protein synthesis Flashcards
Protein synthesis
A process whose end product is a protein. Two main parts: transcription and translation.
Transcription
The synthesis of mRNA using the stored DNA code.
Translation
The synthesis of a polypeptide using the information in the mRNA.
Step 1
RNA polymerase breaks weak hydrogen bonds of one gene, separating the two DNA strands.
Step 2
Only one of the strands is copied to produce mRNA (messenger RNA)
Step 3
RNA polymerase starts attaching free floating nucleotides at a promoter-start section on the non-coding strand according to complementary base pair rules in 5’ to 3’ direction until terminator (stops DNA) section.
Step 4
The premature mRNA goes through a process known as ‘splicing’ to remove the introns as introns do not directly code for proteins. During splicing the exons are joined to create mature mRNA.
Step 5 (alternative splicing) technically not a step??
Some genes can be alternatively spliced, meaning exons from the same gene are joined in different combinations. This leads to different mRNA transcripts, allowing the mature mRNA molecules to produce different proteins from the same initial gene.
Step 6
The single-stranded mRNA floats through nucleus pore and travels to ribosomes in the cytoplasm.
Step 7
Ribosomes bind to mRNA.
Step 8
A start codon indicates to the ribosome that translation should begin.
Step 9
tRNA transfers the first amino acid based on the complementary anti-codon it is carrying. Therefore, the codon determines the specific amino acid that is transferred.
Step 10
The next codon is read and the tRNA drops off the specified amino acid. This is repeated until a chain of amino acids: a polypeptide is made.
Step 11
A peptide bond is formed between amino acids.
Step 12
Polypeptide detaches and folds to become a functional protein.
