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Study Notes 3rd Year > BIOL 2070 Cell Bio > Flashcards

BIOL 2070 Cell Bio Flashcards

1
Q

2 types of prokaryotes

A

Bacteria

Archaea

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2
Q

4 types of eukaryotes

A

Plants
Animals
Fungi
Protists and other complex unicellular organisms

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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

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3
Q

Where does anaerobic bacteria come from

A

Anaerobic bacteria were taken up by ancestral archaea to form the earliest eukaryotic precursor.

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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

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5
Q

What do voltage gated sodium channels have

A

a refractory period

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6
Q

Which organelle is surrounded by 2 membranes

A

nucleus

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7
Q

What does a prokaryotic cell contain

A

Cell membrane

No organelles

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8
Q

What type of cell is e. coli

A

eukaryotic

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9
Q

What decreases membrane fluidity

A

Longer fatty acid tails decrease membrane fluidity.

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10
Q

What do phospholipids not contain

A

ATP

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11
Q

What does not normally occur within lipid bilayers

A

Flip-flop from one side to the other.

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12
Q

Nucleus

A

Contains most DNA in cell

2 membranes

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13
Q

Mitochondria

A

Harness energy from food molecules to produce usable energy for the cell (ATP).

Contains mtDNA

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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

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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

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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.

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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.

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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

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19
Q
A
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20
Q

EndoSymbiont Theory

A

Archaea and bacteria worked symbiotically to create the mitochondria

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21
Q

Primary molecules in membranes

A

Phospholipids

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22
Q

Structure of Phospholipids

A

hydrophilic head(polar) 2 hydrophobic tails(nonpolar)
glycerol

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23
Q

Saturdated lipid

A

No double bonds

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24
Q

Unsaturated lipid

A

1 or more double bonds

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25
Q

3 types of membrane lipids

A

Phospholipids.
Sterols.
Glycolipids

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26
Q

What does amphipathic mean

A

it has hydrophobic and philic properties

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27
Q

3 things cell membrane fluidity is influenced by

A

Density.
Hydrocarbon tail length (14 – 24 carbon atoms).
Presence and number of double bonds (saturated vs. unsaturated)

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28
Q

What side are glycolipids exclusively on

A

the extracellular space

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29
Q

Where does membrane assembly begin

A

ER

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30
Q

What enzyme is present in the ER

A

Scramblase

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31
Q

What does scramblase do

A

catalyzes transfer of random phospholipids from one monolayer to another

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32
Q

What enzyme is present in the Golgi

A

Flippase

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33
Q

What does flippase do

A

catalyzes transfer of specific phospholipids to cytosolic monolayer

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34
Q

What is a lipid raft

A

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

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35
Q

Membrane Proteins

A

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.

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36
Q

Integral Proteins

A

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.

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37
Q

Lipid linked proteins

A

are covalently bonded to the cell membrane

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38
Q

Protein attached membranes

A

non-covalently attached to transmembrane proteins

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39
Q

Lipid Membrane Permeability

A

Lipid bilayer is selectively permeable.

Impermeable to charged molecules.

Ions and polar molecules cannot diffuse freely, their transport must be assisted by proteins

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40
Q

2 types of membrane transport

A

Pasive transport or diffusion

Active transport

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41
Q

Passive transport

A

When molecules move from an area of high concentration to low concentration.

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42
Q

Active Transport

A

Requires input of energy and can move molecules against their concentration gradient.

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43
Q

Gradient Driven Pumps

A

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.

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44
Q

Voltage gated channels

A

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

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45
Q

K leak channels

A

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.

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46
Q

Nerve Signal Transmission

A

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.

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47
Q

Synaptic Transmission

A

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

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48
Q

Adenosine TriPhosphate

A

ATP

Energy currency of the cell

Release of phosphate causes release of energy

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49
Q

3 stages of catabolism of food

A

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.

