1.6.4 - inorganic ions

Question 1

what is ion

Answer 1

atom (or group of atoms) that has an electrical charge

Question 2

positive ion

Answer 2

cation

Question 3

negative ion

Answer 3

anion

Question 4

inorganic ion

Answer 4

an ion that does not contain carbon

Question 5

inorganic ion role

Answer 5

plays an important role in many essential cellular processes

Question 6

inorganic ions occur in solution in

Answer 6

-cytoplasm and body fluids of organisms
-some occur in high concentrations and others in very low concentrations
-the concentration of certain ions can fluctuate and cell be used in cell signalling and neuronal transmission
-each type of inorganic ion has a specific role, depending on its properties

Question 7

inorganic ions

Answer 7

-hydrogen H+
-iron Fe2+/Fe3+
-sodium ions Na+
-phosphate ions PO4 3-
-calcium ions Ca2+

Question 8

what are hydrogen ions

Answer 8

protons

Question 9

what does concentration of H+ determine

Answer 9

pH

Question 10

relationship between pH value and H+ ion present

Answer 10

-inverse relationship between value of pH and H+ ion concentration
-the more H+ ions the lower the pH as more acidic
-the fewer H+ ions the higher the pH as more alkaline

Question 11

how does concentration of pH affect enzyme controlled reactions

Answer 11

-affects the pH
-fluids in the body normally have a pH of approximately 7.4
-the maintenance of this normal pH is essential for many of the metabolic processes that take place within cells
-changes in pH can effect enzyme structure
-for example, abnormal levels of hydrogen ions can interact with side-chains of amino acids and change into secondary and tertiary structures of proteins that make up enzymes
-this can cause denaturation of enzymes

Question 12

what do the iron ions depend on

Answer 12

oxidation states

Question 13

what is Iron (II) also known as

Answer 13

ferrous ions (Fe2+)

Question 14

what is Iron (III) also known as

Answer 14

ferric ions (Fe3+)

Question 15

use of Iron ions in binding oxygen

Answer 15

-haemoglobin is the large protein in red blood cells that is responsible for transporting oxygen around the body
-haemoglobin is made up of 4 polypeptide chains that each contain one Fe2+
-this Fe2+ is a key component in haemoglobin as it binds to oxygen
-Myoglobin in muscles function in a similar way (is an oxygen binding protein) but only made of one polypeptide chain (containing one Fe2+)

Question 16

how are Iron ions used in transfer of electrons during respiration and protein synthesis (key to biological generation of energy)

Answer 16

-iron ions are an essential component of cytochromes (that are themsleves a component of electron transport chains)
-cytochrome c contains an iron ion that is essential to its function
-during the electron transport processes, this iron ion switches between the Fe3+ and Fe2+ oxidation states, which allows for electrons to be accepted and donated

Question 17

what are the two roles of iron ions

Answer 17

-binding to oxyegn –> haemoglobin
-transfer of electrons during respiration and photosynthesis

Question 18

what is use of sodium ion

Answer 18

Na+ is required to transport glucose and amino acids across cell-surface membranes

Question 19

how is Na+ used to transport glucose and amino acids across cell-surface membranes

Answer 19

-glucose and amino acid molecules can only enter cells through carrier proteins alongside Na+
-this processes is known as co-transport
-first, Na+ is actively transported out of the epithelial cells that line the villi
-the Na+ concentration inside the epithelial cells is now lower that the Na+ concentration of the lumen of the small intestine
-Na+ now re-enters the cells (moving down the concentration gradient) through co-transport proteins on the surface membrane of the epithelial cells, allowing glucose and amino acids to enter at the same time

Question 20

Na+ use in nerves

Answer 20

required for the transmission of nerve impulses

Question 21

what 2 things is the sodium ion used for

Answer 21

-Na+ is required for the transport of glucose and amino acids across cell-surface membranes such as in the small intestine
-Na+ is also required for transmission of nerve impulses

Question 22

phosphate ions as phosphate groups

Answer 22

-phosphate ions attaches to other molecules to form phosphate groups which are an essential component of DNA, RNA and ATP
-in DNA and RNA the phosphate groups allow individual nucleotides to join up (to form polynucleotides)

Question 23

phosphate ions use in storing energy

Answer 23

• in ATP, the bods between phosphate groups store energy
  -these phosphate groups can be easily attached or detached
  -when the bonds between the phosphate groups are broken, they release a large amount of energy, which can be used for cellular process

Question 24

phosphate ions in cell membranes

Answer 24

-phosphates are also found in phospholipds which are key components of the phospholipd bilayer of cell membranes

Question 25

use of phosphate ions

Answer 25

-essential component of DNA, RNA and ATP
-store energy in ATP
-component of cell membrane

Question 26

calcium ion use in movement of organisms

Answer 26

-in synapses, calcium ions regulate the transmission of impulses from neurone to neurone

Question 27

calcium ions stimulate muscle contraction

Answer 27

-when an impulse reaches a muscle fibre, Ca2+ is released from the sarcoplasmic reticulum
-this Ca2+ binds to troponin C, removing the tropomyosin from myosin-binding sites on actin
-this allows actin-myosin cross-bridges to form when the muscle fibre contracts

Question 28

calcium ions in regulating protein channels

Answer 28

Ca2+ can help to regulate protein channels which effects permeability of cell membranes
-many enzymes are activated by Ca2+, making these ions key regulators in many biological reactions
-the presence of Ca2+ is also necessary for the formation of blood clots (known as the clotting factor)

Question 29

3 roles of calcium ions

Answer 29

-essential in movement of organisms
-stimulates muscle contraction
-regulate protein channels which affects permeability of cell membranes