Week Eight: DNA

Question 1

Explain how the following pieces of evidence contributed to the model of DNA as a double helix with complementary strands:

1) the amount of A always is equal to T & G is always equal to C,

2) the sugar-phosphates are on the outside of the helix,

Answer 1

1) the amount of A always is equal to T & G is always equal to C, Chargaff’s rule ([A]=[T]; [G]=[C]) shows DNA strands are complimentary

2) the sugar-phosphates are on the outside of the helix,
Sugar phosphate on outside of DNA. Both run in oppsoite directions, this shows DNA is antiparallel

Question 2

What is semiconservative replication?

Answer 2

Semiconservative replication produces two copies that each contained one of the original strands and one new strand. Conservative replication would leave the two original template DNA strands together in a double helix and would produce a copy composed of two new strands containing all of the new DNA base pairs.

Question 3

Where are the covalent bonds in a DNA molecule? the hydrogen bonds?

Answer 3

Covalent bonds in the DNA are between the sugar-phosphate backbone, whereas the hydrogen bonds are between the nucleic acids

Question 4

Genotype

Answer 4

DNA sequence (genetic features)

Question 5

What is an organism’s phenotype?

Answer 5

Individual’s observable traits, such as height, eye color and blood type. A person’s phenotype is determined by both their genomic makeup (genotype) and environmental factors.

Question 6

What are the ingredients of a PCR reaction?

Answer 6

The key ingredients of a PCR reaction are Taq polymerase, primers, template DNA, and nucleotides

Question 7

Cell Division is necessary for:

Answer 7

• growth and development
• maintenance of the body
• reproduction
• wound healing

Question 8

What is a monomer of the DNA polymer? What is it composed of?

Answer 8

Polymer–––composed of monomers