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Level 2 Bio Genetics

Describe genetic variation and change 90459 Key Words

QuestionAnswer
Allele One of two or more forms of a particular gene, see also dominant and recessive.
Allele frequency The proportion of all copies of a gene that is made up of a particular gene variant. Used to depict the amount of genetic diversity at the individual, population, and species level.
Adaptation The evolutionary process whereby a population becomes better suited to its habitat. This process takes place over many generations. The term may also refer to a feature which is especially important for an organism's survival.
Adenine One of the four bases found in DNA and RNA molecules also part of the energy molecule ATP, It is a purine and is given the symbol A.
Artificial selection Describes intentional breeding for certain traits, or combination of traits. The term was utilized by Charles Darwin in contrast to natural selection.
Autosome A chromosome that is not a sex chromosome
Biogeography the study of the distribution of species spatially and temporally.
Bottleneck effect an evolutionary event where a population is drastically reduced leading to a reduction in the genetic variability present in the species.
Centromere a region of DNA typically found near the middle of a chromosome where two identical sister chromatids come in contact. It is involved in cell division as the point of attachment for the spindle fibres.
Chiasma the point where two homologous non-sister chromatids exchange genetic material during chromosomal crossover during meiosis
Chromatid one of the two identical copies of DNA making up a duplicated chromosome, which are joined at their centromeres, for the process of cell division (mitosis or meiosis). In other words, "one-half of a replicated chromosome".
Chromosome an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences.
Chromosome mutation an atypical number of chromosomes or a structural abnormality in one or more chromosomes. They usually occur when there is an error in cell division following meiosis or mitosis. They can be organized into two basic groups, numerical and structural.
Comparative anatomy The study of similarities and differences in the anatomy of organisms. Two main areas are homologous structures - which are similar in different species because the species have common descent. Or Analogous structures - structures which are similar in dif
Comparative embryology Study of similarities in the embryonic stages of organisms that provide evidence of common evolutionary ancestry
Crossing over exchange of genetic material between homologous chromosomes. It occurs when matching regions on matching chromosomes break and then reconnect to the other chromosome.
Cytosine One of the four bases found in DNA and RNA molecules. It is a pyrimidine and has the symbol C and will form bonds with Guanine
Deletion a mutation in which a part of a chromosome or a sequence of DNA is missing.
Dihybrid a cross between offspring (first generation offspring) of two individuals that differ in two traits of particular interest.
Diploid or 2n the number of chromosomes in a somatic or body cell of an individual
Directional selection occurs when natural selection favors a single phenotype and therefore allele frequency continuously shifts in one direction.
Disruptive selection describes changes in population genetics in which extreme values for a trait are favoured over intermediate values. In this case the variance of the trait increases and the population is divided into two distinct groups. Sympatric speciation
DNA Do Not Ask, or deoxyribonucleic acid, the molecule that forms genes and chromosomes
Dominant An allele that is expressed regardless of the other allele
Double helix The shape of a DNA molecule.
Duplication Creation of an identical copy
Evolution the change in the inherited traits of a population of organisms through successive generations.
Fossil the preserved remains or traces of animals, plants, and other organisms from the remote past.
Founder effect the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.
Gametic Pertaining to sex cells such as sperm eggs ovules and pollen see also Haploid and Sexual reproduction
Gene stretch of DNA that codes for a type of protein or for an RNA chain that has a function in the organism.
Gene flow The transfer of alleles of genes from one population to another.
Gene frequency the proportion of all copies of a gene that is made up of a particular gene variant (allele).
Gene mutation changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus.
Gene pool the complete set of unique alleles in a species or population.
Genetic drift the change in the relative frequency in which a gene variant (allele) occurs in a population due to random sampling and chance
Genetic equilibrium A condition where a gene pool is not changing in frequency because the evolutionary forces acting upon the allele are equal, thus, resulting in a population to not evolve even after several generations.
