Biochem Part II - Metabolism

Question 1

Know ethanol metabolism pathway

Answer 1

Ethanol broken down by alcohol dehydrogenase with NAD+ conversion to NADH => acetaldehyde. 2) Acetaldehyde then converted to Acetate through acetaldehyde hydrogenase/NAD+ to NADH conversion in mitochondria. Alcohold dehyrogenase is first order kinetics

Question 2

What is disulfiram

Answer 2

Inhibits acetaldehyde dehydrogenase and causes buildup of acetaldehyde. Acetaldehyde build-up leads to hangover symptoms.

Question 3

What reactions are B7 a cofactor for?

Answer 3

1C carboxylation reactions. 1) pyruvate carboxylase => pyruvate to oxaloacetate (3=>4C). 2) acetyl coA carboxylase => acetyl coA to malonyl CoA (2=>3C) 3) Propionyl CoA Carboxylase: propionyl CoA to methylmalonyl CoA (3C to 4C)

Question 4

TCA cycle produces

Answer 4

10ATP per acetyl CoA. 3NADH, 1FADH, 2GTP, 2CO2

Question 5

Glycosis produces

Answer 5

2ATP, 2pyruvate, 2NADH, 2H+, 2h20

Question 6

Hexokinase - Location, Km, Vmas, Induced by insulin?, Feedback-inhibited by G6P, Gene mutation associated with MODY?

Answer 6

Most tissues but not liver and pancreatic Beta cells, Km is low, Vmax is low, not induced by insulin, yes feedback inhibited, Not associated with MODY

Question 7

Glucokinase - Location, Km, Vmas, Induced by insulin?, Feedback-inhibited by G6P, Gene mutation associated with MODY?

Answer 7

Liver and pancreatic Beta cells, Km is high, Vmax is high, Yes induced by insulin, Not feedback inhibited, Yes associated with MODY

Question 8

What does arenic inhibit? What are the sx of arsenic poisoning?

Answer 8

Lipoic acid. Vomiting, garlic breath, rice water stools

Question 9

What are the cofactors needed for pyruvate dehydrogenase?

Answer 9

TLCFN - thiamine (B1), lipoic acid, coA (B5), FAD (B2), Niacin (B3).

Question 10

NADH electrons from glycolysis enter the mitochondria via

Answer 10

Malarte-apartate shuttle or glycerol-3-phosphphate shuttle.

Question 11

1NADH and 1FADH2 produces

Answer 11

2.5ATP, 1.5ATP

Question 12

What are the 4 paths of pyruvate metabolism and where do they occur

Answer 12

1) Pyruvate to alanine via ALT (cytoplasm) 2) Pyruvate to lactate via lactate dehydrogenase/need NAD+ (cytoplasm 3) Pyruvate to Acetyl CoA via pyruvate dehydrogenase in mitochondria and 4) Pyruvate to oxaloacetate via pyruvate carboxylase. Can be used to replenish TCA cycle or use for gluconeogenesis

Question 13

PDH deficiency symptoms and treatment

Answer 13

Pyruvate gets shunted to alanine and lactic acid. Lactic acidosis and high serum alanine, neuro defects. Tx with Highly ketogenic diet *lysine and leucine

Question 14

Mnemonic to remember gluconeogenesis irreversible enzymes

Answer 14

Pathway produces fresh glucose. 1) Pyruvate carboxylase activated by acetyl CoA, requires biotin, ATP. Pyruvvate to oxaloacetate. Occurs in mitochondria. 2) PEP carboxykinase: oxaloacetate to PEP 3) fructose 1,6 biphosphatase 4) Glucose 6 phosphatase

Question 15

Where does glucogenogenesis occur/ where can it not occur

Answer 15

1) mostly in the liver. Some in kidney and intestinal epithelium. Cannot take place in muscle because muscle lacks glucose 6 phosphatase. Odd chain FA can yield propionyl coA and contribute to gluconeogenesis by entering the cycle as succinyl coA

Question 16

Where is the HMP pathway most active

Answer 16

Places where there is fatty acid or steroid synthesis = mammary lactating glands, liver, adrenal cortex, RBCs.

Question 17

What does the HMP pathway produce/what are the reactions involved?

Answer 17

Oxidative/irreversible. G6P => Ribulose 5P. Produces NADPH. G6PD enzyme needed. Non-oxidative/reversible. Ribulose 5P => Ribose 5P. Transketolases/isomerases. Requires B1

Question 18

What gives sputum its color

Answer 18

MPO - blue green heme containing enzyme

Question 19

Example of an uncoupling reagent. What do uncoupling reagents do?

