin, keratin
38
How are prokaryotes and eukaryotes similar in converting chemical energy into ATP?
* Similar process for the conversion of chemical energy into ATP:
- prokaryotes: plasma membrane
-eukaryotes: mitochondrial membrane
- also have shared metabolic pathways (glycolysis, citric acid cycle)
39
Cytoplasm
is thetotal content of the cell bounded by the plasma membrane; in eukaryotes,
EXCLUDES THE NUCLEUS
40
Cytosol:
Fluid portion of cytoplasm; internal fluid containing organic molecules, proteins, metabolic waste etc.
41
How is the cytoplasm different between prokaryotes and eukaryotes?
prokaryotic cells
- simpler
- lacks membrane-bound organelles,
- has free-floating ribosomes, - therefore made of the cytosol.
In eukaryotic cells
- compartmentalized with organelles, has attached ribosomes
- complex cytoskeleton
- excludes the nucleus
42
What are the differences between prokaryotes and eukaryotes in terms of the nucleus?
In prokaryotes
- there is no nucleus
- Presence of a nucleoid
In Eukaryotes
- presence of a nucleus with linear chromosomes
- made of chromatin (DNA + histone proteins)
43
What is the cell well in bacteria called
peptidoglycan
- Gram-positive bacteria have a peptidoglycan layer in their cell wall
- gram-negative bacteria have a peptidoglycan layer and an outer membrane.
44
What is the cell wall of archaea called?
Pseudomurein
45
Which types of cell walls are absent in animals?
Animal cells lack cell walls containing:
- peptidoglycan (found in bacteria)
- pseudomurein (found in archaea)
- cellulose (found in plants)."
46
What is the cell wall of plans called?
Cellulose; plasma membrane and cell wall in plants is made of cellulose.
47
What is the role of the cell wall in plants?
- maintains the shape of the cell
- prevents excessive water uptake
- acts as a barrier to pathogens
48
Describe the primary cell wall of plants
thin & flexible
49
What is the role of the secondary cell wall in plants cell wall?
- its a strong layer that provides durable protection and support in some plant cells.
- forms between the plasma membrane and the primary cell wall when a cell stops growing.
50
Describe the middle lamella of plants
It is a thin layer of pectin which glues adjacent cells together
51
What does the extracellular matrix of animal cells consists of?
network of glycoproteins, polysaccharides and proteoglycans bonded covalently to short chains of sugar
52
Where are collagen fibers embedded in the extracellular matrix?
Collagen fibers are embedded in a network ofproteoglycan (core protein bonded covalentlyto polysaccharides
53
What do fibronectins do?
Fibronectins connect the extracellular matrix (ECM) to integrins on the cell membrane.
Integrins are transmembrane proteins.
This connection is vital for:
- Cell adhesion
- Cell migration
- Cell signaling and communication.
54
What do integrins do?
can transmit (integrate) information between the ECM and the cytoskeleton
55
How does reproduction/cell division occur in prokaryotes?
- Prokaryotes (e.g., bacteria) do not undergo mitosis or meiosis.
- Reproduction/cell division in prokaryotes is asexual.
- occurs through a process called binary fission.
- In binary fission, one parent cell splits into two identical daughter cells.
56
How does reproduction/cell division occur in eukaryotes?
- through mitosis: eukaryotic cell division using a a microtubule-containing mitotic spindle that separates chromosome
- sexual reproduction: requires meiosis and fertilization
57
How does the no. of RNA synthesizing enzymes differ between prokaryotes/eukaryotes?
RNA synthesizing enzymes aka RNA polymerases: 1 in prokaryotes, and 3 in eukaryote
58
what's a Flagellum
long cellular appendage specialized for locomotion
59
what's locomotion
the ability of an organism or cell to move from one place to another, which can involve various modes of movement depending on the organism's type and context."
60
flagellum in eukaryotes
projects from the cytoskeleton and covered by the plasma membrane
61
flagellum in prokaryotes
Flagellum made of flagellin and inserted in the plasma membrane
62
What kinds of chromosomes are found only in eukaryotes?
Eukaryotes have complex linear chromosomes composed of DNA and associated proteins, such as histones. These chromosomes can compact into structures used in mitosis, a process absent in prokaryotes, which typically have simple, circular chromosomes.
63
What kinds of organelles are found only in eukaryotes?
