Chapter 2 - Nucleic acids

Question 1

What are the two groups of nucleic acids

Answer 1

-Ribonucleic acid (RNA)
-Deoxyribonucleic acid (DNA)

Question 2

describe the nucleotide structure

Answer 2

• pentose sugar
• phosphate group
• organic base ( Thymine, Cytosine, Uracil, Adenine, Guanine

Question 3

How are these bonded

Answer 3

• condensation reaction to form a mononucleotide
• 2 mononucleotides can be joined between the deoxyribose sugar and phosphate group with a phosphodiester bond to form a dinucleotide
• the continued linking of mononucleotides is called a polynucleotide

Question 4

structure of:
+RNA
+DNA

Answer 4

+ single, relatively short polynucleotide chain
- sugar is ribose
- A,U,C and G

+ 2 strands of nucleotides
- extremely long
- joined together by hydrogen bonds
- pentose sugar is deoxyribose
- A,T,C and G

Question 5

Function of DNA

Answer 5

• hereditary material responsible for passing genetic information from cell to cell and generation to generation
• there are around 3.2 billion base pairings in the DNA or a typical mammalian cell
• DNA is a very stable structure which very rarely mutates

Question 6

Explain nuclear division

Answer 6

• process by which the nucleus divides
• two types: mitosis and meiosis

Question 7

explain cytokinesis

Answer 7

-follows nuclear division
- the process where the whole cell divides

Question 8

What are the 4 requirements for semi-conservative replication to happen

Answer 8

1. the four types of nucleotide must be present (A,T,C,G)
2. both strands of the DNA molecule act as a template for the attachment of nucleotides
3. enzyme DNA polymerase
4. a source of chemical energy

Question 9

what are the first 2 steps of semi- conservative replication

Answer 9

1. enzyme DNA helicase breaks hydrogen bonds linking base pairs of DNA
2. the double helix separates into two strands and unwinds

Question 10

what are the final 2 steps of semi- conservative replication

Answer 10

3. each strand acts as a template for complementary free nucleotides to bind to
4. nucleotides are joined together in a condensation reaction by enzyme DNA polymerase

Question 11

what is the result of semi-conservative replication

Answer 11

• each new strand contains one original DNA strand and one new strand of complementary DNA

Question 12

what molecule is ATP and what does it contain

Answer 12

• phosphorylated macromolecule
  contains:
• adenine
• ribose
• phosphates

Question 13

how does ATP store energy

Answer 13

• nucleotide of 3 phosphate groups
• bonds between phosphate groups are unstable so have a low activation energy which means they’re easily broken
• when broken they release a considerable amount of energy

Question 14

how is ATP converted to ADP (word equation)

Answer 14

ATP + water —> ADP + inorganic phosphate + energy

• the reaction is catalysed by the enzyme ATP hydrolase

Question 15

how can ADP be converted back to ATP

Answer 15

• its a reversible reaction so therefore energy can be used to add an inorganic phosphate to ADP
• catalysed by ATP synthase
• as water is removed, its called a condensation reaction

Question 16

roles of ATP and where it is used in energy - requiring processes

Answer 16

• primarily used as a immediate energy source in cells
• metabolic processes
• movement
  active transport
• secretion
• activation of molecules

Question 17

what does it mean by water being a dipolar molecule

Answer 17

water has both +’ve and -‘ve charges which overall makes no charge of the atom

Question 18

How is water used in metabolism

Answer 18

• to break down complex molecules in hydrolysis e.g. AA’s and proteins
• produced in condensation reactions
• chemical reactions take place in an aqueous medium
• water is a major raw material in photosynthesis

Question 19

how can water be used as a solvent

Answer 19

water readily dissolves other substances such as:
- gasses e.g. O2 and CO2
- wastes such as ammonia and urea
- inorganic ions and small hydrophilic molecules
- enzymes whose reactions take place in a solution