Biological molecules - Nucleic acids and DNA Replication

Question 1

Structure of a general nucleotide

Answer 1

Contains a phosphate group, a nitrogen containing organic base and a pentose sugar

Question 2

Structure of DNA nucleotide

Answer 2

• Deoxyribose sugar
• Phosphate
• Base (Adenine, Thymine, Cytosine or Guanine)

Question 3

Structure of RNA nucleotide

Answer 3

• Ribose sugar
• Phosphate
• Base (Adenine, Uracil, Cytosine, Guanine)

Question 4

What bond forms to join nucleotides together and where does this bond form

Answer 4

• Phosphodiester bonds
• Form between the phosphate group of one nucleotide to the pentose sugar in the next nucleotide

Question 5

What is the purpose of phosphodiester bonds

Answer 5

Makes the sugar phosphate backbone of the nucleic acid stable and strong

Question 6

What is the name of the reaction that joins nucleotides together

Answer 6

Condensation reaction

Question 7

What is the shape of a DNA molecule

Answer 7

Double helix structure

Question 8

State the rules of base pairing

Answer 8

• Adenine bonds with Thymine
• Cytosine bonds with Guanine

Question 9

What is the structure of DNA

Answer 9

• Sugar-phosphate background and double helix structure
• Long molecule
• Helix structure
• Base sequence
• Double stranded
• Complementary base pairing
• Hydrogen bonds between bases re weak
• Many Hydrogen bonds in the whole molecule

Question 10

How does the structure of DNA relate to it’s function (Sugar-phosphate backbone and double helix structure)

Answer 10

• Provides strength and and stability
• Protective bases and hydrogen bonding between bases

Question 11

How does the structure of DNA relate to it’s function (Long molecule)

Answer 11

Can store a lot of information

Question 12

How does the structure of DNA relate to it’s function (Helix structure)

Answer 12

Compact

Question 13

How does the structure of DNA relate to it’s function (Base sequence)

Answer 13

Codes for amino acids and therefore proteins

Question 14

How does the structure of DNA relate to it’s function (Double stranded)

Answer 14

Allows semi-conservative replication as each strand can act as a template

Question 15

How does the structure of DNA relate to it’s function (Complementary base pairing)

Answer 15

Allows accurate replication

Question 16

How does the structure of DNA relate to it’s function (Hydrogen bonds between bases are weak)

Answer 16

Hydrogen bonds can be broken so allows strands to separate for replication

Question 17

How does the structure of DNA relate to it’s function (Many hydrogen bonds in the whole molecule)

Answer 17

Strong and stable molecule

Question 18

Why is DNA replication described as semi-conservative

Answer 18

One strand is used as a template during replication

Question 19

Step by step process of DNA replication

Answer 19

1. The enzyme DNA helicase attaches and moves along the DNA molecule, breaking hydrogen bonds between complementary bases
2. The two strands separate and both strands then act as a template
3. New individual DNA nucleotides are attracted to exposed complementary bases on template strands and bind by complementary base pairing
4. The enzyme DNA polymerase now connects the new nucleotides together through a condensation reaction forming phosphodiester bonds between adjacent nucleotides
5. Semi-conservative replication ensures that each new DNA molecule contains an original and a new strand and is identical to the original DNA

Question 20

What is the role of DNA helicase

Answer 20

Breaks the hydrogen bonds between complementary bases so that the 2 strands of the DNA double helix can separate

Question 21

What is the role of DNA polymerase

Answer 21

Forms phosphodiester bonds between adjacent nucleotides via condensation reaction

Question 22

Name the scientist’s that proposed the model for the structure of DNA

Answer 22

Watson and Crick