November 13 Lecture Notes

November 13, 2009
Review

1). Complementary interactions btw the shine-delgarno sequ and rRNA ribosome binding to mRNA
2) Tibosome moves down the mRNA until it reaches the AUG sequence, then brings in the first tRNA (attached to Methionine)
3) Ribosome keeps moving down mRNA, bringing in tRNAs whose anticodons match mRNA codons, tRNA have amino acids attached
4) At stop codon, Release factors bind w/ ribosomes, mRNA stop codon, RFs detach ribosome from mRNA amino acid chain from ribosome

H). Polyribosomes one mRNA w/ lots of ribosomes attached to it in different stages of translating mRNA
-ribosome binds to shine del garno sequence until gets to AUG start codon, and begins to transfer; shine del garno sequence becomes free again and allows a second ribosome to attached and begin to translate again

Kinds of mutations:
IV. Point mutations mutations to DNA that change just one base
Mutation- any change in the DNA sequence of an organism
*not a change in gene expression
JP2 change in gene expressions (did not make the DNA mutate)
*missense mutation- changes the sequence of the DNA and changes only one base in the DNA but changes enough to change the amino acid sequence of the protein
-change to DNA sequence- change to amino acid sequence of protein
*Nonsense mutation: change to DNA so there’s now an early stop codon in the mRNA, so short protein
*Silent mutation: many amino acids have more than one codon that codes from them: change in DNA sequence, but results in NO change to amino acid sequence in the protein

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