topic 1 cell biology Flashcards
(166 cards)
1
Q
the cell theory states that…
A
- All living things are composed of cells (or cell products)
- The cell is the smallest unit of life
- Cells only arise from pre-existing cells
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
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
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)
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)
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)
7
Q
rate of material exchange
A
a function of its surface area (large membrane surface equates to more material movement)
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)
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
10
Q
how to calculate magnification?
A
magnification = image size / real size
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
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
13
Q
What are examples of cells that increase the SA:Vol ratio?
A
intestinal tissue of the digestive tract (villi!!)
alveoli have microvilli
14
Q
organization of multicellular organisms
A
cell, tissue, organ, system, organism
15
Q
example of an organisation of multicellular organism
A
muscle, cardiac, heart, vascular, human
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)
17
Q
what is differentiation?
A
process during development whereby newly formed cells become more specialised and distinct from one another as they mature
18
Q
do cells of an organism share identical genomes?
A
YES
19
Q
how do cells differentiate?
A
different genes are activated within a given cell by chemical signals
20
Q
how are active genes packaged?
A
expanded form called EUCHROMATIN
21
Q
how are inactive genes packaged
A
heterochromatin (saves space, not transcribed)
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
23
Q
what are the four main types of stem cells?
A
totipotent
pluripotent
multipotent
unipotent
24
Q
functions of totipotent stem cells?
A
can form any cell type (as well as placental tissue)
25
function of pluripotent stem cells(
can form any cell type
26
function of multipotent stem cell?
can differentiate into a number of closely related cell types
27
function of unipotent stem cells?
can not differentiate, but are capable of self renewal
28
what is one way stem cells are applied to medicine?
therapeutic option when tissues become damaged
29
process of using stem cells to replace damaged or diseased cells?
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
30
Three examples of stem cell therapy?
Stargardt's Disease
Parkinson's Disease
Leukemia/Paraplegia/Diabetes/Burn victims
31
What is Stargardt's Disease?
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
32
what is parkinson's disease?
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
33
how are stem cells derived?
embyros, umbilical cord blood, placenta, bone marrow
34
what are the ethical considerations to be taken into account when using stem cells therapeutically?
- 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
35
how are artificial stem cells generated? (2 ways!)
somatic cell nuclear transfer (SCNT)
nuclear reprogramming
36
what is somatic cell nuclear transfer (SCNT)
creation of embyronic clones by fusing a diploid nucleus with an enucleated egg cell
more embryos are created by this process than needed
37
what is nuclear reprogramming?
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)
38
what are prokaryotic cells?
organisms that lack a nucleus
39
what kingdom are prokaryotes in? + domains
Monera //
Archaebacteria (extreme environments, like high temperature, salt concentrations or pH)
Eubacteria (traditional bacteria)
40
What are the features of prokaryotic cells? + functions!!
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)
41
how do prokaryotic cells reproduce?
asexual reproduction // binary fission
42
what is binary fission?
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
43
what are eukaryotes?
organisms whose cells contain a nucleus
evolved from prokaryotic cells
compartmentalized by membrane bound structures (organelles) that perform specific roles
44
four kingdoms of eukaryotes?
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
45
what are universal organelles? (structure + function)
Ribosomes
Cytoskeleton
Plasma membrane
46
what are eukaryotic organelles (function + structure)
```
Nucleus
Endoplasmic Reticulum
Golgi Apparatus
Mitochondrion
Peroxisome
Centrosome
```
47
ribosome function and structure
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)
48
cytoskeleton function and structure
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)
49
plasma membrane function and structure?
Structure: Phospholipid bilayer embedded with proteins (not an organelle per se, but a vital structure)
Function: Semi-permeable and selective barrier surrounding the cell
50
nucleus structure and function?
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
51
organelles in plant cell only?
chloroplast
vacuole
cell wall
52
organelles in animal cells only?
lysosome
53
endoplasmic reticulum function + structure?
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)
54
golgi apparatus function + structure?
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
55
mitochondrion function and structure?
Structure: Double membrane structure, inner membrane highly folded into internal cristae
Function: Site of aerobic respiration (ATP production)
56
peroxisome function + structure?
Structure: Membranous sac containing a variety of catabolic enzymes
Function: Catalyses breakdown of toxic substances (e.g. H2O2) and other metabolites
57
centrosome function + structure?
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)
58
chloroplast function + structure?
Structure: Double membrane structure with internal stacks of membranous discs (thylakoids)
Function: Site of photosynthesis – manufactured organic molecules are stored in various plastids
59
vacuole function + structure?
Structure: Fluid-filled internal cavity surrounded by a membrane (tonoplast)
Function: Maintains hydrostatic pressure (animal cells may have small, temporary vacuoles)
60
cell wall function + structure?
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
61
lysosome function + structure?
