Question

Meiosis (what cells are produced by this process?):

• Location of meiosis (where are gametes (eggs and sperm) produced?)

• How many cells are produced from meiosis? Are they haploid or diploid? Are they genetically unique or clones of the parent cell?

• Know that crossing over between chromosomes and independent assortment of chromosomes are the source of genetically unique gametes and offspring.

Answer 1

Meiosis -It is a cell division process which takes place in the sex cells present in reproductive organs in animals and plants.Meiosis in plants produce spores and animals gametes(sperms and eggs).Sex cells are called parent cells and they are diffrent from somatic cells (body cells) as they have half of the chromosomes (23) compared with body cells which have 46 chromosomes.

Diploid (two set of chromosomes) to haploid cell division(single set of chromosomes) happense in meiosis.During fertilization sperm and eggs both haploid fuse to form dipoid sets embryo.

In animals meiosis takes place in reproductive organ testes in male and ovary in female.

In plants meiosis takes place in reproductive organ anther in male to form microsporsngia and ovary in female to form megasporangia.Meiosis followes two division,meiosis i and meiosis ii.

Meiosis i-Reduction division

Two daughter cells are formed from half of the parent cells chromosomes.2 haploid cells

Early prophase-->late prophase--a)leptotene b)zygotene c)pachytene d)diplotene e)diakinese.

metaphase--->anaphase-->Telophase

Meiosis ii-Copying division

2 haploid cells undergo mitotic division to form 4 haploid cells.

Late prophase-->Metaphase--->Anaphase--->Telophase-->Cytokinesis.

Meiosis makes combination of new gene which results in variation in offsprings.Crossing over which takes place in meiosis 1,late prophase is the core stage responsible for variation(geneticaly unique) except identical twins.The exchange of gene fragments from paternal and maternal chromosomes leads to form recombinant chromatid which can influenece species evolution.

Genetic variation are found in organisms which reproduce sexually which results in the formation of all new set of gene combination responsible for variation in different individuals of same species.The random movement of chromosomes to thye opposit poles which happense during anaphase is called independent assortment responsible for maternal and paternal mixture in offspring.Every egg and spem has its unique gene comination,when fused form unique individual which happense just by sheer chance.