Cell Biology CHAP 1 Flashcards
1
Q
What 3 statements make up CELL Theory
A
1) All living things are composed of cells
2) The cell is the smallest unit of life
3) cells only arise from pre-existing cells
2
Q
1) All living things are composed of cells
2) The cell is the smallest unit of life
3) cells only arise from pre-existing cells
A
Cell theory
3
Q
What types of cells are an exception to cell theory?
A
1) striated (striped or streaked) muscle fibres
2) giant algae
3) Aseptate fungal hyphae
4
Q
Why are striated muscle fibres an exception to typical cells?
A
Muscle cells fuse together to form fibres, therefore each fibre has multiple nuclei
5
Q
Why are giant algae an exception to typical cells?
A
Some species of algae grow to large sizes therefore cells may not always be microscopic.
(e.g, ACETABULARIA may exceed 7cm)
6
Q
Why are Aseptate fungal cells an exception to typical cells ?
A
Hyphae (branch of fungus) are separated into cells by internal walls called septa. Some hyphae lack separation and therefore have a continuous cytoplasm.
7
Q
What are the 7 basic characteristics that all living things share? “MR SHENG”
A
M metabolism , R reproduction, S sensitivity, H homostasis, E excretion, N nutrition, G grow/move
MR SHENG
8
Q
What does MR SHENG stand for? than list them.
A
metabolism, reproduction, sensitivity, homostasis, excretion, nutrition, growth/movement
7 characteristics of life
9
Q
Unicellular organisms must carry out all the functions of life. How does a paramecium do this? give an example for each of the 7 characteristics.
A
Paramecium:
M: Heterotrophic, R: asexual reproduction via mitosis,
S: Towards food, H: Regulate gas and water levels, E: Via anal pore, N: Food vacuoles, G: move via cilia.
10
Q
Unicellular organisms must carry out all the functions of life. How does a Chlorella (single celled algae) do this? give an example for each of the 7 characteristics.
A
Chlorella:
M: Autotrophic, R: asexual reproduction via mitosis,
S: Towards light, H: Regulate gas and water levels, E: Via diffusion, N: photosynthesis , G: non-motile
11
Q
Cells produce energy to survive and this requires material exchange. Metabolic rate is a function of its ______
A
Volume
12
Q
What is metabolic rate?
A
The rate in which metabolism occurs in living organisms
13
Q
Cells produce energy to survive and this requires material exchange. Rate of material exchange is a function of its ________
A
Surface area
14
Q
As a cell grows, its volume ________ faster than its surface area
A
Increases
15
Q
What causes a decreased SA: Vol ratio?
A
As a cells grows its volume increases faster than its surface area
16
Q
What happens if material exchange is insufficient to maintain metabolism? How to cells prevent this?
A
The cell dies
Cells remain small by dividing
17
Q
Name a specialised cell for material exchange that will increase their surface area?
A
Microvilli
18
Q
What system of measurement is used to measure size and dimensions of biological materials ?
A
Metric system (metre, milimetre, micrometres, nanometre, picometre)
19
Q
Sort these measurements in order from largest to smallest mentioning the division difference between them
(pm,um,mm,m,nm)
A
m , mm , um , nm , pm
To get from one to another in decreasing order you divide by 1000
20
Q
What is the approximate size of a eukaryotic cell?
A
100 um
21
Q
What is the approximate size of an organelle (e.g, nucleus)
A
> 10um
22
Q
What is the approximate size of a bacteria ?
A
1-5 um
23
Q
What is the approximate size of a virus ?
A
100nm
24
Q
What is the approximate size of a ribosome ?
A
30nm
25
What is the approximate width of a cell membrane ?
7.5nm
26
What is the approximate size of a molecule ?
1nm
27
What is the equation for linear magnification?
Magnification = Image size (with ruler) / Actual size (scale bar)
M I A
28
Define "emergent properties" and say how they're useful
When different cells interact together creating new functions. Useful because multicellular organisms are capable of completing functions that individual cells could not undertake
29
Give an example of emergent properties
Cell -> Tissue -> Organ -> System
| Muscle -> Cardiac -> Heart -> Vascular
30
Define Differentiation
The process in which new cells become more specialised and distinct from one another
31
All cells of an organism share an identical ______
Genome
32
Define Genome
The complete set of genes or genetic material present in a cell or organism. The haploid set of chromosomes in a gamete or microorganisms.
33
What causes a cell to differentiate?
