Protein synthesis

Emily Sutton
Mind Map by Emily Sutton, updated more than 1 year ago
Emily Sutton
Created by Emily Sutton about 4 years ago


AS - Level Biology (Nucleic acids and their functions) Mind Map on Protein synthesis, created by Emily Sutton on 02/26/2016.

Resource summary

Protein synthesis
1 polypeptide synthesis
1.1 sequence of nucleotides on a gene of dna acts as a template
1.1.1 complimentary copy transcribed onto mRNA mRNA acts as a template that is translated into a complimentary chain of tRNA which carry specific amino acids which are linked together
2 Transcription
2.1 produces mRNA from DNA
2.2 base sequence of a gene on DNA converted to a complimentary base sequence on mRNA
2.2.1 rna polymerase links to dna at the start of the gene to be transcribed dna unwinds as hydrogen bonds between the 2 double helix strands break exposing unpaired dna bases only one strand used as template start codon ensures gene is read in right direction rna polymerase moves along dna strand, a molecule of single stranded mRNA is made from free rna nucleotides present in nucleoplasm (that enter nucleus from cytoplasm) complimentary base pairing DNA-RNA: A-U(uracil), T-A, G-C, C-G at end of sequence mRNA detaches and dna rewinds into double helix mRNA moves through nuclear pores into the cytoplasm and attaches to a ribosome (made of ribosomal rna and protein)
3 Translation
3.1 the formation of a polypeptide chain according to original dna code using amino acids on tRNA and the mRNA code
3.2 mRNA held by a ribosome which had two transfer RNA (tRNA) binding site
3.2.1 each tRNA has its own specific amino acid the codons on mRNA join to complimentary anticodons on tRNA by hydrogen bonding ribosomal enzyme catalyses peptide bond formation between an amino acid on one tRNA and the growing polypeptide on the other tRNA ribosome passes along mRNA, one codon at a time, trna with appropriate anticodon fills vacant slot and the amino acid forms a peptide bond with the last member of the chain using energy from ATP the tRNA that has donated an amino acid to chain detaches from mrna and ribosome and is free to attach to another identical amino acid an amino acid activated by ATP and is attached to a specific tRNA molecule which carries amino acid at one end and anticodon at the other different trna molecules with their amino acids are assembles according to the mRNA base sequence
3.2.2 one site binds tRNA carrying the amino acid which has been joined to the growing polypeptide chain while other site is for tRNA carrying the next amino acid in the sequence
4 producing the final proteins
4.1 polysomes: usually a number of ribosomes move along a single piece of mRNA each making a new polypeptide chain
4.2 further modification: primary structure may be modified by golgi body and the final structure may have more than one polypeptide eg. haemoglobin
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