Chromatin and Gene Structure- Lecture 22 Flashcards
What is the structure/ conformation of DNA?
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
Why do double stranded genetic materials separate?
melting temperature
What affects melting temperature?
the amount of G-C content (the higher the content, the higher the melting temperature)
What directs annealing of DNA as it cools from its melting temperature?
complementarity
What composes a histone core?
two each of H2A, H2B, H3, and H4 subunits (an octomer in total)
What composes a nucleosome?
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
What is a chromatin?
DNA in its protein-bound form
What is heterochromatin?
DNA that is tightly wound around histones and is inaccessable to transcription machinery
What is euchromatin?
accessible DNA
What is the enzyme that replicates DNA prior to cell division?
DNA polymerase
Which enzyme transcribes DNA information into RNA?
RNA polymerase
What is a template strand?
the strand of DNA that is used for coding (both strands are templates during DNA replication, where as only one is for transcription)
____ is a DNA sequence that is recognized by RNA polymerase for binding and beginning of transcription.
The promoter
What constitute pre-mRNA?
exonic (expressed) and intronic (intervening) sequences
What constitutes mRNA?
the coding sequence (comprised of the exons not spiced out during splicing) and untranslated 5’ and 3’ regions (UTRs)
What is a silent mutation?
a change in the third base pair of a codon that does not change the protein sequence
What is a missense mutation?
a change in a base pair of a codon that results in an amino acid substitution
What is a nonsense mutation?
a change in a base pair of a codon that substitutes a stop codon for an amino acid
What is a frameshift mutation?
insertion or deletion of nucleotides in the sequence that results in a shift in the reading frame or insertion of a stop codon
What direction is a template strand of DNA read?
from the 3’ to the 5’ end
What direction does is DNA synthesized?
in the 5’ to 3’ direction
