Chapter 13: Mitochondria: Bioenergetics & Peroxisomes Flashcards
1
Q
glucose is _________ to produce ATP
A
oxidized
2
Q
oxidative phosphorylation describes how ATP is synthesized as
A
electron carriers are reoxidized in the presence of O2
3
Q
what are the 2 stages of oxidative phosphorylation?
A
- electron transport chain
- chemiosmosis
4
Q
why does the electron transport chain have so many steps instead of just one?
A
too much free energy released all at once could not be harvested by the cell
5
Q
instead of the ETC releasing all the energy at once there are
A
a series of reactions, each releasing a small amount of energy
6
Q
the ETC has transmembrane complexes that act as
A
proton pumps
7
Q
use of the proton pump results in the
A
active transport of H+ across the IM of the mitochondria
8
Q
pumping H+ along the IM of the mitochondria creates the
A
proton motive force
9
Q
what is the proton motif force?
A
storage of potential energy that drives chemiosmosis
10
Q
the proton pump results in what 2 things
A
- a proton [] gradient
- potential energy
11
Q
describe potential energy
A
an electric charge difference across the IM
12
Q
what is known as a large complex rotary enzyme
A
ATP synthase
13
Q
ATP synthase uses __________ to make _________
A
diffusion energy to make ATP
14
Q
ATP synthase allows
A
the diffusion of H+ back into the mitochondrial matrix
15
Q
ATP uses the energy from H+ diffusion to make ATP from
A
ADP and Pi
16
Q
what are the subunits to ATP synthase
A
- F0 subunit
- F1 subunit
- Gamma subunits
17
Q
the F0 subunit is part of the
A
transmembrane
18
Q
the F1 subunit projects into the
A
mitochondrial matrix
19
Q
the F1 subunit rotates to
A
expose active sites of ATP synthesis
20
Q
the F1 subunit contains binding sites for
A
ADP & Pi
21
Q
the gamma subunit is the unit which
A
rotates
22
Q
F0 and F1 are connected by
A
gamma subunit
23
Q
the F1 subunit is also known as the
A
catalytic subunit
24
Q
the enzyme ATP synthase is
A
reversible
25
what does it mean for ATP synthase to be reversible?
it can transport H+ through F0 against its concentration gradient
26
as H+ pass through F0 subunit, gamma rotates causing a
conformational change in the alpha and beta subunits
27
in Boyer's three-state conformational model 'open' was described to be
- low substrate affinity
- no catalytic activity
28
in Boyer's three-state conformational model 'loose' was described to be
- binding of ADP to Pi
- no catalytic activity
29
in Boyer's three-state conformational model 'tight' was described to be
- high substrate affinity
- catalytic activity
30
the matrix of the MTCH contains
DNA and enzymes for oxidative metabolism
31
what part of the MTCH plays a role in apoptosis?
the OM
32
the OM is highly permeable to
small molecules
33
name for channels on the MTCH
porins
34
porins allow for
passive diffusion
35
what component of the MTCH has a similar composition to the cytosol?
the intermembrane space
36
MTCH own circular DNA codes for
- tRNAs
- rRNAs
- few proteins
37
the extensive surface area of the inner membrane of the MTCH is used for
oxidative phosphorylation
38
the MTCH is rich in proteins involved in
e- transport & chemiosmosis
39
IM in the MTCH is impermeable to
small molecules and ions
40
how is the MTCH network motified?
by constantly fusing and dividing
41
fusion of the MTCH network allows for exchange in
genetic material
42
the growth of the MTCH is done by
- uptake of proteins and lipid synthesis
- budding and division
43
MTCH are localized in
regions of high ATP use
44
what areas of the body are highly enriched in MTCH?
skeletal muscle & nerve synapses
45
what is the main function of phospholipid transfer proteins?
to transfer lipids from the ER and mitochondria
46
describe the process of phospholipid transfer
- phospholipid transfer proteins extract lipids from the cytosolic face of the SER
- protect hydrophobic tails while transporting through cytosol
- release phospholipids at the growing MTCH mem.
