gene to protein Flashcards
What is the initiator codon for protein synthesis
AUG
What is the terminator codon for protein synthesis
UGA, UAA, UAG
What is a promoter
Start site for transcription
it is a DNA sequence that signals the initiation of RNA synthesis.
The promoter indicates the beginning of a gene
What is the TATA box
a conserved sequence in eukaryotic promoters
What are transcription factors:
proteins that assist RNA polymerase II with binding the promoter, which initiates the transcription process
What is the transcription initiation complex
transcription factors and RNA polymerase II bound to a promoter
What are spliceosomes
complexes of proteins and small nuclear ribonucleoproteins that recognize the splice sites on the pre-mRNA
What is RNA splicing
removes the introns and joins exons, creating an mRNA molecule with a continous coding sequence
What is RNA polymerase II
Mediates transcription of mRNA
what is RNA polymerase I/III
transcribes other RNA not destined to become proteins
what are the functions of the 5’ cap and poly-A tail
facilitate export of mRNA
protect mRNA from hydrolytic enzymes
help ribosomes attach to the 5’ end
What are exons and introns
exons are coding sequences for mRNA, they are joined together, introns are noncoding sequences that are removed through splicing
What is the template strand
it is one of the DNA strands that is used to produce a template for the RNA transcript which matches it with complementary base pairs
What are codon specific functions
they are the mRNA base triplets that are read in the 5’ to 3’ direction,
each codon specific the amino acid to be placed at the corresponding position along a polypeptide
What are the three stages of transcription
Initiation, Elongation, Termination
What is the difference in eukarotes and bacteria in RNA polymerase binding
In bacteria the RNA pol binds directly to the promoter
In eukaryotes, transcription factors mediate the bindinf of RNA pol
What is the initiation stage of Transcription
Promoter, transcription factors, and the transcription initiation complex
One gene codes for
one “transcriptional unit” that can be spliced into different mRNAs or “one pre-mRNA”
DNA inherited by organisms ______ results in specific traits _______
genotype
phenotype
Whats the main difference between prokaryotic transcription and eukaryotic
in prokaryotes, mRNA produced by transcription is immediately translated without processing
in Eukaryotes, primary RNA transcripts are modified through RNA processing prior to translation
What is the template strand
one of the DNA strands that provides a template for producing the RNA transcript
what is the general definition of a codon
a block of 3 DNA nucleotides that correspond to an amino acid
what is the promoter
it defines the start of a gene
what are the the template strands
the strand read by RNA polymerase to make mRNA
what is the terminator
it defines the end of a gene
what does the TATA box do
it is recognized by RNA polymerase as the start site and which strand to use
what are the transcription factors
proteins that assist RNA polymerase II
with binding the promoter, which initiates transcription in
eukaryotes (for mRNAs).
what is the process that must occur before RNA pol II can do its job?
transcription factors must bind to DNA prior to RNA pol
then additional transcription factors bind to RNA pol to form the transcription initiation complex
what is Transcription initiation complex
transcription factors and
RNA polymerase II bound to a promoter.
in what direction does RNA pol II add nucleotides
5’-3’
In bacteria, how does RNA pol II know how to stop?
It ends at the terminator sequence
In eukaryotes, how does RNA pol II stop?
RNA pol II transcribes a polyA sequence (AAUAAA).
Then 10-35 nucleotides later, the proteins release the pre-mRNA
Why is Eukaryotic transcription more complicated?
Due to chromatine packing
How many RNA pol do Eukaryotes have?
3
RNA pol I: for transcription of mRNA
RNA I/II: for transcribing other RNA (not for proteins)
Do Bacteria mRNA need to be spliced?
No, they do not have introns or exons
How is RNA splicing carried out?
Through spliceosomes
what are spliceosomes?
complexes of proteins + snRNPS (ribonucleoproteins) that recognize splice sites on pre-mRNA
a single primary transcript can be spliced into _______
several different mRNAS
Because of alternative splicing, the number of different
proteins an organism can produce is ______
much greater than its
number of genes.
what is Alternate Splicing of Exons
Different forms of a protein
from the same gene
sequence.
- RNA polymerase moves along the template strand from which direction?
3’-5’, it adds nucleotides to the 3’ OH end
Alternative RNA Splicing:
Allows production of similar proteins from different primary RNAS
