Chromosomal Inheritance and Mutations

These flashcards cover key concepts related to chromosomal inheritance, mutations, specific genetic disorders, and their implications.

Mutation

A permanent change in the DNA sequence of an organism.

Tay-Sachs disease

An autosomal recessive disorder caused by mutation in the Hex-A gene leading to nonfunctional enzyme that fails to breakdown lipids.

Symptom of Tay-Sachs disease

Progressive neurodegeneration, loss of motor skills, and a 'cherry-red' spot in the eye.

Huntington's disease

An autosomal dominant disorder characterized by CAG repeat expansion, leading to involuntary movements and cognitive decline.

Phenylketonuria (PKU)

An autosomal recessive condition caused by a mutation in the phenylalanine hydroxylase gene.

Variegated leaves

Leaves that have multiple colors in a pattern due to the lack of chlorophyll in certain cells.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during cell division.

Result of nondisjunction in meiosis I

All four gametes will be abnormal (N+1, N+1, N-1, N-1).

Result of nondisjunction in mitosis

Creates a mosaic organism where some cells have an abnormal number of chromosomes, commonly seen in cancer cells.

Symptoms of trisomy 21 (Down syndrome)

Flattened facial structure, almond-shaped eyes, short stature, intellectual disabilities, and heart issues.

Impact of missing or extra chromosomes on plants

Plants are more tolerant to aneuploidy, leading to polyploidy which results in larger flowers, fruits, and increased vigor.

Why mutations are necessary for evolution

They are the ultimate source of genetic variation, allowing populations to adapt to environmental changes.