47
the MTCH is not part of the
secretory pathway
48
MTCH proteins, including ETC complexes must be
imported and accurately localized
49
synthesis of MTCH occurs on
free ribosomes in the cytosol
50
what are the 4 areas for proteins in the mitochondria?
- IM
- OM
- matrix
- IMS
51
what are the 3 general features of MTCH import?
- precuror proteins are targeted to the MTCH matrix by a MSF
- ONLY unfolded proteins are imported
- translocation to matrix occurs where OM and IM are close
52
what are the 3 separate inputs of energy required for transport?
1. ATP hydrolysis in the cytosol
2. electrochemical gradient
3. ATP hydrolysis in the MTCH matrix
53
what is ATP hydrolysis in the cytosol needed for in the MTCH?
to keep the protein unfolded
54
what provides the electrochemical gradient in the MTCH
the proton-motive force across the IM
55
what is ATP hydrolysis needed for in the MTCH matrix
for proper folding of the protein once its in the matrix
56
MPP stands for
matrix protein peptidase
57
PAM is a
ATP-dependent import motor protein
58
PS stands for
presequence
59
SAM stands for
sorting and assembly machinery
60
TIM stands for
translocase of the IM
61
TOM stands for
translocase of the OM
62
precursor proteins possess either an
N-terminus presequence
internal signal sequence
63
the N-terminus presequence can be described as
a + charged amphipathic alpha-helix
64
define amphipathic
has a + charge on only 1 side of the presequence
65
the N-terminus presequence is recognized by receptors in the
TOM complex
66
the N-terrminus presequnce targets proteins to the
matrix
67
an internal signal sequence targets the protein to the
inner/outer MTCH membranes
68
beta-barrel OM proteins are processed by
SAM
69
what are the proteins required for transport of matrix-destined proteins across the IM?
TIM23 and PAM
70
which protein complex inserts carrier proteins into the IM?
TIM22
71
TIM23 is associated w/
PAM
72
TIM23 translocates proteins into the
matrix
73
Hs70 aids
PAM complex in ratchet mechanism
74
explain the ratchet mechanism
ATP binding & hydrolysis of PAM
75
carrier proteins allow the transport of metabolites across the
IMS
76
peroxisomes are small single membrane organelles w/ NO
DNA
77
peroxins are proteins that ONLY function as
peroxisomes
78
what type of enzymes are peroxisomes
metabolic
79
peroxisomes are synthesized on
- cytosolic ribosomes: mem. proteins
- free ribosomes : matrix proteins
80
where is the signal of peroxisomes located?
on the c-terminus
81
peroxisomes are replicated by
division
82
peroxisomes are regenerated when
depleted
83
what is a syndrome caused by the mutation of peroxisome import proteins?
Zellwegar syndrome
84
are peroxisomes a part of the secretory system?
NO
85
what is the byproduct of fatty acid oxidation?
H2O2
86
which enzyme degrades H2O2
Catalase
87
peroxisomes oxidize
- uric acid
- aa
- methanol
- purines
- fatty acids
88
what is the function of peroxisomes in the liver?
synthesize bile salts from cholesterol
89
what is the function of peroxisomes in the brain and heart?
synthesize plasmalogens
90
plasmalogens are critical for
myelination & proper brain development
91
what are the 2 main functions of peroxisomes in the plants?
1. convert fatty acids to carbohydrates
2. photorespiration
92
membrane proteins are translocated into the...and inserted into the...
- ER
- peroxisome membrane
93
the assembly of peroxisomes is done by
the budding and fusing of vesicles containing peroxins
94
pex matrix proteins are synthesized on
free ribosomes
95
pex proteins are imported as
folded polypeptides
96
most pex proteins are targeted by a
PTS1 signal
97
the PTS1 signal are recognized by
Pex5
98
what does the Pex5/cargo complex bind to on the peroxisome?
the docking complex
99
what are the 2 distinct mechanisms of the formation of new peroxisomes?
1. vesicle budding from the ER
2. growth/division of existing peroxisomes
100
what does the MPP cleave from a protein?
presequnce
101
MPP is associated w/
PAM
