Transcript Mol Bio CH 14 Nov 15

Goals:
1 - structure of messenger RNA and translation
2 - preparation of amino acids
3 - building a protein
4 components to protein synthesis (translation):
1 - mRNA
Template
2 - transfer RNA (tRNA) bound to amino acids
Substrate
3 - aminoacyl-tRNA sythetases (charge a.a.s)
Substrate
4 - ribosomes
Machinery
mRNA can be translated 3 ways (3 frames)
Many prokaryotic mRNAs have a Shine-Dalgarno sequence
-Interacts with the ribsome to position next to start codon
-Eukaryotic mRNAs may have a Kozak sequence - similar function
-Other (less well understood) mechanisms function for mRNAs without
these sequences
Anatomy of tRNAs
-All have same generic shape
-Small differences allow specific tRNA to be matched with specific a.a.s
“Charging” an amino acid
requires ATP consumption
-High-energy bond created
between tRNA and a.a.
-Energy used during protein
synthesis
-Different synthetase enzymes
attach a.a. to tRNA at either
the 2’ or 3’ OH of RNA
Each amino acid has its own synthetase enzyme
-RNA nucleotides can be modified
-Clover structure results in nontraditional base pairing
-Unique features of each tRNA are
exploited (though not usually the
anticodon)
The ribosome is made of RNA and protein subunits
Ribosomes are very large and complex
Ribosomes assemble and disassemble with each translation
event
Peptide bond formation uses energy stored in the amino acid
- tRNA high energy bond
-Release of tRNA/formation of peptide bond is a 2 step process
-The most recently added amino acid remains bound to tRNA
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