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Cell Biology Midterm 1 > Cell Biology Midterm 2 > Flashcards

Cell Biology Midterm 2 Flashcards

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1
Q

What are the functions of the Plasma Membrane? (4)

A

Maintain ion and chemical gradients

Control material exchange between cells and its environment

sense and control communication

Malleable: able to change shape

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2
Q

What are membranes composed of?

A

Lipids and proteins!

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3
Q

What are the membrane lipids? (2)

A
  1. Phospholipids
    A.Glycerophospholipids: uses glycerol for backbone
    B. Sphingophospholipids: uses sphingosine for backbone
  2. Sterols
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4
Q

What is the structure of a glycerophosphoipid?

A

Glycerol backbone

ESTERFIED two fatty acid chains attach to glycerol (Hydrophobic)

The 2 fatty acid chain is cis-unsaturated (kinky) reduce packing and rigidity

Phospho-head group linked to glycerol (hydrophilic)

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5
Q

What are the major types of phospholipids? (5)

A

PhosphatidyETHANOLAMINE

PhosphotidylSERINE

PhosphatidylCHOLINE

SphingoMYELIN

SphingoSINE

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6
Q

Why is cholesterol a major component of membranes?

A

STERIOD RING IS HYDROPHOBIC

It is between fatty acid chains of phospholipids

It increase packing of phospholipids and decrease permeability of water

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7
Q

What movement occurs in phospholipid bilayers?

A

Lateral Diffusion

Flexion

Rotation

Flip-flop (rare)

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8
Q

Is transbilayer diffusion of lipids favourable?

A

No its slow.
Lateral diffusion is FAST and favourable

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9
Q

What are membrane rafts?

A

Parts of the membrane that are ENRICHED in specific lipids: Saturated lipids, cholesterol

PACK WELL

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10
Q

What intermolecular force does saturated lipids have?

A

Van der Waals Attraction

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11
Q

What phospholipid is faceing outwards from the cell membrane?

A

PhosphatidyCHOLINE

SphingoMYELIN

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12
Q

What phospholipid is facing inside the cytoplasm?

A

PhosphatidylETHANOLAMINE

PhosphotidylSERINE

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13
Q

Why is it important for the membrane to maitain their ASSYMETRY?

A

Bc loss of PS asymmetry leads to programmed cell death APOPTOSIS

Glycolipids asymmetry is responisble for BLOOD TYPES

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14
Q

What happens why PhosphotidylSERINE is on the cell surface (not suppose to be there)?

A

Cell will undergo apoptosis

Cause a disease: Antipholipid syndrome
genetic mutation alters proteins
Auto-immune

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15
Q

What are signaling molecules?

A

varity of molecules that are attach to membranes to regulate cell function

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16
Q

What are the four types of intergral membrane proteins?

A

Transmembrane alpha helix; multiple pass

Transmembrane alpha helix; single pass

Transmembrane; beta sheet; multipass

Partial Insertion; amphiphilic alpha helix

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17
Q

What proteins covalently modifies proteins with glycolipids (sugar+lipid=glycolipoprotein)

A
  1. Lipid-anchored proteins: Covently modified proteins with lipids
  2. Peripheral membrane proteins: bind non-covalent to transmembrane and/or membrane lipids.
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18
Q

What are the 3 types of covalently attached lipid anchors?

A

Myristoyl achor

palmitoyl anchor

Farnesyl anchor

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19
Q

What can causes a certain alpha-helices to become a transmembrane domain?

A

-most transmembrane proteins cross membrane as a hydrophobic alpha-helix

-Usually 20-30 amino acids long to span the lipid bilayer

-Hydrophobicity can be measure in a hydropathy plot

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20
Q

What is a hydropathy plot?

A

How much a single/multi pass transmembrane protein FREE ENERGY is associated with moving an amino acid from OIL to water

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21
Q

What is a Bacteriohodopsin?

A

is a seven transmembrane alpha helix protein in BACTERIA

capture light to pump H+ out

Make H+gradient to drive ATP production

Was covalently Modified by RETINAL

Photons change retinal shape

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22
Q

What is a disulphide bond? (only bond in extracellular space)

A

Cysteine amino acid residues react to each other to form sulphur to sulphur bridges.
HELPS STABLIZE PROTEIN SHAPE

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23
Q

What is glycosylation?

A

Covalent addition of oligosaccharides to proteins

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24
Q

Where are most plasma membrane proteins mostly glycosylated on?

