Gene Function: Translation Flashcards
What does mRNA look like?
A series of nucleotides
mRNA is the molecule that carries genetic information from DNA to the ribosome for protein synthesis.
How is mRNA read?
As three-letter ‘words’ called codons
Each codon corresponds to a specific amino acid.
What amino acid does the codon AUG encode?
Methionine (Met/M)
AUG is also the start codon for protein synthesis.
What amino acid does the codon AUA encode?
Isoleucine (Ile/I)
How many amino acids are encoded in eukaryotes?
20 amino acids
These amino acids are encoded by combinations of codons derived from four nucleotides.
How many possible codons are there with four nucleotides and a three-letter codon?
64 possibilities
This is calculated as 4^3, reflecting the combinations of nucleotides.
What is meant by redundancy in the genetic code?
Some amino acids are encoded by more than one codon
This differs from ambiguity, as redundancy does not lead to confusion in coding.
What can happen with one base change in a genome?
It can have dramatic effects on a protein or none at all
This highlights the sensitivity of protein synthesis to genetic mutations.
Why does the genetic code matter to veterinarians?
It plays a major role in some horse breeds’ gait
Understanding genetic mutations can help in breeding and health management.
What is DMRT3?
A transcription factor that can introduce a premature stop codon
This is caused by a SNP C>A and affects horse gait.
What recognizes the three-letter codons in mRNA?
Transfer RNAs (tRNAs)
tRNAs have specific anticodons that match the codons on the mRNA.
What do tRNAs critically contain?
Attached amino acids
This ensures that the correct amino acid is added during protein synthesis.
Where do tRNAs encounter mRNAs?
At ribosomes
Ribosomes are the sites of protein synthesis in cells.
What are ribosomes made up of?
rRNA subunits and ribosomal proteins
Ribosomes consist of two subunits that work together during translation.
What are the two subunits of eukaryotic ribosomes?
60S subunit (large) and 40S subunit (small)
Both subunits are essential for the translation process.
What is the difference between eukaryotic and prokaryotic ribosomes?
Eukaryotic ribosomes are larger and structurally different
This difference is significant for antibiotic targeting.
What is the target for macrolide class antibiotics?
50S ribosomal subunit activity
Erythromycin is an example of a macrolide antibiotic.
What is the target for tetracycline class antibiotics?
30S ribosomal subunit activity
Doxycycline is an example of a tetracycline antibiotic.
What is the key to the initiation of translation?
Starting codon
The starting codon is typically AUG, which encodes Methionine.
What is part of the Kozak sequence?
RNNATGG
R represents a purine (A or G) and is crucial for proper initiation of translation.
What recognizes the initiation sequences on the mRNA?
eukaryotic initiation factors (elF)
elF1A and elF2 alpha are involved in the translation initiation process.
Why does translation initiation matter to veterinarians?
It is relevant for mRNA vaccines like those for SARS-CoV-2
Understanding translation can help in vaccine development and efficacy.
What is the enzyme that leads to peptide synthesis during translation elongation?
Peptidyl transferase
This enzyme facilitates the covalent bonding of amino acids between the N-terminal and the C-terminal
What signals the termination of protein synthesis?
The stop codon in mRNA
Stop codons include UGA, UAA, and UAG.
What binds to the ribosome at a stop codon?
Translation release factor eRF1
This factor triggers the termination of translation.
What happens when peptidyl transferase recognizes a stop codon?
It adds a water molecule instead of an amino acid
This releases the synthesized protein from the ribosome.
Can one mRNA be translated by multiple ribosomes?
Yes
Multiple ribosomes can translate the same mRNA strand simultaneously.
