Meiosis Unit Flashcards

Questions and Answers

What does 'homologous' refer to?

One set of chromosomes

Two sets of chromosomes; each chromosome from male has a corresponding chromosome from female (correct)

Only in haploid cells

Cells without genetic material

What does 'diploid' mean?

Two sets of chromosomes

What are other names for diploid?

Body cells, somatic

What does 'haploid' refer to?

One set of chromosomes Signup and view all the answers

What are other names for haploid?

Sex cells, gametes Signup and view all the answers

What is meiosis?

A process where the number of chromosomes per cell is cut in half Signup and view all the answers

Meiosis is to (haploid, diploid)

2 diploid to 4 haploid Signup and view all the answers

What is a tetrad?

A pair of chromosomes that contains 4 chromatids Signup and view all the answers

What is a chromatid?

One half of a chromosome Signup and view all the answers

What is crossing-over?

A process where the chromatids of homologous chromosomes exchange genetic material Signup and view all the answers

What is a zygote?

A fertilized egg Signup and view all the answers

How many sets of genes are found in most adult organisms?

2 complete sets Signup and view all the answers

What does '2N' represent?

The number of diploid chromosomes Signup and view all the answers

What does 'N' represent?

The number of haploid chromosomes Signup and view all the answers

What events occur during prophase I?

Replicated chromosomes pair with homologous counterparts; spindle forms; nuclear membrane starts to dissolve Signup and view all the answers

What events occur during metaphase I?

Paired homologous chromosomes line up at the equator of the cell Signup and view all the answers

What events occur during anaphase I?

Spindle fibers pull homologous chromosomes towards opposite ends Signup and view all the answers

What happens in telophase I/cytokinesis?

Nuclear membrane forms around chromosome clusters; cytokinesis creates 2 new cells Signup and view all the answers

What occurs during prophase II?

Chromosomes become visible; centrioles duplicate Signup and view all the answers

What occurs during metaphase II?

Sister chromatids move to the cell equator Signup and view all the answers

What occurs during anaphase II?

Sister chromatids are pulled apart to opposite poles Signup and view all the answers

What occurs during telophase II?

Nuclear membrane reforms; DNA unwinds; cell membrane begins pinching inward Signup and view all the answers

What happens during cytokinesis after telophase II?

Cell membrane finishes pinching and forms four haploid daughter cells Signup and view all the answers

How is meiosis different from mitosis?

Meiosis produces four genetically different haploid cells, while mitosis produces two genetically identical diploid cells. Signup and view all the answers

What is the purpose of meiosis?

To increase genetic variation and produce haploid gametes. Signup and view all the answers

What kind of cell does meiosis start with and end with?

Starts with diploid, ends with haploid cells Signup and view all the answers

How many cells does meiosis start with and end with?

Starts with 2 diploid, ends with 4 haploid Signup and view all the answers

Where does meiosis happen in the body?

Reproductive organs Signup and view all the answers

How do the cells made compare to the original cell?

They have half the genetic material of the original parent cell Signup and view all the answers

What are some similarities between mitosis and meiosis?

Both replicate DNA, are processes of reproduction, and involve cell division. Signup and view all the answers

What are the differences between mitosis and meiosis?

Mitosis produces 2 identical diploid cells; meiosis produces 4 different haploid cells. Signup and view all the answers

How many usable cells are created in meiosis for males and females?

Males: 4 usable, Females: 1 usable Signup and view all the answers

What are the names of the cells created in males and females?

Male: Sperm, Female: Egg Signup and view all the answers

When does meiosis happen for males?

Constantly; they do not run out Signup and view all the answers

When does meiosis happen for females?

Once a month; eggs will eventually run out Signup and view all the answers

Why is there a difference between males' and females' meiosis?

Males require constant sperm production, while females only need one egg per cycle. Signup and view all the answers

Haploid cells are _____ cells/gametes.

Sex Signup and view all the answers

Diploid cells are _____ cells/somatic.

Body Signup and view all the answers

What process makes diploid cells?

Mitosis Signup and view all the answers

What process makes haploid cells?

Meiosis Signup and view all the answers

What does it mean to be a homologous pair of chromosomes?

Chromosomes with the same traits but different alleles. Signup and view all the answers

The chromosomes in a homologous pair are similar but not identical-what's the same? What's different?

They are coded for the same trait but have different alleles. Signup and view all the answers

What makes up a tetrad?

Two homologous chromosomes Signup and view all the answers

When do tetrads form?

During prophase I of meiosis Signup and view all the answers

What do tetrads have to do with homologous pairs of chromosomes?

They consist of homologous chromosomes. Signup and view all the answers

The word tetrad comes from the root 'tetra' meaning 'four'; what does the 4 have to do with tetrads?

Four chromatids make up a tetrad. Signup and view all the answers

What is the benefit of crossing over?

It creates a new and unique combination of genetic information. Signup and view all the answers

When does crossing over occur?

It occurs in prophase I. Signup and view all the answers

Study Notes

Key Terms and Definitions

Homologous: Sets of chromosomes where each chromosome from one parent corresponds to one from the other parent.
Diploid: Cells containing two sets of homologous chromosomes; also referred to as body cells or somatic cells.
Haploid: Cells with one set of chromosomes, known as sex cells or gametes.
Meiosis: Cell division process reducing the chromosome number by half, producing haploid cells from diploid cells.
Zygote: The fertilized egg resulting from the fusion of sperm and egg cells.

Meiosis Process

Begins with a diploid cell and results in four haploid cells.
Consists of two rounds of division: Meiosis I and Meiosis II, separating homologous chromosomes and then sister chromatids.

Key Stages of Meiosis

Prophase I: Homologous chromosomes pair up, forming tetrads; crossing over occurs.
Metaphase I: Homologous pairs line up at the cell equator, spindle fibers attach to centromeres.
Anaphase I: Spindle fibers pull homologous chromosomes to opposite poles of the cell.
Telophase I/Cytokinesis: Nuclear membranes form around each cluster of chromosomes; two new cells are created.
Prophase II: Chromosomes become visible again; centrioles replicate.
Metaphase II: Sister chromatids align along the equator; centromeres attach to spindle fibers.
Anaphase II: Sister chromatids are pulled apart to opposite poles.
Telophase II: Nuclear membranes reform, resulting in the division of the cytoplasm and yielding four haploid daughter cells.

Genetic Outcomes and Comparisons

Meiosis increases genetic variation through processes like crossing over.
Mitosis produces two genetically identical diploid cells; meiosis produces four genetically different haploid cells.
Male meiosis results in four usable sperm cells, while female meiosis typically results in one usable egg cell due to unequal cytokinesis.

Differences Between Mitosis and Meiosis

Meiosis occurs in sex cells for reproduction while mitosis occurs in body cells for growth and repair.
Meiosis includes two divisions and results in haploid cells, while mitosis results in diploid cells.

Tetrads and Crossing Over

Tetrads consist of two homologous chromosomes, each with two sister chromatids, forming during prophase I.
Crossing over occurs during prophase I, contributing to genetic diversity by exchanging segments between homologous chromosomes.

Additional Facts

Diploid chromosome number is represented as 2N, while haploid as N.
Meiosis occurs in reproductive organs, necessary for gamete formation.
The difference in meiotic processes between males and females is driven by reproductive strategies: males produce continuously, whereas females have a finite number of eggs.

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Test your understanding of key terms related to meiosis with these flashcards. Each card includes a terminology definition that will help solidify your knowledge on concepts such as homologous chromosomes and diploid cells.