Inorganic Ions 🟡 Flashcards
What are inorganic ions?
An inorganic ion is an ion that does not contain carbon
Where are inorganic ions found?
They occur in solution in the cytoplasm of cells and in body fluids as well as in larger molecules.
Inorganic ions play an important role in many essential cellular processes
Inorganic ions occur in solution in the 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 can be used in cell signalling and neuronal transmission
Each type of inorganic ion has a specific role, depending on its properties
What is the role of hydrogen ions?
Hydrogen ions are protons
The concentration of H+ in a solution determines the pH
There is an inverse relationship between the pH value and the hydrogen ion concentration
The more H+ ions present, the lower the pH (the more acidic the solution)
The fewer H+ ions present, the higher the pH (the more alkaline the solution)
The concentration of H+ is therefore very important for enzyme-controlled reactions, which are all affected by pH
The fluids in the body normally have a pH value 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 affect enzyme structure
For example, abnormal levels of hydrogen ions can interact with the side-chains of amino acids and change the secondary and tertiary structures of the proteins that make up enzymes
This can cause denaturation of enzymes
What is the role of iron ions?
There are actually two versions of iron ions (known as oxidation states)
Iron (II) ions, also known as ferrous ions (Fe2+)
Iron (III) ions, also known as ferric ions (Fe3+)
Iron ions are essential as they can bind oxygen
Haemoglobin is the large protein in red blood cells that is responsible for transporting oxygen around the body
Haemoglobin is made up of four polypeptide chains that each contain one Fe2+
This Fe2+ is a key component in haemoglobin as it binds to oxygen
Myoglobin in muscles functions in a similar way (it is an oxygen-binding protein) but is only made up of one polypeptide chain (containing one Fe2+)
Iron ions are also essential as they are involved in the transfer of electrons during respiration and photosynthesis, so they are key to the biological generation of energy
Iron ions are an essential component of cytochromes (that are themselves a component of electron transport chains)
Cytochrome c contains an iron ion that is essential to its function
During the electron transport process, this iron ion switches between the Fe3+ and Fe2+ oxidation states, which allows for electrons to be accepted and donated
What is the role of sodium ions?
Na+ is required for the transport of glucose and amino acids across cell-surface membranes (e.g. in the small intestine)
Glucose and amino acid molecules can only enter cells (through carrier proteins) alongside Na+
This process 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 than the Na+ concentration in 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
Na+ is also required for the transmission of nerve impulses
What is the role of phosphate ions?
PO4^3- 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)
In ATP, the bonds between phosphate groups store energy
These phosphate groups can be easily attached or detached
When the bonds between phosphate groups are broken, they release a large amount of energy, which can be used for cellular processes
Phosphates are also found in phospholipids, which are key components of the phospholipid bilayer of cell membranes
What is the role of calcium as an ion?
Ca2+ is essential in the movement of organisms:
In synapses, calcium ions regulate the transmission of impulses from neurone to neurone
Ca2+ also stimulates muscle contraction
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
Ca2+ can also help to regulate protein channels, which affects the 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 (it is known as a clotting factor)