Structure: Membranous sacs filled with hydrolytic enzymes
Function: Breakdown / hydrolysis of macromolecules (presence in plant cells is subject to debate)
62
key features of prokaryote structure
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
63
key features of animal cell structure
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)
64
key features of plant cell
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)
65
prokaryotic vs eukaryotic cell differences
DORA
DNA
Organelles
Reproduction
Average size
66
structure of phospholipids?
polar (hydrophilic) head composed of phosphate and glycerol
two nonpolar (hydrophobic) tails composed of fatty acid chains
AMPHIPATHIC (both hydrophobic and hydrophilic parts)
67
how do phospholipids arrange in membranes?
bilayer
phosphate heads face out into the surrounding solution
fatty acid tails face inwards and are shielded from the polar fluids
68
what are the properties of the phospholipid bilayer?
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
what are membrane proteins?
the proteins that are embedded in the phospholipid bilayer
70
what are the two main types of membrane proteins?
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
membrane protein functions?
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
what does cholesterol do in mammalian membranes?
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
how are cell membranes represented?
fluid mosaic model
74
why is it called the fluid mosaic model and who proposed it?
membrane components can move (fluid) while the phospholipid bilayer is embedded with protein (mosaic)
proposed by Singer-Nicolson in 1972
75
what are the components of the plasma membrane?
phospholipids
cholesterol
proteins
76
what is the sandwich model?
Davson-Danielli's model where phospholipid bilayer was flanked by two protein layers (sandwich)
77
how was the sandwich model disproven?
- 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
what are the two key qualities of cellular membranes?
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
what is passive transport?
movement of material ALONG a concentration gradient (high concentration to low concentration)
does not require the ATP hydrolysis (expenditure of energy)
80
what are the three types of passive transport
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
what is active transport?
movement of materials against a concentration gradient (low concentration to high concentration)
requires ATP hydrolysis (expenditure of energy)
82
what are the two types of active transport?
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
what is diffusion?
net movement of molecules from a region of high concentration to a region with low concentration
movement is PASSIVE until equilibrium is reached
84
what factors affect the rate of diffusion?
temperature
molecular size
steepness of gradient
85
what is osmosis
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
what is osmolarity?
measure of solute concentration (osmol/L)
87
what are the three ways solutions can be measured (osmolarity)
hypertonic (high solute concentration, gains water)
hypotonic (low solute concentration, loses water)
isotonic (same solute concentration, no net flow)
88
how do solute concentrations affect cells?
animal cells:
hypertonic: shriveled
isotonic: normal
hypotonic: lysed
plant cells:
hypertonic: plasmolysed
isotonic: flaccid
hypotonic: turgid
89
what transport proteins mediate faciliated diffusion?
channel and carrier proteins
90
what are carrier proteins?
glycoproteins that bind a solute and undergo a conformational change to translocate the solute across the membrane
91
channel proteins
lipoproteins that contain a pore via which ions may cross from one side of the membrane to the other
92
which type of transport protein is used to move molecules against concentration gradients?
carrier proteins
93
which transport protein has a faster rate of transport?
channel
94
what are potassium channels?
integral proteins with a hydrophilic inner pore via which potassium ions may be transported
voltage gated
95
what is the structure and fucntion of sodium potassium pumps which permits active functions?
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
how is the energy for active transport generated?
direct hydrolysis of ATP (primary active transport)
indirectly coupling transport with another molecule (secondary active transport)
97
how do carrier proteins / protein pumps work?
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
sodium potassium pump definition
protein that exchanges 3 sodium ions (out of cell) with two potassium ions (into cell)
99
what is the process of ion exchange against the gradient in the sodium potassium pump?
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
what is exocytosis?
materials released from a cell via vesicles
101
what is endocytosis?
materials internalized within a vesicle
102
how are the materials destined for secretion transported around the cell?
vesicles
103
how are materials transported around the cell through vesicular transport?
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
what is abiogenesis
theory that living cells arose from nonliving matter
105
stages of abiogenesis
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
what experiment demonstrated the nonliving synthesis of simple organic molecules?
miller urey experiment
107
what did the Miller-Urey experiment replicate?
conditions of a pre-biotic Earth in order to synthesize organic molecules
108
what is biogenesis?
the principle that living things only arise from other living things by reproduction (not spontaneous generation)
109
how do we know that living cells cannot arise independently (by abiogenenis)
the chemical processes that contributed to the initial formation do not commonly exist on modern earth
110
what conditions were required for the initial formation of biological life?
reducing atmosphere, high temperatures, or lectrical discharges
111
who demonstrated the law of biogenesis?
louis pasteur
112
how was the law of biogenesis demonstrated?
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
what is an endosymbiont?
a cell which lives inside another cell with mutual benefit
114
what are the 5 pieces of evidence for endosymbiosis?
