Structure of DNA and RNA

Question 1

What are the components of a nucleotide?

Answer 1

• Pentose sugar
• Phosphate group
• Nitrogenous base

Question 2

How is a polynucleotide formed?

Answer 2

Polynucleotides are formed via the condensation of nucleotides. The phosphate group of one nucleotide forms a phosphodiester bond with the carbon of a sugar of another.

Question 3

The pentose sugar and phosphate in polynucleotides create a…

Answer 3

sugar-phosphate backbone.

Question 4

What is DNA?

Answer 4

Deoxyribonucleic acid (DNA) is a type of nucleic acid that contains the instructions needed to make proteins.

Question 5

What are the components of a DNA nucleotide?

Answer 5

• Deoxyribose sugar
• Phosphate group
• One of four nitrogenous bases

Question 6

What are the four bases that can be found in a DNA molecule?

Answer 6

• Adenine (A)
• Thymine (T)
• Guanine (G)
• Cytosine (C)

A always binds with T and G always binds with C.

Question 7

What is complementary base pairing in DNA?

Answer 7

The structures of the 4 bases (A, T, G, C) force themseleves to bind together in a specific way.

Question 8

How are the two strands of DNA held together?

Answer 8

They are held together by hydrogen bonds between bases.

• Adenine and Thymine bond via 2 hydrogen bonds
• Guanine and Cytosine bond via 3 hydrogen bonds

Question 9

What is RNA?

Answer 9

Ribonucleic acid (RNA) is a type of nucleic acid that uses information from DNA to synthesise proteins.

Question 10

What are the components of RNA?

Answer 10

• Ribose sugar
• Phosphate group
• One of four nitrogenous bases.

Question 11

What are the four bases found in an RNA molecule?

Answer 11

• Adenine (A)
• Uracil (U)
• Guanine (G)
• Cytosine (C)

In RNA Thymine is replaced with Uracil

Question 12

What are purines?

Answer 12

Larger bases that contain two carbon ring structures
For example, Adenine and Guanine.

Question 13

What are pyrimidines?

Answer 13

Smaller bases that contain one carbon ring structure.
For example, Thymine, Cytosine and Uracil.

Question 14

What are the differences between DNA and RNA?

Answer 14

• DNA has 2 strands, RNA only has 1.
• DNA is long, RNA is relatively short.
• DNA contains a deoxyribose sugar, RNA contains a ribose sugar.
• DNA contains Thymine, RNA contains Uracil.

Question 15

What are the two types of RNA?

Answer 15

• Messenger RNA (mRNA)
• Transfer RNA (tRNA)

Question 16

What features allow DNA to pass genetic information from one generation to another?

Answer 16

• Sugar-phosphate backbone: Protects coding bases on the inside of the helix
• Double stranded: Allows strands to act as templates in DNA replication
• Large molecule: Stores lots of information
• Double helix: Makes the molecule compact
• Complementary base pairing: Allows accurate DNA replication
• Weak hydrogen bonds: Allows strands to separate in DNA replication