exam 3 Flashcards
1
Q
what and where are proteins polymerized by
A
ribosomes- in cytosol or attached to rough er
2
Q
what kind of proteins are made in cytosol
A
soluble
3
Q
where do proteins made in cytosol go
A
-some stay in cytosol
-actively imported to an organelle (fold or unfolded)
4
Q
what are the unfolded and folded proteins into an organelle
A
unfolded- mitochondria, chloroplasts, peroxisomes
folded- nucleus
5
Q
proteins made on the rough er may
A
-cross membrane and enter lumen
(endomembrane system, secretion)
-Stick in er membrane
(go to plasma membrane, or stay in ems membrane)
6
Q
proteins that do not stay in the cytosol have a
A
signal sequence
7
Q
what do proteins that have a signal sequence do
A
direct polypeptides to destination
8
Q
what is a signal sequence
A
amino acids that are recognized by protein receptors that guide a new polypeptide to destination
9
Q
endomembrane system structure
A
membrane compartments linked together by ontogeny and function
10
Q
er membrane thickness vs plasma membrane
A
5nm
8nm
11
Q
what is the smooth er function
A
steroid biosynthesis
assembly of glycerolipids
stores ca2+, triaglycerols
12
Q
structure of smooth er
A
lacks ribosomes
cisternae are tubular
13
Q
rough er function
A
biosynthesis and processing of proteins for secretion and ems
14
Q
structure of rough er
A
receptors for ribosomes
cisternae are flattened
lumen accumulates secretory proteins
15
Q
what directs a ribosome to the er membrane
A
signal sequence and a signal recognition particle
16
Q
glycosylation of membrane proteins and lipids begins where
A
in the er- assembled on cytosolic face ( bound to dolichol phosphate
17
Q
in glycosylation what moves oligosaccharides to lumen side of membrane
A
flippase, then transferred to protein or lipid
18
Q
what does asparagine have to do with glycosylation
A
many proteins are glycosylated on it while in the er
19
Q
importance of protein modifications in er and golgi apparatus
A
each chunk does a different modification
20
Q
golgi apparatus structure
A
flattened cisternae in stacks
cis-golgi= faces er
trans= faces plasma membrane
medial=middle
21
Q
functions of golgi apparatus
A
chemical modification of proteins and lipids
-glycosylation, methylation, phophorylation
22
Q
how does the golgi apparatus sort proteins and target them to specific destinations
A
membrane thickness-traps IMPs
pH and ca2+ -aggregate some secretory proteins
mannose-6-P- targets to lysosomes
KDEL- targeting sequence (a.a)
(ALL RELY ON CHEMICAL AND PHYSICAL PROPERTIES)
23
Q
what are lysosomes
A
organelle that digest biological macromolecules and organelles
-acidic considering digestive enzymes
24
Q
early endosomes mature with addition of more ____ from golgi and become what
A
enzymes/vesicles, late endosomes
25
late endosomes which are more ____ develop into
acidic, lysosomes
26
where would hydrolytic enzymes be found in ems and why
lysosomes because they are only active under acidic conditions
27
vacuoles in plants are similar to what in animals
lysosomes
28
nuclear envelope in relation to ems
fused with the er
gets lipids and proteins from er/golgi
29
vesicle structure/ coated vesicles
proteins that bind to membrane surface and direct vesicle formation
30
type of protein coat- clathrin characteristics
-inside pm
-form at trans golgi and pm, go to endosomes, then lysosomes
-link together by overlapping arms
-"triskelion" subunits, 6 polypeptides each
31
clathrin molecules form _______ cages that help ____ membranes into vesicles
basketlike, shape
32
calthrin-coated vesicles use what type of endocytosis
receptor-mediated ENDOCYTOOSIS
33
how does clathrin use receptor-mediated endocytosis
cargo binds receptor protein in pm then is brought into the cell
34
different proteins form ___ at other membranes in the ___,
____ may dissociate after budding of ____ or may stay on _____ until fusion with target ____
coats, ems
coat, vesicle, membrane
35
trafficking in the ems =
directed movement of vesicles among compartments
36
snare hypothesis in vesicle binding and fusion
proteins protruding from vesicle surface and target membrane link and pull the 2 membranes together
37
describe the 3 steps in the snare hypothesis
-recognition: by tethering complexes of proteins on target membranes
-these then bind the incoming vesicle and pull it to the membrane surface
-SNARES then link
38
what helps direct transport vesicles to their target membranes
Rab proteins, tethering proteins, and SNARES
39
secretion and exocytosis
fusion of vesicle with plasma membrane and release contents out of cell
40
vesicle movement occurs along cytoskeleton, using
