Meiosis & Mitosis Test Review

During Meiosis II, the secondary oocyte divides unevenly, with one cell(the ovum) receiving half of the chromosomes and nearly all the cytoplasm and organelles, while the other cell, the polar body, is much smaller and eventually degenerates. Propose an explanation why the secondary oocyte divides in this way.

The ovum will receive more organelles such as the mitochondria for making energy, which will provide the zygote with all of its cytoplasm and organelles, but nuclear division is necessary to produce the correct number of chromosomes in the oocyte.

Cellular division has two parts- mitosis is the division of the nucleus and cytokinesis is the division of the cell into two new cells. Explain why mitosis has to come before cytokinesis and the cell cycle.

To e sure that each daughter cell gets a complete set of chromosomes.

Are the genes on a recombinant chromatid the same as the original chromatid?

Yes, each chromosome in the homologous pair contains the same genes in the same place on the chromosome, so a switch between chromosomes would not affect the genes present.

How many single chromosomes are in each of the new cells of telophase?

4

Write a grammatically correct sentence that explains what a chromosome is and why it is important.

A chromosome is made up of DNA and carries the genes needed by the cell to make proteins.

Are daughter cells in meiosis monoploid or diploid?

Diploid

At what phase of mitosis do the replicated chromosomes (sister chromatids) separate?

Anaphase

Diploid Number

Number of chromosomes found in the body cells of an organism The diploid number is twice its haploid number

Before fertilization, what happens to the secondary oocyte?

Proceeds to Meiosis II

In which phase of mitosis do you see the spindle fibers forming?

Prophase

What phrase is used to describe the chromatids after crossing over takes place and the homologous chromosomes separate?

Recombinant chromosomes

During fertilization which two cells come together?

Secondary oocyte & mature sperm

In Meiosis II, during Anaphase II- which structures separated- homologue chromosomes or sister chromatids?

Sister chromatids

Once the chromosomes have formed a pair, what are they called?

Tetrads

What is actually dividing during cytokinesis

cytoplasm (cell membrane divides)

What cells are produced during mitosis? And meiosis?

In mitosis body cells are produced In meiosis sex cells are produced

Describe what happens to the nuclear membrane after prophase

It dissolves away

What happens to the diploid number of chromosomes after fertilization?

It doubles

At which stage in Meiosis I do the pairs of homologous chromosomes come together?

Late Phase 1

Where did each of the cells come from that started Meiosis II?

Meiosis I

Meiosis consists of two cell divisions:

Meiosis I & Meiosis II

Are the alleles on a recombinant chromatid the same as the original chromatid?

No, the chromosomes in the homologous pair can have different alleles for each gene, so a switch in a portion of the chromosome would affect the information in that chromatid.

Considering the genetic makeup of the homologous pairs, will the cells at the end of telophase I be genetically identical to each other?

No, they will not be identical because the alleles on each pair are not identical and the homologous pairs separate.

Haploid number

Number of chromosomes found in a gamete

What is the name given to the cells produced at the of meiosis I in females?

Secondary Oocyte

What is the name given to the cells produced at the end of meiosis I in males?

Secondary spermatocyte

Gametes

Sex cells

At the end of meiosis II in males, what cells are produced?

Spermatid

Considering what you know already know about mitosis in cells, what event must take place during interphase before a cell precedes to division?

DNA replication

In meiosis is a parent cell monoploid or diploid?

Diploid

Egg

Females sex cell

What three phases of the cell cycle are considered interphase?

G1, S, G2

What are the number of divisions in mitosis

1

In meiosis I, during anaphase I, which structures separated- homologous chromosomes or sister chromatids?

Homologous chromosomes

How many replicated chromosomes does the cell contain during prophase?

4

Gonads

An organ that produces gametes Male example: testies Female example: ovary

Tetrad

The four chromatids in a pair of homologous chromosomes that come together as a result of synapsis.

Chiasmata

crossing over points

Purpose of mitosis

increases the number of cells to help the organism grow and or replace dying cells

True or false: In mitosis and meiosis, do centrioles both appear?

true

Meiosis

type of cell division that produces gametes

Are daughter cells in mitosis identical to the parent cell

yes

Do both meiosis and mitosis undergo cytokinesis?

yes

In meiosis do homologous chromosomes pair up during prophase

yes

Meiosis and sexual reproduction each lead to variation in the genetic makeup of every person. Explain how meiotic events, as well as the random fertilization of eggs and sperm, together lead to this genetic variation.

