B: Nucleic Acids HL

Question 1

DNA and RNA

Answer 1

DNA

Deoxyribose Nucleic Acid

RNA

Ribonucleic Acid

Question 2

Nucleotides

Answer 2

• Nucleic acids are polymers made up of monomers known as nucleotides
• consist of a 5-carbon (pento) sugar, a nitrogen-containing heterocycle called the base, and a phosphate group
• condensation products of a pentose sugar, phosphoric acid and a nitrogenous base

Question 3

Bases

Answer 3

All derivates of either purine (secondary amine) or pyrimidine (tertiary amine)

Purine

• Adenine (A)
• Guanine (G)

Pyrimidine

• Thymine (T) / Uracil (U)
• Cytosine (C)

Question 4

DNA

Answer 4

• A double strand of nucleotides held together by H bonding
• Contains thymine
• contains 2-deoxyribose
• double helix consisting of 2 polynucleotide strands that spiral around an axis
  
  • each complete turn is 10 nucleotides in length

Question 5

RNA

Answer 5

• A single strand of nucleotides
• contains uracil
• contains ribose

Question 6

Structure of DNA/ RNA

Answer 6

• each strand of nucleotides has a repeating sugar-phosphate-sugar-phosphate backbone
  
  • base attached to each sugar

Question 7

DNA Replication

Answer 7

• Involves the unwinding and separating of the two strands of DNA by breaking the hydrogen bonds between the base pairs
  
  • exposes nucleotides and allows the bases on each of the DNA strands to be used as a template for the formation of a complementary DNA strand
  • Free nucleotides form complementary base pairs with the DNA template strands

Question 8

The Genetic Code

Answer 8

• The sequence of bases in DNA determines the primary structure of proteins synthesized by the cell using a triplet code - the universal genetic code
• Chromosomes are long, coiled strands of DNA wrapped around proteins called histones (positively charged –> attracted to negative phosphate groups)
  
  • contains genes

Question 9

Benefits of GMOs

Answer 9

• increased nutritional content of crops eg golden rice
• increased yield of crops
• ability of crops to grow in adverse conditions
• improved crop resistance to disease
• enhanced taste, texture, quality
• improved animal health
• improved conservation of water, soil and energy

Question 10

Concerns of GMOs

Answer 10

• not enough knowledge about long term effects
• escape of transgenic material into the wild
• upset the current balance of ecosystems and food chains
• alteration of the composition of a balanced diet
• exploitation and monopolisation
• ethical considerations