DNA structure - lesson one

Question 1

what is the structure of DNA

Answer 1

• DNA: deoxyribonucleic acid
• Double helix
• Composed of sub-units called nucleotides (sugar, phosphate, nitrogenous bases)
• four bases

Question 2

what are the different nitrogenous bases

Answer 2

• adenine
• thymine
• guanine
• cytosine

Question 3

what are the corresponding nitrogenous base pairs

Answer 3

• adenine pairs with thymine
• guanine pairs with cytosine

Question 4

how many hydrogen bonds pair adenine and thymine together

Answer 4

two

Question 5

how many hydrogen bonds pair cytosine and guanine together

Answer 5

three

Question 6

what is the structure of the deoxyribose sugar

Answer 6

Deoxyribose sugar is composed of a chain of five carbon atoms, making it a pentose sugar.

Question 7

what is the 5’ to 3’ strand? Use a diagram to support your answer

Answer 7

One of the strands will start with the 5’ carbon and finish with a 3’ carbon

Question 8

what is a 3’ to 5’ strand? Use a diagram to support your answer

Answer 8

The second strand is an upside-down version. This strand starts with a 3’ carbon and ends with a 5’ carbon.

Question 9

what carbon will phosphate attach to

Answer 9

5’

Question 10

what carbon will the nitrogenous base attach to

Answer 10

1’