molecular biology<3 Flashcards
(24 cards)
what are eukaryotes Mrna structural feactures
semi loop - involved in regulating efficiency of translation
define ribosomes
large riboneucleoproteins that synthesis polypeptides
overview of translation
Mina acts as template for amino acid chain
3 bases on RNA= one amino acid
Mrna reads on ribosome
Trina brings amino acids to ribosome and join to previous
one amino acid is coded from by
triplet of bases
how many stop codons
3
what is the wobble hypothesis
first two bp have most specify, 3rd is less stringent
three stages of translation are
initiation
elongation
termination
initiation and elongation require what
energy GTP
translation what is the start codon?
AUG (methionie)
termination what are the stop codons
UAA
UGA
UAG
translation takes place where
ribosome in cytoplasm
what is transfer RNA
small pieces of DNA with a 3D structure (clover leaf)
one end of transfer DNA has —— —– attached and other has ———–
amino acid
anticodon
how many ribosomes can work on same polypeptide?
several
what does several ribosomes working on same stretch of DNA do?
enables several proteins to be made at once
amino acid residues attach to each other with
peptide bond
what do release factors do?
recognise stop codon abd modify ribosome to activate ribosymes which sever polypeptide from final TRNA
what happens if DNA sequence changes
alternative MRNA made and therefore, alternative amino acid sequence
name types of mutations
point
frameshift
point mutation is when
one or a few base pairs are effected
substitutions, insetrions, deletions
frameshift mutation is when
neucleotide triplets after mutation displaced
insertions/deletions
what is substitutions
1 base pair replaced
what is nonsence codon
codon changed to termination codon
polypeptide too short
inactive protein produced
what is a silent mutation
base changed but amino acid is the same
