Key Terms for Biology
Key Terms
Active transport: membrane proteins use cellular energy (usually ATP) to move molecules or ions across a plasma membrane against their concentration gradient.
Allele: different forms of a gene • genotype – the combination of alleles in an organism.
Aquaporin: a specialised channel protein in the plasma membrane of a cell, which is selectively permeable to water.
Attachment protein: a protein in the plasma membrane of a cell that attaches either to the cytoskeleton inside the cell, to other cells or to the extracellular matrix.
Carrier protein: a membrane protein that facilitates the diffusion of specific substances across the membrane. The molecule to be transported binds to the outer surface of the carrier protein; the protein then changes shape, allowing the molecule to move across the membrane.
Channel protein: a membrane protein that forms a channel or pore completely through the membrane and that is usually permeable to one or to a few water water-soluble molecules, especially ions.
Chromosome: a DNA double helix together with proteins that help to organise and regulate the use of the DNA.
Codominance: simultaneous phenotypic expression of two alternative alleles in a heterozygote.
Concentration: the number of particles of a dissolved substance in a given unit of volume.
Concentration gradient: the difference in concentration of a substance between two parts of a fluid or across a barrier such as a membrane.
Diffusion: the net movement of particles from a region of high concentration of that particle to a region of low concentration, driven by the concentration gradient; may occur entirely within a fluid or across a barrier such as a membrane.
Dominant: a variant of a trait the masks the presence of a recessive variant (e.g. T)
Endocytosis: the process in which the plasma membrane engulfs extracellular material, forming membrane-bound sacs that enter the cytoplasm and thereby move material into the cell.
Energy-requiring transport:
Active transport: membrane proteins use cellular energy (usually ATP) to move molecules or ions across a plasma membrane against their concentration gradient.
Allele: different forms of a gene • genotype – the combination of alleles in an organism.
Aquaporin: a specialised channel protein in the plasma membrane of a cell, which is selectively permeable to water.
Attachment protein: a protein in the plasma membrane of a cell that attaches either to the cytoskeleton inside the cell, to other cells or to the extracellular matrix.
Carrier protein: a membrane protein that facilitates the diffusion of specific substances across the membrane. The molecule to be transported binds to the outer surface of the carrier protein; the protein then changes shape, allowing the molecule to move across the membrane.
Channel protein: a membrane protein that forms a channel or pore completely through the membrane and that is usually permeable to one or to a few water water-soluble molecules, especially ions.
Chromosome: a DNA double helix together with proteins that help to organise and regulate the use of the DNA.
Codominance: simultaneous phenotypic expression of two alternative alleles in a heterozygote.
Concentration: the number of particles of a dissolved substance in a given unit of volume.
Concentration gradient: the difference in concentration of a substance between two parts of a fluid or across a barrier such as a membrane.
Diffusion: the net movement of particles from a region of high concentration of that particle to a region of low concentration, driven by the concentration gradient; may occur entirely within a fluid or across a barrier such as a membrane.
Dominant: a variant of a trait the masks the presence of a recessive variant (e.g. T)
Endocytosis: the process in which the plasma membrane engulfs extracellular material, forming membrane-bound sacs that enter the cytoplasm and thereby move material into the cell.
Energy-requiring transport: