common questions

Question 1

characteristics of DNA that allow semiconservative replication

Answer 1

1. double helix –> can be separated into 2 strands that each act as a template strand
2. new DNA formed through complementary base pairing –> adenine forms 2 H bonds with thymine and cytosine forms 3 H bonds with guanine
3. strands held together by H bonds –> weak bonds that can be broken easily to form template strands

Question 2

evidence of semi-conservative replication

Answer 2

1. generation 0 –> only heavy 15N-15N DNA present, making up the lowest band
2. during replication –> strands unzipped and served as templates for new strands | generation 1–> hybrid DNA molecules of original 15N strand and new 14N strand, making up the intermediate band
3. each hybrid is unzipped and used as templates | generation 2 –> half hybrid, half 14N-14N (intermediate and uppermost bands)

Question 3

how does a competitive inhibitor reduce the rate

Answer 3

• structurally similar, similar shape to substrate, competes with substrate for enzyme active site
• results in less substrate attaching to enzyme and forming E-S complexes