6.1.2 patterns of inheritance

Gene

Basic unit of heredity in organisms.

Loci

Specific location of a gene on a chromosome.

Phenotype

Observable traits of an organism.

Gametes

Reproductive cells for sexual reproduction.

Monogenic Inheritance

Inheritance determined by a single gene.

Codominance

Both alleles expressed equally in phenotype.

Multiple Alleles

Three or more alleles for a gene.

Autosomal Chromosomes

Chromosomes not involved in sex determination.

Pure Breeding

Homozygous individuals producing identical offspring.

Dihybrid Inheritance

Inheritance of two different traits simultaneously.

Sex Linkage

Genes located on sex chromosomes.

Continuous Variation

Traits that show a range of phenotypes.

Discrete Variation

Categorical traits with distinct phenotypes.

Chi Squared Test

Statistical test for comparing observed vs expected.

Mutation

Change in DNA sequence of an organism.

Epistasis

One gene suppresses the expression of another.

Gene Pool

Total genetic diversity within a population.

Allele Frequency

Relative frequency of an allele in a population.

Population Genetics

Study of genetic variation within populations.

Null Hypothesis

Assumption that there is no significant difference.

Rhesus Blood Group

Blood type system based on Rh factor.

Wild Type

Most common phenotype in a natural population.

Hemophilia

Genetic disorder affecting blood clotting.

Linked Genes

Genes located close together on the same chromosome.

Normal Distribution Curve

Graphical representation of continuous variation.

Population

Group of organisms of the same species in a habitat.

Epistatic Gene

Gene suppressing the expression of another gene.

Hypostatic Gene

Gene affected by the epistatic gene.

Recessive Epistasis

Requires homozygous recessive epistatic gene.

Dominant Epistasis

Requires at least one dominant allele to suppress.

Founder Effect

Small population samples lead to reduced genetic diversity.

Bottleneck Effect

Population drastically reduced, affecting genetic diversity.

Gene Flow

Movement of alleles between populations through immigration.

Natural Selection

Increases frequency of beneficial alleles in a population.

Directional Selection

Shifts allele frequency towards extreme phenotypes.

Diversifying Selection

Extremes are favored, norm is selected against.

Stabilizing Selection

Favors average phenotypes, extremes are selected against.

Hardy-Weinberg Principle

Allele frequencies remain constant in absence of evolution.

Speciation

Formation of new species through evolutionary processes.

Allopatric Speciation

Population divided by physical barriers leading to isolation.

Sympatric Speciation

New species arise within the same habitat.

Prezygotic Barriers

Prevent fertilization from occurring between species.

Postzygotic Barriers

Prevent hybrid offspring from developing into fertile adults.

Adaptive Radiation

Rapid evolution of diversely adapted species from a common ancestor.

Sexual Selection

Increases alleles for traits improving mating success.

Genetic Drift

Random changes in allele frequencies, significant in small populations.

Catastrophic Events

Natural disasters causing sudden changes in allele frequencies.