L112 Cell Division Meiosis Summary

A series of flashcards summarizing key concepts related to meiosis and cell division, its processes, and implications in genetic diversity.

What is meiosis?

Meiosis is a type of cell division that reduces the number of chromosome sets from diploid (2n) to haploid (n).

How many chromosomes do humans have in somatic cells?

Humans have 46 chromosomes in somatic cells, organized into 23 homologous pairs.

What are homologous chromosomes?

Homologous chromosomes are pairs of chromosomes that are the same length, shape, and carry genes controlling the same inherited characters.

What are the differences between asexual and sexual reproduction?

Asexual reproduction involves one individual producing identical offspring, while sexual reproduction involves two parents creating offspring with unique gene combinations.

What is crossing over and when does it occur?

Crossing over is the exchange of genetic material between non-sister chromatids during prophase I of meiosis, contributing to genetic diversity.

How does independent assortment contribute to genetic variation?

Independent assortment occurs when homologous chromosome pairs orient randomly during metaphase I, leading to different combinations of chromosomes in gametes.

What is the result of nondisjunction in meiosis?

Nondisjunction results in gametes with an abnormal number of chromosomes, which can lead to conditions like trisomy or monosomy.

What is Trisomy 21, and what are some of its characteristics?

Trisomy 21, or Down syndrome, is caused by an extra chromosome 21, leading to features like growth failure, mental retardation, and specific physical traits.

What can cause genetic variation in populations?

Genetic variation can arise from mechanisms like crossing over, independent assortment, random fertilization, mutations, and natural selection.

What is the primary role of meiosis in biological organisms?

The primary role of meiosis is to produce gametes for sexual reproduction, ensuring genetic variation through recombination and halving chromosome number.