Structure Of Nucleotide And Nucleotide Metabolsim

Question 1

Nitrogen bases present in both DNA and RNA

Answer 1

Adenine
Guanine
Cytosine

Question 2

Nitrogen bases present in
DNA only

Answer 2

Thymine

Question 3

Nitrogen base present in RNA
only

Answer 3

Uracil

Question 4

Methylation of uracil makes this nitrogen base

Answer 4

Thymine

Question 5

This is the bond formed between nitrogenous base and pentose sugar of a nucleoside

Answer 5

N-glycosidic linkage

Question 6

This is the bond formed between pentose sugar and phosphoryl group of a nucleotide

Answer 6

Ester bond

Question 7

This bond allows the addition of more phosphoryl bonds at nucleotides to form di- and triphosphates

Answer 7

Anhydride bond

Question 8

Most abundant free nucleotide in mammalian cell

Answer 8

Adenosine triphosphate
(ATP)

Question 9

Nucleic acids are polymers of nucleotides that are joined by this bond

Answer 9

3’-5’ phosphodiester bond

Question 10

Sequence of writing the bases of a DNA

Answer 10

From 5’ end → 3’ end

Question 11

Determinant of the melting point of DNA

Answer 11

Number of G-C bonds

Question 12

Orientation of DNA strands

Answer 12

Antiparallel

Question 13

States that the number of
purines = number of
pyrimidines

Answer 13

Chargaffs rule

Question 14

All types of DNA are right-handed except this type of
DNA

Answer 14

Z-DNA (left-handed)

Question 15

Most common form of DNA physiologically (well-hydrated and w/ low salt concentration)

Answer 15

B-DNA

Question 16

Type of DNA found in low humidity and high salt concentration

Answer 16

A-DNA

Question 17

Type of DNA mostly seen in 5’ end of chromosomes

Answer 17

Z-DNA

Question 18

Most abundant chromatin protein

Answer 18

Histone

Question 19

Histone seen in the linker region

Answer 19

H1

Question 20

Composition of the histone octomer (core histones)

Answer 20

Pairs of HzA, H2B, H3, H4

Question 21

Source of negative charge of
DNA

Answer 21

Phosphate groups

Question 22

Source of positive charge of histones

Answer 22

Lysine (H3, H4)
Arginine (H2A, H2B)

Question 23

Represents the “beads on a string” appearance on electron microscopy

Answer 23

10-nm chromatin fibril

Question 24

DNA is wrapped by around the histone octomer by this amount

Answer 24

1.75 times

Question 25

Condensation of DNA to form chromosomes occur during this phase of mitosis

Answer 25

Prophase

Question 26

The highly condensed chromatin seen in electron microscopy, which is transcriptionally inactive

Answer 26

Heterochromatin

Question 27

The less condensed chromatin seen in electron microscopy, which is transcriptionally active

Answer 27

Euchromatin

Question 28

Most heterogeneous RNA

Answer 28

mRNA

Question 29

Most abundant RNA

Answer 29

rRNA

Question 30

RNA containing significant proportions of nucleosides with unusual bases

Answer 30

tRNA

Question 31

RNAs responsible for gene expression regulation

Answer 31

snRNA miRNA SiRNA IncRNA

Question 32

Rate-limiting enzyme of purine synthesis

Answer 32

PRPP glutamy! amidotransferase

Question 33

Rate-limiting enzyme of pyrimidine synthesis

Answer 33

Carbamoyl phosphate synthetase Il

Question 34

Atom donors of purine molecules

Answer 34

Glutamine, Aspartate, Carbon dioxide, Glycine, N10-formyltetra- hydrofolate

Question 35

Atom donors of pyrimidine molecules

Answer 35

Glutamine, Aspartate, Carbon dioxide

Question 36

Donor of ribose-5-phosphate involved in purine and pyrimidine synthesis

Answer 36

Phosphoribosyl pyrophosphate (PRPP)

Question 37

Structural analogs of PABA that competitively inhibit dihydropteroate synthase

Answer 37

Sulfonamides

Question 38

Structural analog of folate, selectively inhibits bacterial dihydrofolate reductase

Answer 38

Trimethoprim

Question 39

Metabolically converted to 5-FdUMP, which inhibits thymidylate synthase

Answer 39

5-fluorouracil

Question 40

Inhibits dihydrofolate reductase, which reduces the tetrahydrofolate supply for the synthesis of thymine

Answer 40

Methotrexate Aminopterin

Question 41

Reversible inhibitor of IMP dehydrogenase, depriving T and B lymphocytes of nucleic acids

Answer 41

Mycophenolate

Question 42

Functions as an analogue of thymidine when incorporated into DNA, bonds with C rather than A, thus causing a misreading in DNA sequence

Answer 42

5-Iodouracil

Question 43

Used as an antiviral and an anti-tumor agent in man Inhibits DNA polymerase after it has been metabolized to the triphosphate form

Answer 43

Adenosine arabinoside

Question 44

Anti-tumor drug: an analogue of adenine metabolized to a ribonucleotide by the APRT salvage pathway thus inhibiting conversion of IMP to GMP or AMP. Also inhibits the rate-limiting step of de novo pathway

Answer 44

6-mercaptopurine(6MP)

Question 45

Analogue of Gln, thus, inhibits incorporation of N9 and N3 into the purine ring Inhibits formation of GMP from IMP, CTP from UTP

Answer 45

Azaserine

Question 46

Complete deficiency of this enzyme produces characteristics such as: o Hyperuricemia and gout, Psychomotor abnormalities o Mental retardation, Self-mutilation

Answer 46

LESCH-NYHAN SYNDROME

Question 47

Enzyme deficient in VON-GIERKE’S DISEASE

Answer 47

glucose-6-phosphatase

Question 48

This disease manifest as hyperurecemia, hypercholesterolemia, hypoglycemia, lactic acidosis due to the deficiency of glucose 6-phosphate enzyme

Answer 48

VON-GIERKE’S DISEASE