Molecular Biology

Question 1

What 3 structures make up a nucleotide?

Answer 1

pentose sugar

nitrogenous base

phosphate group

Question 2

What is the difference between a nucleoside and a nucleotise?

Answer 2

nucleoside has no phosphate group

Question 3

Which nucleotides are pyrimidines?

Answer 3

cytosine, thymine, uracil

Question 4

which nucleotides are purines?

Answer 4

adenine, guanine

Question 5

what has to happen to a nucleotide before it can become DNA?

Answer 5

add two phosphate groups

Question 6

In DNA, which bases pair?

Answer 6

A-T

C-G

Question 7

In RNA, which bases pair?

Answer 7

A-U

G-C

Question 8

In which segments of DNA does methylation occur?

Answer 8

segments with repeating CG patterns

Question 9

Which nucleotides are methylated?

Answer 9

cytosines

Question 10

What type of response does unmethylated CG cause? why?

Answer 10

immune response, b/c Bacterial DNA differs from mammalian DNA by the presence of unmethylated cytosine-phosphate-guanosine (CpG) motifs

Question 11

What is a nucleosome made up of?

Answer 11

histones + DNA

Question 12

What gives histones the property necessary for binding with the DNA backbone?

Answer 12

They contain a lot of basic amino acids (lysine and arginine) which have a positive charge at human pH, allowing them to interact with the negativly charged DNA phosphate backbone.

Question 13

What is the role of H1 in DNA structure? What chemical properties allow it to do this?

Answer 13

they tie the “beads on a string” together, condensing the DNA.

H1 is more basic and larger

Question 14

antibodies to which part of DNA are implicated in drug-induced lupus?

Answer 14

Histones: anti-histone antibodies are present in >95% of DIL cases.

Question 15

Classic drugs associated with drug induced lupus?

Answer 15

Hydralazine (BP/HF)

procainamide (antiarrhythmic)

isoniazid (TB)

Question 16

what type of genes would be found in areas of heterochromatin? why?

Answer 16

genes that are not essential for cellular functions/not actively needed b/c heterochromatin is very condensed and DNA is heavily methylated

Question 17

what type of genes would be found in areas of euchromatin? why?

Answer 17

genes needed for regular cellular function b/c euchromatin is less condensed, with heavy histone acetylation (alters accessibility of chromatin and allows DNA binding proteins to interact with exposed sites to activate gene transcription and downstream cellular functions.)

Question 18

Which part of histones undergo acetylation?

Answer 18

acetyl groups are added to lysine in the histones

Question 19

what is the effect of histone acetylation? deacetylation?

Answer 19

acetylation causes the chromatin to relax for transcription of genes, deacetylation causes chromatin to close-up

Question 20

Transcription is induced by which modification?

Answer 20

histone acetylation

Question 21

Is DNA or RNA synthesized first?

Answer 21

RNA, then converted (remove OH group) to deoxyribonucleic acids (DNA)

Question 22

which type of nucleotides tend to act as second messengers?

Answer 22

adenosine and guanosine
cAMP - blood flow
cGMP - second messenger

Question 23

what are the purine ingredients?

Answer 23

ribose phosphate
amino acids
carbons from THF or CO2

Question 24

What is PRPP?

Answer 24

first intermediate in purine synthesis, add phosphate group to ribose -5-phosphate

Question 25

what is IMP?

Answer 25

second intermediate in purien synthesis - nucleotide with hypoxanthine base that is converted into adenosine and guanine

Question 26

What is the chemical structure of purines?

Answer 26

2 rings with 2 nitrogens each, 5 member ring and 6 member ring

Question 27

Which amino acids contribute nitrogens to purines?

Answer 27

aspartate, glycine, glutamine