BIOL 2070 Cell Bio Flashcards
1
Q
2 types of prokaryotes
A
Bacteria
Archaea
2
Q
4 types of eukaryotes
A
Plants
Animals
Fungi
Protists and other complex unicellular organisms
3
Q
Compare Prokaryotes and eukaryotes
A
Prok:
No nucleus
unicellular
no membrane bound organelles
Circular
Euk:
Nucleus present
Mostly multicellular
Membrane boudn organelles
Linear multiple
3
Q
Where does anaerobic bacteria come from
A
Anaerobic bacteria were taken up by ancestral archaea to form the earliest eukaryotic precursor.
4
Q
Which direction does an action potential travel
A
An action potential will travel along the length of an axon towards the cell body
5
Q
What do voltage gated sodium channels have
A
a refractory period
6
Q
Which organelle is surrounded by 2 membranes
A
nucleus
7
Q
What does a prokaryotic cell contain
A
Cell membrane
No organelles
8
Q
What type of cell is e. coli
A
eukaryotic
9
Q
What decreases membrane fluidity
A
Longer fatty acid tails decrease membrane fluidity.
10
Q
What do phospholipids not contain
A
ATP
11
Q
What does not normally occur within lipid bilayers
A
Flip-flop from one side to the other.
12
Q
Nucleus
A
Contains most DNA in cell
2 membranes
13
Q
Mitochondria
A
Harness energy from food molecules to produce usable energy for the cell (ATP).
Contains mtDNA
14
Q
Chloroplasts
A
mitochondria of plants
Large, green organelles generally found in plants and algae that capture energy from sunlight.
They contain their own DNA and reproduce by dividing.
Where photosynthesis occurs
15
Q
Endoplasmic reticulum
A
Rough ER – studded with ribosomes which translate RNA into protein.
Smooth ER – no ribosomes, involved in the synthesis/storage of lipids.
Very close to nucleus
16
Q
Golgi Apparatus
A
Composed of stacks of flattened membrane-enclosed sacs.
Typically located near the nucleus.
Modifies and packages molecules made in the ER that are to be secreted or transported to another cell compartment.
17
Q
Cytosol
A
The part of the cytoplasm not contained within intracellular membranes.
Extremely crowded with small and large molecules. Behaves like a water-based gel.
18
Q
Cytoskeleton
A
Made up of protein filaments which are anchored across the cell.
Govern internal organization, strength, shape, and movement
A) Actin filaments
B) Microtubules
C) Intermediate filaments
19
Q
A
20
Q
EndoSymbiont Theory
A
Archaea and bacteria worked symbiotically to create the mitochondria
21
Q
Primary molecules in membranes
A
Phospholipids
22
Q
Structure of Phospholipids
A
hydrophilic head(polar) 2 hydrophobic tails(nonpolar)
glycerol
23
Q
Saturdated lipid
A
No double bonds
24
Unsaturated lipid
1 or more double bonds
25
3 types of membrane lipids
Phospholipids.
Sterols.
Glycolipids
26
What does amphipathic mean
it has hydrophobic and philic properties
27
3 things cell membrane fluidity is influenced by
Density.
Hydrocarbon tail length (14 – 24 carbon atoms).
Presence and number of double bonds (saturated vs. unsaturated)
28
What side are glycolipids exclusively on
the extracellular space
29
Where does membrane assembly begin
ER
30
What enzyme is present in the ER
Scramblase
31
What does scramblase do
catalyzes transfer of random phospholipids from one monolayer to another
32
What enzyme is present in the Golgi
Flippase
33
What does flippase do
catalyzes transfer of specific phospholipids to cytosolic monolayer
34
What is a lipid raft
The non -cytosolic layer may contain microdomains with distinct lipid compositions – lipid rafts.
Lipid rafts are proposed to be concentrated sites of signaling and receptor molecules.
Can move through cells and stay intact
35
Membrane Proteins
Proteins make up ~50% of the mass in animal cell membranes.
These proteins are embedded or attached to the cell membrane.
They have diverse roles, giving cells many of their defining characteristics.
Proteins associate with the lipid bilayer in different ways.
36
Integral Proteins
Arrange to form large aqueous pores.
