Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL 2321 - Cell Biology > Cellular Respiration > Flashcards

Cellular Respiration Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Describe the structure of the mitochondria

A

double membrane

inner membrane folds = cristae

matrix with small circular pieces of mitochondrial DNA

contains over 1000 different types of proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are cristae? What purpose do they serve?

A

the inner membrane folds of the mitochondria expand the surface area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is located in the matrix of the mitochondria?

A

small, circular pieces of mitochondrial DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How many proteins are found in the mitochondria?

A

over a thousand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What proteins does the mitochondrial matrix contain?

A

free enzymes that function in metabolic pathways (ex. pyruvate oxidation to acetyl-CoA, the CAC, the beta-oxidation of fatty acids)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What do the proteins in the inner mitochondrial membrane and cristae do?

A

enzymes are embedded there for the ETC and oxidative phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the typical size of a mitochondria?

A

0.5-1 um

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

T or F: mitochondria are static and do not change shape or move

A

false! they are very dynamic

always moving, changing shape and size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how do mitochondria divide and fuse in relation to the cell they are located in?

A

independently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What process of cell division is mitochondrial division similar to?

A

binary fission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What form of mitochondria do some developing cells have?

A

tubular networks of mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What kind of cells have restricted space for mitochondria?

A

muscle fibres

sperm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are mitochondria often associated with? what does this help with?

A

often associated with the cytoskeleton to determine their orientation and distribution in different cell types

motor proteins can help them travel up and down microtubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a major distinction between the inner and outer mitochondrial membranes?

A

inner: selectively permeable membrane which many things require a transporter to pass through
outer: freely permeable to small molecules and some small proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the IMM most similar to?

A

bacterial plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the OMM most similar to?

A

a membrane that lines the cell walls of some gram negative bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What allows the OMM to be freely permeable?

A

its wide channels (porins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the protein to lipid ratio of the IMM?

A

3: 1 protein: lipid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why are there so many proteins in the IMM?

A

they are critical for cellular respiration and signalling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What major membrane component does the IMM not contain?

A

cholesterol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is cardiolipin? Which mitochondrial membrane contains this and in what quantity?

A

a unique bacterial membrane phospholipid

inner membrane contains a large quantity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How many proteins are synthesized in the mitochondria? What synthesizes it?

A

13

its own DNA and its own ribosomes synthesize these

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How and where are the other proteins for the mitochondria synthesized?

A

coded for in nuclear DNA

synthesized on cytosolic ribosomes

imported post-translation with a mitochondrial signal sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do most proteins synthesized outside of the mitochondria enter the mitochondria?

A

they are translocated across both membranes by translocases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What does TOM stand for?

A

Translocase of the Outer Membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does TIM stand for?

A

Translocase of the Inner Membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What do both TIM and TOM contain?

A

receptors that recognize and bind proteins as well as a translocation channel to move those proteins across the given membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How are new porins embedded within the OMM?

A

porins enter the intermembrane space through a TOM complex

chaperones in the IMM space prevent porins from aggregating there

the unfolded porin binds to a SAM complex which inserts them into the OMM and helps them fold properly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How do porins enter the intermembrane space?

A

through a TOM complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What prevents porins from aggregating in the intermembrane space?

A

chaperones in the intermembrane space prevent porins from aggregating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What do the unfolded proteins bind to in the intermembrane space?

A

the SAM complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What does the SAM complex do with the unfolded proteins that bind to them from the intermembrane space?

A

it inserts them into the OMM while helping them fold properly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How many different TIM channels are there in the IMM? What are they?

A

2

TIM22
TIM23

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is TIM22 for? Where is it located?

A

for inner membrane proteins

embedded in the IMM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is TIM23 for? where is it located?

A

in the IMM

mostly for mitochondrial matrix proteins to pass through the IMM into the matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the targeting peptide that allows inner membrane proteins to move into the mitochondria?

A

an internal hydrophobic amino acid sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

How does TIM22 function?

A

it opens laterally to anchor proteins in the IMM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the targeting peptide for TIM23?

A

an N-terminal positively charged amino acid sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

How does TIM23 function?

