Workshop #4 w/ solutions

Hey guys, here is the workshop, and Caitlin's solutions.  Thanks Cait!

Workshop #4

Workshop #4 Notes

4B) Free Nucleotides + Polynucleotide => Free nucleotides (monophosphates- AMP,GMP, UMP) link together by expending ATP (or any other tri-phosphate) to form a phosphodiester covalent bond. Weak hydrogen bonds form between the base pairs (3 H bonds between A and U or T, 2 btwn C and G) of the polynucleotide and the newly-forming polynucleotide. Template-directed RNA would help to stabilize the reaction and make it occur faster.

4C) A "cell-free" system = E.Coli without membranes in a test tube

How do we get polypeptides? 

Amino Acids bind to tRNA with the expended energy of ATP or another high-energy intermediate

tRNA's anti-codon (3 nucleotide bases) bind to their specific codon (corresponding base pairs) on an mRNA sequence

This process re-occurs with another tRNA binding to mRNA, and the amino acids (attached at the top of the tRNA) are attached by a peptide bond, generating a polypeptide

4D) Codons on mRNA, Anti-codons on aa-tRNA/tRNA

       Also, know that you should associate the amino acid with the correct CODON on mRNA.

4E) AUGUUUGGGCCCUUU => Met- Phe- Gly- Pro- Phe 

       Sequence of mutant mRNA giving rise to the mutant amino acid sequence (shown below)

       AUGUUUAGGCCCUUU=> Met- Phe- Arg-Pro- Phe - There is an A nucleotide base instead of a G.

     Mechanism of Mutation: 

-Know that transcription is template RNA (DNA) to mRNA and translation is mRNA that codes for a protein.

One possible cause for mutation: Transcription error (different base pair codes for a different amino acid)

Another cause for mutation: One of the base pairs is not included in transcription, and the entire protein sequence changes.

4F) -Precursors for the formation of Phospholipids: phosphoglycerol and fatty acids

 -As soon as you make a phospholipid, it is integrated into the protocell boundary membrane. 

 -Lack of an enzyme or inhibited enzyme that separates the phospholipids will limit the growth of the membrane.

4E) For this to occur, : rate of RNA replication > rate of phospholipid formation

 - There must be enough RNA produced before it splits, so that there's enough for both daughter cells