The activation of some genes but not others
34
What causes some genes to activate ?
Chemical signals (e.g hormones, transcription factors)
35
What are stem cells?
Unspecialised cells
36
What 2 qualities do stem cells have ?
Self renewal: Can divide and replicate
| Potency: Capable of differentiation
37
What are the 4 levels of potency regarding stem cells?
Totipotent
Pluripotent
Multipotent
Unipotent
38
What are Totipotent cells?
Cells that can form new organisms
39
What are Pluripotent cells?
Cells that can for most cell types
40
What are Multipotent cells ?
Cells than can form limited cell types
41
What are Unipotent cells?
Cells that cannot differentiate
42
What potency level are Embryonic stem cells?
Totipotent / Pluripotent
43
What potency level are Fetal stem cells?
Pluripotent / Multipotent
44
What potency level are Adult stem cells?
Multipotent / Unipotent
45
Where can you get stem cells from? Live examples
Embryos, the placenta, umbilical cord, certain adult tissues (e.g. bone marrow)
46
What can you use stem cells for?
Used to replace damaged or diseased tissue with healthy tissue
47
Describe the process of replacing damaged tissue with healthy tissue
- Chemicals to trigger differentiation
- Surgical implantation into patient's tissue
- Suppression of immune system to prevent rejection
- Monitoring new cells to ensure they don't become cancerous.
48
Give specific examples of Therapeutic stem cells
- Replacing dead retinal cells to treat macula dystrophy (Stargardt's disease)
- Grafting new skin cells in burns victim
- Replacing nerve cells in spinal injuries
- Bone marrow transplants for patients on Chemotherapy
49
Name some ethics (both positive and negative) associated with therapeutic use of stem cells from EMBRYONIC CELLS
Embryonic cells
Good: Have almost unlimited growth potential
Can be generated artificially by SCNT
Bad: Involves destruction of an embryo
Higher risk of cancer development
50
Name some ethics (both positive and negative) associated with therapeutic use of stem cells from UMBILICAL CORD BLOOD OF A NEWBORN
Umbilical cord blood of newborn
Good: Easy to extract from umbilical cord
Bad: Cells must be stored from birth at cost
51
Name some ethics (both positive and negative) associated with therapeutic use of stem cells from ADULT TISSUES (e.g. Bone marrow)
Adult stem cells
Good: Can be obtained at any stage of life
Bad: Cells may be difficult / painful to extract
Lowest growth potential (multipotent)
52
Name an alternative technology that may be used to generate stem cells
Nuclear programming
53
List one positive and one negative regarding light microscopes
Good: Can view living things in natural colour
Bad: Have lower magnification / resolution
54
List one positive and one negative regarding Electron Microscopes
Good: Have higher magnification / resolution
Bad: Can view dead things in monochrome (Black and white)
55
How can Electron microscopy prepare images ?
As cross-sections (transmission EM)
| As surface renderings (scanning EM)
56
What 2 categories can cells be sorted into?
Prokaryotes
| Eukaryotes
57
What category of cell consists of cells that lack a nucleus and are bacteria
Prokaryotes
58
What category of cell consists of cells that have nucleus and show compartmentalisation (divided into sections)
Eukaryotes
59
Compare Prokaryote and Eukaryote DNA
Prokaryote DNA: Is Naked, Is Circular, No Introns
Eukaryote DNA: Protein bound, Is linear, Has Introns
60
Compare Prokaryote and Eukaryote Organelles
Prokaryote Organelles: No nucleus, 70S ribosomes, No organelles are membrane-bound
Eukaryote Organelles: Have a nucleus, 80S ribosomes, Membrane-bound organelles present
61
Compare Prokaryote and Eukaryote Reproduction
Prokaryote reproduction: Via Binary Fission
Eukaryote reproduction: Mitosis + meiosis
62
Compare Prokaryote and Eukaryote Average sizes
Prokaryote Size: Smaller (1-5 um)
Eukaryote Size: Larger (>10 um)
63
Who do Prokaryotic cells reproduce?
