Lecture 3 1/18/13 Cells and DNA Transcription
BE ABLE TO DRAW STRUCTURE OF DNA
-DNA replication is cells making copy of DNA
-why make copy? Each cell needs instruction set
-“semi-conservativve” ; each daughter cell gets identical copy of DNA.
1. enzyme comes with help of protein and pulls dna apart to separate 2 strands and breaks hydrogen
2. the pulled strands are old strands. Enzyme comes and adds new bases “new strand”
3. each molecule is half old and half new—so semi conservative!
4. dna polymerase is the enzyme which does all this
5.dna polymerase makes polymers (long strands) of dna
-dna is stretched out
-DNA ligase essential for genetic eng
-mutation: when dna polymerase inserts the wrong base
-quality control commity looks at if right base is put and corrects it
-with errors occurring, it creates genetic diversity
Question: if error is corrected, then how is diversity produced?
-correction mechanism is not perfect, so it allows variation to continue
1. variation is essential
1. When dna is replicated, the molecule is first split by: enzyme
2. What would be the distribution of DNA if each strand in replication was completely
conservative? Half double helices old and half new
Shouldn’t it be all old???
3. What would happen if DNA rep was flawless? Evolution is impossibl