Post on 18-Dec-2015
Objective: ◦ Describe the process of protein synthesis◦ Explain how a disruption in the sequence can
cause a change in appearance Journal:
◦ On the top of your note sheet, explain what DNA polymerase does in DNA replication.
RNA’s function is to take DNA’s code, copy it and use it to make proteins
Differs from DNA in that:◦ RNA is single stranded◦ Contains Ribose as sugar◦ Uracil instead of Thymine
U-A
Messenger RNA (mRNA)◦ Copies code from DNA and brings it to the
ribosome
Transfer RNA (tRNA)◦ Brings amino acids to ribosome to assemble
into protein
Transcription◦ Creates mRNA from code contained in a gene
(DNA)
Translation◦ mRNA code is read and “translated” into a string
of amino acids that make up a protein
RNA polymerase “unzips” DNA at a gene
mRNA is built by pairing A-U and C-G
When gene ends, mRNA breaks away from DNA and DNA zips back up
http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/transcription.swf
mRNA leaves the nucleus and heads to a ribosome
mRNA “letters” will be read in groups of 3 called codons
Each codon codes for 1 amino acid
mRNA binds to ribosome
tRNA brings over its amino acid
Next codon is read, next amino acid is brought over by another tRNA
Amino Acids bond together forming a protein
Process repeats until ribosome reaches a stop codon
Protein is released
http://www.columbia.edu/cu/biology/courses/c2005/images/animtransln.gif
TAC-AAA-GCT-TTT-CTA-CCG-ATC
Mutations: changes in DNA sequence
•Point Mutation: affect one nucleotide1. Substitutions – replace one of the nucleotides with another
- Can be lethal
TAC-AAG-GCT-TTT-CTA-CCG-ATC
TAC-AAC-GCT-TTT-CTA-CCG-ATC
OR