A

SERINE OR ASPARAGINE RESIDUES

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25
What is a glycocalyx?
Its glycosylated proteins coated on the cell surface. (sugar polymers) Allows cell to adhere to the matrix and to other cells. GIVES IDENTITY TO CELL
26
What can FRAP do?
Determine lateral diffusion of membrane proteins
27
What is free or unrestrained diffusion?
a proteins can FREELY move across the PS. FRAP: rapid recovery of fluorescence
28
What is No or negligible diffusion?
A protein is completely immobile or its diffusion is slow FRAP:slow to no recovery of fluorescence
29
What is restricted or partial diffusion?
protein is FREE to DIFFUSE BUT only within a subsection of a membrane
30
What are the three subdomains of a sperm?
Anterior head posterior head TAIL use restricted diffusion
31
What are mechanisms to restrict membrane protein movement?
self-assemble into large complexes Tethered to the cytoskeleton inside cells Tethereed to the extracellular matrix interact with proteins on another cell.
32
What is the red blood cell biconcave?
Due to membrane protein interactions with a spectrin cortial cytoskeleton
33
What is spectrin? (peripheral membrane protein)
A protein similar to actin that forms a mesh like struction UNDER the cytosolic face of PS.
34
what is a glycophorin and BAND 3?
two diff integral membrane proteins that binds spectrin, link "skeleton" to membrane
35
What does the junction complex include?
It includes a filamentous actin and it is attached to the membrane by the transmembrane GLYCOPHORIN PROTEIN
36
What are corrals?
spectrin cortical cytoskeleton fenced off the plasma membrane into compartments
37
What is the cortical cytoskeleton?
membrane domains that restrict protein diffusion (small corrals)
38
How can protein diffusion be restricted?
Restricted within small corrals restricted from moving between apical and basolateral membranes in epithelial or endothelial cell layers
39
What happens in the G1 phase?
Preparation of cell for DNA replication
40
What happens in S phase?
DNA replication
41
What happens in G2 phase?
cell growth (size, biomass, materials)
42
What happens in M phase?
Sorting of materials (chromosomes, organelles) TO PREPARE TO SEPERATE Separation of cell into two daughters cells
43
M-phase: prophase
Chromosomes condense, mitotic spindle assemble
44
M-phase; prometaphasr
BREAKDOWN of nuclear envelope ATTACHMENT of chromosomes to spindles
45
M-phase: metaphase
ALIGNMENT of chromosomes
46
M-phase: anaphase
Sister chromatids separate Pulled towards spindles
47
M-phase: telophase
full set of DAUGHTER CHROMOSOMES arrive at spindle Contractile ring pinch the cytosol Nuclear membrane begins to re-form
48
M-phase: cytokinesis
SEPERATING INTO TWO CELLS CONTRACTILE RING SQUEEZE to form TWO DAUGHTERs Generates a cleavage furrow, represent final stages of separation
49
What can a Cdk do?
Cycling dependent kinase can phosphorykate several different substrate proteins
50
What is the switch mechanism to turn the Cdk *on* them?
Binding to one of several specific cyclin proteins
51
What does M-Cdk trigger??
CONDENSIN (protein complex) Cause condensation of chromosomes Forms mitotic spindle
52
What does M-Cdk activate?
Starts at Mitosis and is removed to finish mitosis
53
What is the APC/C ?
A protein complex that is required to allow metaphor to anaphase transition Leads to degradation of M-Cdk
54
Why is control good?
Cyclin-Cdk acts as a timer, cause removal of cycling Some cases cause upregukation of cyclin
55
What triggers G1-Cdk?
favorable extraceller environment
56
What triggers G1/S-Cdk and S-Cdk
DNA damage
57
What triggers M-Cdk?
Unreplicated DNA And DNA damage
58
What triggers APC/C-Cdc20
Chromosome unattached to spindle
59
How can some Cdks be good? (before mitosis)
They are effective has cancer drug targets! Such as -matastatic breast cancer -pancreatic cancer -other cancer
60
When does the mitotic spindle begin?
Assemble in EARLY mitosis. (PROPHASE)
61
What is the mitotic spindle?
A BIPOLAR array of microtublues. Involved in seperation of chromosomes and materials.
62
What is a spindle pole?
has a centrosome and other components. Has three types of microtubules, ASTRAL microtubules KINETOCHORE microtubules INTERPOLAR microtubules
63
What is ASTRAL microtubules?
from spindle pole to cell cortex. Helps ANCHOR spindle poles.
64
What is KINETOCHORE microtubules?
From spindle pile to CHROMOSOME (attach to kinetochore)
65
What is INTERPOLAR microtubules?
From spindle pole to interpolar microtubule coming from other spindle
66
How does a cell know when it is time to proceed from metaphase to anaphase?
In metaphase, ALL CHROMOSOMES SHOULD BE ATTACH TO KINETOCHORE MICROTUBULES. -prevent improper sorting during cell division The metaphase to anaphase transition checkpoint sense if there is no free kinetochore remaining. APC/C
