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topic 1 cell biology Flashcards

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1
Q

the cell theory states that…

A
  1. All living things are composed of cells (or cell products)
  2. The cell is the smallest unit of life
  3. Cells only arise from pre-existing cells
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2
Q

The three exceptions to cell theory are…

A

Striated muscle fibres:
Muscle cells fuse to form fibres that may be very long (>300mm)
Consequently, they have multiple nuclei despite being surrounded by a single,
continuous plasma membrane
Challenges the idea that cells always function as autonomous units

Aseptate fungal hyphae:
Fungi may have filamentous structures called hyphae, which are separated into cells by
internal walls called septa
Some fungi are not partitioned by septa and hence have a continuous cytoplasm along
the length of the hyphae
Challenges the idea that living structures are composed of discrete cells

Giant Algae
Certain species of unicellular algae may grow to very large sizes (e.g. Acetabularia may
exceed 7 cm in length)
Challenges the idea that larger organisms are always made of many microscopic cells

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3
Q

what are the functions of life?

A

Metabolism – Living things undertake essential chemical reactions
Reproduction – Living things produce offspring, either sexually or asexually
Sensitivity – Living things are responsive to internal and external stimuli
Homeostasis – Living things maintain a stable internal environment
Excretion – Living things exhibit the removal of waste products
Nutrition – Living things exchange materials and gases with the environment
Growth – Living things can move and change shape or size

Mnemonic: MR SHENG

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4
Q

how do paramecium carry out all functions of life?

A

Paramecia are surrounded by small hairs called cilia which allow it to move (responsiveness)
Paramecia engulf food via a specialised membranous feeding groove called a cytostome (nutrition)
Food particles are enclosed within small vacuoles that contain enzymes for digestion (metabolism)
Solid wastes are removed via an anal pore, while liquid wastes are pumped out via contractile vacoules (excretion)
Essential gases enter (e.g. O2) and exit (e.g. CO2) the cell via diffusion (homeostasis)
Paramecia divide asexually (fission) although horizontal gene transfer can occur via conjugation (reproduction)

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5
Q

how do scenedesmus carry out the 7 functions of life

A

Scenedesmus exchange gases and other essential materials via diffusion (nutrition / excretion)
Chlorophyll pigments allow organic molecules to be produced via photosynthesis (metabolism)
Daughter cells form as non-motile autospores via the internal asexual division of the parent cell (reproduction)
Scenedesmus may exist as unicells or form colonies for protection (responsiveness)

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6
Q

what is rate of metabolism

A

cell is a function of its mass / volume (larger cells need more energy to sustain essential functions)

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7
Q

rate of material exchange

A

a function of its surface area (large membrane surface equates to more material movement)

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8
Q

why are cells small?

A

as cell size increases, the SA is no longer sufficient to allow these exchanges at a rate that supports life (prevents cells from being big)

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9
Q

how to calculate specimen size (w/ microscope)

A

specimen size = image size / magnification

measure the dimension of the cell

divide this by the magnification

convert to sensible unit

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10
Q

how to calculate magnification?

A

magnification = image size / real size

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11
Q

low SA:Vol ratio results in what?

A

cell dies as the metabolic rate exceeds the rate of exchange of vital materials and wastes

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12
Q

Which type of cells increase the SA:Vol ratio? (specialized)

A

Cells and tissues specialized for gas or material exchanges increase their SA to optimise material transfer

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13
Q

What are examples of cells that increase the SA:Vol ratio?

A

intestinal tissue of the digestive tract (villi!!)

alveoli have microvilli

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14
Q

organization of multicellular organisms

A

cell, tissue, organ, system, organism

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15
Q

example of an organisation of multicellular organism

A

muscle, cardiac, heart, vascular, human

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16
Q

why can multicellular organisms complete functions that unicellular organisms can not undertake?

A

collective actions of individual cells combining to create new synergistic effects (emergent properties)

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17
Q

what is differentiation?

A

process during development whereby newly formed cells become more specialised and distinct from one another as they mature

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18
Q

do cells of an organism share identical genomes?

A

YES

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19
Q

how do cells differentiate?

A

different genes are activated within a given cell by chemical signals

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20
Q

how are active genes packaged?

