bich 2 exam final topics

Question 1

draw isopentyl pyrophosphate and what is the initial substrate?

Answer 1

one doc : initial substrate is Acetyl-CoA

Question 2

Regulation of HMG-CoA reductase and why it is a drug target for cholesterol-lowering medications

Answer 2

Inactivated by cAMP-dependent phosphorylation (this is activated by glucagon (response to low blood glucose)
Protein degradation: high cholesterol increases the rate of degradation
Gene expression: mRNA levels depend on cholesterol: high cholesterol = low mRNA synthesis

Question 3

Structure of the lipoprotein complex that transports fat and cholesterol (powerpoint)

Answer 3

on doc
LDL transports lipids

Question 4

function of VLDL

Answer 4

(very low density lipoprotein) – carry lipids from liver to target sites (muscle and adipose)

Question 5

function of LDL

Answer 5

(low density lipoprotein; highest in cholesterol) - major circulatory complex of cholesterol
and its esters

Question 6

function of HDL

Answer 6

(high density lipoprotein; smallest and densest; highest in protein) - mainly formed in ER
of liver cells (and some in intestine)

Question 7

good vs bad chloesterol

Answer 7

High [HDL]: very little cholesterol or fatty acids requires pickup and disposal: Good!
High [LDL]: too much cholesterol and fatty acids are left over: Bad!

Question 8

recognize derivatives of cholestrol

Answer 8

look on doc

Question 9

draw glutamate dehydrogenase

Answer 9

on doc

Question 10

draw glutamine synthesis

Answer 10

on doc

Question 11

what is the purpose of the urea cycle?

Answer 11

Uric cycle eliminates excess nitrogen from consumption and catabolism of amino acids

Question 12

draw the structure of urea and carbamoyl phosphate

Answer 12

on doc

Question 13

what is the regulation of carbamoyl-phosphate synthetase I?

Answer 13

Regulation: allosteric activation by N-acetylglutamate which is made through N-acetyl Glu synthesis caused by
Increased [glu] (by enzyme glutamate dehydrogenase and aminotransferases.

Question 14

Purpose and reaction of aminotransferases in amino acid synthesis

Answer 14

converts an alpha-keto acid into an amino acid
shown on doc

Question 15

draw methionine metabolisms

Answer 15

on doc

Question 16

What does S-adenosylmethionine do?

Answer 16

universal methyl donor

Question 17

Function of tetrahydrofolate in methionine and serine metabolism

Answer 17

5-methyl-THF adds the methyl group back to methionine to remake methionine and make it a cycle.
In serine metabolism : THF accepts CH2OH to make 10-CH2OH-THF which is used in the adenosine synthesis pathway.

Question 18

name the three coenzymes that are used to transfer single carbons and state the type of reaction
they carry out

Answer 18

Tetrahydrofolate– carry different oxidation states: methyl, methylene, formyl

Biotin- carboxylation

S-adenosylmethionine- Methylation

Question 19

draw guanine and write where each atom came from on it

Answer 19

on doc

Question 20

Know the difference between de novo purine synthesis and purine salvage

Answer 20

De novo the purines are made as shown above (put together from parts of the reaction)

Salvage purines are free purinse recycled from diet and nucleic acid degradation

Question 21

Draw the reaction of adenine phophoribosyltransferase

Answer 21

on doc

Question 22

Draw the reactions (2) of hypoxanthine-guanine

Answer 22

on doc

Question 23

Draw Ribose 5’-phosphate

Answer 23

on doc

Question 24

Draw PRPP

Answer 24

on doc

Question 25

what does PRPP stand for?

Answer 25

5-phosphoribosyl-a(alpha)-pyrophosphate

Question 26

Draw the reaction of adenosine deaminase

Answer 26

on doc

Question 27

draw uric acid

Answer 27

on doc

Question 28

draw the reaction of ribonucleotide reductase

Answer 28

on slide

Question 29

what is the regulation and activity and specificity of ribonucleotide reductase?

Answer 29

Allosteric site:: ATP bound: ON dATP bould: OFF Substrate specificity: achieving optimal ratio of four dNTPs Memorize specificity on doc!!!!

Question 30

Draw reaction of thymidylate synthase

Answer 30

on doc

Question 31

Draw reaction of dihydrofolate reductase

Answer 31

on doc

Question 32

Be able to explain why thymidylate synthase and dihydrofolate reductase are good drug targets for treating cancer and microbial infections

Answer 32

Reduce dTTP availability → reduces DNA replication → stops rapidly dividing cells

Question 33

Lesh-Nyhan syndrome

Answer 33

X-linked recessive Involuntary self harm HGPRT deficiency (less salvage of guanine) *****over production of uric acid and entrance through de novo synthesis*** Allopurinol inhibits degradation

Question 34

Severe combined immunodeficiency syndrome

Answer 34

Mutation in adenosine deaminase that prevents adenosine degradation Converted into dAMP into DATP which inhibits ribonucleotide reductase which makes dNTPs so cells Divides until DNA synthesis is complete, no proliferation in response to pathogens Bone marrow infusions

Question 35

Gout

Answer 35

Excess uric acid accumulation Arthritis (3% of population) Allopurinol (analog that inhibit xanthine oxidase (degradation)