BIOL 411 Lecture Notes - Lecture 10: Alpha Helix, Protein Folding, Transfer Rna
Bio411.01
2/24/16
• Secondary structure:
o regional
o Alpha helix or beta-sheet
o Formed by backbone interactions, but R-groups dictate whether or not they
form
• Tertiary structure:
o R-group interactions (covalent and weak)
o Protein folding
o Putting together regions of secondary structure
• Protein folding occurs during synthesis
o 1. Segments adopt secondary structure
o 2. Hydrophobic regions move to the inside
o 3. R-group interactions stabilize final 3D structure
• How does the sequence of nucleotides in DNA determine the sequence of amino acids?
o 1. Sequence in DNA is transcribed (copy/same language) →mRNA
o sequence in mRNA is translated (different language)→protein
• Translation: vocabulary (genetic codes), grammar (process- how vocabulary is used)
• Codon: universal, redundant, unambiguous- if you know the codon, you know the amino
acid, no overlaps, no gaps
• tRNA: transfer RNA
o adapter molecules because they translate nucleotide sequence into amino acid
sequence
• Two things needed:
o 1.Basis of genetic code is complementary base pairing by which the codon and
the anticodon pair with one another
▪ The polarity of the odo is 5 to 3 so the polarity of the atiodo is 3
to 5
o 2. (2nd genetic code) The right amino acid needs to be on the right tRNA
▪ amino acyl tRNA synthetase: enzyme that takes the two molecules and
puts them together
• recognizes the right tRNAs and the right amino acid and catalyzes
the acyl bond that joins the amino acid to the tRNA
▪ 20 amino acids and 61 different codons
• There are 20 amino acid tRNA synthetases: one for each amino
acid
• Able to recognize all of the codons that go with that amino acid
on the tRNAs
• Process of translation involves: ribosomes (scaffold + catalysis), charged tRNAs, mRNA,
and a bunch of initiation, elongatio, ad teriatio fators
o Ribosomes consist of a small subunit and a large subunit
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