DB Lecture 22: Chromatin and Gene Structure Flashcards
What determines melting intrinsic melting temperature of double stranded DNA/intramolecular double-stranded RNA structures?
the higher the C-G content the higher the melting temperature
ionic strength
pH
List the major histone protein types.
H2A, H2B, H3, H4
What are histone cores?
octamers of two of each histone protein type (H2A, H2B, H3, H4)
Describe the general structure of histones when they are in place on DNA.
~150 bps wound around each histone core (octomer of two of each histone protein)
bundle is secured by H1 monomer
20-80 bps between histone cores
What is a nucleosome?
DNA + Histone Core + H1 monomer
What is heterochromatin?
DNA that is tightly wound around histones and is inaccessible to transcription machinery
What is euchromatin?
DNA that is accessible to transcription machinery
What is DNA polymerase?
the enzyme that replicates DNA prior to cell division
substrate is located at the end of previously replicated DNA and incoming deoxyribonucleoside triphosphates (dATP, dCTP, dGTP, dTTP)
What is RNA polymerase?
the enzyme that transcribes DNA information into RNA
incorporates incoming ribonucleoside triphosphates (ATP, CTP, GTP, UTP) into a growing RNA chain
What is a promoter?
DNA sequence that is recognized by RNA polymerase for binding and beginning of transcription
What is the transcription start site?
the base-pair at which initiation of transcription takes place (+1 site)
When does RNA polymerase terminate?
downstream of the terminator site
How is the coding sequence of mRNA obtained from pre-mRNA?
splicing of the pre-mRNA resulting in a loss of introns and a retention of exons
What are the sections of the mRNA?
5’ UTR
coding sequence
3’ UTR
What are silent mutations?
has no effect on the protein sequence
