Meiosis - Genetic Variation

Questions and Answers

What is the primary outcome of meiosis in terms of chromosome number?

Chromosomes remain the same in number

Chromosomes double in number

Chromosomes are halved (correct)

Chromosomes are tripled

Where does meiosis occur in the human body?

In the brain

In the liver

In the gonads (correct)

In the red blood cells

What is the purpose of genetic recombination in meiosis?

To create identical cells

To distribute the same genetic material

To reduce the number of chromosomes

To increase genetic diversity (correct)

What type of cell division is meiosis classified as?

Sexual reproduction Signup and view all the answers

What are the two main phases of meiosis?

Meiosis I and Meiosis II Signup and view all the answers

Which process specifically produces sperm in males?

Spermatogenesis Signup and view all the answers

How many chromosomes do human gametes contain after meiosis?

23 chromosomes Signup and view all the answers

What happens to polar bodies produced during oogenesis?

They die Signup and view all the answers

What is the term for the close association of homologous chromosomes during meiosis I?

Synapsis Signup and view all the answers

What occurs at chiasmata during meiosis?

Exchange of genetic information Signup and view all the answers

How many pairs of homologous chromosomes do humans have?

23 pairs Signup and view all the answers

What primarily holds homologous chromosomes together during synapsis?

Synaptonemal complex Signup and view all the answers

What is the result of crossing over during meiosis?

Genetic recombination Signup and view all the answers

What is the primary difference between Meiosis II and mitosis?

Meiosis II produces four haploid daughter cells. Signup and view all the answers

During which phase of Meiosis II do sister chromatids separate?

Anaphase II Signup and view all the answers

What occurs during prophase II of meiosis that is similar to prophase of mitosis?

Chromosomes condense and spindle forms. Signup and view all the answers

What is the consequence of fertilization?

The fusion of a sperm and egg to form a diploid zygote. Signup and view all the answers

What is produced at the end of meiosis II?

Four haploid daughter cells. Signup and view all the answers

At what stage in meiosis do the chromosomes line up at the equator?

Metaphase II Signup and view all the answers

What is a karyotype?

An organized picture of chromosomes arranged by size. Signup and view all the answers

Which chromosomes constitute the sex chromosomes in humans?

Both X and Y chromosomes. Signup and view all the answers

What is the definition of a zygote?

A fertilized egg Signup and view all the answers

Which chromosomes are responsible for determining the sex of an offspring?

Both X and Y chromosomes Signup and view all the answers

What is non-disjunction during meiosis?

The failure of chromosomes to separate Signup and view all the answers

What type of disorder is Turner’s Syndrome?

Monosomy disorder Signup and view all the answers

What is an example of a trisomy disorder?

Both B and C Signup and view all the answers

What results from non-disjunction during meiosis?

Abnormal chromosome numbers in zygotes Signup and view all the answers

Which syndrome is associated with Trisomy 18?

Edwards Syndrome Signup and view all the answers

Which statement correctly describes non-disjunction?

It can result in zygotes with abnormal DNA amounts. Signup and view all the answers

What occurs during the S phase of the cell cycle?

Chromosomes replicate Signup and view all the answers

What is the term for the two identical copies of a chromosome after replication?

Sister chromatids Signup and view all the answers

Which of the following phases constitutes the longest duration in meiosis I?

Prophase I Signup and view all the answers

What happens during synapsis in prophase I of meiosis?

Homologous chromosomes pair up Signup and view all the answers

What term refers to chromosomes that carry genes controlling the same inherited traits?

Homologous chromosomes Signup and view all the answers

What is a tetrad in the context of meiosis?

Two homologous chromosomes or four chromatids Signup and view all the answers

Which of the following statements about homologous chromosomes is incorrect?

They are identical copies of a single chromosome. Signup and view all the answers

How many rounds of division occur in meiosis?

Two Signup and view all the answers

Study Notes

Meiosis Overview

Meiosis is a type of cell division that produces gametes, reducing the chromosome number from diploid (2n) to haploid (n).
It occurs in gonads (testes or ovaries) and is essential for sexual reproduction.
In humans, gametes contain 23 chromosomes.

Phases of Meiosis

Meiosis involves two sequential divisions: Meiosis I and Meiosis II.
Meiosis I includes five phases: Prophase I, Prometaphase I, Metaphase I, Anaphase I, and Telophase I.
Meiosis II is similar to mitosis, dividing sister chromatids.

Spermatogenesis and Oogenesis

Spermatogenesis produces sperm, while oogenesis produces eggs (ova).
Each gamete ends up with half the number of chromosomes (n=23).

Importance of Genetic Recombination

Genetic recombination occurs during crossing over in Prophase I, where non-sister chromatids exchange segments of DNA.
This process increases genetic diversity among offspring.

Homologous Chromosomes

Homologous chromosomes are pairs of chromosomes that contain the same genes but may have different alleles.
They align during Meiosis I in a process called synapsis, forming tetrads.

Karyotype

A karyotype is an organized profile of an individual’s chromosomes, arranged by size and shape.
Humans have 23 pairs of chromosomes: 22 pairs of autosomes and one pair of sex chromosomes (XX for females, XY for males).

Fertilization

Fertilization is the union of a sperm and an egg, resulting in a zygote with a diploid chromosome number (2n=46).

Non-Disjunction

Non-disjunction occurs when homologous chromosomes or sister chromatids fail to separate during meiosis.
This results in gametes with abnormal numbers of chromosomes, leading to genetic disorders.

Common Non-Disjunction Disorders

Down Syndrome (Trisomy 21): Extra chromosome 21.
Edwards Syndrome (Trisomy 18): Extra chromosome 18.
Patau Syndrome (Trisomy 13): Extra chromosome 13.
Turner Syndrome (Monosomy 23): Only one X chromosome (X0).
Klinefelter Syndrome (Trisomy 23): Extra X chromosome in males (XXY).

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the fascinating process of meiosis and understand how it contributes to genetic variation in offspring. This quiz delves into the rules of genetic recombination and how traits are inherited from parents. Test your knowledge on the key concepts surrounding meiosis.