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50
Q

where does glycolysis occur

A

In the cytosol

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51
Q

Steps of Glycolysis

A

One molecule of glucose
Fructose 1,6-bisphosphate
Two molecules of glyceraldehyde 3-phosphate
Two molecules of pyruvate

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52
Q

Glucogenesis

A

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

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53
Q

How is glucose stored in plants

A

As a starch

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54
Q

How is glucose stored in animal cells

A

Glycogen

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55
Q

Structure of the mitochondria

A

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

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56
Q

What is in the pyruvate dehydrogenase complex

A

Pyruvate dehydrogenase
Dihydrolipoyl transacetylase
Dihydrolipoyl dehydrogenase

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57
Q

After each cycle of aerobic metabolism we are left with

A

1 acetyl CoA
1 NADH
1 flavin adenine dinucleotide (FADH 2 )

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58
Q

What does the citric cycle do

A

Catalyzes the oxidation of carbon atoms of the acetyl groups in acetyl CoA, converting them to CO 2 .

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59
Q

What does the citric cycle generate

A

Electron carriers

NADH
FADH2
GTP

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60
Q

2 stages that ATP is generated in

A

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.

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61
Q

Photosystem II

A

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

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62
Q

Photosystem I

A

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.

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63
Q

Photosystem II and I

A

Electrons come from water
Light excites electrons and provides energy

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63
Q

Where did membrane enclosed organelles likely evolve from

A

through the process of membrane expansion

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64
Q

What is each organelle separated by from the cytoplasm

A

At least one phospholipid bilayer

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65
Q

Where does transcription take place

A

Nucleus

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66
Q

Where does translation take place

A

Cytosol

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67
Q

How to proteins reach their final destination

A

Protein sorting

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68
Q

3 mechanisms that transport proteins

A

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.

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69
Q

Pores

A

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

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70
Q

Protein Translocators

A

Transport proteins into organelles

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71
Q

Transmembrane proteins

A

Stop transfer sequences can halt the translocation of proteins resulting in a transmembrane protein in the lipid bilayer.

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72
Q

2 ways vesicular transport happens

A

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.

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73
Q

What is vesicel budding driven by

A

Assembly of a protein coat

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74
Q

Clatherins

A

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.

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75
Q

Clatherin coated vesicle (Coat proteins, Origin, destination)

A

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

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76
Q

COPII-coated vesicle (Coat proteins, Origin, destination)

A

COPII proteins
Originat in ER
End up in golgi cisterna

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77
Q

COPI-coated (Coat proteins, Origin, destination)

A

COPI proteins
Originate in golgi cisterna
End up in ER

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78
Q

Vesicular docking

A

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

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79
Q

Vesicle Fusion

A

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.

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80
Q

2 pathways of the endomembrane system

A

Major secretory pathway
Leads from ER to Golgi to plasma membrane.

Major endocytic pathway
Leads from plasma membrane to lysosomes.

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81
Q

5 actions completed in the major secretory pathway

A

Protein modification in the ER
Protein folding in the ER
Vesicular transport through the golgi
Secretion from the golgi
Secretory Vesicles

82
Q

4 actions done in the endocytic pathway

A

Pagocytosis
Pinocytosis
Receptor mediated endocytosis - LDL
Receptor mediated endocytosis - viral entry

83
Q

Pinocytosis

A

“cell drinking”
Indiscriminate ingestion of fluid and molecules via small pinocytic vesicles.
Occurs in all cells, with the aid of coat proteins

84
Q

Phagocytosis

A

“cell eating”
Ingestion of large particles such as microbes via large vesicles called phagosomes.
Occurs in specialized phagocytic cells.

85
Q

Where did anaerobic bacteria come from

A

Anaerobic bacteria were taken up by ancestral archaea to form the earliest eukaryotic precursor.

86
Q

which direction down an axon does an action potential move towards

A

An action potential will travel along the length of an axon towards the cell body

87
Q

What do voltage gated sodium channels have

A

have a refractory period

88
Q

What organelle is surrounded by two membranes

A

Nucleus.

89
Q

What kind of cell is ecoli

A

It is eukaryotic.

