3.24 Mitosis

Mitosis is a form of cell division -> result in growth occurs by increase of numbers of cells


Diploid (2n) = number of chromosomes 


Cell will divide in 2 cells each with a nucleus where they both will have diploid nucleus = Cell identical(1. Same number of chromosomes
2. Same set of chromosomes)


Copy of chromosomes = DNA replication ->creates 2 Copy of the each chromosomes which it hold together by the centro-mere. 


Chromosomes will be pair = ' pair of chromatids'


DNA replication take place in the nucelus while it still intact = INTERphase of the cell cycle


Stages of mitosis 


1.Prophase = The break down of nucleus  ( pair of chromatids are visible)
2. Late Prophase = After the nucleus gone, the protein in the cell called spindle extend one pole of the cell to another. 
3. Metaphase = The pair of chromatids move towards the spindle and join one of the spindle fibre by the centro mere. 


4. Anaphase = The Spindle fibre shorten and pull the chromatics apart each other towards each pole. ( separation of the pair of chromatic)


5. Telophase = The nucleus reformed around the chromosomes = new nucleus. Shows the formation of two nuclei at opposite ends of the cell.


6.CytoKinesis = Cell splits into 2. (Not part of mitosis) 

3.16 DNA and Genetic information

There are four different types of bases: adenine (A) with thymine (T) and cystosine (C) with guanine (G).

The bases are used to holds the double helix together in the molecules. Base pair is the pairing between
adenine - thymine / guanine - cytosine to held the double helix together.

Bases order have a sequence ....
A C T G A A C C A G = GENE

Genes is equal to the number and order of bases.

3.15 Genes

Characteristic of DNA = Doublehelix


Section of the chromosomes = gene


Gene carries out the characteristic of organism eg. blood group, petal colour.


The gene are located in the nucleus and the information pass to the cytoplasm where the genetic information transformed to the protein.


This Protein controlled the characteristic of the organism.

3.14 Chromosomes

• Chromosomes are the genetic information within a cell. 

• The chromosomes are composed of a molecules called DNA (DeoxyriboNucleic Acid).

• Section of the chromosomes are called genes. 1 chromosones will have many genes.

• Each genes carry the information for the construction of protein.

• protein gives us characteristic association with the gene eg blood.

• Different organism have different amount of chromosomes                                                                                                                 
• Chromosomes operates in pairs = Homologous pairs.

The gene loci = same gene

characteristic has 2 version of each gene = called Alleles

3.1 Sexual and Asexual reproduction

Sexual reproduction

1. organism that show sexual reproduction show sexes, which we can define as male and female
2.they manufacture cells named gametes which take the form in a male as a sperm cell. In the female it takes shape as a egg.
plant ---> sperm cell is called pollen grain
---> egg cell is called ovule
3. the cell division that produces gametes is called meiosis
affect of meiosis is half the total of adult chromosones in the gamete cell.
Humans ---> total number of chromosones in cells is 46
in gametes the total number is 23 and from going to 46 to 23 is happening by the process called meiosis.
4. in sexual reproducing population there is the process called fertilisation, this is when the gametes cell of the male and female fuse together.
5.in the population we find variation (difference), which is broad

asexual reproduction 

1. asexual reproduction have no sexes
2. populations have no gametes
3. no meiosos but there is mitosis in nucaritotic cells and binary fission
in these cells the chromosones remain constantly
4. there are no gametes there is no cell fusing
5.this population shows small amount of variation due to muatation
and if they are identical know as a clone


( Credits to Jesper Kwant Corrected by Numob <3)