Mr P bio 8 Protein Synthesis Flashcards
what is the proteome?
the full range of proteins that a cell is able to synthesise
what is the process of transcription?
- H bonds are broken by an enzyme called helicase
2.one strand acts as a template
3.free RNA nucleotides align with their complementary bases
4.uracil instead of thymine
5.RNA polymerase joins nucleotides with a phosphodiester bond
6.pre mRNA is spliced to remove introns
7.passes out the nuclear pores and goes to ribosomes for translation
what is the name for a coding sequence within a gene of DNA?
exon
where does translation occur in all cells?
cytoplasm
where does translation occur in eukaryotic cells?
on the ribosomes of the RER
where does translation occur in prokaryotic cells?
ribosomes in the cytoplasm
what is the process of translation? (12)
- mRNA attaches to the ribosome
2.tRNA carrying a specific amino acid binds to the first codon on the mRNA, via base pairing with its anticodon
3.a second tRNA carrying a specific amino acid will bind to the second codon on the mRNA, via base pairing with the anticodon
4.enzymes join the amino acids together forming peptide bonds with required ATP
5.ribosomes live along mRNA to next codon
6.tRNA lost from 1st codon, no longer has an amino acid - 3rd tRNA carrying a specific amino acid binds to 3rd codon
8.enzymes join amino acids forming a peptide bond - ribosome moves along mRNA to next codon
10.tRNA lost from 2nd codon
11.process repeats adding 1 amino acid each time until reaching the stop codon
12.polypeptide then released
what are the 3 ways in which a mutation can occur?
substitution, deletion or insertion
what is an insertion mutation?
a nucleotide is randomly inserted into the DNA sequence which changes the amino acid that would have been coded for. this can have a knock-on effect
what is a deletion mutation?
when a nucleotide is randomly deleted from the DNA sequence. changes amino acid coded for and can have a knock on effect
what is a substitution mutation?
when a base in the DNA sequence is randomly swapped for another which will only change the amino acid for the codon in which the mutation occurs
what is a silent mutation?
mutation that doesn’t alter the amino acid sequence if the polypeptide (amino acids are degenerate)
what are missense mutations?
alters a single amino acid in a polypeptide chain
what are nonsense mutations?
creates a premature stop codon causing the polypeptide chain to be incomplete so affecting the final protein structure
what factor can increase the risk of mutations?
high energy radiation (X rays and gamma rays)
