12.3- OXIDATIVE PHOSPHORYLATION

Question 1

What is the hydrogen atoms produced from the Krebs cycle important for?

Answer 1

as potential source of energy

Question 2

What happens to the hydrogen atoms produced from the Krebs cycle?

Answer 2

carried by coenzymes NAD + FAD into next stage of process, oxidative phosphorylation

Question 3

What is oxidative phosphorylation?

Answer 3

mechanism by which some of the energy of electrons within hydrogen atoms conserved in formation of adenosine triphosphate (ATP)

Question 4

What is each mitochondrion bound by?

Answer 4

smooth outer membrane + inner one that’s folded into extensions called cristae

Question 5

What does the inner space, matrix of the mitochondrion contain?

Answer 5

protein, lipids + traces of DNA

Question 6

What are mitochondria the site of?

Answer 6

oxidative phosphorylation

Question 7

What are within the inner folded membrane (cristae) of mitochondria?

Answer 7

enzymes + other proteins involved in oxidative phosphorylation + hence ATP synthesis

Question 8

Examples of cells mitochondria occur in greater numbers?

Answer 8

muscles, liver + epithelial cells, which carry out active transport

Question 9

What do the mitochondria in metabolically active cells like?

Answer 9

more densely packed cristae which provide greater SA of membrane incorporating enzymes + other proteins involved in oxidative phosphorylation

Question 10

What does the synthesis of ATP by oxidative phosphorylation involve?

Answer 10

transfer of electrons down series of electron carrier molecules which together form electron transfer chain

Question 11

What do the hydrogen atoms produced by glycolysis + Krebs cycle combine with?- electron transfer chain + synthesis of ATP #1

Answer 11

combine with coenzyme NAD + FAD

Question 12

What do the reduced NAD + FAD do?- electron transfer chain + synthesis of ATP #2

Answer 12

donate electrons of hydrogen atoms they’re carrying to first molecule in electron transfer chain

Question 13

How do the electrons pass along the chain of electron transfer carrier molecules?- electron transfer chain + synthesis of ATP #3

Answer 13

series of oxidation-reduction reactions
as electrons flow along chain, energy they release causes active transport of protons across inner mitochondrial membrane and into inter-membranal space

Question 14

Where do the protons accumulate and then what happens?- electron transfer chain + synthesis of ATP #4

Answer 14

accumulate in inner-membranal space before they diffuse back into mitochondrial matrix through ATP synthase channels embedded in inner mitochondrial membrane

Question 15

What do the electrons do at the end of the chain- electron transfer chain + synthesis of ATP #5

Answer 15

electrons combine with these protons + oxygen to form water

so oxygen is final acceptor of electrons in electron transfer chain

Question 16

What is the process described in the electron transfer chain + synthesis of ATP?

Answer 16

chemiosmotic theory

Question 17

What is the importance of oxygen in respiration?

Answer 17

act as final acceptor of hydrogen atoms produced in glycolysis + Krebs cycle

Question 18

Without the role of oxygen removing hydrogen atoms at the end of the chain in respiration, what will happen?

Answer 18

hydrogen ions (protons) + electrons would ‘back up’ along chain + process of respiration would come to halt

Question 19

In general, what happens when greater energy is released in a single step?

Answer 19

more of it released as heat + less available for more useful purposes

Question 20

When energy is released a little at a time, what can more of it be used for?

Answer 20

more of it can be harvested for benefit of organism

Question 21

For reason that energy released a little at a time being able to be harvested for the benefit of the organism, what happens to the electrons carried by the NAD + FAD?

Answer 21

not transferred in one explosive step

instead passed along series of electron transfer carrier molecules, each of which is it at slightly lower energy level

Question 22

What can be used as alternative respiratory substrates, other than sugars?

Answer 22

both lipids + proteins can be used as respiratory substrates, without being converted to carbohydrates

Question 23

Before lipids are respired, what happens?

Answer 23

lipids first hydrolysed to glycerol + fatty acids

Question 24

What happens to the glycerol? (respiration of lipids)

Answer 24

phosphorylated + converted to triose phosphate which enters glycolysis pathway + subsequently Krebs cycle

Question 25

What happens to the fatty acid component? (respiration of lipids)

Answer 25

broken down into 2-carbon fragments which are converted to acetyl coenzyme A
this then enters Krebs cycle

Question 26

What does the oxidation of lipids produce? (respiration of lipids)

Answer 26

2-carbon fragments of carbohydrate + many hydrogen atoms

Question 27

What are the hydrogen atoms from the oxidation of lipids used to do? (respiration of lipids)

Answer 27

used to produce ATP during oxidative phosphorylation

Question 28

Why do lipids release more than double the energy of the same mass of carbohydrate?

Answer 28

as hydrogen atoms produced form oxidation of lipids used to produce ATP during oxidative phosphorylation

Question 29

Before proteins are used in respiration, what happens?

Answer 29

first hydrolysed to its constituent amino acids

Question 30

What happens to the amino acids? (respiration of proteins)

Answer 30

have their amino group removed (deamination) before entering respiratory pathway at different points depending on number of carbon atoms they contain

Question 31

What are 3- 4- and 5- carbon compounds converted to?

Answer 31

3-carbon compounds converted to pyruvate

4- + 5- converted to intermediates in Krebs cycle