1.8 Inorganic Ions

Question 1

What is an ion?

Answer 1

An atom with an electrical charge due to gaining or losing one or more electrons

Question 2

What are cations and anions?

Answer 2

• Cations have a positive charge and move to the negative electrode
• Anions have a negative charge and move to the positively charged electrode

Question 3

What chemical element do inorganic ions generally not contain?

Answer 3

Carbon

Question 4

What are the different inorganic ions and where do they occur?

Answer 4

1. Hydrogen
2. Iron
3. Sodium
4. Phosphate

Occur in solution in the cytoplasm and body fluids of organisms ( some in high concentrations and others in very low concentrations

Question 5

What is the function of hydrogen ions?

Answer 5

Used in pH
pH is a measure of the H+ concentration in a solution. The more H+ the more acidic the solution. All enzyme controlled reactions are affected by pH

Question 6

What scale is used for pH?

Answer 6

A logarithmic scale

Question 7

What is haemoglobin?

Answer 7

Haemoglobin is a large protein with 4 subunits found in erythrocytes (red blood cells). Each subunit has a polypeptide chain and a non-protein haem group. The haem group has a high affinity (attraction) for oxygen and as each haem group can hold 1 oxygen molecule, each haemoglobin can carry 4 and transport it from the gas exchange system to respiring tissue

Question 8

What is the role of iron in haemoglobin?

Answer 8

• Each haem group contains a single iron atom (Fe2+)
• the iron ion can attract and bind with an oxygen molecule
• so oxygen can be carried around the body (to respiring tissue)

Question 9

Why is haemoglobin rarely ever fully saturated with oxygen?

Answer 9

• When the 1st oxygen binds to the 1st haem group the haemoglobin has a conformational change in shape and reveals other haem groups
• This makes it easier for the 2nd and 3rd oxygen to bind (cooperative binding)
• However it is difficult for the 4th oxygen to bind to the 4th haem group because three out of the four binding sights are occupied and therefore the 4th oxygen only has one opportunity to bind and it rarely does.

Question 10

What are co-transporters?

Answer 10

Specialised intrinsic proteins which span the phospholipid layer

Question 11

What is sodium ions function in co transporters?

Answer 11

• co transporters transfer sodium ions linked with either glucose or amino acids molecules across the membrane into cells

Question 12

What is the role of phosphate ions in DNA, RNA and ATP?

Answer 12

• phosphate ions form the phosphate groups in DNA, RNA and ATP
• the phosphate groups in DNA and RNA allow phosphodiester bonds to form between nucleotides forming polynucleatides
• phosphate bonds in ATP store energy; when this bond is broken energy is released