Biochem Halo-halo 4

Question 1

fructose 2,6 bisphosphate in regulation of glycosysis in the liver

Answer 1

❌allosteric inhibitor of PFK-1
❌ cleaved to triose phosphates in the glycolytic pathway
❌ its formation is catalyzed by a glycolytic enzyme
✅ provides an intracellular signal that’s sensitive to changes in blood glucose levels

Question 2

DOPA enzyme and cofactor

Answer 2

DOPA decarboxylase

vitamin B6

Question 3

end-products of beta oxidation

Answer 3

NADH
FADH2
acetyl-coa

Question 4

what enz converts OAA to PEP in gluconeogenesis

Answer 4

PEP carboxykinase

Question 5

enz defective in orotic aciduria

Answer 5

UMP synthase

Question 6

drugs that cause lupus

Answer 6

Hydralazine
isoniaizid
procainamide
phenytoin

etanercept
methyldopa
sulfa drugs

Question 7

fabry disease

Answer 7

hypohydrosis

Question 8

remarks on glycogen phosphorylase

Answer 8

produce glucose-1-phosphate

Question 9

isocitrate dehydroganase will yield

Answer 9

α-ketoglutarate

Question 10

amino group + _________ = alanine

Answer 10

pyruvate

Question 11

general properties of nucleic acids

Answer 11

negatively charged at physiologic pH

absorbs UV light at wavelength 260 nm at pH 7.0 (due to the conjugated double bond of purine and pyrimidine nucleotide

Question 12

3’5’ phosphodiester bond

Answer 12

3’ hydroxyl group of sugar of 1st mononucleotide is linked to 5’-phosphoryl group of 2nd mononucleotide

Question 13

3 scientists who worked together on studying the structure of DNA

Answer 13

James Watson
Francis Crick
Rosalind Franklin

Despite the efforts of Franklin, she will never win a Nobel prize because she had died of ovarian cancer in 1958 and the Nobel committee does not consider posthumous candidacies

Question 14

watson-crick’s DNA model

Answer 14

right-handed (clockwise) double-stranded DNA helix

Question 15

what’s with the G-C bond?

Answer 15

3 hydrogen bonds

Question 16

remarks on Grooves of the DNA

Answer 16

Grooves often act as sites of DNA-protein interaction needed for regulation of gene expression

DNA-protein itneraction is via hydrophobic interaction and ionic bonding

Question 17

remarks on Z-DNA

Answer 17

12 base pairs per turn
Longger and thinner
LEFT-handed
seen in 5’ end of chromosomes

Question 18

first level of organization of DNA

Answer 18

2 nm DNA double helix

Question 20

remarks on 10 nm chromatin fibril

Answer 20

beads on a strong appearnce on EM
consists of †NUCLEOSOME separated by linker DNA (H1)
DNA is wrapped 1.75x (nearly twice) over a histone octamer in left handed helix

†nucleosome is composed of 146 base pair-DNA

Question 21

remarks on 30 nm chromatin fibril

Answer 21

solenoid

group of nucleosomes

Question 22

remarks on chromosomes

Answer 22

condensation of DNA occurring during PROPHASE of mitosis
23 pairs of chromosomes
22 pairs of autosomes
1 pair of sex chromosomes

*review: Z-DNA is seen in 5’ end of chromosomes (left-handed, 12 base pairs per turn, longer and thinner)

Question 23

uncoiling of chromatin is facilitated by

Answer 23

HAT

histone acetyltransferase

Question 24

gene silencing is facilitated by

Answer 24

methyltransferase
found in CpG islnads
MOA
1. physically impede transcription proteitns?
2. MBDs —> more gene silencing
(methyl CPG binding domain)

Question 25

condensation of chromatin is facilitated by

Answer 25

histone deacetylase
(HDAC)
decreases transcription

Question 26

ribosomal RNA is what % of total rna

Answer 26

80%

Question 27

most heterogenous RNA

Answer 27

mRNA

Question 28

unusual bases seen in nucleosides in tRNA

Answer 28

dihydrouridine
pseudouridine
inosine
ribothymidine

Question 29

levels of DNA organization

Answer 29

2 nm DNA double helix
10 nm chromatin fibril
30 nm chromatin fibril
supercoiled structure
chromosome