A

mitochondrial chaperones aid the entry and folding while a matrix signal peptidase cleaves off the targeting sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What cleaves off the N-terminal positively charged amino acid sequence on mitochondrial matrix proteins using TIM23 to enter the mitochondria matrix?

A

signal peptidase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Where must a protein first translocate through to get to either TIM?

A

through TOM on the OMM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What two routes can integral proteins destined to be embedded in the IMM arrive at the IMM?

A

through TIM22 or TIM23

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

How does an integral protein destined for being embedded in the IMM moved through TIM23?

A

the same way a matrix protein does, but it will be inserted into the IMM by an OXA complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What kind of integral membrane protein can move through TIM22?

A

a multi-pass integral membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Describe the steps of integral membrane proteins being embedded in the IMM via TIM22

A
  1. they enter the intermembrane space through TOM
  2. when in the intermembrane space they are bound by chaperones which take them to TIM22
  3. TIM22 recognizes the internal hydrophobic amino acid sequence in the protein
  4. TIM22 opens laterally to anchor the proteins in the IMM
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Why is the hydrophobic amino acid sequence of multi-pass integral membranes not cleaved off once the protein is in the inner membrane?

A

because it’s in the middle of the protein so cleaving it would cut the protein in half

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

T or F: integral membrane proteins that enter through TIM23 use the same mechanism as the matrix proteins to enter the matrix

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What happens to the integral membrane proteins once they reach the matrix?

A

their N-terminal signal sequence is cleaved to expose a second N-terminal hydrophobic signal sequence which targets them to the OXA complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

How are integral membrane proteins that enter through TIM23 targeted to the OXA complex?

A

when they enter the matrix, their N-terminal signal sequence is cleaved to expose their second N-terminal hydrophobic signal sequence which targets them to OXA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is the function of the OXA complex?

A

it inserts the integral membrane protein which entered the matrix via TIM23 into the IMM

it also inserts membrane proteins that are synthesized on mitochondrial ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

T or F: OXA only inserts integral membranes into the IMM that entered via TIM23

A

False. OXA also inserts integral membrane proteins that were synthesized on mitochondrial ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Which complexes are used when a porin needs to be embedded in the OMM?

A

TOM and SAM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Which complexes are used when a protein needs to be translocated to the matrix?

A

TOM and TIM23 (both are passed through together)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Which complexes are used when a multi-pass integral membrane protein from a nuclear gene needs to be embedded in the IMM?

A

TOM and TIM22 (carried between them in the IMS by chaperones)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Which complexes are used when a single pass integral membrane protein from a nuclear gene needs to be embedded in the IMM?

A

TOM and TIM23 (pass through both together) to get into the matrix and then a second signal to direct it to OXA

so TOM, TIM23, and OXA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Which complexes are used when a protein from a mitochondrial gene needs to be embedded in the IMM?

A

OXA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What does it mean to oxidize a sugar?

A

to REMOVE electrons from it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What’s a useful way to think of electrons in the context of cellular respiration?

A

as little packets of energy that can eventually be used to build ATP molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What is the goal of cellular respiration?

A

to remove as many electrons as possible from a sugar until the most oxidized/depleted remnant is left: CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Where do the electrons end up after they’ve been used to make ATP?

A

O2 which is converted into H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What is the overall reaction of cellular respiration?

A

C6H12O6 (glucose) + 6 O2 –> 6 CO2 + 6 H2O + ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is the waste product of cellular respiration?

A

CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What does it mean to reduce something?

A

to add electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

As each pair of electrons is stripped off a sugar, what temporarily holds them?

A

electron carrier molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Where do the carrier molecules eventually pass off the electrons to?

A

the ETC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

T or F: electrons (And thus energy) is removed from sugars in one step

A

false!! it is done in small steps otherwise energy is not useful to a cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

How are electrons given to carrier molecules and eventually used to make ATP?

A

by extracting electrons (and thus energy) from sugar in small steps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

When a carrier lacks the electrons from sugar, it is in the ____ form?

A

oxidized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

When a carrier receives the electrons from sugar, it is in the _____ form

A

reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

When a carrier donates the electrons to the ETC, it will be in the ____ form

A

oxidized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What else is pulled off when an electron is pulled off a sugar?

