Bioenergetics

Question 1

Name sources of Acetyl Coa for TCA

Answer 1

-Beta oxidation -Glycolysis(pyruvate) -Ethanol oxidation -AA oxidation

Question 2

Rate limiting step in TCA

Answer 2

Conversion of isocitrate to alpha-ketoglutarate

Question 3

Two molecules that are chiral in TCA

Answer 3

isocitrate and malate

Question 4

Name two shuttles for NADH in ETC

Answer 4

malate-aspartate shuttle glycerol-3-phosphate shuttle( part of complex II)

Question 5

What are the names of complexes in ETC

Answer 5

-Complex I NADH dehydrogenase complex -Complex II Succinate- UQ reductase complex -Complex III UQH2- Cytochrome C reductase Complex IV Cytochrome C oxidase

Question 6

Which molecule has the highest reduction potential in ETC

Answer 6

Oxygen

Question 7

What is gluconeogenesis and where does it occur?

Answer 7

anabolic process for making glucose. occurs in liver and kidneys. reverse glycolysis

Question 8

How does gluconeogenesis compare to glycolysis?

Answer 8

It uses the same enzymes and occur in the cytoplasm except for irreversible processes use different enzymes and occur in mitochondrial matrix

Question 9

What are the three irreversible processes in glycolysis the differ in gluconeogenesis?

Answer 9

1. Glucose+ ATP——>Glucose-6-P 2.Fructose 6-P +ATP—->Fructose 1,6, BisP 3.PEP+ADP—->Pyruvate +ATP

Question 10

What enzymes are used instead of glycolytic enzymes for gluconeogenesis?

Answer 10

1. Instead of pyruvate kinase{ pyruvate carboxylase and PEP-carboxykinase PEPCK} 2. Instead of PFK1 {Fructose 1,6 bisphosphatase} 3. Instead of hexokinase {Glucose-6-phosphatase}

Question 11

In glycolysis, what activates PFK, inhibits it?

Answer 11

ADP/AMP activator; ATP inhibitor

Question 12

What activates/inhibits fructose-1,6-bisphosphatase?

Answer 12

ATP activates inhibited by AMP and fructose-2,6-bisP

Question 13

What activates PEPCK?

Answer 13

Glucagon and cortisol

Question 14

What activates pyruvate carboxylase?

Answer 14

acetyl CoA

Question 15

What is glycogenolysis?

Answer 15

Breaking of glycogen into glucose

Question 16

What enzyme is first used for glycogenolysis?

Answer 16

glycogen phosphorylase. Adds a phosphate group and H20. i.e breaks alpha-1,4 glycosidic links to create individual Glucose 1-P molecules

Question 17

What activates glycogen phosphorylase?

Answer 17

glucagon in liver and Epinephrine and AMP in skeletal muscle

Question 18

Difference in glycogenolysis in liver and skeletal muscle?

Answer 18

In skeletal muscle, G1-P is mutated to G-6P and follows on to glycolysis In liver, G6P converted to glucose by G-6-phosphatase in ER of hepatocytes before glucose released to blood

Question 19

What does debranching enzyme do?

Answer 19

A transferase. used in glycogenolyis to move oligoglucose from one branch to the chain using alpha 1-4 links

Question 20

What is glycogenesis?

Answer 20

making of glycogen

Question 21

What enzymes are involved in glycogenesis?

Answer 21

1.Glycogen synthase- creates a-1,4 linkages (activated by insulin) 2.Branching enzyme- moves blocks of oligoglucose from one chain to another branch using a-1,6 linkages

Question 22

Describe the first step in glycogenesis

Answer 22

akin to glycolysis, phosphorylation of glucose to G-6P by glucokinase

Question 23

What are the fates of G-6-P?

Answer 23

-Undergo glycolysis -Undergo PPP -Undergo glycogenesis

Question 24

What enzyme catalyses conversion of G-6-P to G-1-P for glycogenesis to occur?

Answer 24

Phosphoglucose mutase

Question 25

How is G-1-P transported?

Answer 25

Using a carrier UDP-Glucose

Question 26

Which tissues carry out Pentose phosphate pathway?

Answer 26

Those that can do FA, sterol synthesis eg liver, adrenal glands, gonads, adipose tissue, mammary glands,

Question 27

What are the two phases of PPP

Answer 27

1.Oxidative phase(irreversible)- synthesis of pentoses and NADPH- can go make nucleotides and FAs 2.Non-oxidative phase(reversible)- rearranges pentoses, recycles and makes biomolecules

Question 28

What is the rate limiting step in PPP?

Answer 28

oxidation of G-6-P to ribulose by G-6-P dehydrogenase

Question 29

What enzymes are used in the second phase of PPP

Answer 29

Transldolases and transketolases

Question 30

Chemical digestion of lipids done what enzymes?

Answer 30

lingual lipase, pancreatic lipase, colipase

Question 31

Triglycerides are made of what?

Answer 31

A glycerol molecule and 3 FAs

Question 32

How are lipids transported within the body?

Answer 32

As chylomicrons i.e. made of cholesterol, apoproteins, phospholipids and monoglycerides> these transported via lacteals to lymphatic. free fatty acids diffuse into blood.

Question 33

Name two enzymes used for lipolysis

Answer 33

Hormone sensitive lipase in adipocytes and lipoprotein lipase in chylomicrons

Question 34

Where is cholesterol made?

Answer 34

in hepatocytes

Question 35

What is the rate limiting enzyme in cholesterol metabolism?

Answer 35

HMG-CoA reductase- synthesizes malevonate

Question 36

What are saturated FAs, unsaturated FAs

Answer 36

saturated have single bonds with all Cs with Hs. Unsaturated have one or more double bonds

Question 37

Where in the cell are FAs synthesized?

Answer 37

In the cytosol, recall they’re made form Acetyl CoA transferred from the mitochondrial matrix

Question 38

What is the rate limiting step in FA synthesis?

Answer 38

Activation of acetyl- CoA through synthesis of malonyl CoA by enzyme acetyl CoA carboxylase

Question 39

What are the steps in FA synthesis

Answer 39

Malonyl CoA–>attachment–>condense–>reduce–>dehydration–>reduction

Question 40

FA oxidation does what for the cell?

Answer 40

Produces more acetyl CoA for metabolism

Question 41

Where in the cell does FA oxidation occur?

Answer 41

Co- enzyme A is shuttled into the mitochondrial matrix and FA oxidation follows

Question 42

How does FA oxidation compare to its synthesis?

Answer 42

Its reverse order with acyl-CoA (FA-CoA) oxidized–>hydration–>oxidation—>thiolysis to produce acetyl CoA.

Question 43

What enzymes are used for FA oxidation?

Answer 43

1. Carnitine acyltransferase (rate limiting step) 2.Acyl CoA dehydrogenase (uses FAD) 3.Hydratase (creates carbonyl group) 4.Dehydrogenase (uses NAD+) 5.Thiolase sticks S-CoA to 2C cod and kicks out acyl CoA

Question 44

What are the products of FA oxidation?

Answer 44

for a C16 FA 1. 8 Acetyl CoA 2. 7 NADH 3.7 FADH2 this will have 7 rounds of beta oxidation is 7x2C=14 then 2 Cs are lost

Question 45

What are activators for carnitine acyltransferases? inhibitors?

Answer 45

Glucagon activates; insulin inhibits