Patterns of Inheritance - Chapter 10

Flashcards covering the mechanisms of genetic diversity, Mendelian inheritance laws, dominance types, sex-linked traits, and complex inheritance patterns from Chapter 10.

Homologous Chromosomes

Pairs of chromosomes in a diploid ($2n$) cell that contain genes for the same traits, with one inherited from the mother and one from the father.

Sister Chromatids

Identical copies of a chromosome produced during replication that contain identical alleles.

Crossing Over

Also known as recombination; a process during prophase I where homologous chromosomes exchange genetic information to produce recombinant chromatids.

Random Assortment

Also known as independent assortment; the process where homologous chromosomes randomly assemble at the metaphase plate during metaphase I.

Random Fertilization

A mechanism that increases genetic diversity because any sperm can fuse with any egg, leading to approximately $1$ in $70$ trillion chromosome combinations.

True-breeding

A process involving self-fertilization that always produces offspring with the same seed color as the parent plant.

Cross-breeding

Cross-fertilization between different plants that produces hybrid or mixed offspring.

Complete Dominance

A form of inheritance where the dominant allele completely masks the effect of the recessive allele in a heterozygote.

Incomplete Dominance

The expression of an intermediate phenotype between the dominant and recessive alleles because neither allele is completely dominant (e.g., pink flowers).

Codominance

A condition where different alleles are fully and equally expressed, such as the $A$ and $B$ alleles in the ABO blood type gene.

Monohybrid Cross

A genetic cross tracking the inheritance pattern of a single gene.

Dihybrid Cross

A genetic cross tracking the inheritance patterns of two different genes.

Genetic Linkage

A phenomenon where genes located close together on the same chromosome are less likely to be separated by crossing over, violating the law of independent assortment.

Genotype

The genetic makeup or specific DNA sequence of an organism that codes for its phenotype.

Phenotype

The observable physical characteristics or traits of an organism.

Multifactorial Traits

Traits that show continuous variation and are influenced by both multiple genes and environmental factors.

Pleiotropy

An inheritance pattern where a single gene exerts multiple phenotypic effects.

Penetrance

The proportion of individuals with a specific genotype that actually express the corresponding phenotype.

Epistasis

A type of gene interaction where the expression of one gene influences or affects the phenotype of another gene.

X-linked Trait

A trait coded for by a gene located specifically on the $X$ chromosome.

Hemizygous

A term describing males for X-linked traits because they possess only one $X$ chromosome.

Carrier

An individual who carries a non-functional or potentially harmful allele without suffering physical consequences or expressing the phenotype.

Euchromatin

Light, unwound DNA that is accessible for mRNA transcription during interphase.

Heterochromatin

Dense, tightly packed DNA that is not accessible for transcription.

X-inactivation

A process in females during early embryonic development where one of the two $X$ chromosomes spontaneously inactivates in different cells.

Pedigree

A visual family tree diagram that maps the inheritance of specific traits through multiple generations, using squares for males and circles for females.

Hemophilia A

A recessive $X$-linked disorder often tracked through pedigrees to show sex-linked inheritance.

Huntington Disease

An autosomal dominant disorder characterized by a $50$% chance of an affected parent passing the condition to their offspring.

Polyallelic Trait

A trait where a single gene has more than two possible alleles within a population, such as human blood types.

Polygenic Trait

A trait controlled by multiple different genes working together, typically resulting in a spectrum of continuous variation like human height or skin color.