Binary Fission
64
Describe the Process of Binary Fission
1) The circular DNA is first copied
2) Both DNA loops attach to the membrane
3) The cells elongates, drawing loops apart
4) Cytokinesis occurs, forming 2 cells
65
Name what 10 organelles are in an animal cell
Lysosome, Rough ER, Nucleolus, Nucleus, Golgi apparatus, Mitochondrion, Smooth ER, Cell membrane, 80S ribosomes, Cytosol
66
Name what 11 organelles are in an plant cell
Golgi apparatus, Smooth ER, Nucleus, Rough ER, Cytosol, Ribosomes 80s, Cell membrane, Cell wall, Chloroplast, Vacuole, Mitochondrion
67
What are 6 key features of animal and plant cells
- Cells have a nucleus and compartments
- Nucleus has a double membrane and pores
- Animal cells possess lysosomes
- Plant cells have chloroplasts and large vacuole
- Plant cell wall is made up of cellulose
- Eukaryotic ribosomes are 80S
68
Define organelles
Specialised sub-structures within a cell that serve a specific function
69
What is the function of a RIBOSOME ?
The site of protein synthesis : Both in prokaryote and eukaryote
70
What is the function of a CYTOSKELETON ?
Internal scaffolding (a microscopic network of protein filaments and tubules found in the cytoplasm in organisms giving shape) : Both in prokaryote and eukaryote
71
What is the function of a NUCLEUS ?
Stores genetic material (DNA)
| NUCLEOLUS - is the site of ribosome assembly
72
What is the function of the ER ? Distinguish between ROUGH and SMOOTH
Internal transport network
ROUGH = PROTEINS
SMOOTH = LIPIDS
73
What is the function of a GOLGI APPARATUS
| EUKARYOTIC : both animal and plant
Export secretory products
74
What is the function of the MITOCHONDRIA
| EUKARYOTIC : both animal and plant
ATP production (aerobic respiration)
75
What is the function of PEROXISOME
| EUKARYOTIC : both animal and plant
Digests toxic Metabolites
76
What is the function of CENTROSOME
| EUKARYOTIC : both animal and plant
Involved in cell division
77
What is the function of a CHLOROPLAST
| PLANT ONLY
Site of photosynthesis
78
What is the function of the CELL WALL
| PLANT ONLY
Provides mechanical support
79
What is the function of a VACUOLE
| PLANT ONLY
Stores fluid (for internal pressure) (Animal cells may have temporary vacuoles)
80
What is the function of the LYSOSOME
| ANIMAL ONLY
Digests macromolecules
| presence in plants is subject to debate
81
Name the key differences between ANIMAL AND PLANT cells
PLASTIDS:
PLANT CELLS have chloroplasts
ANIMALS cells do not have plastids
CELL WALL:
PLANT CELLS have a cellulose cell wall
ANIMAL CELLS do not have a cell wall
VACUOLE:
PLANT CELLS: Have a large central vacuole
ANIMAL CELLS: Have temporary vacuoles
GLUCOSE STORAG:
PLANT CELLS: Store excess glucose as starch
ANIMAL CELLS: Store excess glucose as glycogen
OTHER:
- Only plant cells have plasmodesmata
- Plant cells do not possess centrioles
- No cholesterol in plant cell membranes
82
Name the 2 key properties of Cell Membranes
SEMI- PERMEABILITY : (only some materials can cross unaided) Small molecules can cross, large cannot
SELECTIVITY: (the passage of materials is regulated) membrane proteins assist material movement
83
What are the two main components in a cells plasma membrane
- Phospholipids (arranged in a bilayer)
| - Membrane Proteins
84
What are the 2 models used to describe MEMBRANE STRUCTURE?
Davson-Danielli Model
| Singer- Nicolson model
85
Distinguish between the Davson- Danieli and Singer-Nicolson model
Davson = Two outer layers of protien flank an inner phospholipid bilayer (Lipo-protein sandwich)
Singer = Proteins embedded within phospholipid bilayer instead of existing as separate layers
86
Which Membrane structure is correct, and which has been rejected ?
```
Singer = Correct
Davson = wrong and rejected
```
87
Describe how BIOCHEMICAL EVIDENCE helps reject the DAVSON-DANIELLI model
1) Not all membranes have a constant ratio of lipid:protein (no to sandwich model)
2) Membrane proteins vary in size and are insoluble in water (can't form an outer layer)
88
Describe how FLUORESCENT ANTIBODY TAGGING helps reject the DAVSON-DANIELLI model
1) Membrane proteins are mobile and are not fixed in place (do not form a static layer)
89
Describe how FREEZE FRACTURING helps reject the DAVSON-DANIELLI model
1) Fracturing the membrane reveals a rough and irregular internal surface
2) These irregularities are interpreted as transmembrane proteins
90
The Fluid-Mosaic model is based on whose model?
