1B - More Biological Molecules

Question 1

What is the job of RNA?

Answer 1

• transfers genetic information from DNA to ribosomes

Question 2

What is a nucleotide made of?

Answer 2

• pentose sugar
• nitrogen-containing organic base
• phosphate group

Question 3

What is the sugar in DNA called and what are the 4 possible bases?

Answer 3

• deoxyribose
• adenine (A)
• thymine (T)
• cytosine (C)
• guanine (G)

Question 4

What is the sugar in RNA called and what base replaces thymine?

Answer 4

• ribose

- uracil (U)

Question 5

What reaction is used to form polynucleotides?

Answer 5

• condensation

- between phosphate group and sugar

Question 6

What bond is formed between polynucleotides?

Answer 6

• phosphodiester bond

Question 7

What is structure of DNA?

Answer 7

• double helix
• complementary base pairing (A-T, C-G)
• 2 hydrogen bonds between A and T
• 3 hydrogen bonds between C and G
• antiparallel strands twist to form double helix

Question 8

What is structure of RNA?

Answer 8

• short polynucleotide chain

Question 9

What happens in semi-conservative replication?

Answer 9

• DNA helicase breaks hydrogen bonds (helix unwinds)
• free floating DNA nucleotides attract to their complementary bases
• condensation joins new strands together (catalysed by DNA polymerase)
• hydrogen bonds form

Question 10

What are the properties of water?

Answer 10

• metabolite in condensation and hydrolysis reactions
• high latent heat of vaporisation (lots of energy needed to break hydrogen bonds)
• high specific heat capacity
• good solvent (polarity makes ions dissolve)
• very cohesive (great at transporting substances)

Question 11

What is the structure of water?

Answer 11

• H2O
• covalently bonded
• partial negative charge on one side and partial positive charge charge on the other

Question 12

What is ATP and how is it made?

Answer 12

• immediate source of energy in a cell
• glucose released through respiration is used to make ATP
• diffuses to the part of the cell that needs energy
• energy is stored in high energy bonds between phosphate groups

Question 13

What is ATP made of?

Answer 13

• adenine, ribose sugar and 3 phosphate groups

Question 14

What happens to ATP when a cell needs energy?

Answer 14

• broken down into ADP and P (inorganic) using hydrolysis
• catalysed by ATP hydrolase
• ATP hydrolysis can be coupled to other energy-requiring reactions in the cell
• inorganic phosphate can be added to a compound to make it more reactive (phosphorylation)
• ATP can be re-synthesised in condensation by ATP synthase

Question 15

What is an ion with a positive charge called?

Answer 15

• cation

Question 16

What is an ion with a negative charge called?

Answer 16

• anion

Question 17

What makes an ion ‘inorganic’?

Answer 17

• does not contain carbon

Question 18

What does the iron ion (Fe2+) bind to in haemoglobin?

Answer 18

• oxygen

- temporarily becomes Fe3+ until oxygen is released

Question 19

What is the rule of hydrogen ions and pH?

Answer 19

• the higher the concentration of hydrogen, the lower the pH

Question 20

Sodium ions help transport what across membranes?

Answer 20

• glucose and amino acids

Question 21

DNA, RNA and ATP all contain what inorganic ion?

Answer 21

• phosphate ions (PO4 3+)

- allow nucleotides to join up and make polynucleotides