A

expanded form called EUCHROMATIN

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21
Q

how are inactive genes packaged

A

heterochromatin (saves space, not transcribed)

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22
Q

what are stem cells?

A

unspecialized cells that can continuously divide and replicate, and have the capacity to differentiate into specialized cell types

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23
Q

what are the four main types of stem cells?

A

totipotent
pluripotent
multipotent
unipotent

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24
Q

functions of totipotent stem cells?

A

can form any cell type (as well as placental tissue)

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25
Q

function of pluripotent stem cells(

A

can form any cell type

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26
Q

function of multipotent stem cell?

A

can differentiate into a number of closely related cell types

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27
Q

function of unipotent stem cells?

A

can not differentiate, but are capable of self renewal

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28
Q

what is one way stem cells are applied to medicine?

A

therapeutic option when tissues become damaged

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29
Q

process of using stem cells to replace damaged or diseased cells?

A

The use of biochemical solutions to trigger the differentiation of stem cells into the desired cell type

Surgical implantation of cells into the patient’s own tissue

Suppression of host immune system to prevent rejection of cells (if stem cells are from foreign source)

Careful monitoring of new cells to ensure they do not become cancerous

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30
Q

Three examples of stem cell therapy?

A

Stargardt’s Disease
Parkinson’s Disease
Leukemia/Paraplegia/Diabetes/Burn victims

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31
Q

What is Stargardt’s Disease?

A

An inherited form of juvenile macular degeneration that causes progressive vision loss to the point of blindness

Caused by a gene mutation that impairs energy transport in retinal photoreceptor cells, causing them to degenerate

Treated by replacing dead cells in the retina with functioning ones derived from stem cells

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32
Q

what is parkinson’s disease?

A

A degenerative disorder of the central nervous system caused by the death of dopamine-secreting cells in the midbrain

Dopamine is a neurotransmitter responsible for transmitting signals involved in the production of smooth, purposeful movements

Consequently, individuals with Parkinson’s disease typically exhibit tremors, rigidity, slowness of movement and postural instability

Treated by replacing dead nerve cells with living, dopamine-producing ones

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33
Q

how are stem cells derived?

A

embyros, umbilical cord blood, placenta, bone marrow

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34
Q

what are the ethical considerations to be taken into account when using stem cells therapeutically?

A
  • limited in the scope of application
  • stem cells from umbilical cord blood need to be stored and preserved –> raising issues of availability and access
  • embryos give the greatest yield of pluripotent stem cells, but requires the destruction of a potential living organism
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35
Q

how are artificial stem cells generated? (2 ways!)

A

somatic cell nuclear transfer (SCNT)

nuclear reprogramming

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36
Q

what is somatic cell nuclear transfer (SCNT)

A

creation of embyronic clones by fusing a diploid nucleus with an enucleated egg cell

more embryos are created by this process than needed

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37
Q

what is nuclear reprogramming?

A

Induce a change in the gene expression profile of a cell in order to transform it into a different cell type (transdifferentiation)

Involves the use of oncogenic retroviruses and transgenes, increasing the risk of health consequences (i.e. cancer)

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38
Q

what are prokaryotic cells?

A

organisms that lack a nucleus

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39
Q

what kingdom are prokaryotes in? + domains

A

Monera //

Archaebacteria (extreme environments, like high temperature, salt concentrations or pH)

Eubacteria (traditional bacteria)

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40
Q

What are the features of prokaryotic cells? + functions!!

A

Cytoplasm – internal fluid component of the cell

Nucleoid – region of the cytoplasm where the DNA is located (DNA strand is circular and called a genophore)

Plasmids – autonomous circular DNA molecules that may be transferred between bacteria (horizontal gene transfer)

Ribosomes – complexes of RNA and protein that are responsible for polypeptide synthesis (prokaryote ribosome = 70S)

Cell membrane – Semi-permeable and selective barrier surrounding the cell

Cell wall – rigid outer covering made of peptidoglycan; maintains shape and prevents bursting (lysis)

Slime capsule – a thick polysaccharide layer used for protection against dessication (drying out) and phagocytosis

Flagella – Long, slender projections containing a motor protein that enables movement (singular: flagellum)

Pili – Hair-like extensions that enable adherence to surfaces (attachment pili) or mediate bacterial conjugation (sex pili)

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41
Q

how do prokaryotic cells reproduce?

