Inheritance

In the nucleus genetic material is arranged as chromosomes. Humans have 23 pairs of chromosomes and every cell but gametes ( 23 chromosomes in total)  have the full number. 

One chromosome is a very long molecule of DNA and a genes is a tiny section of a chromosome. Each chromosome have about 22,000 genes. Genes tell the cell what proteins (enzymes) to produce. this determines its function. Proteins affect characteristics. E.g Melanin has an effect on eye colour. There are different types of each genes and these are called Alleles, Alleles control what characteristic we have.

Gametes are sex cells. They normaly have half the number of chromosomes. This is because at fertilisation they combine to restore the number of chromosomes. In humans we have one pair of chromosomes that affect gender. A male has XY and a female has **. Because the Zygote is has half of the fathers chromosomes and half of the mothers the offspring is not identical to either parent.

Its a technique used to match DNA. It produces banding patterns made up of DNA fragments. It is used to identify suspects, Paternity tests and compering species.

It involves cutting DNA into short pieces and then separating them into bands.

Genetic Engineering is a techniques that changes the genes of a living thing by changing its genes. This can be done by adding new genes from other organisms of by changes existing genes. Organisms that have been genetically engineered are called genetically modified (GM).

It is useded in crops such as soya to increase yeild. Scienists add a herbicide resistant gene from another plant into the genes of a soya plant and it becomes herbicide resistant. This means that herbicide can be sprayed on the field of soya to kill the weeds. In turn this increases the yeild of crop.

example of how it looks.

Gregor Mendel is known as the father of modern genetics.

He observed that some pea plants produced round peas while others produced wrinkled peas.

He experimented by breeding together different pea plants to see what shape the peas would be in the offspring. He observed that that if a wrinked and round pea plant were crossed together then the resulting offspring were always produced round peas. 

He then bred together two of the F1 generation. They produced a mixture of wrinkled and round peas, but never a cross. 

He repeated his experiment several times to make his results reproducable and to show patterns.

Mendel deduced that inherited characteristics are not lost or blended together. He even figured out that two genetic factors were inherited for each character as the characteristics reapeared in the F2 generation. 

His work was ignored as nobody new about DNA or genes, they didn't realise the importance of his findings untill much later.

Genotype: all the genes it has

Phenotype: the characteristics it displays

F1 : first generation

F2 :the offsprings of the F1 generation.

Selfing : when two individuals from the same cohort breed between themselves. (inbreeding)

Heterzygote: Two differerent alleles.

Homozygote recessive: two recessive alleles

Homozygote dominant : two domintant alleles.