90
Q

What is the consequence of membrane lipids on the membrane

A

Longer fatty acid tails decrease membrane fluidity

91
Q

What are two ways that protein switches can be regulated

A

GTP binding and phosphorylation

92
Q

What type of transporters are required at the apical surface, explain how they function

A

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
Q

What type of transporters are required at the basal surface, how do they function

A

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
Q

What prevents transporters at the apical surface from diffusing to the basal surface and vice versa

A

Tight junctions - form seals

95
Q

Describe the structure of microtubules

A

Alpha beta tubulin

plus and minus end

Tubulin dimers form a hollow microtubule

96
Q

How are microtubules formed and oriented

A

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
Q

what conditions favour microtubule growth, explain them

A

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
Q

Which conditions favour cause microtubule shrinking

A

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
Q

Which of the following organelles occupy the most space in a typical liver cell

A

Nucleus

100
Q

Upon reaching its target vesicle, recogonition relies on…

A

Rab

101
Q

Which of the following protein coats are involved in vesicular transport from the Golgi to the ER

A

COPI

102
Q

What are G-protein coupled receptors made from

A

Are composed of a polypeptide chain which traverses the membrane 7 times

103
Q

What major responses is mediated by cyclic AMP

A

glycogen breakdown

104
Q

What is the correct order of myosin II walking

A

Attached, released, cocked, rebinding, and powerstroke

105
Q

Which monomeric GTPase from the Rho family promotes bundle formation

A

Rho

106
Q

4 types of cell signal transduction

A

Endocrine

Paracrine

Neuronal

Contact-dependent

107
Q

Endocrine transduction

A

Signal is transmitted throughout the
entire system via the bloodstream

108
Q

Paracrine transduction

A

Signal is transmitted locally in the
extracellular fluid.

109
Q

neuronal Transduction

A

Signal is transmitted to a specific target

110
Q

Contact dependent transduction

A

Signal is transmitted to cells in direct
contact

111
Q

What is apoptosis

A

cell death

112
Q

Chain of intracellular signalling

A

Extracellular signal, intracellular signaling molecules, effector protein, action

113
Q

2 types of gtp binding proteins

A

monomeric gtpase

G-proteins

114
Q

Monomeric gtpase

A

Controlled by 2 types of regulatory proteins
GEF (guanine nucleotide exchange factor) and
GAP (GTPase-activating protein)

115
Q

G proteins

A

Large, trimeric, relay messages from G
-protein coupled receptors.

116
Q

3 types of cell surface receptors

A

Ion-channel-coupled.
G-protein-coupled.
Enzyme-coupled.

117
Q

Ion-channel-coupled receptors

A

change the permeability of the plasma
membrane to selected ions.

118
Q

G-protein-coupled receptors

A

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
Q

Enzyme-coupled receptors

A

Enzyme-coupled receptors act as enzymes or associate with enzymes inside
the cell.

120
Q

Cytoskeleton

A

The cytoskeleton is an intricate network of protein filaments that extend throughout
the cell.

121
Q

3 types of protein filaments in the cytoskeleton

A

intermediate filament

Actin filaments

microtubules

122
Q

Intermediate filaments

A

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
Q

two types of intermediate filaments

A

cytoplasmic

nuclear

124
Q

Microtubules

A

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
Q

2 types of motor proteins

A

kinesins

dyneins

126
Q

Kinesins

A

Different types of kinesins transport different
types of cargo; although, in some cases
adapter proteins allow kinesins to transport
multiple types of cargo.

127
Q

Dyneins

A

Dyneins always use adapter proteins to interact
with their cargo.

128
Q

Actin filaments

A

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
Q

Treadmilling

A

Occurs in actin filaments, when one monomer is added to the plus end, one is taken off of the minus end

130
Q

2 common families of myosin

A

Myosin I
Myosin II

131
Q

Myosin I

A

Has a head domain that interacts with the filament and a tail that determines what type of cargo it can transport.

