Carbohydrates 6: Terminal respiration

Question 1

what is substrate level phosphorylation?

Answer 1

The direct transfer of a phosphoryl group to form ATP or GTP.

• occurs in glycolysis
• little ATP made

Question 2

what is oxidative phosphorylation?

Answer 2

• The formation of ATP through the complex processes of oxidation coupled to the movement of electrons and production of proton gradients, most of which occurs in the mitochondrial matrix.
• process requires oxygen to act as an electron acceptor coupled to the formation of a proton gradient that drives the formation of ATP through the action of ATPase enzyme.

Question 3

how many electropositive H atoms are being stripped from food molecules at a time?

Answer 3

2 at a time

Question 4

to which two electron carriers are electrons passed to from CAC?

Answer 4

• NAD+

- FAD

Question 5

the now reduced co-reactants, NADH and FADH2 can now be used in abaolism and what other reaction?

Answer 5

terminal respiration (through a series of carrier proteins)

Question 6

what 2 products are produced when glucose (hexose) is split into pyruvate? (during glycolysis/ substrate level phosphorylation)

Answer 6

1. NADH + H+

2. ATP

Question 7

what product is produced when pyruvate is converted to acetyl CoA?

Answer 7

NADH + H+

Question 8

what 3 products are produced when acetyl CoA is made into CO2 during CAC?

Answer 8

1. 3NADH + 3H+
2. 1 FADH2
3. 1 GTP

Question 9

what is the mitochondria the site of?

Answer 9

CAC and terminal respiration (oxidative phosphorylation)

Question 10

what does the mitochondria utilise to produce ATP?

Answer 10

proton gradients

Question 11

what part of the mitochondria is the matrix?

Answer 11

liquid part

Question 12

what part of the mitochondria is the cristae?

Answer 12

the folded/ convoluted part (for max. SA)

Question 13

where is the proton gradient formed?

Answer 13

in the matrix

Question 14

where is majority of NADH and FADH2 formed?

Answer 14

in CAC and B oxidatation of fatty acids

Question 15

where is some NADH also formed?

Answer 15

in cytoplasm (during glycolysis)

Question 16

can cytoplasmic NADH cross the mitochondrial membrane?

Answer 16

no

Question 17

what does NADH combine with to create G-3-P which can pass its electrons to FADH2?

Answer 17

dihydroxy acetone phosphate

Question 18

G-3-P combines with FAD to create which molecule?

Answer 18

FADH2 (which travels to electron transport chain)

Question 19

what is the name of the shuttle which transports cytoplasmic NADH in the form of FADH2 for terminal respiration?

Answer 19

Glycerol phosphate shuttle

Question 20

what produces less ATP in the electron transport chain, oxidation of FADH2 or oxidation of NADH?

Answer 20

oxidation of FADH2 (energy price of the glycerol phosphate shuttle)

Question 21

what enzyme does the complex 1 in the e transport chain use?

Answer 21

NADH-Q oxidoreductase

Question 22

what enzyme does the complex 2 in the e transport chain use?

Answer 22

Succinate- Q reductase

Question 23

what enzyme does the complex 3 in the e transport chain use?

Answer 23

Q-cytochrome C Oxidoreductase

Question 24

what enzyme does the complex 4 in the e transport chain use?

Answer 24

Cytochrome C oxidase

Question 25

what happens at complex 1?

Answer 25

- NADH is oxidised - high energy electrons passed to ubiquinone to give ubiquinol (QH2) - utilises Fe-S centres and FMN (flavin mononucleotide) - pumps H+ into intermembrane space

Question 26

as 2 electorns travel through complex 1, what do they form?

Answer 26

QH2 (ubiquinol)

Question 27

what 3 substances inhibit e flow from Fe-S centres in the proteins to ubiquinone, therefore blocking the transport chain?

Answer 27

1. amytal (barbiturate) 2. piercidin A (antibiotic) 3. rotenone (insecticide)

Question 28

what happens at complex 2?

Answer 28

- FADH2 is oxidised - high energy electrons passed to ubiquinone to give ubiquinol (QH2) - utilises Fe-S centres to channel electrons

Question 29

where else is succinate- Q reductase enzyme used?

Answer 29

in CAC under the guise of sucicnate dehydrogenase

Question 30

what is the function of the heme group (Fe) in the protein?

Answer 30

- blocks stray electrons - if electrons leak from system, they can form free radicals of O2 (superoxide) leading to cancer. - point mutations near heme groups can give rise to paraganglioma

Question 31

what is another name for ubiquinone?

Answer 31

Coenzyme Q10

Question 32

what else can ubiquinone act as?

