a. Define the term crossing over. (2 points) b. Explain why crossing over is imp

ID: 86542 • Letter: A

Question

a. Define the term crossing over. (2 points)

b. Explain why crossing over is important in meiosis. (3 points)

~~1.What are the two main differences between mitosis and meiosis? (4 points)

~~2.Answer the following questions:

a. Explain the difference between mitosis and cytokinesis. (4 points)

b. When does mitosis occur during the cell cycle? (2 points)

c. When does cytokinesis occur during the cell cycle? (2 points)

~~3.Explain the differences that occur during cytokinesis of plant and animal cells. (5 points)

~~1.What are haploid cells and diploid cells? Which stage during meiosis are haploid cells formed? (5 points)

~~2.Why is it important that haploid gametes be produced in animals? (5 points)

~~3.During which stage of meiosis do sister chromatids separate? (3 points)

How might the information gained from this lab pertaining to mitosis and meiosis be useful to you, or how can you apply this knowledge to your everyday life as a non-scientist?

Explanation / Answer

a. Crossing over is a process of exchange of genetic material, nothing but parts of chromatid of a pair of chromosomes to produce an off-spring.

b. The importance of crossing over in meiosis can be of the following reasons;

1. Genetic recombination or diversity is generated as in this crossing over phenomenon there is an exchange of DNA between a pair of chromosomes and finally produces a new genetic recombination.

2. It can be considered of high importance because thus by this crossing over phenomenon new offspring can be generated thus evolving a new evolution.

1. a. Mitosis takes place in the somatic cells of the body whereas meiosis takes place in the germ cells.

b. In mitois, daughter cells are identical to the parent and where as in meiosis the daughter cells are not genetically identical.

2. a.

MITOSIS

CYTOKINESIS

More or less same for eukaryotes

Differs based on the type of cell.

Separates genetic material

Separates cytoplasm and cell organelles

It occurs before cytokinesis

It occurs after mitosis

It includes only karyokinesis

Karyokinesis and division of cytoplasm

Two nuclei are produced

Produces two cells enclosing two nuclei

b. During M-phase of the end of interphase cell cycle mitosis occurs.

C. During M-phase of the end of interphase cell-cycle after the Mitosis cytokinesis occurs.

CYTOKINESIS IN PLANT CELL

CYTOKINESIS IN ANIMAL CELL

Wall formation is seen in the region of cytokinesis

Absent

Cytokinesis occurs through cell plate process, clevage is seen only in lower plants

Clevage process

A mid body is absent

Centrally a mid body develops

Cell plate is formed by the fusion of vesicles

No cell plate formation

Formation of cell plate occurs during telophase

It initiates as a constriction in the cell membrane during early telophase

HAPLOID CELLS

DIPLOID CELLS

One complete set of chromosomes (n), one sex chromosome and reproductive cells

Two complete sets of chromosomes (2n)

Two sex chromosomes and not reproductive cells

During Anaphase-1 of meiosis, separation of homologous pair occurs and haploid cells are formed.

2. The fusion between sperm and egg results in 46 chromosomes in the cell hence it is important that haploid gametes to be produced.

3. During Anaphase-2 sister chromatids separate, the centromere separates initially and the chromatids of each chromosome move to the opposite direction and chromatid separation occurs.

This knowledge which I gained might be helpful to design an experiment in a lab for example using onion bulbs like by using whether lectins increase number of cells in mitosis and also helpful for designing and conducting separate investigation on any lab samples.