Mitosis and meiosis

Diploid

A cell or organism that has two sets of chromosomes, one from each parent.

Meiosis

The process of cellular division that produces gametes with half the chromosome number.

Chromatid

One of two identical halves of a replicated chromosome.

Sister Chromatids

Identical copies of a chromosome that are joined together.

Homologous Chromosomes

Chromosome pairs, one from each parent, that are similar in shape and size.

Crossing Over

The exchange of genetic material between homologous chromosomes during meiosis.

Nondisjunction

Failure of homologous chromosomes or sister chromatids to separate properly during cell division.

Trisomy

A genetic condition where an individual has three copies of a particular chromosome.

Gamete

A reproductive cell (sperm or egg) that has half the chromosome number.

XY Chromosome System

A sex determination system where males have one X and one Y chromosome and females have two X chromosomes.

Phenotype

The physical expression or characteristics of a trait.

Genotype

The genetic makeup of an organism; the combination of alleles.

Allele

Different forms of a gene that can exist at a specific locus.

Codominance

A genetic scenario where both alleles are fully expressed in the phenotype.

Polygenic Inheritance

A trait that is controlled by multiple genes.

X-Linked Traits

Traits that are associated with genes located on the X chromosome.

Punnett Square

A diagram used to predict the outcome of a genetic cross.

Homozygous

An organism that has two identical alleles for a particular gene.

Heterozygous

An organism that has two different alleles for a particular gene.

Autosome

Any chromosome that is not a sex chromosome.

Carrier

An individual who has one copy of a recessive allele but does not express the recessive trait.

SRY Gene

A gene on the Y chromosome that is critical for male sex determination.

Turner Syndrome

A genetic disorder in females where one X chromosome is missing or partially missing.

Klinefelter Syndrome

A genetic condition where a male has an extra X chromosome (XXY).

Down Syndrome

A genetic disorder caused by the presence of an extra copy of chromosome 21.

Genetic Variation

Differences in DNA sequences among individuals.

Independent Assortment

The process by which different genes independently separate from one another when reproductive cells develop.

Zygote

The fertilized egg that forms when a sperm and egg unite.

Histone Proteins

Proteins that help package and manage DNA in the nucleus.

Chromatin

The complex of DNA and protein found in the nucleus that condenses to form chromosomes.

Crossover Chromatids

Chromatids that result from crossing over, which carry mixed genetic information.

Fertilization

The union of sperm and egg to form a zygote.

Gamete Formation

The process of creating reproductive cells through meiosis.

Genome

The complete set of genes or genetic material in an organism.

Mutations

Changes in the DNA sequence that can lead to variations in traits.

Pedigree Chart

A diagram that shows relationships between family members and their genetic traits.

Incomplete Dominance

A genetic situation in which one allele does not completely dominate another allele, resulting in a mixed phenotype.

Pleiotropy

A condition where a single gene influences multiple phenotypic traits.

Autosomal Dominant

A trait expressed in individuals with one copy of the dominant allele.

Autosomal Recessive

A trait expressed only in individuals with two copies of the recessive allele.

Mitosis

The process of cell division that results in two identical daughter cells.

Variability

The genetic differences within a population that contribute to diversity.

Biological Sex

The physical and physiological characteristics that define male and female organisms.

Aneuploidy

An abnormal number of chromosomes in a cell.

Chromosomal Abnormalities

Changes to the normal structure or number of chromosomes.

Gene Therapy

An experimental technique that uses genes to treat or prevent disease.

Biodiversity

The variety of life in the world or in a specific habitat or ecosystem.

Eukaryotic Cell

A cell with a membrane-bound nucleus and organelles.

Prophase 1

The first stage of meiosis where homologous chromosomes pair up and crossing over occurs.

Metaphase 1

The stage of meiosis where homologous chromosomes line up along the metaphase plate.

Anaphase 1

The phase in meiosis where homologous chromosomes are pulled apart to opposite sides of the cell.

Telophase 1

The last stage of meiosis 1 where the cell divides into two haploid cells.

Metaphase 2

The stage in meiosis 2 where chromatids are aligned in the center of the cell.

Anaphase 2

The phase of meiosis 2 where sister chromatids are separated and move toward opposite poles.

Telophase 2

The final stage of meiosis where the cell divides resulting in four haploid daughter cells.

Genetic Drift

A change in allele frequency in a population due to random sampling.

Natural Selection

The process by which organisms better adapted to their environment tend to survive and produce more offspring.

Speciation

The formation of new and distinct species in the course of evolution.

Phenotypic Plasticity

The ability of an organism to change its phenotype in response to environmental changes.

Biological Evolution

The change in the inherited characteristics of biological populations over successive generations.

Adaptive Radiation

The rapid evolution of diversely adapted species from a common ancestor.

Fitness

The ability of an organism to survive and reproduce in its environment.

Convergent Evolution

The process where organisms not closely related evolve similar traits.

Divergent Evolution

The process where two or more related species become more dissimilar.

Gene Flow

The transfer of genetic variation from one population to another.

Sexual Selection

A mode of natural selection where members of one sex choose mates based on certain traits.

Fossil Record

The total number of fossils discovered and their placement in the formation of geological strata.

Comparative Anatomy

The study of the similarities and differences in the anatomy of different species.

Embryology

The study of early development of organisms.

Biogeography

The study of the distribution of species and ecosystems in geographic space and through geological time.

Molecular Biology

The branch of biology that deals with the structure and function of the macromolecules essential to life.

Proteomics

The large-scale study of proteins, particularly their functions and structures.

Bioinformatics

The use of computer technology to manage biological information.

Genomics

The study of the complete set of DNA (the genome) in an organism.

Artificial Selection

The intentional breeding of plants or animals for specific traits.

Taxonomy

The science of classification of organisms.

Phylogeny

The evolutionary history and the relationships among a species or group of species.

Microevolution

Changes in allele frequencies that occur over time within a population.

Macroevolution

Major evolutionary changes that take place over long periods of time.

Extinction

The end of an organism or a group of organisms.

Endemic Species

Species that are native to and found only within a specific geographic area.

Invasive Species

Non-native species that spread widely and cause harm to the environment, economy, or human health.

Ecological Succession

The process of change in the species structure of an ecological community over time.

Symbiosis

A close, long-term interaction between two different species.

Mutualism

A type of symbiosis where both species benefit from the relationship.

Commensalism

A type of symbiosis where one species benefits and the other is neither helped nor harmed.

Parasitism

A type of symbiosis where one species benefits at the expense of the other.

Carrying Capacity

The maximum number of individuals of a species that an environment can support.

Population Dynamics

The study of how and why populations change in size and structure over time.

Trophic Levels

The hierarchical levels in an ecosystem, comprising different levels of feeding.

Food Chain

A linear sequence of organisms through which nutrients and energy pass.

Food Web

A complex network of feeding interactions among organisms in an ecosystem.

Habitat

The natural environment in which a species or community of species lives.

Niche

The role or function of an organism or species within an ecosystem.

Biome

A large geographic biotic unit, a major community of plants and animals with similar life forms.

Ecosystem

A community of living organisms along with the nonliving components of their environment.

Biosphere

The global sum of all ecosystems, where life exists.

Climax Community

A stable and mature ecological community that undergoes little or no change.

Keystone Species

A species that has a disproportionately large effect on its environment relative to its abundance.

Primary Succession

The series of community changes that occur on an entirely new habitat.