Genetics Lesson

Term Definition
Heredity The passing of traits from parent to offspring.
DNA – Deoxyribonucleic Acid The genetic material of all organisms; made up of two twisted strands of sugar-phosphate molecules and nitrogen bases.
RNA – Ribonucleic Acid Carries codes for making proteins from the nucleus to the ribosomes.
Gene Section of DNA on a chromosome that contains instructions for making specific proteins.
Mutation Any permanent change in a gene or chromosome of a cell.
Allele An alternate form that a gene may have for a single trait.
Multiple allele More than two alleles that combine to determine a certain characteristic.
Genetics The study of how traits are inherited.
Hybrid An offspring that was given different genetic information for a trait from each parent.
Purebred An organism that produces the same traits generation after generation.
Trait Characteristics of an organism.
Dominant Traits Traits that cover or dominate a weaker form of that trait.
Recessive Traits Traits that are covered or dominated by a stronger form of that trait and seems to disappear.
Punnett Square A tool used to predict the probability of certain traits in offspring.
Pedigree A visual tool used for following a trait through generations of a family.
Recombinant DNA A segment of DNA that is used to create medications such as insulin.
Genetic Engineering Biological and chemical methods to change the arrangement of a gene's DNA to improve crops, create medicine and change how cells perform their normal functions.
Gene Therapy A normal allele is placed in a virus to stop the virus from harming the organism.
Genotype An organism's genetic make-up.
Phenotype An organism's physical appearance and behavior. The way it looks and acts.
Homozygous Describes an organism with two alleles that are the same for a trait.
Heterozygous Describes an organism with two alleles that are different for a trait.
Incomplete Dominance Production of a phenotype that is between the two homozygous parents.
Polygenic inheritance Occurs when a group of gene pairs act together and produces a specific trait.
Sex Chromosomes Chromosomes that determine the sex/gender of an organism.
Sex-linked Gene An allele inherited on the sex chromosome that can cause human genetic disorders such as color blindness or hemophilia.
Watson & Crick Made a 3-D model of the DNA molecule.
Franklin Proved that the large spiral in the DNA molecule is actually two small spirals. (double helix)
Mendel The first to trace a trait through several generations using pea plants. Father of Genetics.
Chromosomes Rod shaped structures that include traits/genes that are copied and pass from cell to cell.