translation Flashcards
what is translation?
the transmission of the genetic information from mRNA to protein.
explain the process of translation?
Newly processed mRNA is transported from the nucleus to the cytoplasm, where it becomes associated with the ribosomes, which are the site of protein synthesis
Genetic code describe?
-Degenerate or Redundant Code:
-each codon corresponds to only one amino acid or stop signal
-Some flexibility in the genetic code, allowing for certain changes in DNA sequence without altering the protein sequence.
how does mrna molecules get exported from nucelus to cytoplasm
Here they are bound by ribosomes
proteins are??
made up amino acids linked by peptide bonds
describe eukarytic ribosomes?
Ribosomes provide a structure in which translation can take place
They also catalyse the reaction that links amino acids to make a new protein
describe the structure of a ribosome
made up of two basic pieces: a large and a small subunit. During translation, the two subunits come together around a mRNA molecule, forming a complete ribosome
Both subunits contains many ribosomal proteins arranged on a scaffold composed of ribosomal RNA (rRNA)
True or false
true
In order for translation to start, need:
A ribosome
An mRNA with instructions for the protein to be built
An ‘initiator’ tRNA carrying the amino acid in the protein Met (AUG)
Translation - initiation (1)
mRNA contains coding parts (exons) and noncoding parts (5’UTR and 3’UTR). Ribosomes recognize mRNA by binding to the 5’ cap, then scan until they find the start codon AUG
Translation - initiation (2)
A transfer RNA (tRNA) carrying the amino acid methionine attaches to the small ribosomal subunit. This subunit binds to the 5’ end of mRNA, recognizing the 5’ cap, and then moves along the mRNA in the 3’ direction until it reaches the start codon, which codes for methionine (AUG). This start codon marks the beginning of an open reading frame, where codons specify successive amino acids in the protein chain. Finally, the large ribosomal subunit joins the small subunit to form the initiation complex, initiating protein synthesis.
each tRNA has a what>
anti codon
what is an anticodon
a set of 3 nucleotides that binds to a matching mRNA CODON through base pairing
Translation - elongation
(tRNAs) bring amino acids to ribosomes, linking them together to form a protein chain. Different tRNAs, each carrying a specific amino acid, ensure the correct sequence. Ribosomes have three slots (A, P, and E) where tRNAs dock and move as they deliver amino acids and then exit.
Translation – elongation (peptide bonds)
During protein synthesis, peptide bonds are formed between adjacent amino acids, connecting them into a growing polypeptide chain. The ribosome moves along the mRNA, pulling it forward by one codon after each peptide bond formation, exposing a new codon for the next amino acid-tRNA pairing. As each tRNA exits via the E site, a new tRNA enters the A site to continue the process until a STOP codon signals the end of protein synthesis.
Translation - termination
-Translation ends in a process called Termination
-Termination happens when a stop codon in mRNA (UAA, UAG, or UGA) enters the A site
-Stop codons are recognised by proteins called release factors which fit into the P site
summarise tRNA
tRNAs(transfer RNAs) carry amino acids to the ribosome. Act as ‘bridges’ matching a codon in an mRNA with the amino acid it codes for
Deamination
(chemical reaction in which anamide functional group is removed from an organic compound)
Methylation
installation of a methyl group on a substrate)
summarise translation. 1/3
First, a molecule called aminoacyl-tRNA brings the right amino acid to the protein-making machine (the ribosome) and attaches to a specific spot (the A site) on it.
summarise translation. 2/3
Then, the amino acid from the aminoacyl-tRNA forms a bond with the amino acid at the end of the growing protein chain (which is already attached to the ribosome).
summarise translation. 3/3
After that, the mRNA moves along the ribosome, kind of like a conveyor belt, making space for the next set of instructions. This also kicks out the old aminoacyl-tRNA, getting the ribosome ready for the next amino acid.
Aminoacyl-tRNA synthetases catalyze a two-step reaction
- Adenylation of amino acid is the process of attaching an AMP molecule to a protein side chain by covalent bonding)
- Aminoacylation of tRNA
Attachment of AA to tRNA
An enzyme called aminoacyl-tRNA synthetase connects a specific amino acid to its matching tRNA molecule.
where does the AA get attached to the t rna
connection happens at the 3’ end of the tRNA through a high-energy ester linkage with the terminal adenosine.
The anticodon on the aminoacyl-tRNA then pairs up with the corresponding codon on the mRNA,
