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Cell and Molecular Biology > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

mitochondria structure

A

double membrane system:
outer membrane,
inner membrane,
intermembrane space,
matrix

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2
Q

mitochondria outer membrane

A

contains porins (channels highly permeable to small molecules and ions)

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3
Q

mitochondria inner membrane

A

cristae, many proteins for oxidative metabolism and metabolite transport

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4
Q

mitochondria matrix

A

contains mtDNA and metabolism enzymes

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5
Q

mitochondria organization

A

more mitos in high demand tissues and locations, make up dynamic tubular network (fission and fusion)

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6
Q

mitochondria fission

A

division into two units;
cell growth and division, cell polarity, eliminating bad mitos

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7
Q

mitochondria fusion

A

merging of two or more mitos inner and outer membranes;
increase energy production, buffering bad mitos, alleviating oxidative damage

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8
Q

mitochondria oxidative metabolism of ___

A

pyruvate, FAs, and AAs

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9
Q

mitochondria oxidative metabolism processes

A

TCA/CAC/Krebs,
oxidative phosphorylation

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10
Q

mitochondria TCA/CAC/Krebs

A

in matrix;
pyruvate/FAs to acetyl CoA to CO2;
NAD+ and FAD reduced to NADH and FADH2 (carry electrons)

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11
Q

mitochondria oxidative phosphorylation

A

cristae of inner membrane;
energy releasing reactions coupled to energy requiring reactions;
NADH and FADH2;
ATP synthase

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12
Q

mitochondria oxidative phosphorylation energy releasing reactions

A

electron donors to electron acceptors

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13
Q

mitochondria oxidative phosphorylation energy requiring reactions

A

ADP to ATP

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14
Q

mitochondria oxidative phosphorylation NADH and FADH2

A

NADH and FADH2 to complex I and II, to III, to IV, to O2;
exergonic (to O2);
released energy drives pumps I, III, IV to pump into intermembrane space creating potential energy as proton gradient

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15
Q

mitochondria oxidative phosphorylation NADH

A
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16
Q

mitochondria oxidative phosphorylation FADH2

A
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17
Q

TCA/CAC/Krebs metabolites

A

for growth and cell signaling;
used by mito and cytosolic proteins to form nucleotides, AAs, and FAs and cholesterol; also control gene expression by chromatin and post-translational modifications

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18
Q

mitochondria genetics

A

circular dsDNA in nucleoid, polyploid (heteroplasmy), replicate independent from cell division

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19
Q

heteroplasmy

A

two or more mtDNA variants exist in same cell

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20
Q

mitochondria post-translational protein import

A

majority of mito proteins translated by free ribosomes

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21
Q

mitochondria post-translational protein import Tom

A

outer membrane translocase;
translocate N-terminal presequence and internal sequence containing polypeptides;
send to intermembrane space

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22
Q

mitochondria post-translational protein import Tim 23

A

inner membrane translocase;
translocate N-terminal presequence containing polypeptides into matrix or inner membrane;
PAM (import motor), MPP (snips presequence), membrane potential, ATP to ADP

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23
Q

mitochondria post-translational protein import Tim 22

A

inner membrane translocase;
translocate internal sequence containing polypeptides bound to chaperones to inner membrane

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24
Q

mitochondria post-translational protein import Tim 22 chaperones

A

Tim 9 and 10 help stabilize hydrophobic regions of polypeptides going through intermembrane space (Tom to Tim 22 or SAM) (intermembrane space is aqueous like cytosol)

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25
Q

mitochondria post-translational protein import Oxa 1 translocase

A

inner membrane translocase;
for proteins translated inside mitochondria

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26
Q

mitochondria post-translational protein import Mim 1

A

outer membrane translocase;
import α helix integral outer membrane proteins;
cytoplasm to Mim 1 to laterally transported into outer membrane

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27
Q

mitochondria post-translational protein import SAM complex

A

outer membrane translocase;
import ß-barrel integral outer membrane proteins;
cytoplasm to Tom to intermembrane space to SAM complex to lateral transport into outer membrane

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28
Q

mitochondrial disease

A

many syndromes/age of onset/severity of diseases;
inherited pathological mutations (in mom, every tissue);
sporadic pathological mutations (not every tissue);
onset/severity depends on level of heteroplasmy (how much mutant vs mtDNA);
replacement therapy

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29
Q

peroxisome structure

A

single membrane;
dynamic size, number, morphology, and function

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30
Q

peroxisome function

A

major metabolic organelles;
1) lipid synthesis
2) FA oxidation
3) ROS metabolism

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31
Q

peroxisome function lipid synthesis

A

lipids including plasmalogens;
R1 and R2 are fatty acid tails;
enriched in membranes of brain, cardiac, immune tissues

