Lecture 29 - Translation and Protein synthesis Flashcards
what are the 5 key players in translation?
- mRNA (messenger RNAs)
- tRNA (transfer RNAs)
- Ribosome
- codons
- anticodons
what do transfer RNA molecules provide?
-the physical link that decodes the mRNA into the encoded polypeptide
what does tRNA do?
-links the mRNA sequence with the amino acid sequence
what are codons?
three-nucleotide long sequences
what dictates tRNAs?
the mRNA template
what does the anticodon loop recognize?
the 3-nt code on the mrNA template
why have some bases on the tRNA have been post-transcriptionally modified?
to enhance anticodon recognition and specificity
what does the anticodon recognqie?
3-nt codon on the mRNA
what does each codon translate to?
one of the 20 amino acids
what are the 3 top codons?
- UAA
- UAG
- UGA
what is the start codon?
AUG (codes Met)
what are aminoacyl-tRNA synthesases responbile for?
first step in decoding
what does Aminoacyl-tRNA synthetase do?
links the right amino acid to a tRNA
how many aminoacyl-tRNA synthetase for each amino acid?
there is generally one for each of the standard 20 amino aicds
how many subunits do ribosomes have?
two subunits
what else does the ribosome contain?
proteins
how many tRNA binding sites do ribosomes have?
3 binding sites
when do polysomes form?
-they form when multiple ribosomes initiate + elongate multiple mRNAs from the same gene
what are 4 things that translation involves?
- initiate
- elongation
- termination
- ribosome recycling
how can bacterial translation initiation be regulated?
-interrupting binding of 16S rRNA to SD sequence interferes with bacterial translation
what is the 16S rRNA?
-16S rRNA locates the Shine-Dalgarno sequence upstream from the AUG start codon at beginning of open reading frame (ORF)
