RNA and the genetic code Flashcards
This type of RNA is translated into polypeptides after it reaches the ribosome
mRNA (Messenger RNA)
This type of RNA has anticodons that pair with the codons, and allows the RNA to bind the correct AA for the sequence
tRNA (transfer RNA)
This type of RNA helps to catalyze peptide bond formation and form the ribosomes
rRNA
What is the wobble base and why can it lead to silent mutations?
The last (third) base in a codon. Since many codons can code for the same AA, a change in the wobble base doesn’t usually lead to a change in AA sequence.
The wobble base is the best part of the codon to mutate, since it usually doesn’t end up changing the AA sequence
This mutation occurs when 1 AA substitutes for another
Missense
This mutation occurs when a stop codon is inserted early
Nonsense
This mutation occurs when a base is inserted or deleted, and causes the AA sequence to shift (the most catastrophic mutation)
Frameshift
This mutation most often occurs due to a mutation of the wobble base and doesn’t actually change the AA sequence
Silent
Silent, missense and nonsense mutations are referred to as ____ mutations since only one base is being changed
Point
What three things are added to hnRNA to make it into mRNA?
Exons have to be spliced and glued back together, a cap is added to the 5’ end to act as ribosome binding site, and a tail is added to the 3’ to help stop degradation of important genetic info when the RNA enters the cytoplasm
This is the name for the DNA strand that’s used as the template for transcription
Anti-sense
This is the name for the DNA stand that is complimentary to the DNA strand being transcribed, and is ultimately the same as the new RNA strand being created
Sense
This type of RNA polymerase is found in the nucleolus and synthesizes rRNA
RNA polymerase I
This type of RNA polymerase is found in the nucleus and synthezies hnRNA and some small-nuclear RNA
RNA polymerase II
This type of RNA polymerase is found in the nucleus and synthesizes tRNA and some rRNA
RNA polymerase III
During post transcriptional modifications, exons are _____
The part of the sequence that codes for important information and is kept to turn into mRNA
During post transcriptional modifications, introns are _____
The unimportant part of the sequence that’s spliced and thrown out
What is the purpose of spliceosomes and small nuclear RNA?
They separate introns and bind the exons together
Transcription factors help RNA polymerase find this location, which is the site where transcription begins
Promoter
RNA polymerase travels down the _ to _ end so that the strand is transcribed in the 5 to 3’ direction
3 to 5’
For eukaryotes, transcription occurs in the ___ while translation occurs in the ____
Nucleus
Cytoplasm
This site on the ribosome is responsible for holding the incoming tRNA complex so that the next AA can be added without the strand being displaced
A site
This site on the ribosome is responsible for holding the tRNA creating the polypeptide bond, so that the polypeptide is created as the chain passes through this site and to the A site
P site
(P for Polypeptide creation)
This site on the ribosome is responsible for holding the inactivated tRNA before it leaves the ribosome, and also unbinds the mRNA from the ribosome
E site
During this phase of translation, small RNA subunits bind at the 5’ cap while the tRNA binds the start codon
Initiation
During this phase of translation, AA’s are added via the P, A and E sites, ultimately forming the polypeptide chain
Elongation
This phase of translation begins when the stop codon moves into the A site, causing release factors to bind, which then adds H2O to the polypeptide chain and allows peptide transferase and transcription factors to hydrolyze from the tRNA, followed by the polypeptide being released from the P site
Termination
How do transcription and translation differ in prokaryotes and eukaryotes?
In prokaryotes, transcription and translation can occur at the same time, with both happening in the cytoplasm. In eukaryotes, transcription takes place in the nucleus while translation takes place in the cytoplasm, and both have to occur at separate times
This structure is a cluster of genes in a prokaryote that share a promoter because they all transcribe for the same thing
Operon
This type of operon acts like a competitive inhibitor. It only produces genes when needed, because the repressor and operator are bound together, so the repressor has to be pulled off the operating site before it is able to transcribe anything (ex: the lac operon)
Inducible
This type of operon is in constant protein production, but acts with negative feedback. The repressor is inactive until a corepressor binds to it, and this corepressor is often the product the operon is creating (ex: the trp operon)
Repressible
These factors are transcription activating proteins that look for specific sections of DNA
Transcription factors
This domain on the transcription factor binds to the specific DNA sequence
DNA binding domain
This domain on the transcription factor acts like a scaffold in which more transcription factors can bind and control the extent to which a gene is activated/transcribed
Activation domain
This type of gene amplification acts like a hub where many different factors can bind to their own receptors to activate the same gene and enhance transcription rate. Example of things that bind include hormones like estrogen and cortisol, and cAMP
Enhancers
This type of gene amplification occurs when genes are duplicated either on the same chromosome (so that many replicas are made in a row) or by helicase opening specific parts of DNA)
Gene duplication
How does acetylating or deacetylating histone allow for gene expression to be regulated?
Acetylating histones decreases their attraction to DNA (since they become less positive), which means the chromatin unwind a little and create more room for transcription. Similarly, deacetylating histone creates a stronger bond between the histones and DNA, so there will be less room for transcription to occur