Observed in some bacteria as well as mitochondria to allow passage of small nutrients, metabolites, and ions while filtering out larger molecules.
37
Lipid linked proteins
are covalently bonded to the cell membrane
38
Protein attached membranes
non-covalently attached to transmembrane proteins
39
Lipid Membrane Permeability
Lipid bilayer is selectively permeable.
Impermeable to charged molecules.
Ions and polar molecules cannot diffuse freely, their transport must be assisted by proteins
40
2 types of membrane transport
Pasive transport or diffusion
Active transport
41
Passive transport
When molecules move from an area of high concentration to low concentration.
42
Active Transport
Requires input of energy and can move molecules against their concentration gradient.
43
Gradient Driven Pumps
When a substance is moving against the electrochemical gradient, an input of energy is required.
Gradient-driven pumps are transporters that facilitate the movement of 2 different molecules.
Symport – same direction.
Antiport – opposite direction.
44
Voltage gated channels
critical for electrical activity such as that in nerve cells.
The distribution of ions on either side of the membrane gives rise to the membrane potential
45
K leak channels
High internal concentration of K + is maintained by Na + /K + pump.
K + also moves across membranes through K + leak channels (bi - directional).
It is drawn into the cell to balance negatively charged macromolecules but also leaks out down its concentration gradient until electrochemical equilibrium is reached.
46
Nerve Signal Transmission
K + is a large contributor to the potential difference across membranes.
At the steady state, this is called the resting potential (-20 to -200mV) – the membrane is polarized.
A stimulus sufficient to raise the membrane potential to a threshold above the resting potential will cause an action potential.
The membrane will undergo a rapid depolarization and then rapidly return to the resting state.
Voltage-gated Na+ channels are opened by the stimulus and allow Na+ ions to rush into the cell.
Na+ channels then rapidly close and are inactivated for a brief refractory period.
K + moves out of the cell re-polarizing the membrane.
A signal is propagated along the membrane because adjacent Na+ channels are stimulated to open by membrane depolarization.
The signal moves in one direction because the channels are inactivated briefly after closing.
47
Synaptic Transmission
Neurotransmitters stored in vesicles are released into the synaptic cleft.
The neurotransmitters bind to channel proteins on adjacent cells (ex. muscle cell).
In response, channels open and ions flow into the cell generating a membrane potential
48
Adenosine TriPhosphate
ATP
Energy currency of the cell
Release of phosphate causes release of energy
49
3 stages of catabolism of food
Stage 1 (outside of the cell)
Food broken down into simple subunits.
Through digestion and enzymes
Stage 2 (mostly in cytosol)
Simple subunits converted to acetyl CoA.
Limited amounts of ATP and NADH produced.
Glucose taken by epithelial cells
Stage 3 (mitochondria)
Acetyl CoA converted to water and CO2.
Large amounts of ATP produced.
50
where does glycolysis occur
In the cytosol
51
Steps of Glycolysis
One molecule of glucose
Fructose 1,6-bisphosphate
Two molecules of glyceraldehyde 3-phosphate
Two molecules of pyruvate
52
Glucogenesis
Store energy long term
Process to store and increase available glucose.
Builds glucose molecules from pyruvate.
Requires energy input (4 ATP & 2 GTP)
Opposite of Glycolysis
53
How is glucose stored in plants
As a starch
54
How is glucose stored in animal cells
Glycogen
55
Structure of the mitochondria
Matrix - Space contains a highly concentrated mixture of hundreds of enzymes, including those required for the oxidation of pyruvate and fatty acids for the citric acid cycle
Inner Membrane - Folded into numerous cristae, the inner membrane contains the proteins that carry out oxidative phosphorylation, including the electron-transport chain and the ATP synthase that makes ATP. Also contains transport proteins that move selected molecules into and out of the matrix
Outer Membrane - Because it contains large channel-forming proteins (called porins) the outer membrane is permeable to all molecules of 5000 daltons or less
Intermembrane space - This space contains several enzymes that use the ATP passing out of the matrix to phosphorylate other nucleotides. It also contains proteins that are released during apoptosis
56
What is in the pyruvate dehydrogenase complex
Pyruvate dehydrogenase
Dihydrolipoyl transacetylase
Dihydrolipoyl dehydrogenase
57
After each cycle of aerobic metabolism we are left with
1 acetyl CoA
1 NADH
1 flavin adenine dinucleotide (FADH 2 )
58
What does the citric cycle do
Catalyzes the oxidation of carbon atoms of the acetyl groups in acetyl CoA, converting them to CO 2 .
