DNA Structure (L11)

Question 1

What is the function of DNA?

Answer 1

Provides the genetic material of the cell

Question 2

What are the two types of nucleic acids?

What are chromosomes?

Answer 2

• DNA and RNA
• chromosomes are carriers of heritable factors (DNA) + protein too

Question 3

What are the components of DNA? Name them specifically.

Answer 3

Bases: adenine thymine cytosine guanine
Deoxyribose sugar
Phosphate

Question 4

What are the two types of bases? How many rings do each of them have?

Answer 4

Pyrimidine - AT (6 rings) and purine - CG (10 rings)

Question 5

What is considered as the “backbone” of a molecule?

Answer 5

Nucleotide units/polymers = tetranucleotide repeats

Question 6

What is the structure of DNA? What are the strands called?

Answer 6

Double stranded helix structure
- bases perpendicular to the DNA molecule
- two strands: lagging strand and leading strand.

Question 7

What is the macromolecule of DNA? How does this go on to form DNA?

Answer 7

Nucleotides

• the nucleotide monomers are joined together with PHOSPHODIESTER bonds to for a polynucleotide/nucleic acid = DNA

Question 8

What is the phosphodiester bond? How is it formed?

Answer 8

• bond that joins together nucleotide monomers
• OH group on 3rd carbon of one nucleotide reacts with P group attached to 5th carbon on another nucleotide
  =» thus forming the phosphodiester bonds

Remember: formation of bonds starts from 3rd carbon&raquo_space; 5th carbon

Question 9

DNA strands are synthesised in which direction? What does this mean?

Answer 9

5’ to 3’ direction for leading strand.
3’ to 5’ direction for lagging strand.

This means that the direction of synthesis is anti parallel to form a double helix structure.

Question 10

Describe the Watson Crick model of DNA structure:

Answer 10

• DNA has double helix
• sugar Phosphate backbone on the Outside
• Bases on the Inside
• stabilised by Hydrogen Bonds
• Strands are in Opposite directions

POBIHSO

Question 11

What is the purpose of the Watson Crick model of DNA?

Answer 11

• way to decipher genetic code
• a possible mechanism for DNA replication

Question 12

What is the kind of replication DNA belongs to? What does this mean?

Answer 12

Semi-conservative replication.

This means that the parental strands are conserved. That each strand serves as a template for the synthesis of two new strands

Question 13

Why does your cell replicate its DNA?

Answer 13

Because your body needs to make more cells. It needs to make more cells to carry out functions throughout the body.