translation Flashcards
what is translation linked with
tRNA
what are tRNA functions (2)
- picks up a specific amino acid in the cytoplasm
- transfer to correct position on a ribosome that is assembling a polypetide
how many different tRNA are there in the cytoplasm
64
5 steps of translation
- tRNA activating enzyme
- Enzyme binds to ATP and specific amino acid
- amino acid AMP complex formed and specific tRNA mol reunited
- tRNA is bound to amino acid and AMP released
- charged tRNA is produced
steps of translation?
- ribosome attactches at start of mRNA strand
- complimentary codon attracted to first codon on mRNA
- ribosome holds 2 tRNA mols in place (so amino acids can join by peptide bond)
- first tRNA havin passed its amino acid to the second tRNA iis now released into the cytoplasm
how many amino acids are added at a time
one
growing peptide chain is passed to the most recent tRNA
how many subunits are ribosomes made of
2
what does the larger subunit contain in ribosomes
2 sites for attatchment of tRNA mol
so 2 tRNA mol assosciated with ribosomes at any one time
what does smaller subunit of ribosome do
bind to mRNA
what does ribosomes act as
framework moving along the mRNA and holding the codon
3 steps of translation
initiation
elongation
termination
what happens in initiation
ribosome attatches start codon at one end of mRNA mol
what happens in elongation phase
2 amino acids close enough for ribosomal enzyme to catalyse formation of peptide bond between them
ribosomes moves one codon along the mRNA strand
what is termination
sequence repeats unitl a stop codon is reached
what is the gene and polypeptide hypothesis
one gene one polypeptide
gene is a sequence of DNA bases that code for a polypeptide
functions of proteins (5)
enzymes
antibodies
hormones
transport proteins
forming structres
what happens to protein in the golgi body
folded into secondary, tertiary or qauternary strutures
may be chemically modified as well
what is the moodification of a polypetide called
post translational modification
what can polypeptides be chemically modified with
non proteins
carbohydrate - glycoprotein
lipid - lipoproteins
phosphate - phospho-protein
what does tRNA do
carries information in the anticodon and it carries specific amino acid to be incorporated into a growin polypeptide chain
what shape are the tRNA molecule
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