QUESTION 1: Significance of differences between mitosis and meiosis Mitosis and

ID: 100901 • Letter: Q

Question

QUESTION 1: Significance of differences between mitosis and meiosis

Mitosis and meiosis are the two major processes by which eukaryotic cells reproduce. Compare and contrast the processes of mitosis and meiosis. Consider the stages involved in each and their eventual products. How are the differences biologically significant relative to growth and reproduction? Be prepared to discuss how life is dependent upon both types of cellular reproduction.

QUESTION 2: Mendel’s Principles

Mendel used mathematics and experimentation to derive major principles that have helped us understand inheritance. His ideas were totally different than the explanation for passage of characteristics from parents to offspring that was common to his time. List and describe his principles and describe how each contributes to genetic variability. How might biology have be different if his discoveries had not been lost for decades? Be prepared to discuss the significance of Mendel’s discoveries to modern biology.

Explanation / Answer

Answer 1:-Mitosis and Meiosis are two types of cell division processes in eukaryotes. The processes contain few similar phases such as prophase, metaphase, anaphase and telophase; however there are many differences between the two processes.

Following is the table containing distinguishing points of both the processes-

Mitosis

Meiosis

It takes place in somatic cells

It takes place in reproductive cells

It consists of prophase, metaphase, anaphase and telophase.

It consists of Meiosis I and Meiosis II.

Meiosis I consists of prophase I, metaphase I, anaphase I and telophase I.

Meiosis II consists of prophase II, metaphase II, anaphase II and telophase II.

Number of chromosomes remains same in the daughter cells. (Diploid cells)

Numbers of chromosomes are half in the daughter cells as that of parent cells. (haploid cells)

Number of daughter cells - 2

Number of daughter cells- 4

Chromosomes are always single as in itself

Homologous chromosomes (pairing of chromosomes) are formed in Meiosis I

Synapsis and crossing over of chromosomes do not occur

Synapsis and crossing over of chromosomes occur in prophase I

Chromosomes are arranged along the equator in metaphase

Chromosomes are arranged equally on either side of equator in metaphase I

Sister chromatids separate in Anaphase

Homologous chromosomes separate in Anaphase I, thus forming haploid cells

Meiosis II is similar to Mitosis, in which the two haploid daughter cells formed divide to produce further two daughter cells, leading to formation of net 4 haploid daughter cells.

Life is essentially dependent on both types of cell division processes. To grow, cells need to multiply and to multiply they must divide. It also gives additional lifespan to the organ. Example cells of skin surface are replenished by new cells thus increasing the life of skin. Mitotic division is thus necessary for growth and life. Meiotic division is necessary to maintain the genetic make-up (same number of chromosomes) in offspring. The crossing over makes possible genetic variation and thus increased diversity in the species. Thus both processes are basis of life.

Answer 2:- Mendel had put forth few laws

These laws answered the questions such as why children are similar to parents, but it alos describes the genetic variation observed in each individual. As per law of independent assortment, the genes for a trait assort independently and hence various permutations and combinations are possible. Thus mendalian principle describes basis of genetic variability.

Mendel’s laws laid a foundation for Modern Genetics. Mendel discovered the genetic inheritance pattern a century before it was recognised worldwide. Now genetics have made lot of development but still many defects and diseases which are carried forward by inheritance are yet to tackle. If the Mendels work would have been recognised earlier, the possibility of advances in genetic disorders would have been remarkable