A

a hydrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Does the oxidized carrier have more or less hydrogens than the reduced carrier?

A

less hydrogens than the reduced carrier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

Is NAD+ oxidized or reduced?

A

oxidized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Is NADH + H+ oxidized or reduced?

A

reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Is FAD+ oxidized or reduced?

A

oxidized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Is FADH2 oxidized or reduced?

A

reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

What are the 3 metabolic activities?

A

glycolysis + fermentation

pyruvate decarboxylation + citric acid cycle

ETC/chemiosmosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Where does glycolysis or fermentation occur?

A

in the cytosol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Where does pyruvate decarboxylation + the CAC occur?

A

in the mitochondrial matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Where does the ETC/chemiosmosis occur?

A

on the inner mitochondrial membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

T or F: glycolysis and fermentation produce only a little ATP

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

T or F: glycolysis and fermentation can be done without oxygen

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

What process takes all the glucose carbons and releases them as individual CO2 molecules, fully oxidizing the sugar?

A

pyruvate decarboxylation to acetyl CoA and the CAC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

What produces the proton gradient that produces ATP?

A

the ETC / chemiosmosis taking electrons from sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

What is substrate-level phosphorylation?

A

the small amount of ATP produced by glycolysis and the CAC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

How is most of the ATP generated in cellular respiration?

A

by oxidative phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

What are the 2 stages of oxidative phosphorylation?

A

the ETC uses energy from electrons to pump H+ into the intermembrane space

chemiosmosis uses ATP Synthase (F-type pump) in the IMM to move H+ back into the matrix while synthesizing ATP on the matrix side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

How does chemiosmosis use ATP synthase?

A

uses ATP synthase in the IMM to move H+ back into the matrix while synthesizing ATP on the matrix side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What is the basic reaction in glycolysis?

A

glucose (6C) –> 2 pyruvate (3C each)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

What are the 2 stages of glycolysis?

A

energy input stage

energy payoff stage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

What does the energy input stage of glycolysis require?

A

ATP hydrolysis at 2 distinct steps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

How many carbons are in glucose?

A

6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

In the energy input phase, what does glycolysis convert glucose into?

A

6C glucose is converted into 2 identical 3C molecules called glyceraldehyde-3-phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

Why is it called the energy input phase?

A

because 2 ATPs need to be hydrolyzed for glycolysis to split glucose into 2 glyceraldehyde-3-phosphate molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

In the energy payoff stage of glycolysis, what are the 2 glyceraldehyde-3-phosphates converted into?

A

Each glyceraldehyde-3-phosphate is converted into a pyruvate molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

How many carbons does a single glyceraldehyde-3-phosphate have?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

How many carbons does a single pyruvate molecule have?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

During the energy payoff phase of glycolysis, how is ATP made?

A

by substrate-level phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

How much ATP and NADH is made for every 2 glyceraldehyde-3-phosphates (one glucose)?

A

4 ATP total

2 NADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

How many glyceraldehyde-3-phosphates and pyruvates are made per glucose molecule?

A

2 of each

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

Which electron carrier is produced in the energy payoff phase of glycolysis? Is it reduced or oxidized? How many are produced per G3P?

A

1 reduced electron carrier, NADH per G3P = total 2 per glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

What is the reaction that reduces NAD+ to NADH?

A

NAD+ + 2e- + 2H+ = NADH + H+

103
Q

T or F: CO2 is produced in glycolysis

A

FALSE FALSE FALSE

104
Q

What are the NET products of glycolysis per glucose?

A

2 pyruvate + 2 H2O

2 ATP

2 NADH + 2H+

105
Q

Why are only 2 ATP molecules produced per glucose molecule as a net product of glycolysis when 4 are produced during the energy payoff phase?

A

because the energy input phase requires the hydrolysis of 2 ATP per glucose molecule so

4 produced - 2 used = 2 net

106
Q

At the end of glycolysis, are any carbons fully oxidized?

A

no

107
Q

Where is most of the starting chemical energy of glucose stored after glycolysis?

A

in the 2 pyruvate molecules

108
Q

Where is some of the chemical energy extracted during glycolysis?

