Genetics Terms – Flashcards
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Heredity
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The passing of traits from parents to offspring.
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Gene
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A segment of DNA on a chromosome that codes for a specific trait.
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Allele
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An alternative form of a gene.
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Chromosome
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A chromosome is an organized structure of DNA, protein, and RNA found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequence.
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Homozygous
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Term used to refer to an organism that has two identical alleles for a particular trait.
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Heterozygous
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Term used to refer to an organism that has two different alleles for a particular trait.
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Trait
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A characteristic that an organism can pass on to its offspring through its genes.
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Dominant
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Describes a trait that covers over, or dominates, another form of that trait.
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Recessive
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Describes a trait that is covered over, or dominated, by another form of that trait and seems to disappear.
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Genotype
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An organism's genetic makeup, or allele combinations.
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Phenotype
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An organism's physical appearance, or visible traits.
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Pedigree
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A diagram that shows the occurrence of a genetic trait in several generations of a family.
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Punnett Square
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A chart that shows all the possible combinations of alleles that can result from a genetic cross.
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Variation
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Demonstrated by the difference in appearance that offspring show from parents and siblings.
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DNA
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A nucleic acid found in the nucleus of all living cells, which carries the organism's hereditary information.
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Probability
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A measure of the likelihood of an event. It is the ratio of the number of ways a certain event can occur to the number of possible outcomes. A possibility of genetic combinations for the next generation from test crosses.
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Pure Breed
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A group of identical individuals that always produce offspring of the same phenotype when crossed, they are homozygous individuals eg: either BB or bb
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Hybrid
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An organism that has two different alleles for a trait; or is heterozygous for a particular trait eg: Bb
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Genetics
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Scientific study of heredity
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Mitosis
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Cell's division (PMAT) of the nucleus. Final product is 2 cells that are exactly like the parent cell.
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Meiosis
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Cell division that produces reproductive cells (sperm & egg) in sexually reproducing organisms.
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Sex Chromosomes
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The pair of chromosomes (X & Y) responsible for determining the sex of an individual.
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Sex Linked Trait
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A gene located on the X chromosome in males (XY) that causes a specific characteristic (example: colorblindness), the gene has a back up in females (XX) in case it is damaged.
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Polygenic Inheritance
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Occurs when a group of gene pairs acts together and produces a specific phenotypical trait, such as eye color, skin color, or height
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Genetic Engineering
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A technology that includes the process of manipulating or altering the genetic material of a cell resulting in desirable functions or outcomes that would not occur naturally.
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Selective Breeding
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Method of breeding that allows only those individual organisms with desired characteristics to produce the next generation.
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Homologous Chromosome
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Chromosomes that have the same sequence of genes and the same structure.
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Hemizygous
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The single set of genes that males acquire from their mother's X chromosome. A genetic occurrence when an organism has only 1 allele for a trait. In humans, males with only one X chromosome.
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Inheritance
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The process by which physical and biological characteristics are transmitted from the parent (or parents) to the offspring
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Ratio
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A statement of how two numbers compare. It is a comparison of the size of one number to the size of another number.
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Gamete
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Cells involved in sexual reproduction; sperm and egg cells
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Codominance
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In heterozygotes both traits are expressed, for example breeding a white bear with a black bear results in offspring that have both black and white patches together.
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Incomplete Dominance
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A pattern of inheritance in which the alleles inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits. For example a red flower bred with a white flower will produce pink flowers.
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Complete Dominance
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In a heterozygous genotype the dominant allele completely masks the effect of the recessive allele in the organism's phenotype.