A

asexual reproduction // binary fission

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42
Q

what is binary fission?

A

The circular DNA is copied in response to a replication signal

The two DNA loops attach to the membrane

The membrane elongates and pinches off (cytokinesis), forming two cells

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43
Q

what are eukaryotes?

A

organisms whose cells contain a nucleus

evolved from prokaryotic cells

compartmentalized by membrane bound structures (organelles) that perform specific roles

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44
Q

four kingdoms of eukaryotes?

A

protista - unicellular organisms or multicellular organisms without specialized tissue

fungi - cell wall made of chitin, obtain nutrition via heterotrophic absorption

plantae - celll wall made of cellulose, obtain nutrition autotrophically (photosynthesis)

animalia - no cell wall, obtain nutrition via heterotrophic ingestion

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45
Q

what are universal organelles? (structure + function)

A

Ribosomes
Cytoskeleton
Plasma membrane

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46
Q

what are eukaryotic organelles (function + structure)

A 
Nucleus
Endoplasmic Reticulum
Golgi Apparatus
Mitochondrion
Peroxisome
Centrosome
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47
Q

ribosome function and structure

A

Structure: Two subunits made of RNA and protein; larger in eukaryotes (80S) than prokaryotes (70S)

Function: Site of polypeptide synthesis (this process is called translation)

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48
Q

cytoskeleton function and structure

A

Structure: A filamentous scaffolding within the cytoplasm (fluid portion of the cytoplasm is the cytosol)

Function: Provides internal structure and mediates intracellular transport (less developed in prokaryotes)

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49
Q

plasma membrane function and structure?

A

Structure: Phospholipid bilayer embedded with proteins (not an organelle per se, but a vital structure)

Function: Semi-permeable and selective barrier surrounding the cell

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50
Q

nucleus structure and function?

A

Structure: Double membrane structure with pores; contains an inner region called a nucleolus

Function: Stores genetic material (DNA) as chromatin; nucleolus is site of ribosome assembly

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51
Q

organelles in plant cell only?

A

chloroplast
vacuole
cell wall

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52
Q

organelles in animal cells only?

A

lysosome

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53
Q

endoplasmic reticulum function + structure?

A

Structure: A membrane network that may be bare (smooth ER) or studded with ribosomes (rough ER)

Function: Transports materials between organelles (smooth ER = lipids ; rough ER = proteins)

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54
Q

golgi apparatus function + structure?

A

Structure: An assembly of vesicles and folded membranes located near the cell membrane

Function: Involved in the sorting, storing, modification and export of secretory products

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55
Q

mitochondrion function and structure?

A

Structure: Double membrane structure, inner membrane highly folded into internal cristae

Function: Site of aerobic respiration (ATP production)

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56
Q

peroxisome function + structure?

A

Structure: Membranous sac containing a variety of catabolic enzymes

Function: Catalyses breakdown of toxic substances (e.g. H2O2) and other metabolites

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57
Q

centrosome function + structure?

A

Structure: Microtubule organising centre (contains paired centrioles in animal cells but not plant cells)

Function: Radiating microtubules form spindle fibres and contribute to cell division (mitosis / meiosis)

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58
Q

chloroplast function + structure?

A

Structure: Double membrane structure with internal stacks of membranous discs (thylakoids)

Function: Site of photosynthesis – manufactured organic molecules are stored in various plastids

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59
Q

vacuole function + structure?

A

Structure: Fluid-filled internal cavity surrounded by a membrane (tonoplast)

Function: Maintains hydrostatic pressure (animal cells may have small, temporary vacuoles)

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60
Q

cell wall function + structure?

A

Structure: External outer covering made of cellulose (not an organelle per se, but a vital structure)

Function: Provides support and mechanical strength; prevents excess water uptake

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61
Q

lysosome function + structure?

