BIOL140 Lecture Notes - Lecture 10: Stop Codon, Ribosome, Start Codon
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Gene Expression
Transcription ➡Translation
Genetic Code
A)
Mechanism that translates the 4-base DNA into the twenty amino acids
DNA = TAC
mRNA= AUG
Amino Acid= Methionine (MET)
Ex.
○
Triplets of nucleotides refer to/ code for an amino acid
Codes for Amino Acids
○
Triplets- codons- mRNA
Several codons code for the same amino acid
○
Called Redundancy
○
Allows for small changes in DNA to not affect the final protein
○
Some amino acids have more than one codon
Transcription
B)
Building mRNA based on the DNA Template
Gene-instructions for proteins
DNA opens along a particular segment of the chromosomes
1.
DNA= A T C G
○
mRNA= U A G C
○
Free RNA nucleotides
2.
P - S backbone forms on mRNA
3.
mRNA is released from the nucleus
4.
DNA strands re-bond together
5.
Processed in nucleus
○
mRNA Is unprocessed
6.
Steps
unprocessed
Intron-not for Protein
Exon-instructions for
making protein
Processed mRNA
Processed mRNA leaves the Nucleus
7.
Diagram of Transcription
DNA- TAC GGG CCA AGC ATC
mRNA- AUG CCC GGU UCG UAG
Acids- MET PRO Gly Ser Stop
Translation
C)
Based on mRNA Template
○
Building primary structure of protein
Correct
Not correct
Lecture Ten
October 30, 2015
8:26 PM
BIO 140 Page 1