59
What does the citric cycle generate
Electron carriers
NADH
FADH2
GTP
60
2 stages that ATP is generated in
Transfer of high energy electrons, derived from food, pumps protons across the membrane.
Flow of the protons back across the membrane through ATP synthase catalyzes the formation of ATP.
61
Photosystem II
Its reaction center passes electrons to an electron carrier – plastoquinone.
High energy electrons are then transferred to a proton pump which generates the electrochemical gradient necessary for ATP synthase
62
Photosystem I
Its reaction center passes electrons to a different electron carrier – ferredoxin.
High energy electrons are then transferred to an enzyme which reduces NADP + to NADPH.
63
Photosystem II and I
Electrons come from water
Light excites electrons and provides energy
63
Where did membrane enclosed organelles likely evolve from
through the process of membrane expansion
64
What is each organelle separated by from the cytoplasm
At least one phospholipid bilayer
65
Where does transcription take place
Nucleus
66
Where does translation take place
Cytosol
67
How to proteins reach their final destination
Protein sorting
68
3 mechanisms that transport proteins
Pores – selective gates that actively transport specific macromolecules and allow free diffusion of smaller molecules.
Protein translocators – transport proteins (typically unfolded) into organelles.
Transport vesicles – pinch off from the membrane of one compartment and then fuse with another.
69
Pores
They act as gates that allow small molecules through but selectively control the transport of larger molecules.
The directional transport of nuclear proteins is GTP -driven.
Energy for transport through the pores is provided through hydrolysis of GTP by Ran
70
Protein Translocators
Transport proteins into organelles
71
Transmembrane proteins
Stop transfer sequences can halt the translocation of proteins resulting in a transmembrane protein in the lipid bilayer.
72
2 ways vesicular transport happens
Exocytosis
A vesicle fuses with the plasma membrane, releasing its content to the extracellular space.
Endocytosis
Extracellular materials are captured by vesicles that bud inward from the plasma membrane and are carried into the cell.
73
What is vesicel budding driven by
Assembly of a protein coat
74
Clatherins
The best -studied vesicles are those that have an outer coat made of the protein clathrin
Clathrins bind to the adaptins and help shape the vesicle from the cytosolic surface.
75
Clatherin coated vesicle (Coat proteins, Origin, destination)
Clathrin +adaptin 1
Originates at Golgi apparatus
Ends up in lysosome vis endosomes
Clatharin +adaptin 2
Originates in the plasma membrane
Ends up in an endosome
76
COPII-coated vesicle (Coat proteins, Origin, destination)
COPII proteins
Originat in ER
End up in golgi cisterna
77
COPI-coated (Coat proteins, Origin, destination)
COPI proteins
Originate in golgi cisterna
End up in ER
78
Vesicular docking
Vesicles are actively transporeted along the cytoskeleton, so when it arrives to the cytokseleton it must recognize and dock with it specific organelle
Identification depends on Rab proteins on the surface of the vesicle
79
Vesicle Fusion
Once docked, fusion sometimes requires a stimulatory signal.
Fusion complexes bring the membranes closer together so that their lipid bilayers can interact – this means displacing water from the hydrophilic surface.
80
2 pathways of the endomembrane system
Major secretory pathway
Leads from ER to Golgi to plasma membrane.
Major endocytic pathway
Leads from plasma membrane to lysosomes.
81
5 actions completed in the major secretory pathway
Protein modification in the ER
Protein folding in the ER
Vesicular transport through the golgi
Secretion from the golgi
Secretory Vesicles
82
4 actions done in the endocytic pathway
Pagocytosis
Pinocytosis
Receptor mediated endocytosis - LDL
Receptor mediated endocytosis - viral entry
83
Pinocytosis
"cell drinking"
Indiscriminate ingestion of fluid and molecules via small pinocytic vesicles.