A

Structure: Membranous sacs filled with hydrolytic enzymes

Function: Breakdown / hydrolysis of macromolecules (presence in plant cells is subject to debate)

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62
Q

key features of prokaryote structure

A

pili (single lines)
flagella (thicker and longer lines than pilli)
ribosomes (70S)
cell wall (peptidoglycan, thicker than cell membrane)
shape - appropriate for bacteria
size - l = 2w

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63
Q

key features of animal cell structure

A

nucleus (double membrane structure with pores)

mitochondria (double membrane with inner one folded into cristae; half the nucleus in size)

golgi apparatus - enclosed sacs with vesicles leading to and from

endoplasmic reticulumm (interconnected membranes shown as bare (smooth ER) and studded (rough ER)

ribosomes (80S)

cytosol (internal fluid)

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64
Q

key features of plant cell

A

vacuole (large and occupying majority of central space)

chloroplasts (double membrane with internal stacks of membrane discs(

cell wall (cellulose, thicker than cell membrane)

shape (brick like with round corners)

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65
Q

prokaryotic vs eukaryotic cell differences

A

DORA

DNA
Organelles
Reproduction
Average size

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66
Q

structure of phospholipids?

A

polar (hydrophilic) head composed of phosphate and glycerol

two nonpolar (hydrophobic) tails composed of fatty acid chains

AMPHIPATHIC (both hydrophobic and hydrophilic parts)

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67
Q

how do phospholipids arrange in membranes?

A

bilayer

phosphate heads face out into the surrounding solution

fatty acid tails face inwards and are shielded from the polar fluids

68
Q

what are the properties of the phospholipid bilayer?

A

bilayer is held together by weak hydrophobic interactions between the tail

passage of many substances is restricted because of the hydrophobic / hydrophilic layers

individual phospholipids can move within the bilayer –> fluidity and flexibility which allows for spontaneous breaking and reforming of membranes –> ENDOCYTOSIS / EXOCYTOSIS

69
Q

what are membrane proteins?

A

the proteins that are embedded in the phospholipid bilayer

70
Q

what are the two main types of membrane proteins?

A

integral proteins (permanently attached to the membrane and are typically transmembrane)

peripheral proteins (temporarily attached by noncovalent interactions and associate with one surface of the membrane)

71
Q

membrane protein functions?

A

JET RAT
Junctions (connect + join two cells together)

Enzymes (fixing to membranes localizes metabolic pathways)

Transport (facilitated diffusion and active transport)

Recognition (markers for cellular identification)

Anchorage (attachment points for cytoskeleton and extracellular matrix)

Transduction (receptors for peptide hormones)

72
Q

what does cholesterol do in mammalian membranes?

A

reduces membrane fluidity and permeability to some solutes

immobilizes the outer surface of the membrane (reduces fluidity) and makes it less permeable to small water soluble molecules

separates phospholipid tails

anchors peripheral proteins and prevents crystallization

73
Q

how are cell membranes represented?

A

fluid mosaic model

74
Q

why is it called the fluid mosaic model and who proposed it?

A

membrane components can move (fluid) while the phospholipid bilayer is embedded with protein (mosaic)

proposed by Singer-Nicolson in 1972

75
Q

what are the components of the plasma membrane?

A

phospholipids
cholesterol
proteins

76
Q

what is the sandwich model?

A

Davson-Danielli’s model where phospholipid bilayer was flanked by two protein layers (sandwich)

77
Q

how was the sandwich model disproven?

A
  • fluorescent tagging showed the proteins are mobile (membrane proteins from 2 different cells were taggeed with fluorescent markers, and the markers became mixed throughout the membrane of the cell after it fused)
  • not all membranes have a constant lipid : protein ratio
  • freeze fracturing identified transmembrane proteins
78
Q

what are the two key qualities of cellular membranes?

A

semi permeable (only certain materials may freely cross - large and charged substances are typically blocked)

selective (membrane proteins may regulate the passage of material that cannot freely cross)

79
Q

what is passive transport?

A

movement of material ALONG a concentration gradient (high concentration to low concentration)

does not require the ATP hydrolysis (expenditure of energy)

80
Q

what are the three types of passive transport

A

simple diffusion (small or lipophilic molecules, ex. O2, CO2)

osmosis (water molecules)

facilitated diffusion (large or charged molecules via membrane proteins, ex.ions, sucrose, etc)

81
Q

what is active transport?