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32
Q

peroxisome function FA oxidation

A

in peroxisome: fatty acids activated to acyl-CoA shortened to acetyl CoA to acetyl-carnitine;
transferred to mito as acetyl-carnitine;
in mito: acetyl-carnitine to acetyl CoA to Krebs cycle oxidation to CO2

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33
Q

peroxisome function ROS (reactive oxygen species) metabolism

A

cellular metabolism increases ROS which can cause oxidative damage to macromolecules;
ROS metabolizing enzymes decreases ROS levels (such as catalase and SOD)

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34
Q

peroxisome biogenesis types

A

de novo (brand new),
division (making new from old)

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35
Q

peroxisome biogenesis de novo

A

ER vesicles bud with PEX transmembrane proteins;
cytosolic-derived matrix proteins

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36
Q

peroxisome biogenesis de novo transmembrane proteins

A

V1 vesicle and V2 vesicle (diff PEX proteins) fuse to form peroxisome membrane

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37
Q

peroxisome biogenesis de novo matrix proteins

A

cytosol PEXs recognize peroxisome targeting sequences (on polypeptide) then mediate docking and translocation into peroxisome

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38
Q

peroxisome biogenesis division

A

ER vesicles bud and fuse with peroxisome to grow membrane and add more proteins;
peroxisome divides

39
Q

peroxisome disorders

A

diverse but often very severe,
mutations in peroxisome genes (like metabolic enzymes and PEX proteins)

40
Q

cytoskeleton

A

network of protein filaments plus proteins

41
Q

actin filament structure

A

actin monomers (G actin) and actin filaments (F actin)

42
Q

actin monomers

A

G (globular) actin;
head to tail interactions

43
Q

actin filaments

A

F (filamentous) actin;
polymers of G actin (dimerize then trimerize then filament);
distinct polarity, plus (barbed) and minus (pointed) end

44
Q

actin filament assembly

A

nucleation, elongation (unbranched), and steady-state (tread milling)

45
Q

actin filament assembly nucleation

A

profilin activates G actin monomers;
nucleators stabilize first actin dimer and promote elongation at + end

46
Q

actin filament assembly nucleation profilin

A

binds to actin and activates with ATP so it polymerizes better;
ADP to ATP

47
Q

actin filament assembly nucleation nucleators

A

formin dimer for unbranched, Arp2/3 for branched

48
Q

actin filament assembly elongation (unbranched)

A

profilin/ATP bound actin binds at + end of formin dimer;
actin acts as ATPase

49
Q

actin filament assembly elongation (unbranched) actin as ATPase

A

hydrolysis (ATP to ADP) is activated when actin is incorporated into the filament, ADP-actin dissociates more readily

50
Q

actin filament assembly steady-state/tread milling

A

ATP-actin joins + end at the same rate that ADP-actin leaves the - end;
filament length maintenance

51
Q

actin filament organization is maintained by

A

capping proteins, filament stabilizing proteins (tropomyosin),
cross linking proteins

52
Q

actin filament organization capping proteins and filament stabilizing proteins

A

maintain actin filament length

53
Q

actin filament organization cross linking proteins

A

organize actin bundles (parallel arrays, microvilli) and actin networks (orthogonal arrays) between adjacent actin filaments

54
Q

actin at the edge

A

cytoskeletal proteins and cell cortex

55
Q

cytoskeletal proteins

A

link actin to plasma membrane;
spectrin and ankyrin

56
Q

cytoskeletal protein spectrin

A

binds actin filaments and phospholipids

57
Q

cytoskeletal protein ankyrin

A

bind spectrin and transmembrane proteins

58
Q

cell cortex

A

protein + membrane edge of the cell; coordinates shape, movement, interaction with other cells or environment

59
Q

myosin structure and function

A

coordinates the activities of actin;
prototype molecular motor;
dimer;
coiled coil tail groups;
globular head groups contain all functional domains

60
Q

myosin:
prototype molecular motor

A

most myosins walk from - to + end of F actin using ATP;
chemical (ATP) to mechanical (walk) energy

61
Q

myosin:
globular head groups functional domains

A

actin binding;
ATP binding;
lever arm

62
Q

myosin II mechanism with actin:
starting position

A

after previous round, myosin attached to actin but not bound to ATP

63
Q

myosin II mechanism with actin:
ATP

A

ATP binding,
changes head group structure,
actin dissociation/cocking of lever arm,
ATP hydrolysis,
ADP + Pi bound,
contact with actin further toward plus end

64
Q

myosin II mechanism with actin:
power stroke

A

Pi released,
ADP released,
myosin head returns to uncocked position

65
Q

actin-myosin in muscle contraction:
myofibrils

A

rod-like organelles in cytoplasm of muscle fibers (cells);
repeated sections of sarcomeres between two Z discs