132
Q

Myosin II

A

Has two heads that interact with the actin filament to
form contractile bundles driving changes in shape,
movement, and division.

133
Q

Cell Crawling

A

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
Q

GTPases from the Rho family

A

Rho - bundle formation
Rac - lamellapodium formattion
cdc42 - filopodia formation

135
Q

What are skeletal muscle fibers made of

A

myofibrils

myofibrils made of sarcomeres

136
Q

cell cycle phases

A

M phase - Mitosis and cytokinesis.

S phase - DNA replication

G1 and G2 phase - growth

137
Q

3 cell cycle checkpoints

A

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
Q

Cell cycle control relies on cyclins and cyclin-dependent kinases (Cdks). What best describes their relationship

A

The activity of these protein kinases is cyclical
while the concentration of cyclins is cyclical.

139
Q

4 cyclin-cdk complexes

A

G1-Cdk
G1/S-Cdk
S-Cdk
M-Cdk

140
Q

G1-Cdk use and partners

A

Drive progress through G1 toward S phase.

Cyclin D

Cdk4, cdk6

141
Q

G1/S-Cdk use and partners

A

Initiate transition into S phase.

Cylcin E

Cdk2

142
Q

S-Cdk use and partners

A

Launch S phase, trigger DNA replication.

Cyclin A

Cdk 2

143
Q

M-Cdk use and partners

A

Trigger entry into M phase, mediate many
changes during mitosis.

Cyclin B

Cdk 1

144
Q

Consequences of DNA damage

A

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
Q

M-cdk activation

A

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
Q

5 stages of mitosis

A

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

147
Q

Prophase

A

Duplicated chromosomes
condense in the nucleus.

The mitotic spindle assembles
between the two centrosomes.

The centrosomes begin to
move apart.

148
Q

Metaphase

A

Chromosomes are aligned at
the equator, midway between
the poles.

The kinetochore microtubules
keep each chromosome under
tension from attachment at
opposite poles.

149
Q

Prometaphase

A

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
Q

Anaphase

A

Sister chromatids separate and
are pulled towards the poles.

Kinetochore microtubules get
shorter, and the spindle pores
move apart contributing to
segregation.

151
Q

Telophase

A

Chromosomes arrive at poles. * New nuclear envelope forms around each set.

Division of the cytoplasm
begins with the assembly of
the contractile ring.

152
Q

Cohesins

A

Assemble along DNA as it is replicated to hold sister chromatids
together

153
Q

Condensins

A

Reorganize and condense each sister chromatid into discreet structures.

154
Q

apoptosis vs necrosis

A

necrosis is a cell dying of acute injury

apoptosis is programmed cell death

155
Q

ECM

A

Extracellular matrix

The ECM is a large network of
secreted molecules that
surround, support, and give
structure to cells and tissues.

156
Q

What is the ECm primarily composed of in plants

A

carbohydrates.

157
Q

What is the ECm primarily composed of in animals

A

proteins.

158
Q

Four main types of tissue

A

connective
muscular
epithelial
nervous

159
Q

Structure of connective tissue

A

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
Q

Epithelial tissue

A

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
Q

Cells interact with collagen in the ECM via
transmembrane receptor proteins called

A

Integrins

162
Q

What do integrins use to connect with collagen

A

fibronectin

163
Q

Features of GAGs

A

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
Q

Two types of cells on the apical surface of epithelia

A

absorptive cells
goblet cells

164
Q

Types of cell junctions

A

tight junctions
adherens juctions
desmosomes
gap juctions
hemidesmosomes

165
Q

What do tight junctions do

A

seal neighbouring cells together

166
Q

What do adherens junctions do

A

joins actin bundles in one cell to a bundle in a neighbouring cell

167
Q

what do desmosomes do

A

joins intermediate filaments

168
Q

what do gap junctions do

A

forms channels that allow small intracellular water soluable molecules to pass from cell to cell

169
Q

what do hemidesmosomes do

A

anchors intermediate filaments in a cell to the basal lamina

170
Q

During development, a fertilized
egg will repeatedly divide leading
to the formation of a complex
multicellular organism. What is this referred to?

