Biochem

Question 1

What’s the rate limiting rxn in chol synth?

Answer 1

HMG Co reductase

Question 2

Findings in PKU?

Answer 2

1. mousy odor
2. tyrosine missing (must be supplied in diet - can diagnose by amniocentesis and finding the abnormal gene)
3. eliminate phenylalanine from diet (Nutrasweet is aspartate and phenylalanine so cannot use it)

Question 3

I cell disease

Answer 3

inability to phosphorylate the mannose residues of potential lysosomal enzymes, hence they cannot be taken up by the lysosomes to degrade complex substrates

Question 4

Number of lgucoses necessary to build palmitic acid a 16 carbon compound

Answer 4

4 glucoses - each glucose run producing 2 acetyl coA, the latter containing 2 carbons each

Question 5

Insulin lack in DKA does what to glycolysis, glycogenesis, fatty acid synthesis and storage of fat in adipose?

Answer 5

decreases

Question 6

uncoupling agents (e.g. alcohol, salicylates)

Answer 6

produces brown fat from increaed heat from reactions trying to increase the generation of more protons to make ATP

Question 7

Von Gierke’s

Answer 7

decreased glucose 6-phosphatease (glucoeogenic enzyme) with decrease in glucose (fasting hypoglycemia) and increase in glucose 6-phosphate with production of normal glycogen in the liver and kidneys
Stimulation tests with glucagon, fructose, etc cannot increase the glucose levels owing to the missing enzyme

Question 8

Biochem processes in both cytosol and mito

Answer 8

1. urea cycle
2. heme synthesis
3. gluconeogenesis

Question 9

Female with pheochromocytoma. What dietary alteration?

Answer 9

probably dec phenylalanine (essential AA0 and tyrosine (not an essential AA) in the diet

Question 10

pregnant female with PKU. What diet?

Answer 10

low in phenylalanine and high in tyrosine

avoid Nutrasweet since it contains aspartate and pehylalanine

Question 11

Lesch Nyan

Answer 11

SXR with absent HGPRT, self-mutilation, hyperuricemia, mental retardation

Question 12

Enzyme only in the liver
Has high Vm and high Km.
Not inhibited by glucose 6-phosphate

Answer 12

glucokinase

Question 13

Enzyme in all tissues
Low Vm and low Km
Inhibited by Glucose 6 phosphate

Answer 13

Hexokinase

Question 14

Also known as branched-chain ketoaciduria, is a disorder affecting the aliphatic or branched-chain amino acids.

Answer 14

Maple syrup urine disease

Question 15

Breakdown of glycogen to glucose 6 phosphate and glycogen.

Answer 15

glycogenolysis

Question 16

Locations (3) of glucose 6-phosphatase (gluconeogenic hormone)
What disease is it absent in?

Answer 16

1. liver
2. kidney
3. intestinal epithelium (lesser extent than others
   Vongierke’s disease

Question 17

What do the carnitine and malate shuttles carry?

Answer 17

1. carnitine - even chained fatty acids

2. malate - NADH

Question 18

Functions of LDL (4)

Answer 18

1. vit D synthesis
2. other steroid synthesis
3. cell membranes
4. synthesis of bile salts/acids

Question 19

Acetyl CoA uses

Answer 19

1. how many times used in FA synthesis
2. CH synthesis
3. ketone body synthesis

Question 20

purpose of urea cycle

Answer 20

eliminate ammonia

Question 21

If epinephrine is given and only small branched chains are found, what deficiency is present?

Answer 21

debrancher deficiency

Question 22

Origin of

1. apolipoproteins 100
2. apolipoproteins 48

Answer 22

1. liver

2. intestine

Question 23

what’s the rate limiting step in glycogenolysis?

Answer 23

glycogen phosphorylase

Question 24

Why cant the liver use ketones for fuel?

Answer 24

the liver cannot activate acetoacetate in the mito, which requires succinyl CoA: acetoacetate CoA transferase (a thiotransferase enzyme) in order to convert AcAc into Acetoacetyl CoA

Question 25

What disease? Absent mm phosphorylase; increase glycogen in mm; no increase in lactic acid after exercise

Answer 25

McArdles disease

Question 26

If a pregnant woman is a beer drinker, what supplements does she need?

Answer 26

1. Folate bc ETOH inc loss of folate in urine and stool which offsets amt of folate in beer
2. pt should be taken off beer bc of fetal alcohol syndrome and would need folate
3. Fe is NOT affected by beer drinking

Question 27

1. Insulin is the key hormone of the ___ state

2. Glucaon is a key hormone of the ___ state

Answer 27

1. fed

2. fasting

Question 28

What is involved in the transfer of dolichol (lipid) in the RER in the synthesis of O-linked glycosides?

Answer 28

mannose 6-phosphate