1.8 - [Intro to] The structure of DNA & Nucleic Acid

Question 1

What does DNA stand for?

Answer 1

Deoxyribonucleic acid

Question 2

True or False:
DNA strands form a double helix.

Answer 2

True

Question 3

How are DNA strands held together?

Answer 3

Using hydrogen bonds

Question 4

What is a nucleotide?

Answer 4

• It’s a monomer of DNA
• made up of 3 parts: phostphate group, deoxyribose sugar, and a nitrogen base
• these stack together to make a single strand of DNA

Question 5

What is the “backbone of DNA”?

Answer 5

Phosphate and sugar bonded together

Question 6

What is the bond called between phosphate and sugar?

Answer 6

phosphodiester bond
[phospho-di-ester]

Question 7

What are the 2 groups of nitrogen bases?

Answer 7

Purines and Pyrimidines

Question 8

Name the 2 purines

Answer 8

Adenine & Guanine

Question 9

Name the 2 pyrimidines

Answer 9

Cytosine & Thymine

Question 10

True or False:
For each nucleotide in DNA, the phosphate and deoxyribose sugar change.

Answer 10

False.
The phosphate and sugar DO NOT CHANGE

Question 11

True or False:
The carbons in the sugars are numbered 1 to 5.

Answer 11

False.
They are numbered 1’ to 5’
[one prime to five prime]

Question 11

True or False:
The carbons in the sugars are numbered 1 to 5.

Answer 11

False.
They are numbered 1’ to 5’
[one prime to five prime]

Question 12

What is the difference between deoxyribose and ribose sugar (according to their diagrams)

Answer 12

Deoxyribose is missing an OH on C2’

Question 13

Are Purines made of 1 or 2 carbon rings?

(Nitrogen bases)

Answer 13

Purines have 2 rings

Question 14

Are Pyrimidines made of 1 or 2 carbon rings?

(Nitrogen bases)

Answer 14

Pyrimidines have 1 ring

Question 15

Is thymine used in RNA or DNA?

Answer 15

Thymine is used in DNA only

Question 16

What nitrogen bases does RNA use?

Answer 16

Adenine, guanine, cytosine, and uracil.

Question 17

What is uracil?

Answer 17

• It’s a nitrogen base
• used in place of thymine in RNA

Question 18

State the base pairing rules for nucleic acids

Answer 18

1) Purines can ONLY pair with pyrimidines
2) Bases only match if the SAME # OF HYDROGEN BONDS are made

Question 19

What are the results of the base pairing rules?

What bases bonds with what? How many bonds do they make?

Answer 19

Adenine matches with Thymine. Form 2 hydrogen bonds
Guanine bonds with Cytosine. Form 3 hydrogen bonds

Question 20

Single DNA strands have 3’ and 5’ ends. How can you tell which end is which?

Answer 20

If the oxygen in the sugar is pointing downwards (pentagon point facing down), it’s pointing towards the 5’ end.

Question 21

What are the differences between DNA and RNA?

Hint: there are three

Answer 21

Sugars: DNA uses deoxyribose, RNA uses ribose
Strands: DNA is double stranded, RNA is single stranded
Bases: DNA uses thymine, RNA uses uracil