Study Guide Five: Inheritance

Vocabulary practice flashcards covering genetic concepts, molecular processes, inheritance patterns, probability rules, and sex linkage from Study Guide Five.

Central Dogma of Biology

The core framework of molecular biology stating that genetic information flows from DNA to RNA via transcription, and from RNA to functional protein via translation.

Transcription

The cellular process in which a specific DNA gene sequence is copied to synthesize a complementary RNA molecule.

Translation

The biochemical process in which ribosomes synthesize a polypeptide (protein) using the sequence of codons carried by mRNA.

Gene

A discrete sequence of DNA that encodes the information needed to produce a functional RNA or protein molecule.

Allele

An alternative or variant form of a gene located at a specific genetic locus on a chromosome.

Genotype

The specific combination of alleles possessed by an organism at one or more genetic loci (e.g., $RR$, $Pp$, or $I^A I^B$).

Phenotype

The observable physical, biochemical, or physiological characteristics of an organism determined by its genotype and environmental influences.

Chromosome

A threadlike structure of nucleic acids and protein carrying genetic information; human somatic cells contain $46$ chromosomes ($23$ pairs) and gametes contain $23$.

Genome

The complete set of genetic material, including all genes and non-coding regions, present within a cell or organism.

Locus

The specific, fixed physical position or location of a gene on a chromosome (plural: loci).

Wobble Pairing

The flexibility in base pairing at the third codon position that allows multiple distinct codons to encode the identical amino acid, reducing the phenotypic effect of mutations.

Synonymous Mutation

A nucleotide substitution within a coding sequence that does not alter the amino acid sequence of the resulting protein due to codon degeneracy.

Complete Dominance

A form of inheritance where the phenotype of the heterozygote is indistinguishable from the homozygous dominant phenotype because the dominant allele completely masks the recessive allele.

Incomplete Dominance

A pattern of inheritance where heterozygous individuals express an intermediate, blended phenotype between the homozygous dominant and homozygous recessive phenotypes.

Codominance

An inheritance pattern in which both alleles in a heterozygote are fully, equally, and distinctly expressed without blending.

Epistasis

A genetic interaction in which the phenotypic expression of alleles at one gene locus is modified, masked, or dependent on the genotype at a completely different gene locus.

Polygenic Inheritance

An inheritance pattern in which a single phenotypic trait is governed by the additive and cumulative contributions of multiple independent genes.

Pleiotropy

A genetic phenomenon in which a single gene controls or influences multiple, seemingly unrelated phenotypic traits.

Environmental Effects on Phenotype

Variations in phenotypic presentation caused by external surroundings or physiological conditions, such as temperature-sensitive pigment breakdown across different body parts.

Gene Linkage

The condition in which genes located physically close to one another on the same chromosome tend to be inherited together during meiosis, deviating from independent assortment.

ABO Blood Group System

A multiple-allele system governed by three alleles ($I^A$, $I^B$, $I^O$), where $I^A$ and $I^B$ exhibit codominance with each other and complete dominance over the recessive $I^O$ allele.

Chicken Comb Phenotypes

A two-locus trait resulting in four distinct phenotypes based on allele combinations: single comb ($rr\,pp$), rose comb ($R\_\,pp$), pea comb ($rr\,P\_$), and walnut comb ($R\_\,P\_$).

Heterogametic Sex

The sex of an organism that possesses two different sex chromosomes, such as female birds with $ZW$ chromosomes or human males with $XY$ chromosomes.

Homogametic Sex

The sex of an organism that possesses two identical sex chromosomes, such as male birds with $ZZ$ chromosomes or human females with $XX$ chromosomes.

Hemophilia

An X-linked recessive disorder characterized by a deficiency in a clotting protein, leading to excessive bleeding from minor trauma.

X-Linked Recessive Inheritance

A pattern of inheritance for genes located on the X chromosome that causes recessive traits to appear far more frequently in males because they have only a single X chromosome.

Multiplication Rule

A probability principle stating that the likelihood of two independent events occurring together is equal to the product of their individual probabilities ($P(A \text{ and } B) = P(A) \times P(B)$).

Addition Rule

A probability principle stating that the likelihood of an outcome that can occur via multiple mutually exclusive pathways is the sum of their individual probabilities ($P(A \text{ or } B) = P(A) + P(B)$).