Mitosis and meosis

Question 1

What is the chromosome structure

Answer 1

Identical chromatids held together by a centromere.
Short top arm = P.
Long bottom arm = Q.
Telomeres found at the end

Question 2

Metacentric, submetacentric, acrocentric and telocentric mean what?

Answer 2

Different potsitions of centromere. Centromere gets higher in respective order, P arm becomes shorter.

Question 3

Describe mitosis

Answer 3

Division of somatic cells

1) Propahase - nuclear membrane disintegrates and protein called kinetichore binds to centromere
2) prometaphase - kinetichore attaches to spindle fibres
3) metaphase- chromosomes line up on metaphase plate
4) kinetichore fibres attached to spindle and centromere shorten pulling chromatids to opposite poles
5) telophase- nuclear envelope reforms and cytokensis beings

Question 4

What are homologous chromosomes?

Answer 4

2 same chromosomes but one maternal and one paternal

Question 5

Describe meiosis

Answer 5

Division of germline cells

Question 6

Describe meiosis

Answer 6

Division of germ line cells= four non-identical cells. 2n->n

Meiosis 1
Homologous chromosomes line up and separate

Meiosis 2
Chromosomes line up and chromatids separate

Random assortment of chromosomes and crossing over leads to variation

Question 7

What is spermatogenesis?

Answer 7

Cell division to produce male gametes

Spermatogonium (2n) is the germ line stem cell. Differentiates into primary spermatocyte which divides by meiosis to produce 4 spermatids (60 day process).

Question 8

What is oogenesis?

Answer 8

Oogonium (2n) differentiates into a primary oocyte (2n) which divides my meiosis to produce 4 cells. 1 of these is the mature ovum and 3 of these are the polar bodies. Mature ovum is larger because takes all of cytoplasm. Polar bodies are disregarded. (12-50 years)