- endoplasmic reticulum
- Golgi complex
- lysosomes
- endosomes, peroxisome
64
What kinds of specialized organelles are found only in eukaryotes?
- mitochondria
- chloroplasts
65
What parts of the cytoskeletal system are found only in eukaryotes?
Proteins and filaments of the cytoskeletal system :
- actin filaments
- intermediate filaments
- microtubules
- motor proteins.
66
The ability to ingest particulate material by enclosure within plasma membrane vesicle is unique to?
Phagocytosis is found only in eukaryotes
67
The presence of two copies of genes per cell (diploidy) is found only in:
Eukaryotes
68
What are organelles?
- membrane-enclosed structures with specialized functions
- suspended in the cytosol of eukaryotic cells.
(prokaryotes have no compartmentalization (no organelles))
- can move within the cell following cytoskeleton tracks
69
What is the nucleus
organelle in eukaryotes containing genetic material (chromosomes).
Some genes on mitochondrial (and chloroplast) chromosomes
*red blood cells do not have nucleus
70
What is the nucleus surrounded by?
The nuclear envelope: double membrane (two bilayers of lipids) supported by a nuclear lamina (network filamentous proteins)
71
What are the roles of nuclear pore complexes?
regulate the entry and exit of nucleic acids and proteins.
72
What is a chromatin?
complex of DNA + histone proteins
- making up chromosomes in eukaryotes.
- Can coil during cell division
- in human:
- 46 chromosomes (2n=46),
- 22 pairs autosomal chromosomes
1 pair sexual chromosomes (XY):
- gametes have a single set of each
73
What is the nucleolus?
- a specialized structure in the nucleus of eukaryotic cells.
- consists of chromosomal regions containing ribosomal RNA (rRNA) genes + ribosomal proteins imported from the cytoplasm.
- serves as the site for rRNA synthesis + ribosomal subunit assembly with the rRNA
74
How does ribosome synthesis occur in the nucleolus?
- Each ribosomal subunit is linked to ribosomal RNA (rRNA) + exits the nucleus through nuclear pores.
- these subunits will later assemble in the cytoplasm to form a functional ribosome.
- Ribosomes then use mRNA to synthesize proteins in the cytoplasm
75
What is the endoplasmic reticulum?
A membranous network in eukaryotic cells that is continuous with the outer nuclear membrane.
76
Describe the rough ER & function
- Ribosome-studded
Protein Synthesis: Makes proteins.
- Glycoprotein Production: Creates sugar-coated proteins.
- Quality Control: Checks protein quality.
- Secretory Proteins: Makes proteins for export.
- Membrane Building: Helps create cell membranes
77
Where do secretory proteins synethesized by rough ER go?
directed during translation into the ER lumen and transported within transport vesicles
78
membrane proteins in rough ER
Membrane proteins are also inserted directly into the ER membrane before they are also sent to various parts of the cell
79
Describe the smooth ER
ribosome-free and contains many enzymes responsible for many metabolisms
80
What is the function of the smooth ER?
1. Synthesis of lipids, phospholipids, steroids (ex: sexual hormones), cholesterol, carbohydrate metabolism
2. Detoxification (toxins, drugs, ethanol...)
- CYP450 (Cytochrome 450) enzymes that can break down drugs
3. Calcium storage (after the muscle contraction) in sarcoplasmic reticulum of muscle cells
81
What is the Golgi apparatus function?
It is a trafficking center:
- manufactures
- receives
- sorts
- modifies
- ships many molecules
Vesicles arrive from the ER, fuse with the GA membranes and leave the GA
---- (cis-to-trans direction)
82
What kinds of post-translational modifications (PTMs) occur in the GA ( Golgi apparatus) ?
- Proteins can undergo PTMs in the GA, with common PTMs including phosphorylation (addition of phosphate), glycosylation (addition of carbohydrates), and acetylation (addition of an acetyl group).
- The Golgi apparatus is involved in modifying, storing, and shipping glycoproteins and phospholipids within the cell.
- Additionally, it plays a role in synthesizing or modifying polysaccharides.
83
What is the lysosomes function?
- digestive organelles within cells that contain hydrolytic enzymes.
- They function to break down macromolecules through digestion.
- Their content is highly acidic, with lytic enzymes working effectively at a low pH, typically between 4.5 and 5.
84
How do lysosomes digest preys/pathogens?