Independent assortment leads to multiple different and paternal gene combinations being produced in the cells as the end of Meiosis I. Chiasma formation between homologous pairs of chromosomes leads to block of genes being swapped between non sister chromatids during separation at anaphase I. This leads to allele combinations on the chromosomes that end up in egg and sperm after Meiosis II. Random fertilization of eggs and sperm means that when zygotes are found, the gene combination will be different each time, even if they come from the same two parents.

Sperm

Male sex cell

Explain why it is necessary that the nuclear membrane disintegrates during mitosis.

So the chromosomes can attach to spindle fibers, line up on the metaphase plate and separate evenly into anaphase

Look at metaphase & anaphase. Suggest the purpose of the spindle fibers during mitosis.

Spindle fibers help make sure each daughter cell gets a complete set of chromosomes by lining them up and separating them.

In which phase do you see that spindle fibers have disappeared?

Telophase

Use a complete sentence to describe what the new cells in telophase might contain if replication of chromosomes did not occur before cytokinesis.

The cells wouldn't contain a copy of each chromosome

At the end of the Meiosis II are four daughter cells. Are they haploid or diploid?

The daughter cells are haploid because each consists of one chromosome from each homologous pair.

Disjunction

The normal separation or moving apart of chromosomes toward opposite poles of the cell during cell division.

Where does mitosis occur

body cells

Copies of chromosomes during meiosis are held by

centromeres

During meiosis 2, chromosomes line up again along the cell's

equator

Are daughter cells in mitosis monoploid or diploid

monoploid

In mitosis is the parent cell diploid or monoploid?

monoploid

Are daughter cells in meiosis identical to the parent cell?

no

In mitosis do homologous chromosomes pair up during prophase

no

Centrosomes (centrioles) migrate to

opposite poles

In what type of organs are cells that enter Meiosis I found?

sex cells

What do these cells (from the previous question{ at the end of meiosis II in males what cells are produced}) eventually become?

the mature sperm

What two structures make up a single replicated chromosome?

sister chromatids

At what point during mitosis has the nuclear membrane reformed?

telophase

How many chromatids are in each replicated chromosome?

2

In mitosis what are the number of resulting daughter cells

2

If a sex cell has 30 chromosomes, how many chromosomes does a skin cell for this organism have?

30

DNA takes place when?

Interphase (Before meiosis I begins)

Synapsis

The pairing of homologous chromosomes

If something goes wrong during Meiosis

The parent cell does not separate evenly, causing a daughter cell to have an abnormal number of chromosomes. If this gamete joins with a normal gamete during sexual reproduction, the new cell that forms lacks the diploid number. An organism that develops from this cell will have a genetic disorder.

What would the ploidy of the zygote be if egg and sperm were produced by mitosis rather than meiosis? How would this affect the ploidy of each successive generation?

The ploidy of the zygote would be genetically identical to the parent cells. Since mitosis doesn't reduce the number of chromosomes by half, each successive generation would have twice as many chromosomes as the last. The homologous pairs of chromosomes found in the zygote have come from each parent. One half of each pair is maternal and the other half is paternal.

Gametoenesis

The process of creating gametes

Where is mitosis in the cell cycle?

Before cytokinesis and after interphase

What is the ploidy of the zygote produced by fertilization-diploid or haploid?

Diploid

Cells with a full set of chromosomes are referred to as diploid or 2n, whereas cells with half the chromosomes are haploid or n. At which stages of meiosis I are the cells diploid and at which stages are they haploid?

Diploid: Prophase, Metaphase, Anaphase Haploid: Telophase II

Polar bodies

In meiosis, one cell receives most of the cytoplasm, making it much larger than the peter three cells. The large cell becomes the female gamete or an egg cell, the three smaller cells are called polar bodies and are not involved in sexual reproduction

How many daughter cells are produced with mitosis, and how many with meiosis?

In mitosis: 2 daughter cells In meiosis: 4 daughter cells

At the end of meiosis I, two cells have been produced. How many replicated chromosomes are in each of these cells?

2

What is 2n described to n when talking about cell division?

2n describes a cell that has two copies of each chromosome (Body cells) n describes a cell that has only one set of chromosomes (sex cells)