Meiosis and Sexual Reproduction

Flashcards covering key concepts in meiosis and sexual reproduction.

What are gametes?

Gametes are reproductive cells, specifically sperm and eggs.

What is the diploid number of human chromosomes?

The diploid number of human chromosomes is 46.

What are homologous chromosomes?

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

What does meiosis produce in terms of chromosome sets?

Meiosis reduces the number of chromosome sets from diploid to haploid.

What happens during meiosis I?

During meiosis I, homologous chromosomes separate, resulting in two haploid daughter cells.

How many daughter cells are produced at the end of meiosis?

At the end of meiosis, four daughter cells are produced, each with a haploid set of unreplicated chromosomes.

What occurs during crossing over?

During crossing over, homologous portions of two nonsister chromatids trade places.

What is independent assortment of chromosomes?

Independent assortment is when homologous pairs of chromosomes orient randomly at metaphase I of meiosis.

Why do haploid gametes have half the number of chromosomes?

Haploid gametes have half the number of chromosomes to ensure that when fertilization occurs, the diploid number is restored.

What occurs between meiosis I and meiosis II regarding chromosome replication?

No chromosome replication occurs between the end of meiosis I and the beginning of meiosis II.

What defines a zygote?

A zygote is a fertilized egg formed when sperm and egg fuse, resulting in a diploid cell.

How does random fertilization contribute to genetic variation?

Random fertilization allows any sperm to fuse with any ovum, creating diverse zygotes.

What is a key difference between meiosis and mitosis?

Meiosis produces four genetically diverse daughter cells, while mitosis produces two identical daughter cells.

What role do mutations play in genetic variation?

Mutations are the original source of genetic diversity, creating different versions of genes called alleles.

How many possible combinations of chromosomes are there for humans due to independent assortment?

There are more than 8 million possible combinations of chromosomes for humans (2^23).

What phase comes after prophase I in meiosis?

The phase that comes after prophase I is metaphase I.

What is the main outcome of crossing over?

Crossing over produces recombinant chromosomes that combine genes from both parents.

During which stage do sister chromatids separate?

during anaphase II.

What are the four phases of meiosis II?

The four phases of meiosis II are prophase II, metaphase II, anaphase II, and telophase II.

What is the importance of genetic variation in a population?

Genetic variation is important for adapting and evolving populations to changing environments.