Occurs in all cells, with the aid of coat proteins
84
Phagocytosis
"cell eating"
Ingestion of large particles such as microbes via large vesicles called phagosomes.
Occurs in specialized phagocytic cells.
85
Where did anaerobic bacteria come from
Anaerobic bacteria were taken up by ancestral archaea to form the earliest eukaryotic precursor.
86
which direction down an axon does an action potential move towards
An action potential will travel along the length of an axon towards the cell body
87
What do voltage gated sodium channels have
have a refractory period
88
What organelle is surrounded by two membranes
Nucleus.
89
What kind of cell is ecoli
It is eukaryotic.
90
What is the consequence of membrane lipids on the membrane
Longer fatty acid tails decrease membrane fluidity
91
What are two ways that protein switches can be regulated
GTP binding and phosphorylation
92
What type of transporters are required at the apical surface, explain how they function
sodium/glucose symport
Glucose concentration is higher inside intestinal epithelial cells than in the lumen or blood; therefore glucose cannot diffuse passively
Symport transports glucose and sodium inside and outside the cell
sodium is driven into the cell glucose is actively transported into the cell
93
What type of transporters are required at the basal surface, how do they function
Sodium potassium pump, passive glucose transporters (uniport)
sodium is actively transported out of the cell, potassium into the cell
glucose passively diffuses out of the cell
94
What prevents transporters at the apical surface from diffusing to the basal surface and vice versa
Tight junctions - form seals
95
Describe the structure of microtubules
Alpha beta tubulin
plus and minus end
Tubulin dimers form a hollow microtubule
96
How are microtubules formed and oriented
negative end begins at organization centers i.e. centrosome
Gamma tubulin rings act as nucleation cites
Start at centrosome, grow outwards towards the positive end
97
what conditions favour microtubule growth, explain them
slower hydrolysis of gtp favours growth
gtp tubulin dimers add to the growing end of the microtubule which forms a GTP-cap
GTP forms strong bonds with neighbours which create efficiency and promotes growth
Rate of gtp addition must be faster than hydrolysis in order for stability
98
Which conditions favour cause microtubule shrinking
The rate of hydrolysis being faster than the addition of gtp dimers
Causes instability in the bonds between the tubular dimers which causes fraying and loss of gtp cap
99
Which of the following organelles occupy the most space in a typical liver cell
Nucleus
100
Upon reaching its target vesicle, recogonition relies on...
Rab
101
Which of the following protein coats are involved in vesicular transport from the Golgi to the ER
COPI
102
What are G-protein coupled receptors made from
Are composed of a polypeptide chain which traverses the membrane 7 times
103
What major responses is mediated by cyclic AMP
glycogen breakdown
104
What is the correct order of myosin II walking
Attached, released, cocked, rebinding, and powerstroke
105
Which monomeric GTPase from the Rho family promotes bundle formation
Rho
106
4 types of cell signal transduction
Endocrine
Paracrine
Neuronal
Contact-dependent
107
Endocrine transduction
Signal is transmitted throughout the
entire system via the bloodstream
108
Paracrine transduction
Signal is transmitted locally in the
extracellular fluid.
109
neuronal Transduction
Signal is transmitted to a specific target
110
Contact dependent transduction
Signal is transmitted to cells in direct
contact
111
What is apoptosis
cell death
112
Chain of intracellular signalling
Extracellular signal, intracellular signaling molecules, effector protein, action
113
2 types of gtp binding proteins
monomeric gtpase
G-proteins
114
Monomeric gtpase
Controlled by 2 types of regulatory proteins
GEF (guanine nucleotide exchange factor) and
GAP (GTPase-activating protein)
115
G proteins
Large, trimeric, relay messages from G
-protein coupled receptors.
116
3 types of cell surface receptors
Ion-channel-coupled.
G-protein-coupled.
Enzyme-coupled.
117
Ion-channel-coupled receptors
change the permeability of the plasma
membrane to selected ions.
118
G-protein-coupled receptors
G-protein-coupled receptors activate membrane-bound GTP-binding proteins
(G proteins).
G-protein-coupled receptors (GPCRs) form
the largest family of surface receptors.
composed of 3
protein subunits – alpha, beta,
and gamma.
