Nucleic Acids and Inorganic Ions

Question 1

what is DNA made up of?

Answer 1

DNA (mono)nucleotide

Question 2

Components of a nucleotide

Answer 2

A pentose sugar
A phosphate group
A nitrogen containing organic base (Cytosine, Uracil, Thymine, Guanine)

Question 3

Bond formed between the sugar of one nucleotide and phosphate group of another

Answer 3

phosphodiester bond

Question 4

Difference between RNA and DNA nucleotide

Answer 4

Ribose sugar
Uracil instead of thymine

Question 5

Base pairs, what type of bond and how many?

Answer 5

C and G (3 Hydrogen bonds)
A and T (2 Hydrogen bonds)

Question 6

Adaptations of DNA

Answer 6

Stable, passed from generation to generation and rarely mutates

2 separate strands only bound by hydrogen bonds (easy to separate for DNA replication)

large molecules carrying its of genetic information
base pairs are protected by backbone (from outside chemical and physical forces)
Base pairs allow replication and transfer (as mRNA)

Question 7

DNA helicase

Answer 7

Breaks hydrogen bonds between bases during semi conservative replication

Question 8

Template strand

Answer 8

the strand to which complimentary free nucleotides join during semi conservative replication

Question 9

DNA polymerase

Answer 9

joins the free nucleotides (to each other) during semi conservative replication, to form the complimentary polynucleotide strand

Question 10

what is semi conservative replication?

Answer 10

DNA replication where an original strand acts as a ‘template’ to form a new complimentary polynucleotide strand. The new DNA is made up of one original stand and one new strand.

Question 11

components of ATP

Answer 11

Adenine (nitrogen containing organic base)
Ribose sugar (5C)
chain of 3 phosphates

Question 12

how is ADP formed

Answer 12

hydrolysis of ATP by ATP hydrolase

ATP + water –>ADP +Pi (+Energy)

Question 13

why is water a DIPOLAR molecule and why is it important

Answer 13

Oxygen is slightly negative
Hydrogen is slightly positive
(but no overall charge)
Forms hydrogen bonds (between + of one molecule and - of another)
Makes water slightly cohesive:
1. allows transpiration and movement through xylem in plants.
2. creates surface tension in bodies of water (strong enough to support small organisms)

Question 14

Roles of ATP

Answer 14

1)Metabolic processes (e.g. building molecules)
2)Movement (e.g. energy for muscle contraction)
3)Active transport (changes shape of carrier proteins)
4)Secretion (needed to form lysosomes)
5)Activation of molecules (phosphorylates other compounds to make them more reactive (adding a phosphate group))

Question 15

What is specific heat capacity of water and why is it important

Answer 15

high specific heat capacity
so a lot of energy needed to heat a given mass
so water acts as a buffer against temperature variations :
1. in aquatic environment
2. in living organisms (as they are made up of water)

Question 16

What is latent heat of vaporisation of water and why is it important

Answer 16

surface water molecules can gain enough kinetic energy to break off and evaporate.
This is important in mammals sweating to cool the body down.

Question 17

Water in metabolism

Answer 17

breaking molecules by hydrolysis
major raw material for photosynthesis
produced in condensation
chemical reactions take place in cytoplasm (in water)

Question 18

Hydrogen Ions

Answer 18

More H+ ions -> Lower pH
Enzymes have an optimum pH. If too many H+ ions are present they interact with side chains of amino acids in active site of enzymes changing their tertiary structure and denaturing the enzyme

Question 19

Iron Ions

Answer 19

Each of the 4 polypeptide chains in haemoglobin contain one Fe2+ ion.
It makes up part of the haem group which binds to the oxygen molecule.
Necessary for oxygen transport around the body.

Question 20

Sodium Ions

Answer 20

Sodium potassium pump is necessary for the absorption of glucose and amino acids into the blood from the lumen of the ileum.

Sodium ions active transport out of epithelial cells into blood, creates concentration gradient higher to lower form lumen to epithelial cells, sodium ion diffuse in and glucose and amino acids are co-transported in, they then enter the blood via facilitated diffusion

Question 21

Phosphate Ions

Answer 21

Component of DNA and ATP.

ATP: hydrolysis of phosphate group form ATP to form ADP releases a large amount of energy.

DNA: forms phosphodiester bonds with pentose sugar of a different nucleotide to form a phosphate sugar backbone, which protects the bases in DNA