7.2 Transcription and Gene Expression Flashcards
what is transcription
the process of rewriting DNA to RNA
what is one important function of a non-coding region?
act as promoters
mRNA
Encodes amino acid sequence of a polypeptide
tRNA
brings amino acids to the ribosome
rRNA
with ribosomal proteins, makes up the ribosomes
The process by which genetic information is transferred from DNA to RNA is called _________________
transcription
During transcription, the synthesis of the mRNA strand proceeds in which direction?
5’ to 3’
.
.
In eukaryotic, where does transcription take place ___
in the nucleus
in eukaryotes, precursor mRNA molecules are processed in the ___________
Nucleus
THE POLY(A) tail of an mRNA __________________________________
keeps the coding sequences from being degraded.
self-cleaving RNAs that function catalytically are called ______________
ribozymes
a prokaryotic mRNA transcript is __________
translated as it is being transcribed
which parts of a eukaryotic gene are transcribed?
Both exons and introns
pre-mRNA transcript
When the entire gene is transcribed into mRNA
RNA polymerase
Enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription
Transcription steps
initiation, elongation, termination
initiation of transcription
RNA polymerase attaches to the promoter region on the DNA and begins to unzip the DNA into two strands.
Exons
Coding segments of eukaryotic DNA.
Introns
Noncoding segments of nucleic acid that lie between coding sequences.
elongation (transcription)
RNA polymerase unzips the DNA and assembles RNA nucleotides using one strand of DNA as a template.
termination of transcription
RNA polymerase reaches a terminator sequence (Stop codon) and detaches from the template
spliceosome
A large complex made up of proteins and RNA molecules that splices RNA intron, releasing the intron.
epigenome
The epigenome is a multitude of chemical compounds that can tell the genome what to do.
TATA box
A TATA box is a DNA sequence that indicates where a genetic sequence can be read and decoded. It is a type of promoter sequence, which specifies to other molecules where transcription begins.
histones
A histone is a protein that provides structural support to a chromosome.
Epigenetic tags
Epigenetic tags regulate gene expression by acting as gatekeepers, blocking or allowing access to a gene’s ‘on’ switch. These chemical tags (such as methyl or acetyl groups) are added directly to DNA or onto histones
5’
the end of the DNA or RNA strand
3’
3’ carbon a hydroxyl (-OH) group. This asymmetry gives a DNA strand a “direction”.
enhancers elements
Enhancers are DNA-regulatory elements that activate transcription of a gene or genes to higher levels than would be the case in their absence
silencers elements
Silencers are regulatory DNA elements that reduce transcription from their target promoters; they are the repressive counterparts of enhancers.
promoter-proximal elements
Any regulatory sequence in eukaryotic DNA that is located close to (within 200 base pairs) a promoter and binds a specific protein thereby modulating transcription
DNA methylation
DNA methylation regulates gene expression by recruiting proteins involved in gene repression or by inhibiting the binding of transcription factor(s) to DNA
