Unit 7 – Cell Division, Genetics and Molecular Biology- cell cycle- heredity- life cycles- patterns of inheritance- cellular level populations

MITOSIS – Why?When?

MEIOSIS Why?When?

Background1) Growth = more cells not bigger cells! Why?2) Cells come from cells (spontaneous generation = WRONG!!) Parent cell (1) Daughter cells (2)3) Life cycle of cell = CELL CYCLE4) Division = new cells!5) Not all cells divide at the same rate. Skin, mouth = fast, blood = 3 months, nerve cells = never?6) Structure and function of cells is determined by genetic material within the nucleus.7) Body cells are called SOMATIC cells and they only undergo a kind of division known as MITOSIS.

What is in the nucleus?

Chromosome Related Terms1) All eukaryotic organisms have the same genetic material just different numbers of chromosomes

to “hold” it.- humans = 46 chromosomes- ant = 2- bean = 22- carp = 104- fruit fly = 8

2) Human somatic cells = 46 chromosomes

22 = AUTOSOMES 2 = SEX CHROMOSOMES- Homologous (similar looking)- carry the same genes but different forms (ALLELES) of them at the samelocus

Cells can be:a) Diploid – contains pairs of homologous chromosomes (proper number) (2n = _____)

b) Haploid – contains unpaired chromosomes (n = )

c) Polyploid – sets of more than 2 homologous chromosomesa) Triploidb) Tetraploidc) Octoploid

* Structure of chromosomes – see next slide

* Examining an organisms genetic material = karyotype – Pg. 553- Chromosomes vary in: length, centromere location and staining properties (banding

pattern- Chromosomes can be matched and abnormalities detected- Pairing and numbering of chromosomes (from longest to shortest) is a KARYOTYPE (sex

chromosomes are last)

- Investigation 16.A – Page 554 – Modelling a Karyotype – complete for a normal human and then one with an abnormality – find out what it is.

(1) Chromatid. One of the two identical parts of the chromosome after S phase.

(2) Centromere. The point where the two chromatids touch, and where the microtubules attach.

(3) Short arm (4) Long arm. In accordance with

the display rules in Cytogenetics, the short arm is on top.