When inactive, the alpha subunit is
bound to GDP.
119
Enzyme-coupled receptors
Enzyme-coupled receptors act as enzymes or associate with enzymes inside
the cell.
120
Cytoskeleton
The cytoskeleton is an intricate network of protein filaments that extend throughout
the cell.
121
3 types of protein filaments in the cytoskeleton
intermediate filament
Actin filaments
microtubules
122
Intermediate filaments
Enable cells to withstand mechanical stress.
Toughest and most durable of the cytoskeletal filaments.
Commonly found throughout the cytoplasm and as a
meshwork within the nucleus.
rope-like structure with many strands twisted together to provide tensile strength
123
two types of intermediate filaments
cytoplasmic
nuclear
124
Microtubules
Crucial role in organization within all eukaryotic cells.
System of tracks along which vesicles, organelles and other macromolecules can be transported.
They can be rapidly disassembled in one location and
reassembled in another depending on the cell’s needs
125
2 types of motor proteins
kinesins
dyneins
126
Kinesins
Different types of kinesins transport different
types of cargo; although, in some cases
adapter proteins allow kinesins to transport
multiple types of cargo.
127
Dyneins
Dyneins always use adapter proteins to interact
with their cargo.
128
Actin filaments
Comprised of actin subunits – one of the most common proteins in almost all cell types.
Essential for maintaining shape and movement.
Similar to microtubules in that they can be dynamic but also form stable structures.
Each filament is made up of a twisted chain of
actin monomers – each of which points in the
same direction; therefore, there is polarity – a
plus and minus end.
129
Treadmilling
Occurs in actin filaments, when one monomer is added to the plus end, one is taken off of the minus end
130
2 common families of myosin
Myosin I
Myosin II
131
Myosin I
Has a head domain that interacts with the filament and a tail that determines what type of cargo it can transport.
132
Myosin II
Has two heads that interact with the actin filament to
form contractile bundles driving changes in shape,
movement, and division.
133
Cell Crawling
Actin polymerization - extension of motile structures
Attachment - transmembrane integrins
adhere to molecules in the extracellular
matrix and actin filaments in the cortex
Contraction - myosin motor proteins slide
along actin filaments to drag the cell body
forward.
134
GTPases from the Rho family
Rho - bundle formation
Rac - lamellapodium formattion
cdc42 - filopodia formation
135
What are skeletal muscle fibers made of
myofibrils
myofibrils made of sarcomeres
136
cell cycle phases
M phase - Mitosis and cytokinesis.
S phase - DNA replication
G1 and G2 phase - growth
137
3 cell cycle checkpoints
Late G1 - Ensures a favourable environment before DNA replication.
G2/M - Confirm DNA is undamaged and fully replicated.
Mid M - Chromosomes are appropriately attached to the mitotic spindle before separation.
138
Cell cycle control relies on cyclins and cyclin-dependent kinases (Cdks). What best describes their relationship
The activity of these protein kinases is cyclical
while the concentration of cyclins is cyclical.
139
4 cyclin-cdk complexes
G1-Cdk
G1/S-Cdk
S-Cdk
M-Cdk
140
G1-Cdk use and partners
Drive progress through G1 toward S phase.
Cyclin D
Cdk4, cdk6
141
G1/S-Cdk use and partners
Initiate transition into S phase.
Cylcin E
Cdk2
142
S-Cdk use and partners
Launch S phase, trigger DNA replication.
Cyclin A
Cdk 2
143
M-Cdk use and partners
Trigger entry into M phase, mediate many
changes during mitosis.
Cyclin B
Cdk 1
144
Consequences of DNA damage
In G1, DNA damage leads to an increase in
the concentration and activity of a protein
called p53
– a transcription regulator.
p53 then activates transcription of a protein
called p21
– a Cdk inhibitor.
This prevents entry into S phase and allows
time for DNA repair before replication.
145
M-cdk activation
In late G2, the phosphatase Cdc25
removes inhibitory phosphates to
activate M-Cdks which in turn indirectly
activate more Cdc25.
Additionally, active M-Cdk complexes
suppress inhibitory kinases. M-Cdks also turn on APC/C which eventually directs the degradation of M-
cyclin, inactivation of M-Cdks, and exit from M phase.
