Mendelian & Molecular Genetics

Map Units

A unit of measure for genetic linkage, representing the frequency of recombination between genes on a chromosome

Autosome

Any chromosome that is not a sex chromosome

Sex chromosome

Chromosomes that determine the sex of an organism, typically represented as X and Y in mammals

Nonnuclear DNA

DNA found outside the cell nucleus, such as in mitochondria and chloroplasts

Maternal inheritance

A mode of genetic inheritance where traits are passed down from mothers to their offspring through lineage, typically involving mitochondria

Phenotypic Plasticity

The ability of an organism to change its phenotype in response to environmental conditions. This adaptability allows for a range of expressed characteristics based on varying factors.

Law of Segregation

The principle stating that during the formation of gametes, the two alleles for a trait separate, so that each gamete carries only one allele for each gene

Law of Independent Assortment

The principle that states that genes for different traits are inherited independently of each other during the formation of gametes

Codominance

A genetic scenario where both alleles in a heterozygote are fully expressed, resulting in offspring with a phenotype that is neither dominant nor recessive

Incomplete dominance

A genetic scenario in which the phenotype of heterozygotes is intermediate between the phenotypes of the homozygotes

Pleriotropy

The ability of a single gene to affect multiple traits in an organism

Polygenic Inheritance

A genetic scenario where multiple genes contribute to a single trait, resulting in a continuous range of phenotypes

Back cross

A breeding method where an F1 hybrid organism is crossed back with one of its parent strains to explore the inheritance of specific traits

Cline

A gradual change in a trait or characteristic across a geographical area or population

Dihybrid Cross

A genetic cross between two organisms that considers two traits, leading to a 9:3:3:1 phenotypic ratio in the offspring

F1 Generation

The first filial generation of offspring resulting from a cross between two genetically distinct parents

F2 Generation

The second filial generation that arises from the self-pollination or crossing of the first generation

Monohybrid Cross

A genetic cross that focuses on the inheritance of a single trait, or gene

Non-disjunction

The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division

Sex limited traits

Traits that are expressed only in one sex, despite being present in both

Activator

A protein that increases gene expression by binding to an enhancer or promoter region

Cell differentiation

The process by which a less specialized cell becomes a more specialized cell type, leading to the formation of different cell types with distinct functions

Constituitive Gene

A gene that is continuously expressed or transcribed at a constant level, regardless of environmental changes or regulatory signals

Coding strand

The DNA strand that is complementary to the template strand and carries the same sequence as the mRNA

Embryonic Induction

A process during embryonic development where one group of cells influences the fate of another group through signaling pathways

Gene Induction

The process by which a gene's expression is activated or increased, often in response to specific signals or environmental conditions

Gene Repression

The process by which a gene's expression is reduced or inhibited, usually through regulatory proteins that bind to the gene's promoter or associated regions

Genetic transplantation

The technique of transferring genetic material or cells from one organism to another

Helicase

An enzyme that unwinds the DNA helix during replication, allowing each strand to serve as a template for new DNA synthesis

Homeotic genes

Genes that control the development of anatomical structures in various organisms by regulating the expression of other genes

HOX genes

A subset of homeotic genes that play a crucial role in the body plan organization and segmentation of organisms, particularly along the anterior-posterior axis

Morphogenesis

The biological process that causes an organism to develop its shape, involving growth, differentiation, and spatial organization

Morphogens

Substances that govern the pattern of tissue development and the positions of various specialized cell types during embryonic development

RNAi

A biological process where RNA molecules inhibit gene expression by targeting mRNA for degradation or preventing translation

siRNA (small interfering RNA)

A class of double-stranded RNA molecules, induces the degradation of complementary mRNA.

Small regulatory RNA

Plays key roles in the regulation of gene expression, often through mechanisms like RNA interference.

Transcription factors

Proteins that bind to specific DNA sequences to control the transcription of genetic information from DNA to mRNA

Transgenic Organism

An organism that has been genetically modified to contain DNA from another species, allowing it to express new traits or characteristics

Southern blotting

A technique used to detect specific DNA sequences in DNA samples by transferring DNA fragments onto a membrane and probing with a labeled DNA probe

Northern blotting

A technique used to study gene expression by detecting specific RNA sequences in a sample through gel electrophoresis and membrane transfer, followed by probing with labeled RNA probes