Genome the entirety of an organism's hereditary information. It is encoded in DNA
Genotype the genetic constitution of a cell, an organism, or an individual (i.e. the specific allele makeup of the individual)
Germ Cells the cells that give rise to the gametes of organisms that reproduce sexually as opposed to somatic or body cells.
Guanine One of the four bases found in DNA and RNA molecules. It is a purine and has the symbol G and will form bonds with Cytosine
Haploid / monoploid the number of chromosomes in a gamete produced in the final stage of meiosis containing only one copy of each chromosome.
Heritable variation Genetic variation that can be passed on to successive generations
Heterozygous Condition where allele pairs on homologous chromosomes are different eg Hh.
Histone proteins found in eukaryotic cell nuclei, which package and order the DNA into structural units called nucleosomes.
Homologous pair Chromosomes that have the same genes in the same locations. One came from mummy and one from daddy.
Homozygous Condition where the allele pairs on matching chromosomes are the same.
Immigration The movement of individuals into an area.
Independent assortment Mendels second law describing the process by which alleles of different genes assort independently of one another during gamete formation.
Insertion the addition of one or more nucleotide base pairs into a DNA sequence.
Locus the position of a gene (or other significant sequence) on a chromosome
Mate selection The choosing of a sexual partner
Meiosis The type of cell division that results in the production of gametes with a haploid number of chromosomes
Mitosis The type of cell division that results in the production of identical daughter cells used for growth and repair of organisms
Molecular biology the study of biology at a molecular level. It concerns itself with understanding the interactions between the various systems of a cell, including the interactions between DNA, RNA and protein biosynthesis as well as learning how these interactions are re
Monohybrid the inheritance of a single characteristic. The different forms of the characteristic are usually controlled by different alleles of the same gene.
Mutagen a physical or chemical agent that changes the genetic material, usually DNA, of an organism
Mutation changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. Mutations are caused by radiation, viruses, transposons and mutagenic chemicals, as well as errors that occur during meiosis or DNA replication.
Natural selection process by which genetically heritable traits become more or less common in a population over successive generations. It is a key mechanism of evolution.
Nucleotide molecules that, when joined together, make up the structural units of RNA and DNA. composed of a (nitrogenous base), a five-carbon sugar, and a phosphate groups.
Pentadactyl limb he condition of having five digits on each limb. It is believed that all living tetrapods are descended from an ancestor with a pentadactyl limb, although many species have now lost or transformed some or all of their digits by the process of evolution.
Phenotype any observable characteristic or trait of an organism: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior (such as a bird's nest). They result from the expression of an organism's genes as well
Population all the organisms that both belong to the same species and live in the same geographical area. The area that is used to define the population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding wi
Recessive Allele that will only be expressed if present in two copies
Recombination process by which a molecule of nucleic acid is broken and then joined to a different one. It occurs in meiosis where chromosomes crossover. Offspring result with different combinations of genes from those of their parents.
Selection pressure Any cause that reduces reproductive success in a proportion of a population resulting in a change in phenotype in the remaining population
Semi-conservative Refers to the fact that a newly replicated DNA molecule comprises one strand from the parent molecule.
Sex chromosome A chromosome that is responsible for determining the gender of an organism.
Somatic A body cell not a sex cell.
Speciation the evolutionary process by which new biological species arise.
Species a group of organisms capable of interbreeding and producing fertile offspring.
Stabilising selection is a type of natural selection in which genetic diversity decreases as the population develops a particular trait value.
Substitution Mutation in which a sequence of one or more DNA bases in a gene are replaced with some different bases
Test cross used to determine if an individual exhibiting a dominant trait is homozygous or heterozygous for that trait.
Thymine One of the four bases found in DNA molecules. It is a pyrimidine and has the symbol T and will form bonds with Adenine
Translocation chromosome abnormality caused by rearrangement of parts between non-homologous chromosomes. See also mutation
Variation differences within a species
Vestigial organs homologous characters of organisms that have seemingly lost all or most of their original function in a species through evolution.
Created by: richardedw