A

when 2 NADH were produced

109
Q

what is a key step in glycolysis?

A

fructose-6-phosphate getting a second phosphate to make fructose 1,6-bisphosphate

110
Q

What helps in the phosphorylation of fructose-6-phosphate?

A

the enzyme phosphofructokinase converts fructose-6-phosphate into fructose 1,6-bisphosphate

111
Q

Why is the phosphorylation of fructose-6-phosphate a key step in glycolysis?

A

because once it occurs, the carbons are irreversibly committed to glycolysis

112
Q

Why is phosphofructokinase’s activity heavily regulated?

A

because once it phosphorylates fructose-6-phosphate, the carbons are committed to glycolysis

113
Q

What are the basic steps of glycolysis?

A
  1. starts with one molecule of glucose
  2. molecules of ATP hydrolyzed
  3. fructose-6-phosphate is phosphorylated by fructophosphokinase
  4. glucose (6C) is cleaved into 2 molecules of G3P (3C)
  5. 4 ATP + 2 NADH produced
  6. 2 molecules of pyruvate (3C)
114
Q

What is the basic reaction of pyruvate decarboxylation?

A

pyruvate –> acetyl-CoA + CO2

115
Q

What happens to each pyruvate molecule if oxygen is present?

A

the pyruvate molecule crosses the outer mitochondrial membrane through the non-selective porin channels and the inner mitochondrial membrane through a transporter into the matrix

116
Q

What are the 3 basic steps of pyruvate oxidative decarboxylation? Where do these occur?

A

in the mitochondrial matrix:

  1. pyruvate is broken into CO2 + acetate
  2. NAD+ is reduced to NADH
  3. acetate group is linked to Coenzyme A = Acetyl-CoA
117
Q

What is each pyruvate broken down into?

A

CO2 + an acetate

118
Q

What is coenzyme A?

A

a large molecule that includes an adenine base, ribose sugar, some phosphates, and a thioester functional group

119
Q

What is the function of Coenzyme A?

A

it activates or primes the acetate group so that it can jump into the citric acid cycle

120
Q

What happens to CoA after it helps the acetate group enter the CAC?

A

CoA is recycled

121
Q

What is the overall reaction that occurs in the citric acid cycle?

A

Acetyl CoA –> 2 CO2

122
Q

How many carbons are in acetyl-CoA?

A

2

123
Q

How does acetyl-CoA enter the citric acid cycle?

A

it joins with oxaloacetate (4C) and CoA is removed

124
Q

How many carbons does oxaloacetate have?

A

4

125
Q

What is the product of oxaloacetate + acetyl-CoA?

A

the 6C citrate/citric acid

126
Q

How many carbons does citrate/citric acid have?

A

6

127
Q

Why is the citric acid cycle called a cycle?

A

because citrate is reconverted into oxaloacetate (ie., oxaloacetate is regenerated)

then a new acetyl-CoA can combine with oxaloacetate and enter the CAC

128
Q

How many turns of the CAC occur per glucose? why?

A

2 turns because there’s 2 pyruvates per glucose and only one can enter at a time

129
Q

What are the products of the CAC per turn?

A

2x CO2

3x NADH

FADH2

ATP (substrate level phosphorylation)

130
Q

Why do 2 CO2s need to be produced for every turn of the CAC?

A

because citrate is 6 carbons and needs to be converted back into the 4C oxaloacetate so 2 carbons need to be released as CO2

131
Q

What reactions does the cycle from citrate back to oxaloacetate include?

A

2 decarboxylations producing 2 CO2s

3 reductions of NAD+ to NADH

1 reduction of FAD to FADH2

1 addition of Pi to ADP to make ATP by substrate level phosphorylation

132
Q

How is ATP produced in the CAC?

A

by substrate level phosphorylation when Pi is added to ADP

133
Q

What has happened to all 6 of the carbons in the glucose by the end of 2 turns of the CAC?

A

they have all been fully oxidized to CO2

134
Q

what’s another name for the CAC?

A

the Krebs cycle

135
Q

How many pairs of electrons are given to the ETC from each cycle of the CAC? What carries these electrons to the ETC?

A

each cycle gives 4 pairs of electrons

3 carried by NADH

1 carried by FADH2

136
Q

How many electrons are carried to the ETC from the CAC per molecule of glucose?

