Exam 4- Bio 305

RNA polymerase I

rRNA

RNA polymerase II

mRNA, various noncoding RNA

RNA polymerase III

tRNA, 5s rRNA, Repetitive DNA sequences

5 subunits of prokaryotic RNA polymerase holoenzyme

a, a’, B, B’, omega

How many different RNA polymerase in Eukaryotes?

3

Two main structural differences between DNA and RNA

Uracil not Thymine, -OH group on 2’ carbon

RNA features between protein and DNA

Structure: complex 3D folding (like Proteins)

Function: Holds genetic info (like DNA)

RNA stability?

LOW

3 steps of prokaryote transcription

Initiation, Elongation, Termination

Prokaryotic initiation

At promotor, polymerase moves towards +1 nucleotide

Two main components of prokaryotic promotor

-35 and -10 regions

Prokaryotic elongation

RNA polymerase reads coding sequence, synthesizes RNA

Prokaryotic termination

Stops at terminator sequence

Sigma Subunit

necessary part to bind to DNA for transcription, different sigma subunits recognize varying promoters

Most important part of essential genetic material features

regulated expression

Exons

part that is kept of the RNA

Introns

part that is spliced and removed from RNA

TATA Box

core element of eukaryotic promotor region

TF IID

TATA binding protein

CTD

C-terminal domain

Synonymous mutation

results in no change to AA sequence

Missense Mutation

results in change to ONE AA

Nonsense mutation

codes for a STOP codon, terminates translation

Frameshift

alters the sequence of AA by shifting the reading frame

Point Mutations

mutations in DNA at a defined location

INDEL

Insertion or Deletion of BP

Germ-line mutation

can be passed down to offspring

Somatic cell mutation

can only be passed to daughter cells via mitotic division

Mutation Rate

Rate of mutation per unit of time

Phenotypical mutation

mutation observed/counted at the phenotypic level

Molecular level

frequency of mutations per bp

Mutation Hotspots

location in gene or genome where mutation occurs more often

Large cause of Mutation Hotspots

Large genes

Random Mutation

mutations occur by chance, each bp has same chance of mutating

“Fluctuation Test” 1943

Experiment that produced evidence for random nature of mutations

Transition mutation

Purine→Purine OR Pyrimidine→ Pyrimidine

Transversion Mutation

Purine→Pyrimidine OR Pyrimidine→ Purine

8 different possible mutations

Regulatory Mutation

alters gene expression, occur in noncoding regions

Promotor Mutations

Alter promoter sequence and function

Splicing mutations

Alter normal splicing pattern of pre-mRNA

Cryptic Splicing sites

not normally used splice sites, unless mutation near authentic splice site

Polyadenylation mutation

mutation to polyadenylation sequence

Forward Mutation

Converts Wild-Type allele to a Mutant Allele

Reverse mutation

Convert mutation to wild-type or near wild-type state

True Reversion

reversion that exactly reverses original mutation

Intragenic reversion

reversion caused by a second mutation at a different location in the same gene

Second site reversion/ Suppressor Mutation

reversion taking place at a location separate from the site altered to generate the original mutation

Epigenetic

Changes in gene expression that are not a result of DNA change

Chromatin Compaction

Compactedness of Chromatin can impact the ability to transcribe DNA

Eukaryotic mRNA vs Archeal mRNA Stability

Eukaryotic is more stable

Northern Blot

Detects specific RNA molecules

Western Blot

Detects specific proteins