Transcription and Translation Flashcards
Where is the transcription start site and end
Not at start codon, but at promoter region and goes until termination sequence then it causes RNA polymerase to drop
Where is the translation start site and end site
Starts at start codon, AUG, encoding for methionine. Ends at stop codon and has 3 termination codons, UAG, UAA, UGA
what is the use for sigma factor
responsible for promoter recognition in transcription, recognizes different promoter sequence and provides specificity
Why is RNA polymerase used
It is used to direct RNA synthesis from DNA template, and no primer is required for initiation
What 6 subunits do the holoenzymes contain
sigma factor, 2 alpha subunits, 2 beta subunits and one omega subunit
Why are transcription factors important in transcriptional regulation?
They are proteins that influence the ability of RNA polymerase to transcribe DNA into RNA. They recognize base sequences in the DNA and control the rate of transcription.
What is the TATA box
core promoter element that binds TATA-binding protein of transcription factor TFIID and determines start site of transcription
What does alternative RNA splicing lead to
multiple polypeptides from a single gene
What is the Wobble Hypothesis
Predicts that though the first two base positions are critical, H-bonding between codon and anticodon at the 3rd position is subject to modified base-pairing rules
Transcription start site
site where transcription begins
What are regulatory elements
DNA sequences bound by transcription factors
what happens “post-transcriptional” processing to produce mature mRNAs
addition of a 5’ cap
addition of a 3’ poly A tail
excision of introns
Cis-acting elements are a type of factor that controls gene expression, what are they?
DNA sequences that exert effects only over a particular gene
ex: enhancers that stimulate transcription and silencers that reduce transcription
Trans-acting factors are also another type of factor that controls gene expression, what are they?
they are regulatory proteins that bind to cis-acting elements
what does the DICEr do?
it recognizes double stranded RNA and cuts it into short double stranded pieces
What is translation and what does it require
biological polymerization of amino acids into polypeptide chains and it requires amino acids, mRNA, ribosomes and tRNA
What does it mean when a genetic code is degenerate?
It means that many amino acids are specified by more than one codon
Why is code degenerate?
Due to the wobble hypothesis, first two bases are critical and the 3rd position is subject to modified base-pairing rules, and a single amino acid may be coded for by more than one cell
What is the start codon and what does it indicate?
AUG is the start codon to encode methionine and indicates the start of translation
What are the codons that serve as termination codons
UAG,UAA, and UGA
what are tRNAs
They are adaptor molecules to convert codons in mRNA to correct amino acids, they have secondary structure in form of cloverleaf, has anticodons that complement mRNAs codons, and covalently attached to corresponding amino acids
what are ribosomes
they consist of ribosomal protein and RNAs they provide important catalytic functions
tRNAS have what that pairs with the codons in mRNA
they have anticodons that base-pair with the codon in mRNA
What are the 3 steps in translation
initiation, elongation, termination
what does the protein structure contain
carboxyl group, and amino group terminals