- Lysosomes digest prey or pathogens through the fusion of lysosomes with phagocytic vesicles.
- This process breaks down the invaders into simple sugars or amino acids, which are then released into the cytosol for the cell to use
85
What is a peroxisome?
- single-membrane organelle within cells that contains enzymes, often in the form of crystals.
- Peroxisomes function to remove hydrogen atoms from various substrates
- transfers H+ atoms to oxygen, resulting in the production of hydrogen peroxide (H2O2).
86
What is the role of the peroxisome?
1. Breaks down fatty acids into smaller molecules, which are used for cellular respiration in mitochondria.
2. Detoxifies the cell by oxidizing harmful compounds like alcohol.
3. Converts hydrogen peroxide (H2O2), a reactive and potentially toxic substance, into water (H2O) before it leaves the peroxisome.
87
Glyoxisome function
A specialized type of peroxisome found in plants, glyoxisomes enable seedlings to grow by breaking down stored fatty acids. This process allows for growth before the establishment of photosynthesis
88
What is a vacuole
- large storage component;
- large vesicles derived from ER/GA
- Semi-permeable membrane (high selectivity) -as in transport inside of only very specific molecules
89
What is the role of the vacuole?
- Stores nutrients
- toxins
- pigments
- maintains turgor pressure for cell growth
- structural support.
90
What is endosymbiosis theory?
- A possible explanation for the origin of mitochondria and chloroplasts.
- mitochondria & chloroplasts derived from prokaryotes integrated inside another prokaryote
91
What is endosymbiosis?
Relationship between two species in which one organism lives inside the cell or cells of another organism
92
mitochondrion and plastids are organelles that possess what...
organelles possessing its own membrane circular DNA
their own transcription/translation proteins, ribosomes/membrane proteins similar to those of bacteria.
93
Describe serial endosymbiosis:
Serial endosymbiosis is a theory explaining the origin of organelles in eukaryotic cells. It involves:
- Mitochondria originating from the engulfment of an aerobic bacterium by an archaeal cell.
- Chloroplasts originating from the engulfment of a photosynthetic bacterium by a eukaryotic cell.
94
What are the benefits of serial endosymbiosis?
the cell gains new metabolic systems, such as aerobic respiration in the presence of increasing oxygen concentrations.
95
What is unique about the membranes of mitochondria/chloroplasts?
have double membranes: an outer membrane and an inner membrane, making them distinct from other cellular organelles. (derived from endosymbiosis..)
96
explain why and how mito and chloroplasts have double membranes
derived from endosymbiosis, the outer membrane likely represents the host cell's membrane that initially engulfed the bacterium, while the inner membrane corresponds to the bacterial membrane.
97
What is the mitochondrion & what is its function?
- Double membrane-bound organelle that converts chemical energy acquired from the environment (ex: glucose) into chemical energy that is directly usable by the cell (ATP), which is done thru cellular respiration
- chem. energy stored in the bonds between atoms of carbon & phosphate
98
What is the role of cristae in the mitochondrion?
Infoldings of the inner membrane (cristae) separate the intermembrane space from the mitochondrial matrix:
--> increases the surface area for cellular respiration
--> enzymes necessary for cellular respiration are within the intermembrane space, others are embedded in the inner membrane (Ex: ATP synthase)
99
Do mitochondria possess their own DNA/ribosomes?
Yes
- some genes were lost during evolution & transferred to nucleus
100
What structure separates both membranes of the chloroplasts?
An intermembrane space
101
What are thylakoids?
- membranous flat and interconnected sacs inside the chloroplast and that are stacked (granum) and that contain the photosynthetic pigments (chlorophylls)
- they float inside the stroma (fluid containing the chloroplast DNA, ribosomes and many enzymes)
102
Can Chloroplasts grow, divide, and move within the cell
Yes, chloroplasts are dynamic organelles that exhibit growth, division, and movement within plant cells.
They can :
- increase in number through division
- grow in size,
- move within the cell to optimize photosynthesis and respond to environmental cues.
103
What family of closely related plant organelles do chloroplasts belong to?
plastids
104
Plastids include
1. chloroplasts: photosynthesis ,
2. chromoplasts: fruit & flower pigmentation
3. amyloplasts storage of starch (amylose) in roots and tuber
105
Do plant cells have mitochondria?
yes, to convert the chemical energy produced from photosynthesis into ATP
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