1.5 NUCLEIC ACIDS

Question 1

What does DNA do?

Answer 1

Holds genetic information

Question 2

What does RNA do?

Answer 2

Transfers genetic information from the DNA to the ribosomes to make a polypeptide.

Question 3

How are ribosomes formed?

Answer 3

• rRNA combine with proteins to form the subunits of ribosomes.
• A large and small subunit together makes a ribosome

Question 4

What are the monomers of DNA & RNA?

Answer 4

Nucleotides

Question 5

What is the structure of a nucleotide?

Answer 5

A phosphate group bound to a pentose sugar, which is also bound to a nitrogenous base.

Question 6

How do nucleotides join together?

Answer 6

• Condensation reaction between the phosphate group of one nucleotide, and the pentose sugar of another.

Question 7

What is the bond between two nucleotides called?

Answer 7

A phosphodiester bond

Question 8

What are the nitrogenous bases?

Answer 8

• Adenine
• Thymine
• Guanine
• Cytosine
  ( Uracil –> only in RNA)

Question 9

What is the structure of RNA?

Answer 9

• Strand of nucleotides.
• Single stranded.
• Shorter than DNA
• Has the pentose sugar: RIBOSE
• Contains bases: A-U, C-G

Question 10

What is the structure of DNA?

Answer 10

• Two strands of nucleotides.
• Double stranded helix.
• Nucleotide strands are longer than in RNA.
• Has the pentose sugar: DEOXYRIBOSE
• Contains bases: A-T, C-G

Question 11

How is the DNA helix held together?

Answer 11

Hydrogen bond on complementary nitrogenous bases on opposite strands hold them together.

Question 12

What are the functions of DNA related to its structure?

Answer 12

• Very stable structure due to the strong phosphodiester backbone.
• Polynucleotide strands run antiparallel creating the helix shape.
• Very big and compact, so can hold lots of genetic information in a small space.
• Specific base pairings allow DNA to be replicated and copied to make polypeptides.

Question 13

What is the name of the process of DNA replication?

Answer 13

Semi-Conservative

Question 14

Outline semi conservative replication

Answer 14

1. DNA helices breaks H bonds and separates the two polynucleotide strands of DNA.
2. Both strands act as template strands.
3. Free DNA nucleotides go and join up to complementary base pairs, forming H bonds.
4. DNA polymerase joins the nucleotides together, forming phosphodiester bonds.
5. This continues until two identical DNA helices are formed.

Question 15

In which direction does DNA replicate?

Answer 15

5’ - 3’

Question 16

Which end are new nucleotides added to during DNA replication?

Answer 16

The 3’ prime end.