week 6 - exam 2

Question 1

You find a way to attach either a red or green fluorescent dye to nucleotides. Double-stranded DNA molecules with both strands labeled red fluoresce red, those with both strands labeled green fluoresce green, and those with one strand labeled red and the other green fluoresce yellow. You grow human cells in the presence of “red” nucleotides until both DNA strands of all chromosomes fluoresce red. You then allow one round of DNA replication in the presence of “green” nucleotides.

What pattern of fluorescence do you expect to see in the sister chromatids of each chromosome?

one chromatid red, the other green
both chromatids yellow
one chromatid red, the other yellow
one chromatid green, the other yellow

Answer 1

both yellow

Question 2

When we say that DNA replication is semiconservative, we mean that:

Answer 2

when DNA is replicated each new double helix contains one parental strand and one newly synthesized daughter strand.

Question 3

During nucleic acid synthesis, a polymerase enzyme catalyzes the reaction that covalently joins the ——-of the incoming nucleotide to —–the first nucleotide via a chemical reaction called——

Answer 3

5’ phosphate

3’ hydroxyl

dehydration synthesis