Transcription and RNA Flashcards
Changes in gene expression
- response of cells due to environmental changes
- regulation of cell cycle
- distinct activities of multitude of differentiated cell types.
- cell differentiation and development
Promoters
DNA sequence to initiate and regulate the rate of transcription of a gene
RNA polymerase
enzyme, synthesis of RNA from DNA template
Differences of eukaryotes to pro (gene expression)
- chromatin
-Compartmentalization in nucleus - Extensive RNA processing
RNA polymerase 1-3
mRNA
template for protein synthesis,
uses polymerase II
rRNA
component of ribosomes, uses polymerase I
tRNA
serve as adaptor molecules that align amino acids along the mRNA template. uses polymerase III
DNA sequence element
denotes a specific short sequence of DNA base pairs within a gene promoter
Cis-acting DNA sequences (promoter)
Regions of non coding DNA that regulates expression of genes
Basal or core promoter
genes transcribed by RNA polymerase II that includes TATA box and an initiator DNA sequence.
Upstream promoter and enhancers
transcriptional regulatory sequences located at sig. distance from promoter. impacts when and how much trancsctiption will occur
Transcription factors
proteins required to for RNA polymerase to initiate transcription.
reporter gene (adjacent to regulatory sequence)
reports on the activity of gene regulatory sequence or promoter
Position of enhancer
functions in any orientation or position relative to the promoter
Initiation
process leading to RNA polymerase II beginning to synthesize mRNA
Elongation
process of synthesizing a mRNA complementary to the coding strand of the DNA
General transcription factors
initiate transcription but does not allow for much transcription to occur
Gene specific factors
reponsible for regulating transcription rate of basal transcription complex
DNA methylation
one of the two parental alleles of genes is expressed during embryotic development
Pre-mRNA
primary transcript that is processed to form mRNA
Processing of mRNA
Capping
polyadenylation
splicing
7 methylguanosine cap
added to pre-mRNA, at 5’end of transcript.
Polyadenylation
process of adding a poly-Adenine tail to pre-mRNA. AAUAA (polyadenylation signal on mRNA)
Splicing
process of removing introns
Spliceosomes
large complexes composed of proteins and RNAs.
Small nuclear ribonucleoprotein particles
complexes of snnRNAs with proteins that play central roles in splicing
Small nuclear ribonucleoprotein Adenine
form the RNA component of spliceosomes.range in size from 50 to 200
Alternative splicing
process of varying pattern of pre- mRNA splicing . creates multiple different, but related, proteins fro the same gene
SR slicing factos
dictate where splicesome (U1) will form to exon sequences
Dscam
cell surface adhesion molecule important in allowing neurons to find target cells
fundamental activity of upstream promoter elements (enhancers)
binding sites for the gene specific transcription factors that modulate activity for basal transcription complex
transcriptional symphony
combination of transcription factors interacting at a specfiic genes promoter/enhancer sequences at any one point in time
Steroid Hormone receptors
contain zinc finger domains. Transcription factors that regulate gene transcription in response to hormones
homodeomain proteins
contain helix turn helix. play critical roles in the regulation of gene expression during embryonic development
Transcriptional activators
- interact with mediators and general transcription factors
- interact coactivators, which modify chromatin structure
Transcriptional repressors
- blocks binding of activator to DNA sequence element
Mediator
large protein complex that binds to reinitiation complex and plays key role in liking general transcription factors to the gene-specific transcription factors that regulate gene expression
DNA looping
allows transcription factors bound to an enhancer interact with proteins in RNA polymerase at core promoter
Elongation
release of RNA polymerase from basal complex to initiate transcription
Chromatin remodeling
moving, removal, and/or addition of histones
Histone code
- histone tail acetylation and deacetylation
- other histone modifications
Histone acetylation
modification of histones by addition of acetyl groups to specific lysine residue
Histon acetylation
Coactivator
HAT, recruits acetlyate histones active chromatin. gives transcription factors more access to chromatin
Histone aceytlation corepressor
HDAC, recruits decetylated histones, inactive chromatin. gives rise to a less- permisseable environment for transcription factors by condensing chromatin