A

since one molecule of glucose requires two turns of the CAC,

there’s 6 NADH and 2 FADH2

137
Q

How many electrons are ACTUALLY taken to the ETC from CAC, glycolysis and pyruvate decarboxylation?

A

glycolysis provides 2 NADH total

pyruvate decarboxylation provides 1 NADH per pyruvate = total 2 NADH

6 NADH from CAC per glucose

2 FADH2 from CAC per glucose

TOTAL = 10 NADH + 2 FADH2 PER GLUCOSE ENTER THE ETC

138
Q

How many ATP molecules are given to the ETC from CAC and glycolysis (aka by substrate level phosphorylation)?

A

per glucose:

2 ATP from CAC + 2 ATP in glycolysis

= 4 ATP

139
Q

How are the ATPs produced in the CAC and glycolysis made?

A

by substrate level phosphorylation

140
Q

What are the two electron carriers that donate their electrons to the ETC? What happens to them once they donate their electrons?

A

reduced NADH and FADH2

they become re-oxidized NAD+ and FAD

141
Q

What is the ETC?

A

Electron Transport Chain

a series of integral membrane protein complexes in the inner mitochondrial membrane

142
Q

What are the integral membrane protein complexes of the ETC made of?

A

a collection of proteins and prosthetic groups tightly bound to them

143
Q

What are prosthetic groups?

A

chemicals that are tightly bound to the collection of proteins that together make up an integral membrane complex in the ETC

144
Q

What do prosthetic groups also carry?

A

electrons

145
Q

What is a reduction potential?

A

the tendency to accept an electron and be reduced

146
Q

How are the complexes of the ETC arranged in the IMM?

A

so that electrons will move from complexes with low reduction potential to complexes with high reduction potential

147
Q

What would it mean for a complex to have a high reduction potential?

A

it has a higher tendency to accept electrons and wants to be more reduced

148
Q

Where are most electron carriers of the ETC embedded?

A

in one of the four protein complexes

149
Q

T or F: all the electron carriers within the ETC are embedded in one of the four protein complexes

A

false, some are mobile in them membrane and not embedded

150
Q

Describe how electrons are moved through the ETC

A

they are passed from electron carrier to electron carrier with progressively higher reduction potentials until they are given to the terminal electron acceptor, O2

151
Q

What is the terminal electron acceptor in the ETC? why is it the terminal one?

A

O2 because it has the highest reduction potential

152
Q

What are the 5 types of electron carriers in the ETC?

A

flavoproteins

cytochromes

copper proteins

iron-sulfur proteins

ubiquinone

153
Q

What are flavoproteins?

A

polypeptides bound to FAD or FMN (derivatives of vitamin B12)

a type of electron carrier

154
Q

what are cytochromes?

A

proteins with bound heme groups, each has either Fe or Cu metal ions

a type of e- carrier

155
Q

What are copper proteins?

A

a single protein complex that contains 3 copper atoms

alternates between Cu2+ and Cu3+

a type of e- carrier

156
Q

What are iron-sulfur proteins?

A

proteins that contain iron atoms linked to the sulfur groups of cysteine residues

electron carriers

157
Q

What is ubiquinone?

A

aka coenzyme Q

a lipid-soluble molecule that functions as a e- carrier

158
Q

What is another name for ubiquinone?

A

coenzyme Q

159
Q

What is the difference between the oxidized and reduced form of flavoproteins?

A

2 electrons and 2 H+

oxidized form has 2 e- + 2 H+ less

reduced has 2 e- + 2 H+ more

160
Q

What is the difference between the oxidized and reduced forms of cytochromes?

A

the central iron ion is altered

1 e- removed = Fe3+ (oxidized)

1 e- added = Fe2+ (reduced)

161
Q

Which cytochrome is not fixed within a protein complex?

A

cytochrome c

162
Q

What does cytochrome c do?

A

it associates with the outer surface of the IMM through electrostatic interactions so that it can shuttle electrons between 2 protein complexes

163
Q

How are the irons and sulfurs arranged in the iron-sulfur proteins? How are these e- carriers oxidized or reduced?