A

movement of materials against a concentration gradient (low concentration to high concentration)

requires ATP hydrolysis (expenditure of energy)

82
Q

what are the two types of active transport?

A

primary (direct) active transport (direct use of metabolic energy to mediate transport)

secondary (indirect) active transport (coupling the molecule with another moving along an electrochemical gradient)

83
Q

what is diffusion?

A

net movement of molecules from a region of high concentration to a region with low concentration

movement is PASSIVE until equilibrium is reached

84
Q

what factors affect the rate of diffusion?

A

temperature
molecular size
steepness of gradient

85
Q

what is osmosis

A

net movement of water molecules across a semi permeable membrane from a region of low solute concentration to a region of high solute concentration (diffusion of free water molecules)

86
Q

what is osmolarity?

A

measure of solute concentration (osmol/L)

87
Q

what are the three ways solutions can be measured (osmolarity)

A

hypertonic (high solute concentration, gains water)

hypotonic (low solute concentration, loses water)

isotonic (same solute concentration, no net flow)

88
Q

how do solute concentrations affect cells?

A

animal cells:

hypertonic: shriveled
isotonic: normal
hypotonic: lysed

plant cells:

hypertonic: plasmolysed
isotonic: flaccid
hypotonic: turgid

89
Q

what transport proteins mediate faciliated diffusion?

A

channel and carrier proteins

90
Q

what are carrier proteins?

A

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

91
Q

channel proteins

A

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

92
Q

which type of transport protein is used to move molecules against concentration gradients?

A

carrier proteins

93
Q

which transport protein has a faster rate of transport?

A

channel

94
Q

what are potassium channels?

A

integral proteins with a hydrophilic inner pore via which potassium ions may be transported

voltage gated

95
Q

what is the structure and fucntion of sodium potassium pumps which permits active functions?

A

axons of nerve cells transmit electrical impusles by translocating ions to create a voltage difference across the membrane

pump expels sodium ions from the nerve cell and accumulates K+ within

when neuron fires, ions swap locations via facilitated diffusion via sodium and potassium channels

96
Q

how is the energy for active transport generated?

A

direct hydrolysis of ATP (primary active transport)

indirectly coupling transport with another molecule (secondary active transport)

97
Q

how do carrier proteins / protein pumps work?

A

a specific solute binds to the protein pump on one side of the membrane

hydrolysis of ATP (to ADP + Pi) causes a conformational change in the protein pump

solute molecule is consequently translocated across the membrane (against the gradient) and released)

98
Q

sodium potassium pump definition

A

protein that exchanges 3 sodium ions (out of cell) with two potassium ions (into cell)

99
Q

what is the process of ion exchange against the gradient in the sodium potassium pump?

A
  1. 3 sodium ions bind to intracellular sites on the sodium potassium pump
  2. phosphate group is transferred to the pump via the hydrolysis of ATP
  3. pump undergoes a conformational change, translocating sodium across the membrane
  4. the conformational change exposes two potassium binding sites on the extracellular surface of the pump
  5. the phosphate group is released which causes the pump to return to its original conformation
  6. this translocates the potassium across the membrane, completing the ion exchange
100
Q

what is exocytosis?

A

materials released from a cell via vesicles

101
Q

what is endocytosis?

A

materials internalized within a vesicle

102
Q

how are the materials destined for secretion transported around the cell?

A

vesicles

103
Q

how are materials transported around the cell through vesicular transport?

A
  1. Rough ER synthesizes proteins, smooth ER synthesizes lipids
  2. materials are transported from the ER when membrane bulges and forms a vesicle
  3. vesicle fuses to the internal face of the complex of the golgi apparatus
  4. materials move from the internal cis face to the external trans face of the golfi apparatus
  5. materials are secreted externally or transported to the lysosome

–
extracellular use material goes to the plasma membrane (vesicle fuses with the cell membrane)

104
Q

what is abiogenesis

A

theory that living cells arose from nonliving matter

105
Q

stages of abiogenesis

A
  1. nonliving synthesis of simple organic molecules (from primordial inorganic molecules)
  2. simple organic molecules became assembled into more complex polymers
  3. certain polymers formed the capacity to self replicate
  4. molecules became packaged into membranes with an internal chemistry different from their surroundings
106
Q

what experiment demonstrated the nonliving synthesis of simple organic molecules?

