3.24c - Mitosis

interphase

- this is where DNA replication occurs

prophase

-Membrane breaks down

- chromosomes become visible, visible as a pair of chromatidss

late prophase

-inside the cell the network of protein molecules known as the spindle/ fibres 

-chromosome pairs will move towards the spindle and will eventually join to one of the spindle

metaphase

-pair of chromatids --> attach to spindle fibre = centromere

- arranged across the middle, which is arranged across the equator ot the cell

anaphase

- the spindle fibres shorten puling the spindle fibres apart

- the pair of chromatics are moving apart

- moving to the poles of the cell

- separation of pair of chromatics

telophase

- nucleus begin to reform around the chromosomes at either end of the cell

- formation of two nuclei at opposite ends of the cells

cytokinesis

- cell split into two (not part of mitosis)

- in the middle part of the cell it begins to move inwards dividing the cytoplasm in half- membrane fusing across the equator forming two cells ( each contain a chromosome)

3.24b - Mitosis

The chromosomes have to be copied first in order for the cell to split in half, this is called DNA replication

3.24a Mitosis

mitosis=

cell division resulting in growth/ increase in number of cells

beginning with a normal cell with its nucleus 

--> number of chromosomes in the nucleus its called "diploid number" (2n)

humans 2n=46

cats 2n=38

- inside the nucleus each cell have a diploid nucleus which are identical (daughter cell) 

- same # of chromosomes 

- same set of chromosomes

whatever you found in one of the nucleus you will find the same chromosome in the other nucleus

How are the copies made and how will they be separated?

3.16 DNA and Genetic information

chromosomes= contain 1000's gene

gene loci--> double helix ( theres two, theres a pair to be parallel) --> sugar-phosphate backbone ( no chemical details required) is holding these two strands together

In the center theres a group of molecule called bases which there is 4 different type of base:

-adenine (A)

-thymine  (T)

-cytosine (C)

-guanine (G)

These bases are holding the two helixes they are held together by paring each other:

A=T

G=C

these are base pairs, these are always found in the DNA, they are glueing together from one side of the double helix with the other

(expand) =ACTGAACCAG : order of molecule this order is the GENE (inside the nucleus/order of bases/number of bases= construction of protein in the cytoplasm--> giving us the characteristic) 

Q: how to each molecule know which one to pair to?

3.15 Genes

-- the gene carries information:

--characteristics of the organism

-- blood group

-- petal colour

- there will be a gene for each one of those

-the genes are located in the nucleus and the information is pass to the cytoplasm and in the cytoplasm the genetic information is transformed into the protein 

-which this protein controls the production of the characteristics

Q:Why and how do different people have different types of DNA/genes?

3.14 Chromosomes

-chromosomes are the genetic information within a cell

-in each cell there will be a nucleus which contains a number of chromosomes 

- chromosomes are compose of a molecule called DNA (Deoxyribonucleic acid) which forms a shape known as the double helix

- and within the section is called genes

-1 chromosomes contains many genes about 1000 of genes

- each genes carry the information for the construction of a protein 

- the protein gives out the characteristic associated with the genes such as the blood group

- different organism has different number of chromosomes

Q: If chromosomes can't be reproduce, where do we get it from?
- does the chromosomes live inside you forever?
- or do they reproduce

3.1 Sexual and Asexual reproduction

 In a sexual reproduction it involves in a male and a female
--male = sperm cell
-- female = egg cell
as for the plant
-- male=pollen grains
-- female= ovules

-- type of cell meiosis= ( has a number of effect )
-->which half the total number of chromosomes in the gametes cell

fertilisation- this is when a sperm and an egg fuse together which this happens in the sexual reproduction

the variation in a sexual reproduction is broad, so there a lot of differences. however, in asexual reproduction there is small variation.

when does asexual reproduction happen and how does it happen?