A

irons are linked to the sulfur atoms of the cysteine amino acids of the protein

the iron-sulfur (Fe-S) proteins accept and donate a SINGLE electron

164
Q

How many electrons are accepted or donated by flavoproteins?

A

2

165
Q

How many electrons are accepted or donated by cytochromes?

A

1 (by heme)

166
Q

How many electrons are accepted or donated by Fe-S proteins?

A

1 by the iron atom

167
Q

T or F: ubiquinone is a protein

A

FALSE, it’s a lipid-soluble molecule

168
Q

What happens to ubiquinone when it is reduced?

A

it becomes even more lipid-soluble

169
Q

What is the difference between the reduced and oxidized version of ubiquinone?

A

2 e- and 2H+

ubiquinone = oxidized

ubiquinol = reduced

170
Q

How many electrons and protons does ubiquinone/ubiquinol donate or accept?

A

2 e- and 2 H+

171
Q

How can ubiquinone be abbreviated when it is fully oxidized?

A

Q

172
Q

How can ubiquinol be abbreviated when it’s fully reduced?

A

QH2

173
Q

Is ubiquinone/ubiquinol embedded in the membrane or is it mobile?

A

it is mobile

174
Q

Which two electron carriers are not embedded in protein complexes of the ETC?

A

coenzyme Q (ubiquinone) and cytochrome c

175
Q

How does ubiquinone/ubiquinol move through the membrane to shuttle e- between complexes?

A

laterally in the membrane with its hydrophobic tail

176
Q

Which electron carriers are embedded in protein complexes of the ETC?

A

flavoproteins
cytochromes (except C)
copper proteins
Fe-S proteins

177
Q

Outline the basic steps of electron movement through the ETC

A
  1. entry of electrons into Complex I (NADH) or Complex II (FADH2)
  2. electrons passed to Coenzyme Q pool
  3. electrons moved to complex III
  4. electrons moved through intermembrane space by cytochrome c
  5. cytochrome c brings electrons to Complex IV
  6. from Complex IV, electrons added to O2 to form H2O
178
Q

Is the passage of electrons from carrier to carrier exergonic or endogonic? why? What type of Gibbs free energy is this?

A

exergonic because energy is being released

negative gibbs free energy

179
Q

How does the released energy from the electron transfer in the ETC relate to H+ concentration gradient?

A

the energy released by the electron transfer is used to drive protons against their concentration gradient from the matrix into the intermembrane space

180
Q

What direction on their concentration gradient are protons moved and from where to where?

A

against their concentration gradient from the mito matrix to the intermembrane space

181
Q

How is the release of energy along the ETC coupled with the movement of protons?

A

some of the proteins in the ETC complex are related to the Na+/H+ antiporters that move H+ against its gradient

the energy released from the ETC (exergonic) is used to move protons against their conc. gradient (endergonic)

182
Q

Describe complex I

A

it is the largest (45 sub units)

contains FMN (flavoprotein) and Fe-S clusters

accepts electrons from NADH

183
Q

Which electron carrier does complex I accept electrons from?

A

NADH

184
Q

Where does the energy from the transfer of electrons from NADH to Complex I go?

A

it moves 4 H+ from the matrix into the intermembrane space

185
Q

Which electron carrier does Complex II accept e- from?

A

FADH2

186
Q

Describe complex II

A

contains FAD/FADH2 because it is also an enzyme in the CAC

also contains an Fe-S cluster

it completes the CAC step that produces FADH2 making it so the reduced carrier doesn’t have to travel anywhere

187
Q

T or F: Complex II does not transport protons

A

true

188
Q

Where do electrons go from Complex I or Complex II? How many electrons move?

A

Ubiquinone accepts 2 electrons from either complex and becomes ubiquinol (QH2)

189
Q

How are electrons transferred from ubiquinol to complex III?

A

ubiquinol is mobile so it moves electrons laterally to complex III

190
Q

WHat happens when ubiquinol donates the electrons to complex III?

A

it is re-oxidized to ubiquinone and returns back to complex I or complex II

191
Q

What role does complex III play in the transfer of electrons from QH2 to cytochrome c?

