Nucleic acids

Question 1

What are the components of a nucleotide

Answer 1

• phosphate group
• pentose sugar
• bases

Question 2

DNA vs RNA

Answer 2

DNA - Deoxyribose sugar - double helix - A=T

RNA - Ribose sugar -single stranded - U=T

Question 3

DNA structure linked to function

Answer 3

stable double stranded structure - rarely mutates
2 separate strands - allowed to separate for transcription
big/large molecule - carry large amount of genetic information

Question 4

Describe the process of DNA replication (semi-conservative replication)

Answer 4

• DNA helicase breaks down the hydrogen bonds between bases
• free nucleotides bind to the complementary bases of the DNA
• DNA polymerase forms phosphodiester bonds between nucleotides to form a polynucleotide
• two identical molecules of DNA are formed

Question 5

Why does DNA polymerase work forward on one strand and backwards on the other

Answer 5

DNA polymerase works from 3’ to 5’ end on the DNA template and 5’ to 3’ end on the daughter strand

Question 6

What are the 3 components of an ATP molecule

Answer 6

• adenine molecule
• ribose molecule
• three phosphate molecules

Question 7

What is the ATP cycle

Answer 7

ATP

↓ hydrolysis leaving ADP+Pi

energy released for cell use

↓ condensation back to ATP

energy supplied for respiration

Question 8

Link structure to function of ATP

Answer 8

Phosphate group can be readily removed or added for fast energy source

Question 9

What does dipolar mean

Answer 9

a molecule with both positive and negative poles

Question 10

Structure of water and functions

Answer 10

cohesive - due to hydrogen bonds water molecules stick together and allows transpiration stream in the xylem

acts as a solvent - can readily dissolve other substances

not easily compressed - can be used as a hydrostatic skeleton for worms/plants

transparent - aquatic plants can still photosynthesise