A

miller urey experiment

107
Q

what did the Miller-Urey experiment replicate?

A

conditions of a pre-biotic Earth in order to synthesize organic molecules

108
Q

what is biogenesis?

A

the principle that living things only arise from other living things by reproduction (not spontaneous generation)

109
Q

how do we know that living cells cannot arise independently (by abiogenenis)

A

the chemical processes that contributed to the initial formation do not commonly exist on modern earth

110
Q

what conditions were required for the initial formation of biological life?

A

reducing atmosphere, high temperatures, or lectrical discharges

111
Q

who demonstrated the law of biogenesis?

A

louis pasteur

112
Q

how was the law of biogenesis demonstrated?

A

Broths were stored in sealed vessels that were sterilised

Bacterial growth occurred if vessel was unsealed, but
did not occur if vessel stayed sealed (no contamination)

113
Q

what is an endosymbiont?

A

a cell which lives inside another cell with mutual benefit

114
Q

what are the 5 pieces of evidence for endosymbiosis?

A

Membranes (double membrane bound)
Antibiotics (susceptibility to antibiotics)
Division (occurs via fission-like process)
DNA (presence and structural composition / naked, circular DNA)
Ribosomes (70S ribosomes)

MAD DR

115
Q

what did prokaryotes evolve into?

A

eukaryotic cells (prokaryotes that were engulfed by phagocytosis)

116
Q

stages of endosymbiosis

A
  1. ancestral prokaryote
  2. infolding of plasma membrane (nucleus forming)
  3. endosymbiosis
  4. ancestral eukaryote!
117
Q

what is the RNA world hypothesis?

A

The RNA world hypothesis proposes that a world filled with RNA-based life predates current DNA-based lifeforms

118
Q

why does the RNA world hypothesis work? (key qualities of RNA)

A

self replication + ability to act as a catalyst

119
Q

what did the appearance of photosynthetic organisms lead to?

A

rapidly increasing oxygenation of the Earth’s environment

120
Q

how did oxygenation change oceans?

A

iron oxide was formed as earth’s oceans used to have high levels of dissolved iron

121
Q

how did oxygenation change rock deposition?

A

insoluble iron formed banded iron formations

122
Q

how did oxygenation change the atmosphere

A

oxygen started accumulating as the dissolved iron was completely consumed

123
Q

what are the two main phases of the cell cycle?

A

interphase and M phase

124
Q

What are the three phases of interphase?

A

G1
S
G2

125
Q

what happens in the three phases of interphase?

A

G1 - cell grows and prepares for DNA replication
S - synthesis stage/DNA replication
G2 - cell finishes growing and prepares for cell division

126
Q

What are the two phases of M phase?

A

mitosis, cytokinesis

127
Q

what happens in the two phases of the M phase?

A

mitosis - nuclear division (DNA separates into two identical nuclei)
cytokinesis - cytoplasmic division, cellular contents are segregated and the cell divides into two

128
Q

what happens during interphase to prepare the cell for successful division?

A 
DNA replication (S phase)
Organelle duplication 
Cell growth
Transcription/Translation 
Obtain nutrients
Respiration (cellular, ATP production)

DOCTOR

129
Q

what is a chromosome?

A

condensed form of DNA

130
Q

what are sister chromatids?

A

genetically identical strands in the chromosome

131
Q

what are sister chromatids held together by?

A

central region called the centromere

132
Q

how is chromatin packed and why?

A

loosely packed, DNA can be transcribed and translated

133
Q

how are chromosomes packed and why?

A

tightly, DNA can be segregated

134
Q

what is mitosis?

A

process of nuclear division whereby duplicated DNA molecules are arranged into two separate nuclei

135
Q

what are the four stages of mitosis?

A

prophase, metaphase, anaphase, telophase

136
Q

what happens during prophase

A

DNA supercoils and condenses
paired centrosomes move to opposite poles
nuclear membrane breaks down and the nucleus dissolves

137
Q

what happens during metaphase?