146
5 stages of mitosis
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
147
Prophase
Duplicated chromosomes
condense in the nucleus.
The mitotic spindle assembles
between the two centrosomes.
The centrosomes begin to
move apart.
148
Metaphase
Chromosomes are aligned at
the equator, midway between
the poles.
The kinetochore microtubules
keep each chromosome under
tension from attachment at
opposite poles.
149
Prometaphase
Phosphorylation of nuclear
pores and lamina.
Breakdown of the nuclear
envelope into small membrane
vesicles.
Chromosomes attach to
spindle microtubules and
undergo active movement.
150
Anaphase
Sister chromatids separate and
are pulled towards the poles.
Kinetochore microtubules get
shorter, and the spindle pores
move apart contributing to
segregation.
151
Telophase
Chromosomes arrive at poles. * New nuclear envelope forms around each set.
Division of the cytoplasm
begins with the assembly of
the contractile ring.
152
Cohesins
Assemble along DNA as it is replicated to hold sister chromatids
together
153
Condensins
Reorganize and condense each sister chromatid into discreet structures.
154
apoptosis vs necrosis
necrosis is a cell dying of acute injury
apoptosis is programmed cell death
155
ECM
Extracellular matrix
The ECM is a large network of
secreted molecules that
surround, support, and give
structure to cells and tissues.
156
What is the ECm primarily composed of in plants
carbohydrates.
157
What is the ECm primarily composed of in animals
proteins.
158
Four main types of tissue
connective
muscular
epithelial
nervous
159
Structure of connective tissue
Cells are loosely organized, attached to one another,
rigid scaffold or both.
The bulk of connective tissue is composed of ECM
and the cells that produce the matrix are
scattered within.
The tensile strength is primarily provided by
fibrous proteins
– primarily collagens
160
Epithelial tissue
Sheets of polarized cells with discrete functions at
apical and basal ends.
ECM is sparse, cells are directly joined to one
another and carry the mechanical load.
161
Cells interact with collagen in the ECM via
transmembrane receptor proteins called
Integrins
162
What do integrins use to connect with collagen
fibronectin
163
Features of GAGs
Glycosaminoglycans
Glycosaminoglycans (GAGs) aid
tissues in resisting compression.
Comprised of negatively charged
polysaccharide chains made of
repeating disaccharide units.
In each disaccharide, one of the
monomers is an amino sugar.
Chains of GAGs are often covalently linked to
a core protein to form proteoglycans.
164
Two types of cells on the apical surface of epithelia
absorptive cells
goblet cells
164
Types of cell junctions
tight junctions
adherens juctions
desmosomes
gap juctions
hemidesmosomes
165
What do tight junctions do
seal neighbouring cells together
166
What do adherens junctions do
joins actin bundles in one cell to a bundle in a neighbouring cell
167
what do desmosomes do
joins intermediate filaments
168
what do gap junctions do
forms channels that allow small intracellular water soluable molecules to pass from cell to cell
169
what do hemidesmosomes do
anchors intermediate filaments in a cell to the basal lamina
170
During development, a fertilized
egg will repeatedly divide leading
to the formation of a complex
multicellular organism. What is this referred to?
Totipotency
171
Three main factors contribute to stability
of tissue renewal
Cell communication
Selective cell adhesion
Cell memory
172
2 ways cells facilitate memory
Activation of master transcription regulators –typically results in a positive feedback loop.
DNA methylation – methylation of cytosine residues
which attract proteins that inhibit transcription.
173
Cells that replace terminally differentiated cells are generated from a stock of proliferating
Precursor cells
174
These systems are typically controlled via extracellular signals exchanged between the stem cells themselves, their progeny, and other cell types as well as the intracellular signaling pathways they activate.
Stem cell systems
175
What happens In the absence of Wnt signaling
the adenomatous polyposis coli (APC)-containing
complex degrades the signal molecule beta - catenin.
the APC - containing complex is inactivated leading to
the transcription of genes that promote the
proliferation of stem cells and precursor cells
Active TCF complex
176
Two heritable properties that define cancer cells
They and their progeny proliferate in defiance of normal constraints.
