Term | Definition |
DNA | A double stranded nucleic acid that carries the genetic code and is always found in the nucleus. |
Gene | A unit of heredity. A portion of a gene that codes for a trait. |
Protein | A large molecule, chain of amino acids, essential to many functions in the body and responsible for expression of traits. |
Transcription | The process where a copy of mRNA is made from one gene in DNA. Occurs in the nucleus. |
Translation | The process of making a protein, where tRNA matches amino acids to the codons in mRNA. Occurs in the ribosome. |
Monomer | Single unit - a small single molecule that makes a biomolecule |
Polymer | Multi-piece unit - a large molecule made up of many smaller parts |
Nucleic Acids | A biomolecule made up of nucleotides. Examples are DNA and RNA. |
Nucleotides | A monomer made up of a sugar, phosphate, and nitrogen base. Build together to make DNA and RNA. |
mRNA | A type of RNA that creates a copy of DNA inside the nucleus, then carries this code out to the ribosome for protein synthesis. |
Amino Acid | A monomer that builds to make proteins. Each codon in mRNA codes for one of these. |
Mutation | A permanent change in the DNA sequence of a gene, which alters the amino acid sequence of the protein coded by the gene |
Adaptation | A characteristic or trait that helps an organism survive in its specific environment. |
Natural Selection | The process by which individuals in a population with beneficial traits survive and reproduce, passing down these beneficial traits to the future generation. |
Evolution | The gradual change in a species over time. This change occurs in populations, not in individuals. |
Common Ancestor | The most recent species from which two different species evolved. |
Fossil Record | This term refers to the total number of fossils that have been discovered, helping scientists analyze the change over time in a species |
Vestigial Structures | Organs or structures that no longer have a function in a species. Examples: hind leg bones in whales, appendix in humans. |
Homologous Structures | Structures with different functions, but similar structures, due to the presence of a common ancestor. Example: The flipper of a whale and the leg of a dog. |
Analogous Structures | Structures with similar functions, but different structures. Occurs due to convergent evolution when organisms are not closely related. |
Embryology | The study and comparison of embryo development that can provide clues to the evolution of present day organisms. |
Heritable Traits | Traits that can be inherited, or passed down from generation to generation in DNA |
Genetic Variation | Differences in DNA that exist within the gene pool of a population. Caused by mutations and genetic recombination. |
Directional Selection | Occurs when one extreme phenotype is selected for |
Stabilizing Selection | Occurs when the average phenotype is selected for, and the extreme phenotypes are selected against |
Disruptive Selection | Occurs when both extreme phenotypes are selected for, and the average phenotype is selected against |
Genetic Drift | The random change in the frequency of an allele in a population due to chance or random sampling |
Gene Flow | The movement of alleles from one population to another |
Gene Pool | All of the alleles in a population |
Sexual Selection | Organisms are selective in their choice of mates, resulting in a particular set of traits being selected for and passed on to future generations. Example: Colorful plumage on male peacocks. |
Bottleneck Effect | Genetic drift that occurs after an event greatly reduces the size of a population. Decreases genetic variation. |
Genetic Recombination | The change in genetic sequences during sexual reproduction that leads to an increase in genetic variation between organisms |
Sickle Cell Anemia | A homozygous, recessive genetic disease that causes red blood cells to be flattened and can be fatal |
Convergent Evolution | Different species become more similar as they adapt to the same environment. This can lead to analogous structures, such as the flipper on a whale and fins on a fish. |
Divergent Evolution | Related species change to adapt to different environments, become more and more different from each other, and can eventually undergo speciation. |
Speciation | Over time, isolated populations become very different, and one species can change enough to become two different species. |
Extinction | Occurs when all individuals in a species die and there are no longer any surviving individuals of a species. Evidence of these species can be found in the fossil record. |
Reproductive Isolation | Occurs when two individuals are no longer able to reproduce with one another. |