Answer 32

antioxidant (dietary supplement believed to reduce free radicals)

Question 33

what happens at complex 3? (2)

Answer 33

- electrons taken from ubiquinol (QH2) and passed to cytochrome C - protons pumped to intrermembrane space

Question 34

how many ubiquinols (QH2) are oxidised to produce how many reduced cytochrome Cs?

Answer 34

1 QH2 is oxidised to yiled 2 reduced cytochrome C

Question 35

what happens at complex 4? (3)

Answer 35

- electrons taken from cytochrome C and passed on to molecular O2 - electrons channeled through Fe-CU centre - protons pumped into intermembrane space

Question 36

What is oxidised at complex 1?

Answer 36

NADH

Question 37

what is oxidised at complex 2?

Answer 37

FADH2

Question 38

what is formed at complex 3?

Answer 38

Cytochrome C from ubiquinol (from complexes 1 and 2)

Question 39

what are electrons passed to at complex 4?

Answer 39

electrons from cytochrome C passed onto O2 molecule

Question 40

where is the NADH used in terminal respiration from? (3)

Answer 40

- glycolysis - CAC - B oxidation

Question 41

where is the FADH2 used in terminal respiration from? (2)

Answer 41

- B oxidation | - NADH via glycogen phosphate shuttle

Question 42

what is set up across the inner mitochondria membrane?

Answer 42

proton gradient

Question 43

what is chemiosmosis?

Answer 43

as electrons pass through the complexes of the transport chain, protons move from the matrix to the outside of the inner mitochondrial membrane

Question 44

what is the movement of protons with particular spatial directionality called?

Answer 44

vectoral movement (energy transformation)

Question 45

what do protons on the outside of the membrane act as?

Answer 45

store of potential energy

Question 46

what is proton motive force?

Answer 46

when electrons are allowed to flow back down their gradient, they release energy to work

Question 47

what is ATP synthase? (ATPase for short?)

Answer 47

large multi-unit protein complex on the mitochondrial membrane where protons flow down their concentration gradient back into mitochondrial matrix

Question 48

what does ATPase allow?

Answer 48

Protons to pass through it

Question 49

What are the 2 parts which make up ATPase and what do they do?

Answer 49

F0 part: membrane bound proton conducting unit (10 subunits) F1 part: protrudes into the mitochondrial and acts as a catalyst for ATP synthesis (produces lots of ATP form proton motive force energy collected by F0)

Question 50

Which part of the ATPase does "all the work"?

Answer 50

F1 part (produces the ATP)

Question 51

in which subunits of the F1 is ATP produced from?

Answer 51

Beta subunits

Question 52

as proton enter F0, rotation of F0 cylinder and gamma shaft causes what to Beta-subunits of F1?

Answer 52

conformational change

Question 53

In what way (positive/negative) do protons move from?

Answer 53

From positive to negative side of the membrane

Question 54

where is the higher concentration of H ions, outside or inside the mitochondrial membrane

Answer 54

Outside

Question 55

what are the steps for generating energy at the ATPase complex?

Answer 55

1. 1 proton enters the ATPase complex from intermembrane space 2. upper part of the ATPase complex rotates every time a new proton enters 3. once 3 protons entered the matrix space, there is enough energy in ATPase to generate 1 ATP.

Question 56

what happens once the gradient has disapperared when there is no more protons in intermembrane space?

Answer 56

no more energy available to make ATP which is why in biological system this gradient ALWAYS exists

Question 57

As electrons pass through complexes 1,2,3 and 4, how many protons from the matrix move outside of the membrane?

Answer 57

8 protons

Question 58

ATPase can produce how many ATPs for every 3 protons which move back into the matrix?

Answer 58

1 ATP

Question 59

what would happen if the inner mitochondrial membrane became permeable to protons?

Answer 59

proton gradient could not be generated and neither could ATP

Question 60

what does it mean when a process is coupled?

Answer 60

electron transport is said to be coupled to ATP synthesis

Question 61

what does it mean when a process is uncoupled?

Answer 61

no ATP is made since proton gradient is not established, energy is released as heat

Question 62

what disease is caused by "leaky" mitochondrial membranes that uncouple electron transport and ATP synthase?

Answer 62

Malignant hypothermia

Question 63

what are people with malignant hypothermia exposed to which makes their mitochondrial membranes leaky?

Answer 63

halothane

Question 64

what is an example of intentional uncoupling?

Answer 64

brown fat formation in newborn infants

Question 65

what is the name of the channel which sits inside a protein on inner mitochondrial membrane of brown fat cells?

Answer 65

thermogenin

Question 66

what causes brown fat to be a brown colour?

Answer 66

haem group in proteins

Question 67

what are examples in plants which generate intentional uncoupling?

Answer 67

- arum lily to attract insects -skunk cabbage to melt snow (generate heat by uncoupling oxidative phosphorylation)