Chromosomes and Meiosis 2022

This set covers chromosomal abnormalities including Klinefelter and Turner syndromes, the mechanical causes of aneuploidy and polyploidy, and the application of polyploidy in agriculture.

Klinefelter syndrome

A form of aneuploidy occurring in males born with an extra copy of the X chromosome ($XXY$), resulting from uneven splitting of sex chromosomes.

Symptoms of Klinefelter syndrome

Lack of facial, pubic, and underarm hair; breast tissue development; small testicles and penis; poor muscle development; and sterility.

Turner syndrome

A condition occurring when a zygote receives only one sex chromosome ($X$), resulting in an $XO$ female embryo.

Symptoms of Turner syndrome

Stunted growth, non-functioning ovaries (infertility), webbed neck (extra skin on the neck), and heart defects.

Nondisjunction

The failure of chromosomes to separate during meiosis, which serves as the cause for aneuploidy conditions.

Diagnosis

The identification of a specific condition.

Prognosis

A prediction regarding how a condition or illness will develop.

Polyploidy

A condition resulting from total nondisjunction where a full set of chromosomes does not separate during meiosis, forming diploid gametes.

Total non-disjunction

A version of failed meiosis where a full set of chromosomes does not separate, resulting in gametes that are diploid ($2n$).

Triploid ($3n$)

A zygote that results from the fusion of a diploid ($2n$) gamete with a haploid ($n$) gamete.

Tetraploid ($4n$)

A zygote that results from the fusion of two diploid ($2n$) gametes, containing four sets of chromosomes.

Artificial Polyploidy

A technique where plant breeders use chemicals to prevent the spindle from forming, stopping chromosomes from separating and creating cells with twice the normal number of chromosomes.

Advantages of polyploidy in plants

Larger and more vigorous plants, larger flowers or fruits, and the production of seedless fruits due to sterility.

Triploid crops

Examples include bananas, apple, citrus, and watermelon.

Tetraploid crops

Examples include potato and peanut.

Hexaploid crops

Examples include wheat and oats.