Biological Molecules - Inorganic Ions Flashcards
Where do inorganic ions occur?
In solution in the cytoplasm and body fluids of organisms, some in high concentrations and others in very low concentrations.
What does the concentration of hydrogen (H+) ions in a solution relate to?
It 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)
Why is the H+ concentration so 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
Why are Iron (Fe2+) ions essential?
As they can bind oxygen
What are Iron (Fe2+) ions used for?
In haemoglobin which 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+)
What are Sodium (Na+) ions required for?
The transport of glucose and amino acids across cell-surface membranes (e.g. in the small intestine)
The transmission of nerve impulses
How is Na+ used in the transport of glucose and amino acids?
Glucose and amino acid molecules can only enter cells (through carrier proteins) alongside Na+ (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
What are phosphate (PO4, 3-) ions required for?
Attaches to other molecules to form phosphate groups, which are an essential component of DNA, RNA and ATP
Phosphates are also found in phospholipids, which are key components of the phospholipid bilayer of cell membranes
What are the roles of PO4, 3- ?
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
What are calcium (Ca2+) ions required for?
essential in the movement of organisms
stimulates muscle contraction
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)
Where is Ca2+ essential in the movement of organisms?
In synapses, calcium ions regulate the transmission of impulses from neurone to neurone
How does Ca2+ stimulate 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
