Chromatin and Gene Structure- Lecture 22

Question 1

What is the structure/ conformation of DNA?

Answer 1

double stranded, running antiparallel to each other in a double helix that is stabilized by H bonds between C/G and A/T base pairs that stack

Question 2

Why do double stranded genetic materials separate?

Answer 2

melting temperature

Question 3

What affects melting temperature?

Answer 3

the amount of G-C content (the higher the content, the higher the melting temperature)

Question 4

What directs annealing of DNA as it cools from its melting temperature?

Answer 4

complementarity

Question 5

What composes a histone core?

Answer 5

two each of H2A, H2B, H3, and H4 subunits (an octomer in total)

Question 6

What composes a nucleosome?

Answer 6

about 150 bps, a histone core (octamer of H2A, H2B, H3, and H4), and one monomer of H1 that binds the wound DNA to the histone core

Question 7

What is a chromatin?

Answer 7

DNA in its protein-bound form

Question 8

What is heterochromatin?

Answer 8

DNA that is tightly wound around histones and is inaccessable to transcription machinery

Question 9

What is euchromatin?

Answer 9

accessible DNA

Question 10

What is the enzyme that replicates DNA prior to cell division?

Answer 10

DNA polymerase

Question 11

Which enzyme transcribes DNA information into RNA?

Answer 11

RNA polymerase

Question 12

What is a template strand?

Answer 12

the strand of DNA that is used for coding (both strands are templates during DNA replication, where as only one is for transcription)

Question 13

____ is a DNA sequence that is recognized by RNA polymerase for binding and beginning of transcription.

Answer 13

The promoter

Question 14

What constitute pre-mRNA?

Answer 14

exonic (expressed) and intronic (intervening) sequences

Question 15

What constitutes mRNA?

Answer 15

the coding sequence (comprised of the exons not spiced out during splicing) and untranslated 5’ and 3’ regions (UTRs)

Question 16

What is a silent mutation?

Answer 16

a change in the third base pair of a codon that does not change the protein sequence

Question 17

What is a missense mutation?

Answer 17

a change in a base pair of a codon that results in an amino acid substitution

Question 18

What is a nonsense mutation?

Answer 18

a change in a base pair of a codon that substitutes a stop codon for an amino acid

Question 19

What is a frameshift mutation?

Answer 19

insertion or deletion of nucleotides in the sequence that results in a shift in the reading frame or insertion of a stop codon

Question 20

What direction is a template strand of DNA read?

Answer 20

from the 3’ to the 5’ end

Question 21

What direction does is DNA synthesized?

Answer 21

in the 5’ to 3’ direction