Krebs and OP

Question 1

what are the energy stores and requirements for a 70kg male

Answer 1

triglyceride (fat) 400MJ
usable protein 100 MJ
liver glycogen 2.4 MJ
blood glucose 0.16 MJ
daily needs - 12

Question 2

what is the average concentration of ATP in cells

Answer 2

6mM

Question 3

what is the turnover of ATP and how much does the average human body contain

Answer 3

75g of ATP at any one time but the turn over is 75kg/day

Question 4

how much of ATP is produced in the mitochondria

Answer 4

95% under aerobic conditions

Question 5

what is the difference between the inner and outer membrane of the mitochondria

Answer 5

outer: smooth and freely permeable to molecules under 5000 Da, no ionic or electrical gradients

inner: folded into chirstae, permeable to a small number of molecules only via specific transporters
very good electrical insulator, capable of minting large iconic and electrical gradients
contains more protein than lipid, respiratory enzymes transporter proteins

Question 6

what is the role of pyruvate dehydrogenase (PDH) and where does it act

Answer 6

pyruvate travels from cytosol to mitochondrial matrix where the enzyme converts it to acetyl CoA

Question 7

what does the dysfunction of PDH cause and what is it due to

Answer 7

caused by lack of thiamine which leads to beriberi - neurological and cardiovascular symptoms

Question 8

what is wsernickes-korsakoff syndrome

Answer 8

lack of thiamine seen in alcohol addicts

Question 9

what is the “key decision point” of PDH

Answer 9

Acetyl CoA cannot be converted back to glucose and there commits those C atoms from glucose for energy production

Question 10

what are the two stages of the kerbs cycle

Answer 10

synthesis of 6-C compound citrate which then loses 2 C as Co2 to become 4-C compound succinyl CoA

oxidation of the 4-C compound to reiterate oxaloacetate and initiate another round of cycle

Question 11

what are the main outputs of the krebs cycle

Answer 11

reduced co-enzymes NADH and FADH2 - electron carriers

CO2

Question 12

how is the krebs cycle controlled

Answer 12

entry of pyruvate via need for energy
availability of A CoA from fat oxidation
need for energy monitored by ATP:ADP ratio and NADh:NAD+ ratio

Question 13

what are the three key enzymes of the krebs cycle

Answer 13

citrate synthase
isocitrate dehydrogenase
a-ketoglutartae dehydrogenase

Question 14

why do type 1 diabetes patients synthesise ketones

Answer 14

diabetic patients can’t use glucose due to absence of insulin
inhibits glycolysis and low pyruvate
fatty acids are mobilised from adipose tissue and oxidised to acetyl CoA - lack of oxaloacetate prevents A CoA entering krebs and ketones are made instead

Question 15

what are the two processes within the electron transport chain

Answer 15

electron transport - energy of electrons in NADH and FADH2 is used to create a proton gradient across the inner mitochondrial membrane - oxidation

ATP - synthesis - energy from the proton gradient is used to phosphorylate ADP to synthesise ATP - phosphorylation

Question 16

where does oxidative phosphorylation occur

Answer 16

across inner mitochondrial membrane

Question 17

what are all the components of the OP system

Answer 17

complex 1-4
ubiquinone (between 2 and 3) 
cytochrome C (between 3 and 4) 
f0f1 ATPase
adenine nucleotide transporter 
Pi transporter

Question 18

where do these molecules enter the transport chain
NADH
FADH2
O+2H+

Answer 18

complex 1
complex 2
complex 4

Question 19

how does cyanide affect the ETC

Answer 19

blocks complex 4 and formation of water

Question 20

what is released between each complex and which complex does the most

Answer 20

movement of molecules releases energy

biggest change is complex 3 to complex 4

Question 21

how many protons are pumped into the mitochondrial inter membrane space from each pair of electrons from NADH

Answer 21

10

Question 22

which molecule allows movement of electrons back from the inter membrane space into the mitochondrial matrix

Answer 22

F0F1 ATPase down the proton gradient

Question 23

what happens when protons move through the F0 portion in the membrane

Answer 23

causes it to rotate the stem inside the F1

Question 24

what is required for the formation of ATP from other transporters in the membrane

Answer 24

ADP which comes in with H+ and Pi

Question 25

how many protons are required to make 1 ATP

Answer 25

4

Question 26

what happens to NADH in the cytosol vs in the matrix as it cannot pass the inner membrane

Answer 26

oxidised in the cytosol and reduced in the matrix

Question 27

what type of compound can uncouple oxidation from phosphorylation

Answer 27

weak acids soluble in the membrane - they then associate with protons which dissipates the proton gradient

Question 28

can electric transport occur without ATP synthesis

Answer 28

yes

Question 29

what is the reason for uncoupling

Answer 29

creates non-shivering heat in newborns

Question 30

how does uncoupling cause thermogenesis

Answer 30

contains brown adipose tissue which has thermogenin (uncoupling protein 1)
when temp drops SNS releases NA which increased free fatty acids in cytosol which activates thermogenin
as ET is uncoupled from ATP synthesis energy is rebased as heat instead

Question 31

what molecule is used to identify BAT in adults

Answer 31

18-fluorodeoxyglucose

Question 32

what causes levels of BAT to decrease

Answer 32

age and obesity

Question 33

what can be used as a therapeutic target to promote triglyceride clearance and weight loss

Answer 33

beige adipose tissue which can switch between brown and white forms

Question 34

what is Dinitrophenol

Answer 34

“weight loss product”
(1930’s)
side effects caused hyperthermia, tachycardia, excess sweating, blindness (cataracts) and withdrawn symptoms