BIOL SCI 215 Lecture Notes - Lecture 7: Frameshift Mutation, Sickle-Cell Disease, Open Reading Frame
28 Jun 2018
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Prok: -10 and -35
Euk: TATA
Transcription - adding nucleotides from 5’ end to the 3’ end
Base pairing at the bottom strand, T becomes U - during transcription
Proteins are polymers made of amino acids, amino group, carboxyl group with an R
group. When amino acids are joined together with a dehydration reaction
Amino End is called the N end and Carboxyl end is the C end
R group gives the chemical specificity
Amino Acids Folding
oSecondary structure with nearby amino acids to form helix structures
oBeta pleated sheets which provides local folding
oMore happens at larger distances
Only 4 DNA Bases (A,G,T,C), 20 amino acids so you would need 3 bases to encode
each amino acid
oCodons are 3 bases of mRNA read by the ribosome into an amino acid
oGenetic information in mRNAs is stored in a non-overlapping code thus
codons are read in a non-overlapping manner [don’t have to memorize
genetic codes]
oAUG is the start codon (MET), possible to have AUGs in the middle but it will
always be the first translated amino acid in Euk
oSTOP codon: UAG, UAA and UGA
oCodons are written to 5’ to 3’ so for AUUG it would be 5’ - AUG 3’ -M
oEuk: Remember it will be capped at the 5’ end, ribosome will hop onto the 5’
end and to the 3’ end of mRNA, it will find the first AUG codon and translate it
into Methionine. Decode subsequent codons using the table and it will end
when a stop is reached
omRNA : 5’ → 3’ and proteins are N to C
oH2N - Met - ……… - one of the 3 stop codons and then - COOH
oCoding sequence = open reading frame for Exons
oReading frame - set by the Met:
How does the cell decode the message
oCricks adaptor hypothesis: Connect information from mRNA to amino acids
and this adaptor is called tRNA
otRNAs: do not encode but they fold back on themselves, attaches to the
Amino Acid attachment site at OH
oIn order for the hypothesis to work, there must be a way in which the tRNA
works, Aminoacyl-tRNA synthetases binds to specific tRNAs and amino acids
and covalently links them together
The genetic code is degenerate meaning that there are multiple codons that can
encode for the same amino acid
oExpanded base pairing that is allowed so a single tRNA can often recognize
more than one codon because of expanded base pairing “wobble”: third base
which recognizes two codons
oJust need to know how codons and anticodons recognize, predict optimal
base pairing
oMultiple tRNAs for codons of each amino acid, e.g. for Phe, AUU and CUU
codons are allowed
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Transcription - adding nucleotides from 5" end to the 3" end. Base pairing at the bottom strand, t becomes u - during transcription. Proteins are polymers made of amino acids, amino group, carboxyl group with an r group. When amino acids are joined together with a dehydration reaction. Amino end is called the n end and carboxyl end is the c end. Amino acids folding: secondary structure with nearby amino acids to form helix structures, beta pleated sheets which provides local folding, more happens at larger distances. In order for the hypothesis to work, there must be a way in which the trna works, aminoacyl-trna synthetases binds to specific trnas and amino acids and covalently links them together. Just need to know how codons and anticodons recognize, predict optimal base pairing o: multiple trnas for codons of each amino acid, e. g. for phe, auu and cuu codons are allowed.