A

Totipotency

171
Q

Three main factors contribute to stability
of tissue renewal

A

Cell communication
Selective cell adhesion
Cell memory

172
Q

2 ways cells facilitate memory

A

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
Q

Cells that replace terminally differentiated cells are generated from a stock of proliferating

A

Precursor cells

174
Q

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.

A

Stem cell systems

175
Q

What happens In the absence of Wnt signaling

A

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
Q

Two heritable properties that define cancer cells

A

They and their progeny proliferate in defiance of normal constraints.

They invade and colonize territories normally reserved for other cells.

177
Q

What is the underlying cause of cancer

A

somatic
mutation.

178
Q

Types of chromosomal damage

A

chromosome breaks, rearrangements, and gain or loss of whole chromosomes (aneuploidy).

179
Q

Features of oncogenes

A

gain-of-function mutations
have a dominant effect
only one copy of the gene needs to be
mutated to promote cancer development

180
Q

Features of tumor supressor genes

A

loss -of-function mutations
generally recessive
require both copies of the gene to be eliminated or
inactivated to contribute to cancer treatment.

181
Q

Which types of microtubules position the centrosomes at each pole?

A

Astral tubule

182
Q

During G1, DNA damage leads to the activation of p53. What best describes p53

A

transcription regualtor

183
Q

At which checkpoint is progression monitored to confirm chromosomes are correctly attached to the mitotic spindle before separation?

A

Mid M phase

184
Q

Sister chromatids are separated during which stage of mitosis

A

anaphase

185
Q

True or False: Glucosaminoglycans (GAGs) non- covalently link to a core protein to form proteoglycans

A

False: Glucosaminoglycans (GAGs) covalently link to a core protein to form proteoglycans

186
Q

What are essential for cell crawling.

A

integrins

187
Q

Which cell junctions are typically linked to intermediate filaments

A

Hemidesmosomes. and desmosomes

188
Q

Compression resistance of tissue is primarily provided by

A

GAGs

189
Q

Hyperextensible skin is most likely the product of a gene defect in the organization of what

A

Collagen

190
Q

Aneuploidy refers to which type of chromosomal damage?

A

Gain or loss of whole chromosomes.

191
Q

In the presence of Wnt, what is prevented

A

beta-catenin degradation is prevented.

192
Q

What are the two essential steps for evolution of life

A

Development of macromolecules
Self-replication

193
Q

What are the major components of cell membranes

A

A phospholipid bilayer.
Other lipids.
Embedded proteins.
Associated carbohydrates.

194
Q

What characteristics of a molecule influence how easily it can cross the membrane in the absence of
membrane proteins?

A

Size
Polarity
Concentration gradient

195
Q

What is glycolysis, where does it take place and why is it important in the cell?

A

Occurs in cytosol
Converting glucose to 2 molecules of pyruvate
important fro glucose generating energy for the cell

196
Q

What is protein sorting and what are the three distinct ways by which proteins enter organelles?

A

The way in which molecules enter cells
Pores, protein translocators, transport vesicles

197
Q

What is autophagy? What two cell compartments are involved in the process?

A

conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent regulated mechanism

Cytosol and organelles

198
Q

What are two ways protein switches are regulated? For each, explain how they are activated or
inactivated.

A

phosphorylation, sodium pumps

199
Q

What are the three steps of cell crawling? What cell structures are involved?

A

actin polymerization, attachment, contraction

200
Q

What is the difference between apoptosis and cell necrosis?

A

apoptosis is programmed celll death
necrosis is When a cell dies of acute injury it releases their contents across their neighbours

201
Q

What are glycosaminoglycans? Explain how they influence resistance to pressure.

A

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
Q

What is cell potency? List two types and explain each

A

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
Q

Steps to LDL receptor mediated endocytosis

A

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.

204
Q

Bcl2 family

A

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.

Study Notes 3rd Year (10 decks)

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