Singer-Nicolson
Integral protein (the channel between)
Phospholipid (the heads of the "sperm")
Peripheral protein (the big lump attached)
Cholesterol (The hexagonal small in comparison bits)
91
Explain the structure of Phospholipids
- Polar head (hydrophilic) consisting of phosphate and glycerol
- Non-polar tail (hydrophobic) consisting of 2 fatty acid chains
92
Explain the arrangement of the phospholipid membrane
- Phospholipids arrange into bilayer
- Hydrophobic tail regions face inwards (shielded from fluid)
- Hydrophilic head regions face outwards towards the surrounding fluids
93
Explain the structural properties of the phospholipid membrane
- Bilayer held together by hydrophobic interactions (weak associations)
- Weak associations allow for membrane fluidity and flexibility
- Fluidity allows membrane to break and reform (exocytosis / endocytosis)
- Hydrophilic / hydrophobic layers restrict entry of certain substances
94
What are the 2 types of membrane proteins?
1) Integral proteins (Transmembrane = existing or occurring across a cell membrane)
2) Peripheral proteins (localised to one side)
95
Describe INTEGRAL PROTEINS and their 2 structural forms
Integral proteins are permanently attached to a membrane and span into the bilayer (may move via fluidity)
1) Helical bundles (Gated transporters / pumps)
2) Beta barrels (channel proteins
96
Describe PERIPHERAL PROTEINS
Peripheral proteins are temporarily attached via weak bonds and associate with ONE membrane surface (may attach to the inner or outer surface
97
What 6 functions do membrane proteins serve
Junctions, Enzymatic, Transport, Receptors, Anchorage, Transduction.
JETRAT
98
Cholesterol interacts with PHOSPHOLIPIDS to moderate membrane properties, What are the 3 interactions
1) Reduces fluidity (immobilises phospholipids)
2) Reduces permeability (to hydrophilic ions)
3) Prevents crystallisation (increase flexibility)
99
Plant cell membranes have a DIFFERENT sterol compound. Why?
Plants have a cell wall
100
All transport across a plasma membrane involve one of two processes. What are they?
PASSIVE TRANSPORT
| ACTIVE TRANSPORT
101
Describe PASSIVE TRANSPORT
Movement ALONG concentration gradient (from region of high concentration to low)
-Does NOT require the use of ATP
102
Describe ACTIVE TRANSPORT
Movement AGAINST the concentration gradient (from region of a low concentration to high)
-Does REQUIRE ATP
103
What type of transport mechanism is SIMPLE DIFFUSION
Passive Transport
104
Describe SIMPLE DIFFUSION
A passive transport mechanism for materials that can FREELY cross the plasma membrane. SMALL molecules may freely move via the gaps between phospholipid molecules (e.g. Water, Urea, Oxygen, Carbon Dioxide)
105
What are LIPOPHILIC molecules?
molecules that can combine or dissolve with lipids/fats
106
LIPOPHILIC molecules are ________ soluble and hence can dissolve across the membrane. Fill the word and name some examples
LIPID
| e.g. Alcohol, chloroform, steroids
107
Simple diffusion continues until ______
Equilibrium
108
Describe FACILITAED Diffusion.
Facilitated diffusion is a passive transport mechanism for materials that CANNOT freely cross the plasma membrane. LARGE and CHARGED substances cannot freely cross the hydrophobic bilayer (E.g. Ions, macromolecules)
Membrane proteins facilitate (make it easier) the transport of these materials across the membrane.
- Channel proteins form a hydrophilic pore
- Carrier proteins translocate substances
109
Give an example of a channel protein
Example: Channel protein - the voltage-gated potassium channel in axons.
110
Define OSMOSIS
Passive transport for free water molecules. Osmosis is the movement of water across a permeable membrane from a concentration of low solute to high solute
111
Define OSMOLARITY
The measure of the level of solutes in a solution (units: osmol/L)
112
Solutions may be categorised as either: HYPERTONIC, HYPOTONIC, ISOTONIC. Explain the difference between them.
```
Hypertonic = High solutes -> gains water
Hypotonic = Low solutes -> Loses water
Isotonic = equal solutes -> not net flow
```
113
What happens to an animal and plant cell in a HYPERTONIC solution ?
```
Animals = Cells will shrivel from water loss
Plants = Membrane retracts from cell wall
```
114
What happens to an animal and plant cell in a HYPOTONIC solution?