A

complex III catalyzes the transfer of electrons between QH2 to cytochrome c (the electrons move from QH2 to the e- carriers in complex III then to cytochrome c)

192
Q

Describe complex III

A

contains cytochromes and an Fe-S complex

193
Q

how many electrons can cytochrome c pick up at a time?

A

1

194
Q

What does the energy from the electron transfer from complex III to cytochrome c produce?

A

the movement of 4 H+ from the mito matrix to the intermembrane space

195
Q

What role does complex IV play in the transfer of electrons from cytochrome c to oxygen?

A

it catalyzes the transfer (the e- move from cytochrome c to the electron carriers in complex IV to the O2)

196
Q

Which electron carriers are found in complex IV?

A

cytochromes and copper proteins

197
Q

What does the energy created from transferring electrons from cytochrome c to oxygen produce?

A

the movement of 2 H+ from the matrix to the intermembrane space

198
Q

What is formed when cytochrome c passes electrons to oxygen?

A

water

199
Q

What is the equation for forming water?

A

1/2 O2 + 2e- + 2H+ –> H2O

OR

O2 + 4e- + 4H+ –> 2 H2O

200
Q

What is the proton motive force (PMF)?

A

the gradient of protons built up by the ETC as a source of energy

201
Q

what does the PMF power?

A

the synthesis of ATP from ADP + Pi

202
Q

What is chemiosmosis?

A

the process of producing ATP from a chemical gradient (the PMF)

203
Q

What is oxidative phosphorylation?

A

ETC + chemiosmosis

204
Q

What are the 2 components of the PMF?

A

charge and pH

205
Q

What does the relative contribution of the charge and pH on the PMF depend on?

A

the permeability properties of the IMM

206
Q

In mammals, how much of the PMF is from charge? from pH?

A

80% from charge

20% from pH

207
Q

Once the gradient is established, what are the conditions like on the matrix side vs the intermembrane space?

A

intermembrane: low pH (high H+ concentration), positively charged
matrix: high pH (low H+ concentration), negatively charged

208
Q

Describe the structure of ATP synthase

A

a multi-subunit complex consisting of 2 major structures:
F1 spheres and F0 channels

the spheres are connected to the channels by 2 stalks

209
Q

What are the 2 stalks of ATP synthase?

A

a central stalk that rotates

a peripheral stalk that’s fixed and connects F1 and FO

210
Q

Which of the ATP synthase stalks rotates?

A

central stalk

211
Q

Which of the stalks of ATP synthase is fixed and connects F1 and FO?

A

peripheral stalk

212
Q

In ATP synthase, how are the spheres connected to the channels?

A

by the two stalks: central + peripheral

213
Q

Which domain of ATP synthase is catalytic (where ATP is synthesized)

A

the F1 sphere is where ATP is synthesized

214
Q

What are the F1 subunits?

A 
3x alpha
3x beta
1 gamma
1 delta 
1 epsilon
215
Q

Where are the catalytic sites on the F1 sphere of ATP Synthase?

A

on the 3 beta subunits

216
Q

Where are the alpha subunits of the F1 sphere of ATP Synthase located?

A

in alternation with the beta subunits

217
Q

Where is the gamma subunit of the F1 sphere of ATP Synthase located?

A

it is the central stalk

218
Q

What is the delta subunit on the F1 sphere of ATP synthase?

A

it helps form the peripheral stalk

219
Q

What is the purpose of the FO channel of ATP synthase?

A

it allows protons through to power ATP synthesis

220
Q

What are the subunits of the FO channel of ATP synthase?

A

1a
2b
10-14c

221
Q

What do the b subunits of FO channels of ATP synthase do?

A

they help make the peripheral stalk (with the delta subunit from the F1 sphere)

222
Q

Describe the a subunit of the FO channel of ATP synthase

A

it contains the pore which is divided in half into the entry and exit channels (where H+ comes in and out)

223
Q

Describe the 10-14c subunits of the FO channels in ATP synthase?

A

they form a ring in the IMM which rotates to move H+ through to the exit pore

224
Q

How and where do ATP synthases exist?

A

as complexes in the mito cristae

225
Q

Where is the ETC located? How does this support ATP synthase in its production of ATP?