They invade and colonize territories normally reserved for other cells.
177
What is the underlying cause of cancer
somatic
mutation.
178
Types of chromosomal damage
chromosome breaks, rearrangements, and gain or loss of whole chromosomes (aneuploidy).
179
Features of oncogenes
gain-of-function mutations
have a dominant effect
only one copy of the gene needs to be
mutated to promote cancer development
180
Features of tumor supressor genes
loss -of-function mutations
generally recessive
require both copies of the gene to be eliminated or
inactivated to contribute to cancer treatment.
181
Which types of microtubules position the centrosomes at each pole?
Astral tubule
182
During G1, DNA damage leads to the activation of p53. What best describes p53
transcription regualtor
183
At which checkpoint is progression monitored to confirm chromosomes are correctly attached to the mitotic spindle before separation?
Mid M phase
184
Sister chromatids are separated during which stage of mitosis
anaphase
185
True or False: Glucosaminoglycans (GAGs) non- covalently link to a core protein to form proteoglycans
False: Glucosaminoglycans (GAGs) covalently link to a core protein to form proteoglycans
186
What are essential for cell crawling.
integrins
187
Which cell junctions are typically linked to intermediate filaments
Hemidesmosomes. and desmosomes
188
Compression resistance of tissue is primarily provided by
GAGs
189
Hyperextensible skin is most likely the product of a gene defect in the organization of what
Collagen
190
Aneuploidy refers to which type of chromosomal damage?
Gain or loss of whole chromosomes.
191
In the presence of Wnt, what is prevented
beta-catenin degradation is prevented.
192
What are the two essential steps for evolution of life
Development of macromolecules
Self-replication
193
What are the major components of cell membranes
A phospholipid bilayer.
Other lipids.
Embedded proteins.
Associated carbohydrates.
194
What characteristics of a molecule influence how easily it can cross the membrane in the absence of
membrane proteins?
Size
Polarity
Concentration gradient
195
What is glycolysis, where does it take place and why is it important in the cell?
Occurs in cytosol
Converting glucose to 2 molecules of pyruvate
important fro glucose generating energy for the cell
196
What is protein sorting and what are the three distinct ways by which proteins enter organelles?
The way in which molecules enter cells
Pores, protein translocators, transport vesicles
197
What is autophagy? What two cell compartments are involved in the process?
conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent regulated mechanism
Cytosol and organelles
198
What are two ways protein switches are regulated? For each, explain how they are activated or
inactivated.
phosphorylation, sodium pumps
199
What are the three steps of cell crawling? What cell structures are involved?
actin polymerization, attachment, contraction
200
What is the difference between apoptosis and cell necrosis?
apoptosis is programmed celll death
necrosis is When a cell dies of acute injury it releases their contents across their neighbours
201
What are glycosaminoglycans? Explain how they influence resistance to pressure.
GAGs are strongly hydrophobic and tend to adopt extensive conformations which occupy large volumes relative to their mass – making them excellent space fillers.
Their multiple negative charges attract positively charged cations which draw water into the ECM giving rise to swelling pressure.
In dense, compact connective tissues (ex. tendon or bone) the amount of GAGs is low and the amount of collagen is high.
202
What is cell potency? List two types and explain each
potency - cell's ability to differentiate into other cell types
totipotency - the ability of one cell to divide and produce all differentiated cell types in an organism. - fertilized egg
pluripotent - can give rise to all cell types and tissues in an organism. - Embryonic stem
203
Steps to LDL receptor mediated endocytosis
Cholesterol binds to (LDL) to be transported through the bloodstream.
LDL binds to receptors on the plasma membrane and is internalized in clathrin-coated vesicles.
Vesicles lose their coat and then fuse with endosomes.
LDL dissociates from its receptor.
The LDL is delivered to a lysosome, where it is degraded to release free cholesterol.
The LDL receptors are returned to the plasma membrane to be used again.
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Bcl2 family
The main family of proteins that regulate the activation of caspases
Two which promote cell death are Bax and Bak – promote cell death by inducing the release of cytochrome c from the mitochondria to the cytosol.
Other members of the Bcl2 family, including Bcl2, prevent apoptosis by preventing the action of Bax and Bak.