```
Animals = Cell expands until it ruptures
Plant = Cell wall prevents rupturing
```
115
Define ACTIVE TRANSPORT
The movement of materials against a concentration gradient (regions of a low -> high concentration)
116
Give an example of ACTIVE TRANSPORT
Sodium-Potassium pump in axons
117
Explain ACTIVE TRANSPORT
1) Protein pumps use energy from ATP to translocate molecules against a gradient
2) The hydrolysis of ATP causes a change in the conformation of the protein pump, resulting in forced substance movement
3) Protein pumps are specific for a given molecule, mediating regulated transport
118
What is CO-TRANSPORT and what does it involve
Co-transport is a simultaneous movement of two substance by one transport protein. This can involve either:
SYMPORT (same directional movement)
ANTIPORT (opposite directional movement)
119
Describe SECONDARY active transport
Substance moving along a gradient provides driving energy for substance moving against a gradient. NO ATP hydrolysis is required.
120
Give an example for both ANTIPORT AND SYMPORT
```
ANTIPORT = K+ in and Na+ out
SYMPORT = NA+ in GLUCOSE in
```
121
Outline the sequence of VESICULAR TRANSPORT
1) Polypeptides destined for secretion are synthesised by ribosomes on rough ER
2) They are transported to the Golgi body via vesicles (formed from the ER membrane)
3) The Golgi body will potentially sort, store and modify these secretory products
4) The proteins are then transported by another vesicle to the cell membrane for secretion via the process of exocytosis
5) External materials can be internalised into cellular vesicles via endocytosis
Nucleus - Rough ER -V esicle-golgi -vesicle - Outerfluid
122
The phospholipid bilayer of membranes is held together by _________.
(This means they can break and reform)
Hydrophobic associations
123
Describe ENDOCYTOSIS (material entry)
```
An invagination (folding back on itself/being turned inside out) of the membrane creates a depression which envelopes material.
Phagocytosis = the engulfment of solids
Pinocytosis = the engulfment of fluids
```
124
What is PHAGOCYTOSIS
Engulfment of solids
125
What is PINOCYTOSIS
Engulfment of fluids
126
Describe EXOCYTOSIS (material exit)
Vesicles from the golgi body fuse with the cell membrane, expelling contents
- Proteins attached to the vesicle bilayer will become membrane proteins upon fusion
127
What is the theory of ABIOGENESIS
The theory that life spontaneously arose from non-living matter
128
What are the 4 stages of ABIOGENESIS
1) Abiotic synthesis of organic molecules
2) Assembly of molecules into polymers
3) Formation of self-replicating polymers
4) Packaging molecules into membranes
= a cell with stable internal chemistry
129
What did Miller and Urey recreate
The conditions of a pre-biotic earth within a closed system.
- These conditions included reducing atmosphere, high temperatures and electrical discharges.
- Water was boiled to form vapour before mixing with other gases
- The mixture was then allowed to cool and after one week was analysed
- Some simple amino acids and complex oily hydrocarbons had formed
130
The conditions required for the non-living synthesis of life are distinct and unusual. Where did these conditions exist
```
HYDROTHERMAL vents and volcanoes
EXTRACELLULAR locations (panspermia)
```
131
What is the law of BIOGENESIS ?
cells only arise from pre-existing cells
132
Briefly outline Pasteur's experiment demonstrating biogenesis
- Broths were stored in vessels with ducts that did not allow external dust to pass
- Broths were heated to kill any living cells
- Growth occurred if ducts were broken, exposing broth to external contaminants
- lack of growth in broken vessels proved that spontaneous generation won't occur
133
What is an ENDOSYMBIONT
a cell which lives inside another cell with mutual benefit
134
Mitochondria and chloroplasts are likely to have originated via_______
Endosymbiosis
135
What is evidence for endosymbiosis ?
| MAD DR
```
Membrane, Antibiotics, Division, DNA, Ribosomes
M: Double membrane
A: has susceptibility
D: Fission-like
D: Naked and circular
R: 70S Ribosomes
MAD DR
```
136
What does MAD DR stand for?
```
Evidence for Endosymbiosis.
Membrane, Antibiotics, Division, DNA, Ribosomes
M: Double membrane
A: has susceptibility
D: Fission-like
D: Naked and circular
R: 70S Ribosomes
MAD DR
```
137
How do Prokaryotes reproduce ?
