Terminal respiration

Question 1

How many complexes are there in the ETC

Answer 1

4

Question 2

what is terminal respiration

Answer 2

oxygen is the final acceptor of H+ ions and electrons

FADH+ and NAD+ pass hydrogen ions, via a series of redox carriers called the terminal respiratory system, to oxygen to form water.

Question 3

complex 1

Answer 3

complex 1 oxidises NADH. High energy electrons are passed from NADH to ubiquinone. They flow through Fe-S centres and at the top of the protein (bit in the membrane) they join with protons to form
ubiquinol (QH2).
H+ pumped into intermembrane space

Question 4

complex 2

Answer 4

succinate- Q reductase(complex 2) oxidises FADH2 and again high energy electrons are passed through Fe-S centres protein to ubiquinone (Q10). This then becomes ubiquinol –BUT A DIFFERENT (QH2) TO COMPLEX 1– once it gets the electrons.

Question 5

what does ubiquinone sit next to and what is this thing’s purpose?

Answer 5

it sits next to a haem group
this acts as a ‘trap door’ to stop electrons from going somewhere else (this leakage could form free radicals and lead to cancer)

Question 6

point mutation in complex 2 protein near haem group causes what?

Answer 6

mutation causes haem group not to sit as it should and is at a slight different angle so electrons can leak out and this can lead to benign tumours

Question 7

What is ubiquinone?

Answer 7

it captures electrons

- a dietary supplement believed to reduce free radicals and thus act as an antioxidant

Question 8

complex 3

Answer 8

takes the electrons from complex 2 ubiquinol and transfers them to cytochrome c

1 oxidised QH2: 2 reduced cytochrome c

in QH2 there are 4 electrons- 2 go to one cytochrome c molecule and 2 go to the other
this movement flow of electrons to differen molecules results in H+ BEING PUMPED INTO INTER MITOCHONDRIAL MEMBRANE SPACE

Question 9

Complex 4

Answer 9

takes the electrons from cytochrome c molecules and transfers them to molecular O2 (final acceptor) to make H20
electrons are channeled through Fe-Cu centre ALSO PUMPS H+ INTO INTERMEMBRANE SPACE

Question 10

Which complexes result in H+ being pumped into intermembrane space?

Answer 10

1,3 and 4

Question 11

how is energy that is being stored up in the H+ gradient used?

Answer 11

1. electron motive force- in this case proton gradient- will kick in and flow back down gradient to release energy to do work
2. molecular turbine- ATP synthase

Question 12

what is chemiosomosis

Answer 12

the movement of H+’s from matrix to intermembrane space (due to electrons moving through E.T.C)

Question 13

what word is used to describe the movement of electrons through the complexes.

Answer 13

vectoral- particular spatial directionality

Question 14

what is ATP synthase?

Answer 14

a large multi-unit protein complex that protons can pass back through

Question 15

what is the name of the mechanism ATP uses to allow return flow of protons?

Answer 15

binding change mechanism

Question 16

what is the final step in metabolising the food molecules we eat into energy?

Answer 16

ATP taking the potential energy from H+ protons to do work in the cells of the body

Question 17

What are the two parts that make up ATP synthase?

Answer 17

F0- membrane bound proton conducting unit (top part)- has 10 subunits

F1- protrudes into the matrix and acts as the catalyst for ATP synthesis- produces a lot of ATP

Question 18

how does the binding change mechanism work?

Answer 18

3 protons move into the F0 part separately
and it clicks round 3 individual times after this it clicks round too much and gets sprung to the next beta subunit
- ADP and Pi then binds into the active site and another 3 H+ go in with 3 more clicks.
Catalysis then occurs and ATP is made- another 3 H+ go in and ATP is kicked out

every time an H+ comes in one has to go out so if 3 come in 3 go out into matrix

Question 19

what are the 3 states of the active site

Answer 19

• empty
• has ATP ready to shove out
• has ADP and Pi ready to react

Question 20

what is responsible for the binding change mechanism proceeding?

Answer 20

the physical movement of the central shaft protein but the - (F0) intermembrane part twisting causes the movement of the shaft.

Question 21

on which subunits do the ADP and Pi subunits bind

Answer 21

beta subunits

there is sequential conformational changes of the beta subunits

Question 22

what is the shaft for?

Answer 22

ADP and ATP bind to beta subunits in the shaft

H+ don’t go into the shaft they just enter the F0 part and leave it

Question 23

electron transport is said to be coupled to what process?

Answer 23

ATP synthesis

Question 24

what is the energy released from e-s passing through E.T.C released as?

Answer 24

heat

Question 25

malignant hypothermia is caused by what

Answer 25

‘leaky’ mitochondrial membranes that uncouple electron transport and ATP synthase as it is then permeable to H+ ions and no gradient can be made

muscle cells become irreversibly damaged from the excessive heat build up