Answer 19

Block ATP synthesis but electron transport, O2 consumption continues. Generates heat. Does ethis by increasing permeability of membrane and decreasing proton gradient. 2,4-dinitrophenol, thermogenin are examples

Question 20

Rotenone, cyanine, CO, antimycin A are examples of

Answer 20

Electron transport inhibitors

Question 21

Oligomycin is a ?

Answer 21

ATP synthase inhibitor

Question 22

GPPD confers resistance to what?

Answer 22

Malaria

Question 23

What are heinz bodies and bite cells?

Answer 23

Heinz bodies - oxidized Hb ppted within RBCs. Bite cells - results from phagocytic removal of heinz bodies by splenic macrophages.

Question 24

GPD deficiency is what kind of inheritance

Answer 24

X linked recessive

Question 25

Mnemonic for Urea cycle

Answer 25

Ordinarly careless crappers are also frivolous about urination

Question 26

Mnemonic for glucogenic essential amioa acids

Answer 26

My handsome valentine: methionine, histidine, valine

Question 27

Mnemonic for glucogenic/ketogenic essential amino acids

Answer 27

Is picking three trips: isoleucine, proline, threonine, trytpophan

Question 28

Pyruvate Dehydrogenase Complex deficiency leads to? Tx?

Answer 28

Pyruvate being shunted to alanine and lactate. Increased serum alanine levels from infancy and lactic acidosis. Neuro defects. Increased ketogenic diet.

Question 29

Know how the alanine and cori cycle works/transport of ammonia by glutamate and alanine

Answer 29

pg 109

Question 30

What does hyperammonemia lead to?

Answer 30

Results in excess NH4+ which depletes alpha ketoglutarate and therefore inhibits TCA cycle. Tx: limit protein diet, give lactulose which traps NH4+ for excrretion, benzoate or phenylbutyrate (binds to aa and lead for excretion)

Question 31

What is N acetylglutamate? Deficiency leads to what?

Answer 31

Cofactor for carbamoyl phosphate synthetase I. Deficiency leads to rise in ornithine. Same ppt cab syn I deficieny except increase in ornithine suggests hereditary N acetylglutamate deficiency

Question 32

Sx of hyperammonemia

Answer 32

Slurring asterixis (tremor), cerebral edema blurring of vision

Question 33

B complex deficiencies cause

Answer 33

Dermatitis, glossitis, diarrhea

Question 34

What microorganism can cause B12 deficiency

Answer 34

Diphyllobathrium latum

Question 35

Pellagra/Niacin defiency can be caused by

Answer 35

1) hartnup disease (decreased tryptophan 2) malignant carcinoid syndrome (increased tryptophan metabolism and 3) isoniazid decreased vit B6

Question 36

What vitamin should children affected with measles get?

Answer 36

Vitamin A

Question 37

Derivatives of Arginine

Answer 37

CUN - creatinine, urea, NO (BH4)

Question 38

Know the tyrosine catabolism/catecholamine synthesis pathway

Answer 38

pg 110

Question 39

Know homocystein metabolism pathways

Answer 39

Pg 111

Question 40

Know glycogen regulation by insulin/glucagon/Epi

Answer 40

pg 112

Question 41

In prolonged starvation and diabetic ketoacidosis what source of energy is used?

Answer 41

Oxaloacetate is depleted in gluconeogenesis => start using ketone bodies.

Question 42

In chronic alcoholism what leads to increased production of ketone bodies?

Answer 42

Increased NADH leads to conversin of oxaloacetate to malate and build up of acetyl CoA => ketone body production

Question 43

Where are ketone bodies made and used?

Answer 43

Ketone bodies made in the liver. Used mostly by skeletal muscle and the brain during starvation. RBCs cannot use it because it lacks mitochondria and hepatocytes cannot use ketone bodies because it lacks thiophorase

Question 44

What is the source of energy in the fasting (between meals state)

Answer 44

Major: hepatic glycogenolysis, some hepatic gluconeogenesis, FFA release from adipocytes

Question 45

What happens during starvation Days 1-3? When do glycogen reserves get depleted?

Answer 45

Glycogen reserves depleted in 1 day. 1) hepatic glycogenolysis 2) Adipose release of FFA 3) Muscle and liver shift fuel use from glucose to FFA 4) hepatic gluconeogenesis from peripheral lactage and alanine, and from propionyl CoA

Question 46

What happens during starvation after day 3? When do glycogen reserves get depleted?

Answer 46

adipose stores. Ketone bodies are the main source of energy for brain. After adipose is depleted, protein degradation accelerates => organ failure and death