4-4-3 The Structure of DNA

Question 1

British biologist Francis Crick (1916-2004) and American researcher James Watson (1928 - present). (Significance)

Answer 1

. Together they built the first successful model of DNA

Question 2

British microscopist Rosalind Franklin (significance)

Answer 2

produced exceptionally clear X-ray images of DNA.

Question 3

Linus Pauling (significance)

Answer 3

had determined that proteins were helically coiled.

Question 4

Erwin Chargaff (1905-2002), a Ukrainian-born U.S. biochemist

Answer 4

Chargaff determined that the amount of purines approximately equal the amount of pyrimidines. The amounts of A equal the amounts of T and the amounts of C equal the amounts of G for any given species.

Question 5

Watson and Crick model of DNA (our model)

Answer 5

The Watson and Crick model shows DNA as a double helix, with the nitrogenous bases to the center (like steps on a ladder).

The sugar-phosphate units are along the sides of the helix (like the sides of a twisted ladder).

Adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). (a double-ringed purine is always bonded to a single ring pyrimidine).

Consequently, If we know the base sequence of one strand, then we know the base sequence on its complement.