BIOL 151-001 Unit 11: Meiosis and Sexual Reproduction Ppt.

Flashcards created to help review key concepts from the lecture on Meiosis and Sexual Reproduction.

What is meiosis?

A form of cell division that creates gametes for sexual reproduction.

What type of cells undergo meiosis in humans?

Cells of the ovaries and testes (germ cells).

What is a gamete?

A cell with only half the DNA, such as sperm or egg in humans.

What are somatic cells?

All other cells of the body that divide by mitosis and produce identical new cells.

How many rounds of cell division are involved in meiosis?

Two rounds of cell division.

What is the advantage of sexual reproduction over asexual reproduction?

It combines genetic material from two organisms, producing unique offspring with almost unlimited variation.

What is the role of meiosis in sexual reproduction?

It reduces the diploid chromosome number to form haploid gametes.

What is a chromosome?

Structures found in cells that contain genetic information.

How many chromosomes do humans have?

46 chromosomes, arranged in 23 pairs.

What is a karyotype?

A picture of a person’s complete set of chromosomes.

What does 'n' represent in genetics?

The number of chromosome copies in a cell.

What are diploid cells?

Cells that have two copies of each chromosome, designated as '2n'.

What are haploid cells?

Cells that have only one copy of each chromosome, designated as 'n'.

What is a zygote?

A fertilized egg that forms when two gametes combine.

How many gametes are produced from one diploid cell undergoing meiosis?

Four gametes are created.

What is independent assortment?

The random distribution of maternal and paternal chromosomes to gametes.

What occurs during crossing over in meiosis?

Exchange of DNA between homologous chromosomes during synapsis.

What are the phases of meiosis 1?

Prophase, Metaphase, Anaphase, and Telophase.

What is the goal of meiosis 1?

To separate homologous pairs into two haploid cells.

What happens during anaphase of meiosis 1?

The spindle pulls one member of each chromosome pair to opposite sides of the cell.

What is the end result of meiosis?

Four non-identical haploid cells (gametes).

What is nondisjunction?

The failure of chromosome pairs to separate during meiosis.

What is aneuploidy?

An abnormal copy number of one or more chromosomes.

What is trisomy 21?

A condition where an individual has a third copy of chromosome 21, also known as Down syndrome.

What are the consequences of trisomy 21?

Mild to moderate mental impairment and characteristic physical abnormalities.

How is the chromosome number reduced in meiosis?

From diploid (2n) to haploid (n) through two rounds of cell division.

What do homologous chromosomes contain?

Corresponding genetic information that may not necessarily be identical.

What type of reproduction do single-celled organisms predominantly use?

Asexual reproduction through mitosis.

What is the difference between sexual and asexual reproduction?

Sexual reproduction involves two parents and genetic variation; asexual reproduction produces clones from a single parent.

How do gametes differ from somatic cells?

Gametes have half the genetic information and are haploid, while somatic cells are diploid and have full genetic information.

What is the significance of crossing over in meiosis?

It increases genetic diversity among offspring.

How does sexual reproduction contribute to environmental adaptability?

It produces genetically varied offspring that may be better suited for survival in changing conditions.

What is the haploid number for humans?

23 chromosomes.

What are the two types of gametes produced in humans?

Sperm and egg cells.

What role do spindle fibers play in meiosis?

They help align and separate chromosomes during cell division.

What is the significance of cytokinesis in meiosis?

It divides the cytoplasm of the parent cell into two daughter cells after telophase.

What condition results when aneuploidy occurs in a zygote?

Most aneuploid zygotes will not survive.

What is an example of a more serious aneuploidy than trisomy 21?

Trisomy 18, also known as Edwards syndrome.

What is the typical outcome of fetuses affected by trisomy 18?

80% of affected fetuses die before birth.

How many chromosomes are present in a diploid adult organism?

46 chromosomes (23 pairs).