Genetics and Evolution

• DNA

  Deoxyribonucleic acid; the genetic material that carries information about an organism and is passed from parent to offspring.
• Chromosome


  a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes (humans have 46 in most cells)
• Gene


  A small section of DNA on a chromosome that codes for a particular sequence of amino acids to make a specific protein
• nucleotide

  A building block of DNA, consisting of a deoxyribose sugar covalently bonded to a nitrogenous base and a phosphate group.
• allele


  different versions of the same gene
• meiosis


  a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes
• gamete


  sex cell made during meiosis
• acquired trait


  A trait that is not in your genes but is picked up from environmental factors (dyeing your hair blue)
• genetic trait


  a genetically determined condition or characteristic
• dominant


  A term given to alleles that are always expressed when present
• recessive


  A term given to alleles that are only expressed when two recessive alleles are present
• sexual reproduction


  A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents
• asexual reproduction


  A reproductive process that involves only one parent and produces offspring that are identical to the parent.
• genotype


  the collection of alleles that determine the physical or phenotypic characteristics of an organism
• phenotype


  the physical characteristics of an organism, controlled by the interaction of an organism's genotype with the environment
• homozygous


  this is when an organism has two of the same alleles for a particular gene
• heterozygous


  this is when an organism has two different alleles for the same gene
• punnett square


  A chart that shows all the possible combinations of alleles that can result from a genetic cross
• variation


  the differences in characteristics between organisms in a population
• mutation


  a change in the genetic material of an organism
• adaptation


  a characteristic or trait that helps an organism to survive in the environment in which it lives
• fitness


  a word used to describe the ability of an organism to survive in its environment and mate successfully
• evolution


  the gradual change in the heritable characteristics or traits of living things over time
• natural selection


  the process by which evolution occurs, sometimes referred to as "survival of the fittest"
• selective breeding

  also known as artificial selection, this is when humans intentionally breed animals with desirable traits
• classification


  The process of grouping things based on their similarities
• taxonomy


  The scientific study of how living things are classified
• dichotomous key


  a key for the identification of organisms based on a series of two choices
• binomial nomenclature


  A system for giving each organism a two-word scientific name that consists of the genus name followed by the species name