AQA A level Biology
AQA A level Biology
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Topic 1: Biological molecules
Topic 1: Biological molecules
Inorganic ions
Inorganic ions
Atoms with a different number of electrons compared to protons are known as ions and possess strong, permanent charges.
Ions that have gained electrons are negatively charged, while ions that have lost electrons are positively charged.
Inorganic ions occur in solution in the cytoplasm and body fluids of organisms, some in high concentrations and others in very low concentrations.
Some functions of inorganic ions in organisms include:
Structural roles such as phosphate ions (PO4³⁻) in phospholipids, DNA, and RNA.
Cotransport such as sodium ions (Na⁺) moving with glucose or amino acid molecules into ileum epithelial cells.
Controlling pH: hydrogen ion (H⁺) concentration determines the pH of a solution.
Functional roles within larger molecules such as iron ions (Fe²⁺) in haemoglobin.
Definitions
Definitions
Amino acid: the monomer from which proteins are made.
ATP (adenosine triphosphate): a nucleotide derivative formed from a molecule of ribose, a molecule of adenine and three phosphate groups.
Co-transport: the transport two substances across a membrane through the same protein. One molecule moves down its concentration gradient while the other moves against it. Movement can be in the same direction or opposite directions.
DNA (deoxyribonucleic acid): a polymer of nucleotides, and it holds the genetic information. Each nucleotide is formed from a pentose sugar (deoxyribose), a nitrogen-containing organic base and a phosphate group.
Glucose: hexose monosaccharide found in either alpha or beta isoforms.
Haemoglobin: globular protein that can bind to up to four molecules of oxygen.
Hydrogen ion: formed when a hydrogen atom loses an electron resulting in an ion with a single positive charge.
pH: a measure of the concentration of hydrogen ions in a solution.
Phosphate: negatively charged ionic molecule made up of PO4-. Found naturally in sedimentary rocks, dissolved in water sources. Forms part of phospholipids and nucleotides.
RNA (Ribonucleic acid): a polymer of nucleotides and transfers genetic information from DNA to the ribosomes. Each nucleotide is formed from a pentose sugar (ribose), a nitrogen-containing organic base and a phosphate group.
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