Genetics and Inheritance - Review (Meiosis, Mendelian and Non-Mendelian Patterns)

A set of practice flashcards covering meiosis vs. mitosis, Mendelian inheritance, non-Mendelian patterns, genetic risks, and related examples from the notes.

What is the difference between meiosis and mitosis?

Meiosis involves two rounds of cell division producing haploid gametes with genetic variation; mitosis involves one division producing diploid somatic cells with identical copies.

What does Mendel's law of probability describe in genetics?

The predictable segregation and independent assortment of alleles, leading to expected genotype/phenotype ratios in offspring.

What is a carrier for cystic fibrosis?

An individual with one mutant CF allele and one normal allele; phenotypically healthy but able to pass the mutant allele to offspring.

If both parents are carriers for cystic fibrosis, what is the chance a child will have CF?

25% affected, 50% carrier, 25% unaffected (non-carrier).

Incomplete dominance (blending inheritance)

Heterozygous cross yields an intermediate phenotype, such as pink flowers from red and white.

Pleiotropy

One gene influences multiple, seemingly unrelated traits.

Epigenetics

Study of heritable changes in gene expression caused by mechanisms other than changes in DNA sequence; environment can turn genes on or off.

Polygenic trait

A trait controlled by multiple genes, leading to continuous variation (e.g., skin color).

Genetics of skin color

determined by multiple genes affecting melanin production; more pigment yields darker skin.

Human chromosome basics

Humans have 22 autosome pairs and 1 pair of sex chromosomes; females are XX, males are XY.

Hemophilia and X-linked inheritance

Hemophilia is an X-linked recessive disorder; with a carrier mother, the distribution among offspring can be 25% non-carrier daughters, 25% carrier daughters, 25% healthy sons, 25% affected sons.

Inbreeding and disease risk

Inbreeding (e.g., royal lineages, purebred dogs) increases the chance of recessive diseases due to a small gene pool.

Baldness and X-linkage

Pattern baldness is discussed as an X-linked trait involving the AR gene, contributing to male-pattern baldness.

Mutation timing and development

If a mutation occurs in the zygote or early embryo, it can be carried into many tissues as development proceeds, leading to widespread effects.

Non-Mendelian inheritance patterns

Patterns that do not follow simple dominant-recessive rules, including polygenic traits and epigenetic effects where environment influences gene expression.