ch369_sum10_ch20_notes

ch369_sum10_ch20_notes - Chapter 20 - Protein synthesis C e...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 20 - Protein synthesis Central dogma of molecular biology: 3 base pairs DNA ==> 3 bases of mRNA ==> 1 amino acid
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Translation ” refers to the process of protein synthesis, where tRNAs tRNAs &
Background image of page 2
Genetic code: DNA structure was known by 1953, but how it coded for proteins was unknown for several more years. Artificial mRNA templates were made, and used to break the code. For example, it was observed in 1961 that poly U made poly- phenylalanine. poly U => poly Phenylalanine poly G => poly Glycine Poly A => poly Lysine poly C => poly Proline After several more years, the full genetic code was figured out.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Interestingly, a change in the 3rd nucleotide of a codon often does not change the amino acid, or changes to a similar a.a. Some amino acids have one codon, some have 3, 4, or 6 codons.
Background image of page 4
Reading frames. Notice there are 3 different reading frames for the triplet code. The a.a. translated depends on where the ribosome starts. Can you see how a mutation that deletes a single nucleotide could change the identities of many of the amino acids in a protein, by changing the reading frame ?
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
All tRNAs have a similar cloverleaf structure. All end in -CCA at their 3’ end (where the amino acid is attached). Amino acids are delivered to the ribosome, covalently attached to the 3’ end of transfer RNA (tRNA) at the acceptor stem . The anticodon loop of tRNA reads the mRNA.
Background image of page 6
tRNAs contain some modified nucleotides (dihydrouridine, etc.)
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Enzymes called “ aminoacyl tRNA synthetases ” link the a.a. to the 3’ end of the tRNA. A different tRNA synthetase for each tRNA type, to assure the correct a.a. is coupled to the correct tRNA. Amino acid attachment requires ATP. Gln tRNA synthetase (green) bound to tRNA (red) and ATP (yellow) FYI - there are 2 classes of tRNA synthetases (called “class 1” and “class 2”) which operate by 2 distinct mechanisms.
Background image of page 8
Chemical structure of tRNA with a.a. attached:
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Attaching the a.a. to the tRNA (called “ aminoacylation of tRNA ”) is a 2 step reaction, catalyzed by the tRNA synthetase : (next page)
Background image of page 10
“activated amino acid” “charged tRNA”
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
aminoacyl tRNA synthetase error rates are very low.
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/26/2010 for the course CH 369 taught by Professor Kbrowning during the Spring '07 term at University of Texas at Austin.

Page1 / 44

ch369_sum10_ch20_notes - Chapter 20 - Protein synthesis C e...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online