Binary fission
138
How do Eukaryotes Reproduce ?
```
Somatic (body) cells divide by mitosis
Sex cells (gametes) divide by meiosis
Some eukaryotes don't reproduce sexually and use mitosis for asexual reproduction
```
139
What is the cell cycle?
Describes the events that occur over the typical life cycle of the cell
140
Very briefly explain Interphase and its stages
G1:Cell grows and duplicates organelles
S: DNA replication occurs
G2: Cell prepares for division
(Replicated DNA proofread for errors in G2)
141
What is M phase ?
Mitosis: Division of the nucleus
Cytokinesis: Cytoplasmic division
(if a cell is not actively dividing, it will enter a quiescent phase (G0) following division).
142
Interphase in an active period in the cell cycle. What events occur ? DOCTOR
DNA replication, Organelle cloning, Cell growth, Translation, Obtain nutrients, Respiration
DOCTOR
143
In eukaryotic cells, DNA is usually loosely packed within the nucleus as _______
Chromatin
144
When a cell undergoes mitosis, this DNA supercoils to a condensed ____________
Chromosome
145
When is DNA replicated ?
In Interphase
Because DNA is replicated in interphase chromosomes have duplicate chromatids.
(these chromatids separate during division, so daughter cells have identical chromosomes)
146
Define MITOSIS
The division of nucleus to produce two genetically identical nuclei
147
What stages occur in Mitosis
Prophase, Metahase, Anaphase, Telophase
148
What happens before mitosis in INTERPHASE ?
- cell grows in size, - Organelles are duplicated, - DNA is replicated (s phase) to form identical chromatids
149
What happens in PROPHASE ?
- DNA Supercoils and condenses, - Nuclear membrane dissolves, - Centrosomes move to poles and begin to form spindle fibres
150
What happens in METAPHASE ?
- Centrosome spindle fibres attach to chromosome centromere, - Spindle fibres contract and move chromosomes to centre of cell
151
What happens in ANAPHASE ?
- Sister chromatids separate and move to opposite sides of cell, - Sister chromatids now regarded as two identical chromosomes
152
What happens in TELOPHASE ?
- Chromosomes deconense, - Nuclear membranes reform, - Cytokinesis occurs concurrently (cells divide in 2)
153
What happens after MITOSIS?
- Two daughter cells are formed, - Each cell contains one of the duplicated chromatid pair, - Cells are genetically identical
154
Define CYTOKINESIS
The process of cytoplasmic division, whereby a cell splits into two
(occurs concurrently with telophase)
155
Outline cytokinesis in animals
- Microtubule filaments form a concentric ring around the middle of the cell
- Filament contraction creates a cleavage furrow, which pinches off to form 2 cells
- Separation is centripetal because it starts at the outside and then moves in
156
Outline Cytokinesis in plants
- Carbohydrate- rich vesicles form in a row at the centre of the cell (equatorial plane)
- Vesicles fuse to form an end plate, which extends out to separate the cell in two
- Separation is centrifugal because it starts in the centre and then moves out
157
Mitosis is involved in 4 key processes. What are they?
| TOAD
Tissue repair, Organism growth, Asexual reproduction, Development of embryo
TOAD
158
How can you identify cells are undergoing mitosis?
- The lack of clearly identifiable nucleus
| - The presence of visible chromosomes
159
The mitotic index is a measure of the proliferation status of a cell population. Whats the calculation equation?
Mitotic Index = cells in Mitosis/Total number of cells
160
What are Cyclins ?
A family of regulatory proteins that control progression of the cell cycle
161
Explain Cyclins
- Cyclins bind cyclin dependent kinases (CDKs) and form an activated complex
- This complex phosphorylates proteins involved in specific cell cycle events
- After the events has occurred, the cyclin is degraded and CDK rendered inactive
- Cyclin concentrations must be tightly regulated to ensure proper progression.
162
What are the 2 methods of cell death?
Necrosis (uncontrolled cell death)
| Apoptosis (programmed cell death)
163
What is Necrosis ?
-The premature death of a cell
-There is destabilisation of the membrane that leads to swelling and eventual lysis
(Released contents may cause inflammation)
164
What is Apoptosis ?
- The controlled destruction of a cell in response to molecular signals
- The membrane bulges and contents are repackaged for removal
(Released content is recycled by other cells
165
What is a carcinogen ?
Something that gives you cancer
166
There is a strong positive correlation between ______ and cancer
Smoking