motor proteins
41
what is oxidative phosphorylation
making atp from energy derived by oxidation of molecules
42
what is oxidative metabolism
pathways that catabolize organic molecules to retrieve energy
43
electrons are carried to the electron transport chain in the
inner mito membrane
44
as electrons move through the electron transport chain, energy ____ is used to set up H+ ___ across membrane
released, gradient
45
after H+ gradient is established across mito membrane, that proton gradient ____ energy that is then used by _____ Factor( F-type ATPase) to make ___
stores, coupling, atp
46
in summary what are the 4 steps of oxidative metabolism
1. electrons move down free energy through the e.t.c to O2
2. O2 is reduced to H2O
3. establish proton gradient
4. gradient stores energy then is used up by F-type ATPase to make ATP
47
where is the electron transport chain
the inner mitochondrial membrane
48
what does the etc do
sets up proton gradient for chemiosmotic ATP synthesis
49
activated carriers generated during the citric acid cycle power the production of
atp
50
what are the four separate compartments of the mitochondrion
matrix, outer membrane, inner membrane, and the folds
51
where are porins present in the mitochondria
the outer membrane
52
inner mito membrane and cristae
curved folded surface (cristae) -high surface area
protein; lipid ratio high
53
what is cardiolipin
lipid unique to mitochondria- relates to lipid composition, low sterols, high PE
54
cardiolipid is ___ weight percent of inner mito membrane lipids
20
55
what may enable high curvature of cristae
cardiolipin - may trigger apoptosis
56
what is the mitochondrial matrix
innermost space, protein rich solution
enzymes fro citric acid cycle, b-oxidation
57
intermembrane space
between intermembrane mito membrane and outer
-continuous with cytosol via porins
58
intracristal space
within tubules and folds of cristae
-where H+ accumulates during electron transport
-limited connection to intermembrane space
59
where does oxidative phosphorylation occur
cristae membrane of eukaryotes
plasma mebrane of aerobic prokes
60
5 steps of oxidative phosphorylation
1. e.t.c lets electrons flow down gradient from NADH to FADH2 to O2
2. electron transport is coupled to the active transport of H+ out of the matrix to intracristal space
3. proton gradient across cristal membrane stores potential energy
4. energy released, protons diffused back into matrix
5. energy can be used to fuel ATP synthesis when protons move through FoF1 coupling complex in cristae
61
electron carriers are _____, mostly attached to ____ membrane proteins in respiratory complexes
cofactors, integral
62
what is an example of an integral membrane protein
cytochrome c
63
coenzyme Q -lipid soluble electron carrier can be found where
in core of cristal membrane
64
what are respiratory complexes
groups of integral membrane proteins with attached cofactors
65
high energy electrons are transferred through ___ respiratory enzyme complexes in the ____ mitochondrial membrane
3, inner
66
each complex is doing what by pumping protons
work- active transport
67
what are the 2 major entry points of the three respiratory complexes and what are the names
complex 1- NADH dehydrogenase complex
complex 2- cytochrome c reductase
68
what is the major endpoint in oxidative phosphorylation
complex 4- cytochrome c oxidase
69
what does complex 2 not do
pump protons, not much work being done, succinate FADH not NADH
70
what is bound to complex 2
FADH- succinate in
71
electrons move ___ redox potential gradient but ____ free energy gradient
up, down
72
all complexes feed to what
coenzyme Q
73
oxidative metabolism- endergonic or exergonic
exergonic
74
electron carriers - nucleotide based
NADH/NAD+ water soluble, carries e- to e.t.c
FAD/FADH
FMN/FMNH2 -bound to flavoproteins
75
what are cytochromes and what complexes
proteins with a heme prosthetic group
complexes 3 and 4
76
how do hemes differ from one another
by side groups- makes different cytochromes
77
one cytochrome will be a _____ protein others are all parts of _____ membrane proteins
peripheral, integral
78
where does redox occur in cytochromes
Fe ion, alternating between +2 and +3 states
79
what are the most common protein bound carriers in mito e.t.c
Fe-S centers
80
other examples of carriers in oxidative phosphorylation
Cu centers and Cu cytochromes
-alternating between +1 and +2 states
Cu center- aa side chains
cytochrome-has Cu and Fe in heme
81
what is the last example of a carrier in oxidative phosphorylation
quinones; ubiquinone,, coenzyme Q