67
What drugs target the mitotic spindle assembly? (cancer therapy)
PACLITAXEL AND DOCETAXEL - bind and stabilize microtubles, prevents assembly of mitotic spindle -trigger metaphase-anaphase checkpoint arrest
68
What types are passive transport? (2)
1. channel mediated (continous pore) 2. transporter-mediated
69
What types are active transport? (3)
1. coupled transporter 2. ATP-driven pump 3. light-driven pump
70
What happens to the membrane when charged solutes are transported by passive transport?
created a electrochemical gradient (membrane potential) Helps molecules move by faciliated diffusion
71
What are the conformational states during passive transport?
Outward-open occluded inward-open
72
What are the 3 couples transporter pump?
Uniport- only 1 molecule in Symport- 2 molecules can go in same direction Antiport- 2 molecules can go in opposite directions
73
What does Na+ glucose symporter do?
recover glucose from extracellular medium before excretion. Glucose is passivly diffused by the electrochemical gradient of Na+
74
What does ATP-Driven pumps do?
membrane transport enzymes that use energy released by ATP HYDROLYSIS to drive transport
75
What are the types of ATP-driven pumps? (4)
1. P-type-transport IONS 2. ABC transporter- Transport small molecules 3. V-type proton pump- transport H+ and CONCUSME ATP 4. F-type ATP synthase- transport H+ and makes ATP
76
How does P-type Na+ K+ pump work?
Exchange 3 Na+ to 2K+ IT IS ELECTROGENIC drives electrical currect accross the membrane
77
What does P-type Na+ K+ control ?
CONTROL OSMOLARTIY the Na+ electrochemical gradient draw Cl- and balanced the inter and extracellular
78
What are the gating mechanisms of ion channels? (4)
Voltage gated Ligand-gated(extracellular) Ligand-gated (intracellular) mechanically gated
79
What are the functions of channels?
regulate electrical signals in neurone regulate neuron to neuron communication muscle contraction and senses leaf-closing response MEMBRANE POTENTIAL
80
How does a K+ channel select K+ and excludes Na+?
Bc there's a bacterial K+ channel Four subunits -negative charges on CYTOSOLIC side allows +ve ions to pass -Vestibule is a hydrating area (H2O bound ions) -Pore helix also selects for +ve ions -Selectivity filter allows only K+ to pass
81
What is an action potential?
signal is a change in MEMBRANE POTENTIAL that goes a long the length of the neuron
82
What is the process of an action potential?
short, local DEPOLARIZATION of the plasma membrane that migrates along the axon MORE POSITIVE OR NEUTRAL MEMBRANE POTENTIAL controled by VOLTAGE GATED CATION CHANNELS
83
What is happing to the electrochemical gradients during action potential>
Before AP: Lots of Na+ OUTSIDE Lots of K+ INSIDE During AP: Na+ rush IN Na+ channels openning
84
How is membrane polarity reestablished?
Voltage gated Na+ channels INACTIVATION DELAYED VOLTAGE GATED K+ CHANNELS k+OUT and Na+ INN CELL
85
What are the types of glial cell
Schwann cells enclose PERIPHERAL NERVES Oligodendrocytes enclose nerves of the CNS
86
What is a neuronal synapse
neurons form contact sites with other neurons permind UNIDIRECTIONAL chemical communication between cells
87
Whats happens when an action potential is activated? (6 steps)
1. It activates voltage-gated Ca+2 channels to open the presynaptic neurone. Ca+2 cause secretion of ACETYLCHOLINE 2. ACETYLCHOLINE binds and OPENS acetylcholine receptors, causing Na+ to enter and DEPOLARIZE Cell 3. nearby voltage-gated Na+ channels open to further DEPOLARIZE and speak action potential in MUSCLE CELL 4. plasma membrane voltage-gated Ca+2 channels open ALLOWING Ca+2 to enter cells 5. Sarcoplasmic reticulum voltage gated Ca+2 channels open to release stored Ca+2 into cytosol 6. VERY LARGE SPIKE IN CYTOSOLIC CA+2 CAUSES MUSCLES TO CONTRACT
88
What are the 2 membrane transport proteins?
Channels Carriers or permeases (Active and Passive)
89
Are all membrane transport proteins MULTIPASS INTEGRAL membrane proteins?
YES
90
What is the electrochemical gradient?
A net driving force that consist of concentration and ELECTRON POTENTIAL DIFFERENCE
91
What can remove integral membrane proteins?
DETERGENTS
92
What can remove peripheral membrane proteins?
CHANGES IN PH AND SALT
93
What is a P-type pump?
Self-phosphorylate and transports ions MAINTAIN ION GRADIENTS ACCROSS MEMBRANWS
94
wHAT are membrane rafts?
PARTS OF MEMBRANE ENRICHED IN SPECIFIC LIPIDS: SATURATED LIPIDS AND CHOLESTORL
95
What are two examples of membrane proteins?
Bacteriorhodopsin, and GLYCOPHORIN
96
What is the partial repolarization stage?
Closing Na VOLTED gated channels
97
What is complete repolarization stage?
Closing K+ VOLTED gated channels Activity of the sodium-potassium pump K+ leak channels

Cell Biology Midterm 1 (3 decks)

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