BIOENERGETICS

Question 1

Autotrophic organisms

Answer 1

obtain free energy by: sunlight (plants, green sea slug)

Fe2+ ->Fe3+ (bacteria)

Question 2

Heterotrophic organisms:

Answer 2

obtain free energy by coupling their metabolism to the

breakdown of complex organic molecules in their environment.

Question 3

WHY DO WE NEED ATP?

Answer 3

1) Energy currency
2) Phosphate-donor for phosphorylation reactions
3) Precursor of cAMP
4) Co-transmitter released in the extracellular space acting on purinergic receptors

Question 4

HIGH-ENERGY PHOSPHATES

Answer 4

Vertebrates: creatine phosphate
Invertebrates: arginine phosphate

Question 5

Function of phosphanges

Answer 5

compounds that can maintain a reserve of high-energy phosphates that can be used when needed, to provide the energy that could not be immediately supplied by glycolysis or oxidative phosphorylation. Phosphagens supply immediate but limited energy.

Question 6

Substrate-level phosphorylation

Answer 6

results in the formation of ATP or GTP by the direct transfer of a phosphoryl (PO3) group to ADP or GDP from another phosphorylated compound.

Question 7

Combustion

Answer 7

If electrons were to be DIRECTLY transferred from to oxygen then all of the free energy
changes would be converted to heat

Question 8

intermediary metabolism

Answer 8

electrons are transferred to oxygen INDIRECTLY by electron carriers
and in a step-by-step mode

Question 9

Three states for ubiquinone

Answer 9

ubiquinone, ubiquinol, ssemiubiquinone

Question 10

heme is present in

Answer 10

Present in cytochromes (terminal oxidation, cytochrome p450 monooxygenases) and catalase

Question 11

Enzymes OXIDOREDUCTASES

Answer 11

1) Oxidases
2) Dehydrogenases
3) Hydroperoxidases
4) Oxygenases

Question 12

OXIDASES

Answer 12

Oxidases catalyze the removal of hydrogen from a substrate using oxygen as a hydrogen acceptor,
forming water or H2O2.

Question 13

Cytochrome oxidase

Answer 13

is the terminal component of the electron transport chain in
mitochondria (next lecture).
- is also known as cytochrome aa3.
- contains two molecules of heme, each having one Fe atom that
oscillates between Fe2+ and Fe3+ during oxidation and reduction.
-also contains two atoms of Cu.

Question 14

Flavoproteins

Answer 14

contain flavin mononucleotide (FMN) or flavin adenine nucleotide (FAD)
as prosthetic group (FMN and FAD are both formed from the vitamin
riboflavin).

Question 15

DEHYDROGENASES

Answer 15

cannot use oxygen as a hydrogen acceptor.

1) Transfer of hydrogen from one substrate to another during a redox reaction.
2) Transfer of electrons in the mitochondrial respiratory chain of electron transport

Question 16

What are NAD + or NADP made from

Answer 16

vitamin niacin

Question 17

What are FAD + or FMN made from

Answer 17

Vitamin riboflavin

Question 18

HYDROPEROXIDASES

Answer 18

Two types

i) Peroxidases and ii) Catalases

Question 19

Function of peroxidase

Answer 19

• reduce peroxides using various electron acceptors (typically ascorbate, quinones,
  cytochrome c)
• found in milk and in leukocytes, platelets and other tissues involved in
  eicosanoid metabolism.

Question 20

Catalase structure and functio

n

Answer 20

• is a hemoprotein containing four heme groups

- Uses Hydrogen Peroxide as Electron Donor & Electron Acceptor

Question 21

OXYGENASES

Answer 21

s catalyze the direct transfer & incorporation of oxygen into a substrate molecule
occurs in two steps:
1) oxygen is bound to the enzyme at the active site and
2) the bound oxygen is reduced or transferred to the substrate.

Question 22

Monooxygenases

Answer 22

ncorporate only one atom of

molecular oxygen into the substrate

Question 23

Cytochromes P450

Answer 23

are heme-containing, located mainly in the ER of liver and intestines, but also in mitochondria of some tissues. In the liver found with cytochrome b5 and have a major role in drug metabolism and detoxification;

Question 24

SUPEROXIDE DISMUTASES

Answer 24

They protect aerobic organisms against oxygen toxicity
H2O2 will be further processed by
catalase to water and oxygen.

Question 25

Found in complex I, II, III

Answer 25

• Iron-sulfur proteins (nonheme iron proteins, Fe-S) are found in Complexes I, II, and III

Question 26

Coenzyme Q ( complex 1)

Answer 26

Complex I is a large L-shaped multisubunit protein that catalyzes electron transfer from NADH to Q, coupled with the transfer of 4 H+ across the membrane:

Electrons are transferred from NADH to FMN initially, then to a series of Fe-S centers, and finally to Q

Question 27

THE Q CYCLE

Answer 27

Couples Electron Transfer to Proton Transport in Complex III

Question 28

Complex IV

Answer 28

• Of the 8 H+ removed from the matrix, 4 are used to form two H2O molecules and 4 are
  pumped into the intermembrane space.
• The O2 remains tightly bound to Complex IV until it is fully reduced, and this minimizes the release
  of potentially damaging intermediates such as superoxide anions or peroxide.

Question 29

COmponents of Atp synthase

Answer 29

F1- in inner embrane, rotates

F0- attached outside, produces ATP

Question 30

THE ‘P:O’ RATIO

Answer 30

the ATP produced per oxygen atom reduced by
the respiratory chain.
For NADH-linked substrates : ~2.7
For FADH2-linked substrates:~1.6

Question 31

Amount of NADH and FADH porduced

Answer 31

NADH: 10
FADH:6

Question 32

INHIBITOR OF: Complex I, II,III,IV, Atp synthase

Answer 32

I: barbieturates
II: Malonate
III: CN, H2S, 
IV: Antimycin A
Atp synthase: Oligomycin

Question 33

Chemiosmotic theory

Answer 33

The transport of protons from matrix to intermembrane space is accombanied by the generation of proton gradient across membrane that can be used to produce atp

Question 34

Uncoupler

Answer 34

2,4 dinitrophenol

Question 35

Effect of uncoupler

Answer 35

ATP syn: decreases
O2: increases
H+ gradient: decreases

Question 36

Apoenzyme

Answer 36

Needs coenzyme in order to function

Question 37

Highest—> lowest energy phosphate compounds

Answer 37

1. PEP
2. Cyclic AMP
3. 1,3 BPG
4. creatine
5. Pyrophosphate
6. Acetyl-coA
7. ATP