Lipid soluble- isprenoid chain
can diffuse across 1,2,and 3
82
where does coenzyme Q carry electrons from in the complexes
from complex 1 and 2 to complex 3
83
where does coenzyme Q carry protons from
across the inner mito membrane from matrix to intercristal space
84
electrons move from ____ to carrier, always moving to a ____ with a higher ____ potential (greater ____ for e-)
carrier, carrier, redox, affinity
-downhill towards O2
85
what if there is no oxygen to accept in oxidative phosphorylation
whole system will become reduced
86
how do electrons flow when talking about numbers- redox potentials
smallest to biggest
negative to positive
87
does NADH or FADH pump more protons to O2
NADH- 10
FADH-6
88
protons are pumped out of matrix in which complexes
1,3,4
89
what does the proton gradient across the inter mito membrane depend on
membrane potential and pH gradient -proton motive froce pulls H+ back into matrix
90
atp synthase acts like a ____ to convert the ____ of protons flowing ____ their free energy gradient to ____ bond atp
motor, energy, down, chemically
91
characteristics of F1 knob
has 3a and 3b subunits
sticking outside-big
3b subunits have active sites with atpase activity
92
characteristics of Fo knob
integral to membrane
"a" subunit is stationary, passes H+ across inner mito membrane
10 "c" subunits form rotating ring next to "a"
93
conformational changes and atp synthase in F1 are driven by what
H+ flux through Fo
94
uncoupling atp synthesis from H+ flux and electron transport characteristics
1. energy released as heat
2. occurs when proteins move through uncoupling proteins or cross membrane liked to chemical
3. can occur if electron transport does nit set up proton gradient
95
cytoskeleton consists of ___ throughout cell
what do these do?
protein fibers
give form strength, and help in movement
96
what are the 3 types of protein fibers
microfilaments, microtubules, and intermediate filaments
97
diameter of each of the protein fibers
microfilaments- 7nm
microtubules- 25nm
intermediate filaments- 8-12nm
98
intermediate filaments characteristics
hold cell together in pictures
provide mechanical strength to cells and tissues
mostly in animals
99
intermediate filaments _____ cells against _____ stress
strengthen, mechanical
100
what is the intermediate filament structure made of
"ropes" made of long, twisted fibrous proteins
alpha helix
twist=strength
-hydrogen bonds
101
microtubules are _____ tubes with structurally ____ ends
hollow, distinct
102
the ____ is the major microtubule-_____ center in animal cell
centrosome, organizing
103
mictrotubules display _____ instability
dynamic
104
dynamic instability is driven by ____ hydrolysis
GTP
105
microtubule _____ can be _____ by drugs
dynamics, modified
106
motor proteins drive _______ transport
intracellular
107
what are the motor proteins in microtubules and microfilaments
microtubules- kinesin and dynein
micofilaments- myosin
108
______ and motor proteins _____ organelles in the ____
microtubules, position, cytoplasm
109
_____ and flagella contain stable ____ moved by ____
cillia, microtubules, dynein
110
microtubules polymers of protein is called
tubulin
111
cytoplasmic microtubules or intracellular
mitotic spindle
vesicle trafficking - walking traffic pattern in the endomembrane system
112
why are cytoplasmic microtubules important
help organize and maintain cell structure
113
structure of cytoplasmic and axonemal microtubules
axonemal- highly structured -doublet ring- cilia and flagella-causes movement
cytoplasmic- loosely organized and dynamic
114
tubulin is a family of
globular proteins
115
eahc tubulin is about how many amino acids
450
116
profilaments are polymers of ___-tubulin heterodimers which causes _____ in microtubules
ab
polarity
117
how many protofilaments form tubule
about 13
118
where is the microtubule organizing center aka site where most microtubules initiate polymerization
basal bodies or centrosomes
119
where are centrosomes located in animal cells
near nucleus
120
what is y-tubulin
rings of this isoform are only found in centrosomes
anchor minus end of microtubule
121
centrosomes contain 2 _____ and rings of _____
centrioles
y tubulin
122
what are basal bodies
organize axonemal microtubules of cilia and flagella
123
the centriole _____ microtubule doublets that form _____. This is located at ______ membrane
nucleates, axoneme, plamsa
124
microtubules that constantly assemble and disassemble is called what
dynamic instability
125
what drives dynamic instability
GTP
126
steps of polymerization/dynamic instability
1. GTP binds to each subunit of heterodimer
