Question

1. Compare the processes of mitosis and meiosis. Be sure to describe the similarities and major differences.

2. Explain what alleles are and describe the difference between an autosomal dominant and autosomal recessive disorder.  

Answer 1

Similarities: 1.Both Mitosis and Meiosis are types of cell division in which one cell gives rise to more than one cell. 2.Both follow duplication of chromosomes. Both include breakdown of the nuclear membrane.

3.Both require spindle fibers to move chromosomes around.

4.Both require chromosomes to line up in the middle of the cell (although in mitotic division, the chromosomes line up single file, whereas in meiosis 1 of meiotic division, the chromosomes line up in pairs (homologous).

5.Meiosis 2 of meiotic division is similar to mitotic division in that the chromosomes line up single file.

There are many differences in meosis and mitosis:

1-Meosis takes place in generative cells while mitosis takes place in somatic cells.
2-At the end of meosis, four progeny cells are produced while in mitosis two progeny cells are produced..
3-Meotically produce progeny cells have half number of chromosomes as there parental cells while mitotically produced progeny cells have same number of chromosomes as there parental cells.
4-During meosis, crossing over takes place in meosis I (pachytine stage of prophase I) which is one of the man cause of natural variation while in mitosis crossing over doesn't take place.

ALLELES

An allele is a variant form of a gene. Some genes have a variety of different forms, which are located at the same position, or genetic locus, on a chromosome.

>The difference between the autosomal recessive from the autosomal dominant trait is that in the former both alleles of the trait that received from both parents are recessive (homozygous), while in the latter the alleles are dominant.

Also autosomal recessive traits are traits which are not able to express themselves in a heterozygous condition while autosomal dominant diseases are caused by autosomal dominant traits which can express in hetetozygous condition.