Translation and the Role of tRNA's Flashcards
Define translation.
The conversion of information in mRNA to protein
What is the genetic code?
The rules by which nucleotide sequence of a gene is translated into an amino acid sequence of a protein
How is the mRNA sequence decoded?
The mRNA sequence is decoded in sets of 3 nucleotides
What is the intermediate between genes and amino acids?
Transcription
What is a triplet of nucleotides called?
A codon
What does a codon specify?
Either an amino acid or a stop codon
What is a stop codon?
A stop to the translation process
What sequence of nucleotides acts as a start codon?
AUG
What does AUG code for?
Methionine
What are the three ways a stop codon can be indicated?
UAA
UAG
UGA
What does AUG code for?
A start codon
What three RNA molecules are involved in translation?
4
mRNA
tRNA
rRNA
(snRNA - forms spliceosome)
In general what happens during translation?
The cell interprets a genetic message and builds a polypeptide accordingly
What carries the genetic message?
An mRNA molecule
What acts as the interpreter of mRNA?
Transfer RNA
What does tRNA do?
tRNA transfers amino acids from cytoplasmic pool of amino acids to a ribosome
What do ribosomes do?
They add each amino acid brought to it by tRNA to the growing end of a polypeptide chain
What are the two most crucial molecules in translation?
tRNA
Ribosomes
What does tRNA have to bind to?
Both a codon and an amino acid
What does tRNA consist of?
A single RNA strand
How long is tRNA?
About 80 nucleotides long
Describe the shape of tRNA.
Looks like a cloverleaf (2D)
Describe the 3D shape of tRNA.
L-shaped structure
What are the two most crucial regions of tRNA?
Anticodon
Amino acid binding site
What is an anticodon?
A set of 3 nucleotides which pairs with a complementary codon in an mRNA molecule
What is an amino acid binding site?
2
A short single stranded region at the 3’ end of tRNA site
This is where the amino acid that matches the codon is attached to tRNA
What couples tRNAs to their correct amino acid?
Specific enzymes
What happens to tRNA when it links to it’s amino acid?
The tRNA becomes ‘charged’
What enzymes are responsible for recognition and attachment of correct amino acid by tRNA?
Aminoacyl-tRNA synthetases
What are the two recognition steps on key sites of tRNA?
There must be a correct match between a tRNA and an amino acid
Must be a correct match between the tRNA anticodon and an mRNA codon
What facilitates the specific coupling of tRNA anticodons with mRNA codons?
Ribosomes
What is the main role of ribosomes in translation?
They facilitate the specific coupling of tRNA anticodons with mRNA codons during protein synthesis
How many different types of aminoacyl-tRNA synthetases are there?
There are 20 -> one for each amino acid of the genetic code