66
Q

actin-myosin in muscle contraction:
A band

A

thick filaments of myosin overlapping with actin;
myosin anchored at M line

67
Q

actin-myosin in muscle contraction:
I band

A

only thin filaments of F actin;
plus end anchored to Z disc

68
Q

actin-myosin in muscle contraction:
sliding filament model

A

sarcomeres shorten, bringing Z discs closer;
myosin orientation reverses at M line;
titin springs hold myosin in place

69
Q

actin-myosin in muscle contraction:
regulation of contraction by Ca2+

A

nerve sends action potential,
travels through T-tubules of sarcolemma,
Ca2+ release from sarcoplasmic reticulum,
binds to troponin bound to tropomyosin which is moved
reveals myosin binding sites where myosin head can bind actin

70
Q

actin-myosin in cytokinesis:
contractile ring

A

constricts plasma membrane in two

71
Q

actin-myosin in cytokinesis:
regulation of contraction

A

Ca2+ binds calmodulin causing shape change;
calmodulin binds to MLCK;
MLCK activates myosin II with Pi

72
Q

microtubule structure smallest unit

A

heterodimer of α and β tubulin;
each encoded by small family of genes;
both bind GTP in dimer form;
β has GTPase activity;
α stimulates β GTPase activity

73
Q

microtubule structure polymer

A

made up of tubulin heterodimers;
protofilaments, long strands of dimers arranged in parallel;
centrosome assembles 10-15 protofilaments around hollow core and stabilizes - end;
distinct polarity, - end is α, + end is β

74
Q

microtubule assembly and disassembly

A

GTP dimers bind at + end;
GTPase activity;
dynamic instability at + end;
microtubule associated proteins (MAPs)

75
Q

microtubule assembly and disassembly:
GTPase activity

A

when dimers polymerized hydrolysis is activated;
GDP bound tubulin dissociates more readily

76
Q

microtubule assembly and disassembly:
dynamic instability

A

catastrophe and regrowth at the + end

77
Q

microtubule assembly and disassembly:
MAPs

A

microtubule associated proteins (MAPs) regulate + end stability;
polymerase accelerates growth;
depolymerase promotes shrinkage;
CLASP stops shrinkage

78
Q

microtubule growth

A

when GTP-dimer addition exceeds hydrolysis (GDP-dimer formation)

79
Q

microtubule shrinkage (catastrophe)

A

when hydrolysis (GDP-dimer formation) exceeds GTP-dimer formation

80
Q

microtubule regrowth (rescue)

A

when GDP-dimer leaving is stopped allowing GTP-dimer cap formation

81
Q

microtubule organization in prototypical animal cell

A

microtubules grow and extend from microtubule organizing center (MTOC)

82
Q

microtubule organizing center (MTOC) in animal cells

A

centrosome;
pair of centrioles at center;
pericentriolar material

82
Q

MTOC in animals pair of centrioles

A

9 triplets of microtubules arranged in wheel structure

83
Q

MTOC in animals pericentriolar material

A

matrix of proteins surrounding centrioles;
γ tubulin (gamma) initiates microtubule polymerization;
microtubule anchoring proteins hold - ends

84
Q

microtubules in neuron

A

determine polarity;
stable microtubules in axons and dendrites;
ends terminate in cytoplasm (not MTOC)

85
Q

stable microtubules in neuron

A

transport of cargo to the processes;
retrograde transport of signals to the cell body (nucleus)

86
Q

ends of microtubules in neuron

A

terminate in cytoplasm (not MTOC);
capped and stabilized by MAPs (MAP1, MAP2, tau);
distinct orientation in each process

87
Q

orientation of ends of microtubules in neuron

A

dendrites polymerize in both directions (+ and - ends both terminate in cytoplasm);
axons polymerize anterograde (- ends terminate in cytoplasm)

88
Q

microtubular motor proteins

A

walk along stable microtubules;
two families kinesins and dyneins;
homodimers with heavy and light chains

89
Q

microtubular motor proteins:
kinesins

A

move toward + end;
carry vesicles anterograde in cell endocytic and secretory pathways

90
Q

microtubular motor proteins:
dyneins

A

move toward - end;
carry vesicles retrograde in cell endocytic and secretory pathways

91
Q

microtubular motor proteins:
heavy chains

A

ATPase activity and tubulin binding;
hydrolysis changes conformation causing movement

92
Q

microtubular motor proteins:
light chains

A

carry cargo

93
Q

microtubule intracellular organization and transport

A

microtubule - ends located near nucleus/cell interior;
transport of vesicles in endocytic and secretory pathways (kinesins anterograde, dyneins retrograde);
without microtubules ER would collapse and gogli unstacking

Cell and Molecular Biology (4 decks)

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