Nucleic Acids

Question 1

What are the monomers of nucleic acids

Answer 1

nucleotides

Question 2

What do nucleotides consist of

Answer 2

• pentose sugar
• nitrogenous base
• phosphate group

Question 3

What are the names of the bonds that link nucleotides together

Answer 3

phosphodiester bonds

Question 4

Through which process do nucleotides bond together

Answer 4

condensation reaction + water released

Question 5

Examples of polynucleotides

Answer 5

RNA and DNA

Question 6

What are the base pairings + n° of H bonds

Answer 6

• Adenine & Thymine (2H bonds)
• Guanine & Cytosine (3H bonds)

Question 7

What causes the stability of DNA in terms of hydrophobic and hydrophilic components

Answer 7

The hydrophilic phosphate and sugar backbone is found on the outside of the DNA, with the hydrophobic nitrogenous bases wrapped tightly inside. This makes the outside of the DNA soluble in water because its exterior is hydrophilic due to the polar OH groups on the sugar and ionic negative charges on the phosphate. This makes DNA very stable as its hydrophilic exterior ‘protects’ the hydrophobic bases from water

Question 8

What are the two types of nitrogenous bases

Answer 8

• purines (adenine and guanine)
• pyrimidines (thymine and cytosine)

Question 9

The difference between purines and pyrimidine

Answer 9

purines: 1 fused ring
pyrimidines: 2 fused rings

Question 10

Differences between RNA and DNA

Answer 10

RNA: uracil, single-strand, ribose
DNA: thymine, double helix, deoxyribose

Question 11

Why is DNA negatively charged

Answer 11

due to the phosphate groups that link the deoxyribose sugars
- results of these opposite charges is a strong attraction and high binding affinity between histones and DNA

Question 12

Outline DNA packaging

Answer 12

DNA wraps around special proteins called histones, which forms loops of DNA called nucleosomes

Question 13

Outline the importance of the sequences of DNA

Answer 13

• it determines the primary structure of proteins which is synthesised by triplet codons (genetic code) which is universal

Question 14

What contributes to DNA’s stability

Answer 14

• double helix structure (non-polar bases surrounded by charged phosphate groups)
• the H bonds

Question 15

What are the benefits of genetically modified foods

Answer 15

• increases crop yield
• improved food quality
• increased resistance to pests & harsh weather

Question 16

What are the concerns about genetically modified foods

Answer 16

• lack of information regarding the long-term effect
• trigger allergies in humans
• other organisms in the ecosystem could be harmed