Translation Younger Flashcards
First step in protein synthesis: code contained in a mRNA is put into a particular series of amino acids to form a polypeptide.
Translation
The protein coding region of an mRNA contains a series of nucleotide triplets called what?
Codons
How many different orientations are there for codons?
4^3= 64 possible codon combinations
Nucleotides are read 5’ to 3’ and the protein is synthesized from its __________ (start) to its _________ (end).
N-terminus
C-terminus
All start codons are ____.
AUG
True/False: Not every AUG is a start codon.
True. only the first AUG encountered (5’ to 3’) is the start codon.
AUG encodes for which amino acid?
Methionine
What are the 3 stop codons? IMPORTANT
UGA, UAA, UAG
U go away
U are away
U are gone
How many amino acids does this encode for?
5’-Cap- GGGUAGGCCUAUGGACUUAAUAGUAUGUUGAGGCAAAAAA-3’
Recognize start site, (counts for 1) + however many amino acids are between start and stop codon (don’t count the stop codon.)
ANSWER: 6 amino acids
Each codon is specific for an _________.
amino acid
True/False: Each amino acid can code for several codon.
True, there are as many as 6 codons for a specific amino acid
If the DNA sequence is mutated, so that the codon is changed, but still encodes the same amino acid, it is called a _________ mutation.
Silent
eg. UCA to UCU both still encode serine
If the point mutation results in a codon that defines a different amino acid, is called a ________ mutation.
missense
e.g. UCA to UCU- serine to proline
If the mutation results in a change from an amino acid to a stop codon, it is called a _______ mutation.
nonsense
e.g. UCA to UAA serine to a stop codon
If the insertion/deletion is NOT a multiple of 3, the mutation is called a ________ mutation.
frameshift
IF the insertion/deletion IS a multiple of 3, it results in the ____________ of amino acids.
INsertion/deletion
This mutation usually results in a premature stop codon and a truncated protein.
Frameshift mutation… The closer to the beginning of the protein, generally the more severe the mutation.
Regions in a gene where a sequence of bases is repeated many times.
trinucleotide repeat expansions
Where in the reading frame is a trinucleotide repeat?
Both within the cell and outside of the cell. They cause different problems
For methionine AUG, what is the anticodon sequence of tRNA that would bind to codon and deliver amino acid? IMPORTANT
what is the direction?
5’ AUG 3’—- in 5’ to 3’ direction CAU
What enzymes recognize amino acids and all of the tRNAs so that they attach amino acids to the corresponding tRNA.
Aminoacyl-tRNA synthetases
dictionary/translator from amino acid to codon sequence
How many different aminoacyl-tRNA synthetases are in humans?
20
How many Pi bonds are broken to get amino acids onto DNA?
2 inorganic phosphates are cleaved and let go
RIbosome site that binds an incoming aminoacyl-tRNA.
A site
Ribosome site that binds peptidyl-tRNA.
P site
Ribosome exit site, contains empty tRNA as it is about to exit the ribosome (note, eukaryotic ribosomes do not contain this site)
E site
Protein that is generated on the ribosome that is associated with the ER is what? important
Secretory proteins
Charging the tRNA, 2 high energy bonds from ___ (energy).
ATP
Binding the aminoacyl-tRNA to the A site is from one ___ (energy).
GTP
Translocation step- movement of the ribosome to the next codon- uses one ___ (energy).
GTP
A total of how many high energy bonds are required for each amino acid that is added?
4
tRNAs can recognize more than one codon for a specific amino acid… What is the name of this hypothesis?
Wobble hypothesis
baby
Wobble
baby wobble baby wobble… Get in there
Difference between polycistronic and monocistronic…
polycistronic- (mRNA could have multiple genes associated with it) prokaryotes
monocistronic- eukaryotes
What in the small subunit contains a sequence complementary to the shine dalgarno sequence that allows correct alignment of the small ribosomal subunit with the AUG start codon.
16s rRNA
The vey first methionine after start codon (AUG) is going to be a _________ methionine.
Formylated
General understanding of Translation, translocation of 3 nucleotides to the next codon.
A site empty, Formylated Meth in P site (holding site), next tRNA is put on A site and ribosome moves down RNA, and tRNA enters into the polypeptide chain.
Once you have a stop codon what signals happen?
termination step begins.
