Protein Synthesis Flashcards
What do genes code for?
The sequence of bases in a DNA molecule codes for a sequence of animo acids in a protein. Each gene codes for one protein
How many bases code for an amino acid?
3
What is transcription?
The portion of DNA that makes the gene forms 2 single strands. One of the strands acts as a template for the formation of a corresponding strand of mRNA.
What happens after transcription?
mRNA molecules are made in the nucleus, where the DNA is located. DNA cannot leave the nucleus, but mRNA can because it is much shorter. Once in the cytoplasm the mRNA will go to the ribosome where protein synthesis will take place.
What is translation?
tRNA pairs with triplets of bases on mRNA and transfers the required amino acids to the ribosomes. Each amino acid has a specific tRNA molecule
What do the codon and anti-codon do?
In addition to carrying the amino acid the tRNA carries a triplet of bases called an anti-codon, which recognises the corresponding triplet on the codon,on the mRNA molecule.
How is the peptide bond formed?
The anticodon on the tRNA and the codon on the mRNA match, so the amino acid is put in place. The second mRNA codon is translated in the same way and a second amino acid is placed along side the first. A peptide bond forms to hold the amino acids together. This repeats and the chain becomes longer and longer and a polypeptide is formed. The polypeptide chain will twist or fold as it is being built to forma protein.
What happens when there is a stop codon?
Some codons in mRNA don’t code for amino acids and instead act as stop signals. If a stop codon is reached then it means that the polypeptide is finished and translation stops.
What is the role of the ribosome?
They hold the mRNA, tRNA and amino acids in the correct position for protein synthesis to take place. Any ribosome can translate any piece of mRNA.