2. GTP on B-tubulin is hydrolyzed to GDP
3. GTP- tubulin stabilizes microtubule-polymerization
4. GDP-tubulin destabilizes microtubule-depolymerization
5. when rate of GTP hydrolysis exceeds rate of dimer addition, microtubules rapidly depolymerize
127
what are the motor microtubule proteins
kinesin and dynein
128
what do the non motor MAPs do
some stabilize microtubules
some promote polymerization
some cross link and bundle microtubules
129
what are the ways that microtubules are involved in motility
intracellular vesicle trafficking
cilia and flagella
spindle formation and mitotic division of chromosomes
130
intracellular motility is mediated by what
motor proteins
-in microtubules kinesin and dynein
in microfilaments- myosin
131
organelles and vesicles attach to ____ protein and are ___ along microtubule
motor, walked
132
what motor proteins are on each end of the microtubule
kinesin is on plus end
dynein on minus end
133
what is kinesin important for
the binding and hydrolysis of ATP
134
what are cilia and flagella and what do they use to cause motion
extensions of cell that beat to move cell
dynein (no kinesin)
135
size difference in cilia and flagella
cilia -5-25 micrometers long
flagella- 50-75 micrometers long
136
what is primary cilia
used in sensory structures, important during development- non motile
137
what is a axoneme
core of cilium -9+2 arrangement of microtubules
2= singlet microtubules
primary cilia lack central pair
138
dynein crawls along ______ and makes microtubules ____ along each other to cause ____ of cilia and flagella
microtubule, slide, beating
139
what is the mitotic spindle
separates chromosomes during mitosis, formed of microtubules
140
mitotic spindle steps
1. organize chromatids. separate during mitosis
2. centrosome is duplicated prior to mitosis
3. centrosomes separate at start of prophase, opposite sides of nucleus
4. centrosomes nucleate the formation of mitotic spindle as prophase begins
5. cytoplasmic microtubules mostly depolymerize
141
what is the kinetochore
binds spindle microtubules, link them to chromosomes
142
many proteins bind to ____ and modify its properties
actin
143
actin and ____ polymerize by similar mechanisms
tubulin
144
cell crawling depends on what
cortical actin -actin and myosin working together pushing and pulling
145
actin-binding proteins ____ the type of _____ formed at the leading ____
influence, protrusions, edge
146
a cortex rich in ____ microfilaments underlies the ____ membrane of most eukaryotic cells
actin, plasma
147
extracellular signals can ____ the arrangement of ____ microfilaments
alter, actin
148
microfilaments are polymers of protein called what
actin
149
types of movements in microfilaments
cell crawling, amoeboid motion
muscle contraction
cleavage furrow -animal cells
150
cell shape and structure of microfilaments
cell cortex= dense network of microfilaments below plasma membrane
microvilli core is bundle of actin microfilaments
151
actin microfilaments ____ animal cells to ____ a variety of shapes and _____ a variety of function
allow, adopt, perform
152
microfilaments have binding sites for
atp/adp
myosin
other proteins
153
polymerization in microfilaments
1. pool of actin monomers in cytosol polymerize to form actin filaments
2. polarity- plus end polymerizes more quickly
154
actin monomers mus bind ____ to polymerize
ATP
155
in microfilaments ____ is hydrolyzed after actin _____
ATP, polymerization
156
actin binding proteins control the ___ of actin filaments
behavior
157
what does the dense cortex beneath the plasma membrane that microfilaments form contain
actin and myosin
can change shape using contractile forces
generates motile surface projections
158
what movement does myosin cause in microfilaments
-muscle contraction
-cytoplasmic streaming
-amoeboid motion
-cytokinesis
159
what does myosin require
ATP
160
the extracellular matrix is the structure ____ cells, to which cells ____, that gives form and _____ to tissues and ____
surrounding, adhere, function, organs
161
function of extracellular matrix
support -strength
regulation of development -cell division
physical barriers to movement of molecules,cells, and pathogens- filter
162
extracellular matrices have ____ fibrous molecules in a ____ of cushioning ____
strong, network, molecules
163
animals versus plants extracellular matrices
animals - fibers of collagen(main structural protein) in a network of proteoglycans
-proteins and polysachharides
plants- fibers of cellulose (or elastin) in a network of pectin
-both polysachharides
164
what is cellulose
beta 1-4 linked glucose polymer
165