A

microtubule spindle fibres connect to the centromere of each chromosome and the chromosomes align along the centre of the cell (because of depolymerization causing the spindle fibres to shorten)

138
Q

what happens during anaphase?

A

sister chromatids separate and move to opposite poles as spindle fibres continue to contract

139
Q

what happens during telophase?

A

spindle fibres dissolve, chromosomes decondense, nuclear membranes reform around each chromosome set, cytokinesis occurs at the same time

140
Q

what is cytokinesis?

A

process of cytoplasmic division

141
Q

how does cytokinesis vary between animals and plants?

A

animals: microtubules form a concentric ring and contract towards the centre (centripetal)
plants: vesicles form at the cell centre and fuse outwards to form a cell plate (centrifugal)

142
Q

define the mitotic index

A

measure of the proliferation status of a cell population (i.e. the proportion of dividing cells)

acts as a prognostic tool for cancer (elevated during growth)

143
Q

what is the mitotic index?

A

mitotic index = cells in mitosis / total number of cells

cells in mitosis lack a clearly defined nucleus

144
Q

KEY EVENTS of interphase

A

DNA is uncondensed

DNA is replicated to form genetically identical sister chromatids

cell grows in size and organelles are duplicated

145
Q

what happens during cytokinesis

A

cytoplasmic division

146
Q

what are cyclins

A

family of regulatory proteins that control the progression of the cell cycle

147
Q

full form of CDK? what do CDKs do?

A

cyclin dependent kinases

control cell cycle processes through phosphorylation

148
Q

how do cyclins control the progression of the cell cycle?

A
  1. cyclins bind to CDKs
  2. activated complex phosphorylates proteins involved in specific cell cycle events (triggering it) (ex. centrosome duplication)
  3. after the event has occured, cyclin is degraded and the CDK is rendered inactive again
149
Q

role of cell cycle checkpoints?

A

ensure the fidelity and viability of continued cell divisions

150
Q

what does the G1 checkpoint do

A

monitors potential growth conditions (nutrients etc)

assesses level of DNA damage

151
Q

what does the G2 checkpoint do?

A

monitors state of pre mitotic cell (suitable size, etc.)

identifies and repairs any DNA replication errors

152
Q

metaphase

A

ensures proper alignment

153
Q

what are tumours and what are they caused by?

A

abnormal cell growths

uncontrolled cell division

154
Q

what is cancer

A

disease caused by the growth of tumours

155
Q

what is a mutagen

A

agent that changes the genetic material of an organism

156
Q

what are carcinogens?

A

mutagens that lead to the formation of cancer

157
Q

what is an oncogene?

A

gene with the potential to cause cancer

158
Q

what are the two basic classes of genes that cause cancer when mutated?

A

protooncogenes (proteins that stimulate the cell cycle and promote cell growth)

tumour suppressor (proteins that repress cell cycle progression)

159
Q

what is metastasis?

A

spread of cancer from one location (primary tumour) to another (secondary tumour)

160
Q

what are benign tumour cells

A

tumour cells that remain in their original location

161
Q

what are malignant tumour cells

A

cells that invade neighbouring tissue

162
Q

what are the functions of mitosis?

A 
Tissue repair / replacement
Organismal growth
Asexual reproduction
Development of embryos
TOAD
163
Q

what are the two ways a cell dies?

A

necrosis

apoptosis

164
Q

what is necrosis?

A

uncontrolled cell death

uncontrolled cell homicide

destablization of membrane due to injury, toxics, etc. which leads to swelling, leading to the bursting of a cell

165
Q

what is apoptosis?

A

programmed cell suicide

controlled event triggered by mitochondrial proteins where cell contents are packaged in membranous protrusions (blebs) and cell fragments into apoptotic bodies

166
Q

what are the differences between apoptosis and necrosis?

A

size (necrosis = swelling, many cells apoptosis = shrinkage, one cell)
uptake (destination of contents –> macrophage vs neighbouring cell and localized effects–> inflammation)
membrane (integrity of bilayer)
organelles (preserved or destroyed)

SUMO

biology (11 decks)

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