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Science Term 1
Genetics + Evolution
| Term | Definition |
|---|---|
| adenine | The base that combines with thymine to form a base pair |
| allele | A version of a gene |
| amino acid | A small molecule that joins with others to form proteins |
| anaphase | when the chromosomes separate and are pulled away from each other to opposite sides of the cell. |
| autosomal | a specific gene is not on a sex chromosome and is a numbered chromosome. |
| base | Part of a DNA molecule that comes in four types: A, C, G and T |
| base pair | Two bases joined together known as 'rungs' in only two combinations: A-T or G-C |
| cell cycle | The repeated process of cell growth and division |
| cell division | The splitting of a cell to form new cells that allows organisms to grow, repair damage and reproduce. There are two types: mitosis and meiosis. |
| chromosome | A DNA molecule that condenses during cell division Most human cells contain 46 chromosomes but sex cells only contain 23 chromosomes. |
| crossing over | The swapping of genes between chromosomes in a homologous pair Crossing over only occurs in meiosis, during prophase I. It increases the genetic variety of the sex cells produced. |
| cytosine | the base that combines with guanine to form a base pair |
| daughter cell | Any new cell formed by cell division that has its own nucleus and set of DNA. |
| DNA, or deoxyribonucleic acid | a very large molecule that contains genetic information. |
| dominate allele | A version of a gene that is expressed even when only one copy is present represented by an uppercase letter |
| dominate trait | A feature that appears when at least one allele is present |
| double helix | A structure consisting of two chains twisted around each other while the 'rungs' (base pairs) connect the two chains. |
| fertilisation | The joining of an egg and a sperm to form a new organism, combining DNA from the mother and father so the child gets half of its chromosomes from each parent. |
| gene | A unit of genetic information within a section of a DNA molecule that provides instructions for building a specific protein. |
| generation | Members of a family that are born and live at about the same time |
| genotype | A pair of alleles that influence the appearance of a particular trait (phenotype) and represented by two letters |
| guanine | The base that combines with cytosine to form a base pair |
| heterozygous | A genotype in which the two alleles are different, consisting of one dominant allele and one recessive allele – Yy. |
| homologous pair | Two chromosomes that contain versions of the same genes where one chromosome in a homologous pair is inherited from the mother and the other from the father. |
| homozygous | A genotype in which the two alleles are the same consisting of either two dominant alleles – YY – or two recessive alleles – yy. |
| inheritance | The passing down of traits via genes from one generation to the next through sexual reproduction. |
| interphase | The stage of the cell cycle in which a cell grows and copies its DNA, covering most of a cell's life span. |
| meiosis | A type of cell division that produces sex cells for reproduction, producing egg and sperm cells. One cell divides into four sex cells by two cycles of cell division. |
| metaphase | when the chromosomes line up in the middle of the cell. |
| mitosis | A type of cell division that produces cells for growth and repair, producing 2 daughter cells that are genetically identical to the parent cell. |
| parent cell | Any cell that divides to form new cells |
| pedigree | A family tree that shows how a trait is passed down through generations. In a pedigree, filled symbols show the presence of a trait and open symbols show its absence. Circles represent females while squares represent males. |
| phenotype | The collection of traits observable in an organism determined by the organism's genotype. |
| prophase | when the cell prepares to divide. The chromosomes condense and the nucleus starts to break down. |
| protein | A large molecule made up of amino acids that form structures and perform functions in an organism. |
| recessive allele | A version of a gene that is only expressed when two copies are present represented by a lowercase letter |
| recessive trait | A feature that only appears when two alleles are present |
| sex chromosome | A chromosome that helps determine an organism's gender. Sex chromosomes come in two types: X or Y. Most females have two X chromosomes while most males have an X and a Y. |
| simple inheritance | When the appearance of a trait is controlled by a single gene |
| telophase | when two new nuclei form, each with its own set of DNA. |
| thymine | The base that combines with adenine to form a base pair |
| trait | A feature of an organism |
| acquired trait | A feature that is gained during an individual's lifetime which cannot result in the evolution of a population. |
| adapations | A genetic trait that helps an organism survive in its environment and give them a greater chance of reproducing and passing their genes to the next generation. |
| antibiotics | A medicine that kills bacteria or prevents their growth |
| antibiotic-resistance | Able to survive in the presence of antibiotics, known as superbugs. |
| behavioural adaptation | A behaviour or action that helps an organism survive, including migrating, burrowing and building dams or nests. |
| common ancestor | A species that two or more other species have evolved from |
| competition | The struggle between organisms for resources, such as food or mates resulting in many organisms will not survive long enough to reproduce. |
| evolution | A change in the genetic traits in a population over many generations |
| evolutionary tree | A diagram that shows how species are related and evolved from common ancestors. |
| extinction | The dying out or complete disappearance of a species |
| genetic diversity | The amount of genetic variation in a population which is needed for evolution because it makes some individuals better adapted to the environment than others. |
| genetic trait | A feature that can be passed down by genes to the next generation |
| mutation - evolution | A small random change in an organism's DNA that can be passed on to offspring through reproduction, increasing the genetic variation in a population. |
| natural selection | The survival of organisms that are better adapted to their environment which causes populations over generations to evolve in response to its environment. |
| physiological adaptations | An internal bodily process that helps an organism survive including, production of venom and regulation of body temperature. |
| population | A group of organisms of the same species living in the same place |
| selection pressure | A challenge that affects an organism's ability to survive and reproduce, including hunting by predators, access to resources, diseases and weather conditions. |
| speciation | The formation of a new species occurring when a population splits into two isolated populations that evolve under different selection pressures. |
| species | A group of similar organisms that can breed to produce fertile offspring |
| structural adaptations | A physical feature of the body that helps an organism survive including scales, fur, feathers, long tails and bright colours. |
| variation | A difference in traits between individuals of the same species |
| RNA, or ribonucleic acid, | a copy of information from DNA, but a a single strand still using the same four bases except T=U |
| Uracil | RNA uses it instead of Thymine (T) because it is energetically cheaper to produce and more efficient for short lived molecules |
| Nucleotide Structure | Phosphate, sugar, and nitrogen bases (A, T, C, or G) |
| Five fingers of evolution - Thumb | Natural Selection/Adaptations: Often called "Survival of the Fittest." This is the only process of the five that consistently leads to adaptation. It favours traits that improve an organism's ability to survive and reproduce in its specific environment. |
| Five fingers of evolution - Pointer finger | Movement (Gene Flow): Represents movement or migration. When individuals move into (immigration) or out of (emigration) a population, they take their genes with them, altering the gene pool's composition. |
| Five fingers of evolution - Middle finger | Mutation: Represents new genetic material entering the gene pool. Random mutations in DNA create new alleles, which can increase genetic variation and potentially introduce new traits. |
| Five fingers of evolution - Ring finger | Non-Random Mating: Also known as sexual selection. If individuals choose mates based on specific traits (like appearance or location), the frequency of those genes will change over generations. |
| Five fingers of evolution - Pinky finger | Small Population Size: Represents genetic drift. In small populations, chance events can significantly change the gene pool because there are fewer individuals to buffer random losses of specific alleles. |
| Order of Speciation | 1. Isolation 2. Selection pressures 3. Genetic variation 4. Natural selection 5. Reproduction 6. Adaptations 7. Distinct species |
Created by:
LilyB28
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