Question

3.) It was Rosalind Franklin that helped Watson and Crick realize that the sugar-phosphate backbone of DNA would be facing outwardly and the nitrogen bases would be facing inwardly in the double helix. What properties of these molecules made her so sure of that? 4.) Enzymes are often named for what they do, that is, the reaction that they catalyze. Give three examples of enzymes like that from this chapter, giving the enzyme and its function. 5.) During DNA replication, the two strands of DNA are pried apart and then serve as templates for synthesis of new strands. However, there are some big differences in how the two strands are copied. Why is this so? Please describe in 4-5 sentences of your own words how replication proceeds on the two strands.

Answer 1

3). Rosalind Franklin: Since nitrogen molecules are not water soluble, they cannot be facing outward in the water environment, hence nitrogen molecules are facing inwards away from the water molecules. Also, she argued that sugar and phosphate which are soluble in water can be placed outward, surrounded by water molecules in the cells.

4). Lipases- digests lipids/fats present in the gut.

Lactases- breaks lactose into glucose and galactose, present in the small intestine

Proteases- splits proteins into amino acids

Peptidases- breaks peptides into amino acids.

5). Once the DNA strands are separated (5'-3', leading strand and 3'-5',lagging strand), RNA primers attaches to the 5' end of the each strand and then replication proceeds simultaneosly in both the strands from 5' to 3' direction. This type of replication is known as replication fork.