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
what did prokaryotes evolve into?
eukaryotic cells (prokaryotes that were engulfed by phagocytosis)
116
stages of endosymbiosis
1. ancestral prokaryote
2. infolding of plasma membrane (nucleus forming)
3. endosymbiosis
4. ancestral eukaryote!
117
what is the RNA world hypothesis?
The RNA world hypothesis proposes that a world filled with RNA-based life predates current DNA-based lifeforms
118
why does the RNA world hypothesis work? (key qualities of RNA)
self replication + ability to act as a catalyst
119
what did the appearance of photosynthetic organisms lead to?
rapidly increasing oxygenation of the Earth's environment
120
how did oxygenation change oceans?
iron oxide was formed as earth's oceans used to have high levels of dissolved iron
121
how did oxygenation change rock deposition?
insoluble iron formed banded iron formations
122
how did oxygenation change the atmosphere
oxygen started accumulating as the dissolved iron was completely consumed
123
what are the two main phases of the cell cycle?
interphase and M phase
124
What are the three phases of interphase?
G1
S
G2
125
what happens in the three phases of interphase?
G1 - cell grows and prepares for DNA replication
S - synthesis stage/DNA replication
G2 - cell finishes growing and prepares for cell division
126
What are the two phases of M phase?
mitosis, cytokinesis
127
what happens in the two phases of the M phase?
mitosis - nuclear division (DNA separates into two identical nuclei)
cytokinesis - cytoplasmic division, cellular contents are segregated and the cell divides into two
128
what happens during interphase to prepare the cell for successful division?
```
DNA replication (S phase)
Organelle duplication
Cell growth
Transcription/Translation
Obtain nutrients
Respiration (cellular, ATP production)
```
DOCTOR
129
what is a chromosome?
condensed form of DNA
130
what are sister chromatids?
genetically identical strands in the chromosome
131
what are sister chromatids held together by?
central region called the centromere
132
how is chromatin packed and why?
loosely packed, DNA can be transcribed and translated
133
how are chromosomes packed and why?
tightly, DNA can be segregated
134
what is mitosis?
process of nuclear division whereby duplicated DNA molecules are arranged into two separate nuclei
135
what are the four stages of mitosis?
prophase, metaphase, anaphase, telophase
136
what happens during prophase
DNA supercoils and condenses
paired centrosomes move to opposite poles
nuclear membrane breaks down and the nucleus dissolves
137
what happens during metaphase?
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
what happens during anaphase?
sister chromatids separate and move to opposite poles as spindle fibres continue to contract
139
what happens during telophase?
spindle fibres dissolve, chromosomes decondense, nuclear membranes reform around each chromosome set, cytokinesis occurs at the same time
140
what is cytokinesis?
process of cytoplasmic division
141
how does cytokinesis vary between animals and plants?
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
define the mitotic index
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
what is the mitotic index?
mitotic index = cells in mitosis / total number of cells
| cells in mitosis lack a clearly defined nucleus
144
KEY EVENTS of interphase
DNA is uncondensed
DNA is replicated to form genetically identical sister chromatids
cell grows in size and organelles are duplicated
145
what happens during cytokinesis
cytoplasmic division
146
what are cyclins
family of regulatory proteins that control the progression of the cell cycle
147
full form of CDK? what do CDKs do?
cyclin dependent kinases
control cell cycle processes through phosphorylation
148
how do cyclins control the progression of the cell cycle?
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
role of cell cycle checkpoints?
ensure the fidelity and viability of continued cell divisions
150
what does the G1 checkpoint do
monitors potential growth conditions (nutrients etc)
assesses level of DNA damage
151
what does the G2 checkpoint do?
monitors state of pre mitotic cell (suitable size, etc.)
identifies and repairs any DNA replication errors
152
metaphase
ensures proper alignment
153
what are tumours and what are they caused by?
abnormal cell growths
uncontrolled cell division
154
what is cancer
disease caused by the growth of tumours
155
what is a mutagen
agent that changes the genetic material of an organism
156
what are carcinogens?
mutagens that lead to the formation of cancer
157
what is an oncogene?
gene with the potential to cause cancer
158
what are the two basic classes of genes that cause cancer when mutated?
protooncogenes (proteins that stimulate the cell cycle and promote cell growth)
tumour suppressor (proteins that repress cell cycle progression)
159
what is metastasis?
spread of cancer from one location (primary tumour) to another (secondary tumour)
160
what are benign tumour cells
tumour cells that remain in their original location
161
what are malignant tumour cells
cells that invade neighbouring tissue
162
what are the functions of mitosis?
```
Tissue repair / replacement
Organismal growth
Asexual reproduction
Development of embryos
TOAD
```
163
what are the two ways a cell dies?
necrosis
| apoptosis
164
what is necrosis?
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
what is apoptosis?
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
what are the differences between apoptosis and necrosis?
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