A

ATP synthase is located in the cristae and the ETC is located nearby in the IMM so the protons that leave the ETC are nearby ATP synthase

226
Q

Describe the movement of H+ protons through the subunits of the FO channel

A

a proton enters a half-channel in the a subunit on the IMS side

the proton binds to one of the c subunits in the ring and travels nearly 360 degrees as the c wheel spins to reach the exit half channel

the proton exits through the half channel into the matrix

227
Q

Is the movement of H+ protons passive or active?

A

passive, they move down their gradients

228
Q

What drives the rotation of the central gamma stalk?

A

the rotation of the c subunit ring

229
Q

What drives ATP synthesis?

A

the gamma subunit of the stalk interacts with the beta subunits

230
Q

What happens to the electrical energy of the proton gradient when the stalk rotates?

A

the energy becomes mechanical energy in the rotation of the stalk

231
Q

How much ATP is produced per beta subunit? How much total?

A

1 360 degree turn of the gamma subunit results in 1 ATP per beta subunit

there’s 3 beta subunits in the F1 sphere, so total of 3 ATP produced

232
Q

What happens as the gamma subunit rotates?

A

it makes contact with each different beta which induces a conformational change in each

233
Q

Where is the gamma subunit relative to the alpha and beta subunits?

A

it projects into the central cavity between alpha and beta subunits

234
Q

What determines the conformation of the beta subunits?

A

contact with the gamma subunit as gamma rotates

235
Q

How many conformations does each beta subunit have?

A

3

236
Q

how does each beta subunit move through the 3 conformations?

A

sequentially

237
Q

What are the 3 conformations of beta? What is the difference between them

A

open
loose
tight

they each have different affinities for substrate and product

238
Q

Describe the open conformation of beta subunit

A

there’s some affinity for ADP + Pi, low affinity for ATP (releases ATP)

239
Q

Describe the loose conformation of beta subunit

A

high affinity for ADP + Pi (cannot be released)

240
Q

Describe the tight conformation of beta subunit

A

spontaneous ATP formation occurs here

241
Q

T or F: at any given time, more than one beta can be in the same conformation

A

FALSE, the 3 betas will always be in a different conformation to each other

242
Q

How do the beta subunits move through their conformations?

A

sequentially and staggered to one another (ie., one will be tight, one will be open, one will be loose)

243
Q

If a beta subunit currently has tight conformation, what will the following conformations be?

A

tight –> open –> loose

244
Q

If a beta subunit currently has open conformation, what will the following conformations be?

A

open –> loose –> tight

245
Q

If a beta subunit currently has loose conformation, what will the following conformations be?

A

loose –> tight –> open

246
Q

Briefly outline the steps involved in ATP Synthesis

A
  1. proton from IMS enters ‘a’ subunit entry half channel
  2. proton binds to one c ring subunit
  3. c ring rotates and proton moves almost one full rotation and the energy in the proton gradient is converted into mechanical energy
  4. proton leaves subunit exit half channel into the matrix (down its gradient)
  5. gamma stalk is rotating with the c ring, meeting a new catalytic beta subunit every 120 degrees
  6. beta conformations are staggered
  7. each beta subunit forms a new ATP per rotation as it encounters the tight conformation
  8. 3 ATP formed per H+ and gamma stalk rotating 360 degrees
247
Q

Which conformation of beta is ATP produced in?

A

tight

248
Q

What does the entire process of cellular respiration (except for ATP synthase + generation of ATP) require?

A

an impermeable IMM

249
Q

Describe uncoupling and what is does

A

uncoupling proteins can move protons across the IMM without going through ATP synthase which uncouples glucose oxidation and oxidative phosphorylation

250
Q

What is the result of uncoupling?

A

the energy of the proton gradient is lost as heat instead of used to make ATP

251
Q

What is an example of uncoupling?

A

thermogenin and brown fat

252
Q

Describe uncoupling in relation to thermogenin and brown fat

A

thermogenin is an example of an uncoupling protein in brown adipose tissue (found in newborns and hibernating animals)

brown fat produces heat as glucose is oxidized to keep babies and hibernating animals warm

253
Q

What type of mammals have brown fat?

A

hibernating animals and newborns

BIOL 2321 - Cell Biology (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions