Lecture 14: Cellular Respiration (Part 2) Flashcards
What are the two linked components required for oxidative phosphorylation?
- Electron Transport Chain (ETC)
- ATP Synthase
Why is oxidative phosphorylation called that way?
because it links the phosphorylation of ADP with NADH and FADH2 oxidation
What is the oxidative part of oxidative phosphorylation?
involves the electron transport chain
What is the phosphorylation part of oxidative phosphorylation?
its the phosphorylation that occurs via ATP synthase
What are the two linked processes that happen in oxidative phosphorylation?
- The creation of an electrochemical proton gradient by the ETC
- The synthesis of ATP by chemiosmosis using ATP synthase
What is the ETC made of (general components)?
a collection of chemicals in (or associated with) the inner mitochondrial membrane.
These chemicals are:
A. Proteins
B. Organic Molecules
C. Metal Ions
What do the organic molecules and metal ions act as in the ETC?
cofactors in redox reaction.
What is the structure of the ETC?
A. 4 types of respiratory complexes (I-IV).
B. Cytochrome C (Cyt C)
C. Ubiquinone(Q)
What is Cytochrome C?
a peripheral protein that acts alone (not part of a complex).
What is Ubiquinone(Q)?
a small organic molecule that can move throughout the membrane
What does the ETC do?
- Accepts electrons from electron carriers.
- The electrons are transferred from one component in the chain to another through a series of redox reactions.
What happens to the electrons as they move through the ETC?
The high potential energy of the electrons is gradually decreased after each transfer.
How do you call the last electron acceptor of the ETC?
the terminal electron acceptor
Where does the potential energy of the electrons is transferred to as it decreases along the ETC?
it is converted into a H+ ion electrochemical gradient.
Which respiratory complex does not pump H+ ions across the membrane?
complex II
What is a respiratory complex and what is it made of?
protein groups in which the components of the ETC are organized into
Proteins in complexes contain cofactors that act as redox centers: accept and donate electrons.
complexes range in size, number and composition of subunits used, and the cofactors used as redox centers.
By which genome are most of the polypeptide of the protein complexes encoded by? By Which genome are the others encoded by?
Most polypeptides are encoded by the nuclear genome but some are encoded by the mitochondrial genome.
What is the name of complex I of the ETC?
NADH-Q oxidoreductase
What is the name of complex II of the ETC?
Succinate-Q oxidoreductase
What is the name of complex III of the ETC?
Q-Cyt c oxidoreductase
What is the name of complex IV of the ETC?
Cyt c Oxidase
How many polypeptides are encoded by the nuclear genome in complex I?
43
How many polypeptides are encoded by the nuclear genome in complex II?
4
How many polypeptides are encoded by the nuclear genome in complex III?
11
How many polypeptides are encoded by the nuclear genome in complex IV?
13
How many polypeptides are encoded by the mitochondrial genome in complex I?
7
How many polypeptides are encoded by the mitochondrial genome in complex II?
0
How many polypeptides are encoded by the mitochondrial genome in complex III?
1
How many polypeptides are encoded by the mitochondrial genome in complex IV?
3
Which cofactors are in complex I?
FMN
Fe-S
Which cofactors are in complex II?
FAD
Fe-S
Which cofactors are in complex III?
Heme
Fe-S
Which cofactors are in complex IV?
Heme
Cu-S
Complete this chart:
Which cofactor do cytochromes contain?
heme
Where other than cytochromes is there also heme?
hemoglobin and other proteins
Which complex of the ETC is not embedded in the inner membrane of the mitochondrion? Where is it?
complex II
it is associated with the inner side of the membrane
What does the flow of electrons follow in the ETC? What characteristic of the ETC allows that?
Electrons flow from one better electron acceptor to another through the chain until they reach the terminal electron acceptor.
The architecture of the ETC promote the stepwise transfer of electrons down the chain.
What is the link between electron flow and pumping H+ ions by the complexes?
The redox reactions by the cofactors of the complexes take up protons in reduction and releases them during oxidation
the architecture of the ETC allows the protons to be taken up from the mitochondrial matrix side and released on the intermembrane space side
Do NADH and FADH2 part of the same complex?
No;
NADH donates electrons to complex I
FADH2 donates to complex II that passes electrons directly to Q (Electrons from FADH
2 bypass Complex I.)
Which electron carrier produces more ATP when it transfers its electrons to the ETC?
NADH because it contributes to the making of the proton electrochemical gradient more than FADH2
Which electron acceptor is the strongest in the ETC?
the terminal electron acceptor
In aerobic cellular respiration, which molecule is the final electron acceptor?
O2
In anaerobic cellular respiration, which molecule is the final electron acceptor?
one of the three:
SO42-, NO3-, Fe3+
What is the structure of ATP synthase?
How do you call the F0 unit of ATP synthase?
the base
How do you call the F1 unit of ATP synthase?
the knob
How do you call the part that connects the stationary units of the F0 and F1 units of ATP synthase?
the stator
How do you call the part that connects the mobile units of the F0 and F1 units of ATP synthase?
the rotor
How many types of subunits and how many total subunits compose ATP synthase?
8 different types of subunits, total of 22 subunits
What exactly are the F1 and F0 units of ATP synthase? What are their roles?
they are two motors that connect ATP synthesis to the H+ gradient:
Fo unit: acts as a proton channel (electrical motor)
F1 unit: acts as the catalytic site (chemical motor)
What is the current model of the ATP synthase mechanism?
A. A flow of protons through the Fo unit causes the membrane ring and the attached rotor to spin.
B. As the rotor turns, the catalytic subunits of F1 are thought to change shape in a way that catalyzes the phosphorylation of ADP to ATP.
What allows the the three different conformations of the subunits in ATP synthase?
Each conformation has specific affinities for products and reactants
What are the energy conversions that happen during cellular respiration?
What are the work powered during cellular respiration (in order)
About how many ATP does cellular respiration yield per glucose molecule?
30-32 ATP
What is the theoretical maximum yield of ATP in cellular respiration? Show how it is calculated:
About how much percent of the 30-32 ATP produced by cellular respiration comes from substrate level phosphorylation?
about 4 of the 30-32
About how much percent of the 30-32 ATP produced by cellular respiration comes from oxidative phosphorylation?
about 26 of the 30-32
Why can there only be an approximation of the amount of ATP that can be produced by cellular respiration?
- because of the conversion of the approximate amount of H+ ions needed to make 1 ATP by ATP synthase
- several reasons why the efficiency (number of ATP produced per glucose molecule) can vary from cell to cell.
What are the possible reasons for the efficiency of ATP production per glucose molecule to vary from cell to cell?
A. Electrons in NADH produced in glycolysis end up in FADH2 in some tissues during import into the mitochondrion.
B. Some NADH and FADH2 may be used in anabolic pathways.
C. Proton motive force used for other purposes.
Give an example of how efficiency of ATP production per glucose molecule can be reduced in the example of pyruvate processing.
The electrons from NADH end up in FADH2
What percentage of the energy in a glucose molecule is recuperated as ATP after cellular respiration? Where does the rest of the energy go?
about 39-40%
rest of the energy:
1. dissipated as heat
2. Utilized for other metabolic processes or stored as potential energy in molecules
Why do facultative anaerobes rarely use fermentation if O2 is available as an electron acceptor for cellular respiration?
because fermentation s extremely inefficient compared to aerobic cellular respiration:
Fermentation produces just 2 ATP molecules per glucose while about 30 ATP molecules per glucose are produced in aerobic cellular respiration.
Which two processes of cellular respiration are major intersections in various catabolic and anabolic pathways?
glycolysis and citric acid cycle
How do glycolysis and the citric acid pathway interact with other pathways?
Some intermediates:
A. Leave to join
other pathways.
B. Join in from other
pathways.
What type of organic molecule can be used as substrates (fuel) for cellular respiration?
Proteins, carbohydrates, and fats
Where are the organic molecules broken down in animals?
in the small intestine
Where do small components of the fuel is absorbed and for what purpose?
into the blood
for storage, building or energy
In what order of “priority” do cells use the organic molecules that serve as fuel to produce ATP?
Carbs -> fats -> proteins
Which of the three fuels produce the most ATP per gram?
fats
Do all types of fuels have the same entry point into glycolysis?
No; several entry points exist
What is the enzyme that breaks down fats?
lipases
What does lipase breaks down fats into?
glycerol and fatty acids
Where are fatty acids processed and what into during glycolysis? What is the process called?
into acetyl Co A in a process called beta-oxidation
carried out in the mitochondrion (and peroxisome)
Where does glycerol feeds into cellular respiration?
in glycolysis as G-3-P
Where does acetyl Co A feeds into cellular respiration?
through the Krebs cycle (citric acid cycle)
What enzymes breakdown proteins into amino acids?
proteases and peptidases
What do enzymes do to amino acids (proteins) to make them into organic acids?
(organic acids used in the citric acid cycle)
they deaminate the amino acids (remove the amino groups)
Where do excess amino groups go after protein is broken down?
converted to urea by the liver for excretion by the urinary system.
Where do organic acids feeds into cellular respiration?
through pyruvate, acetyl CoA or directly into the citric acid cycle
For what can cellular respiration intermediates be used for?
- to build amino acids, nucleotides, fatty acids, and other important building blocks in anabolic biosynthesis pathways.
- Some intermediates can be converted back into glucose.
- Excess glucose can be stored as glycogen or starch.
