Genetics

=Genetics=

In each human cell there are 23 chromosomes.It is found in the nucleuas of each human cell, in the chromosome there is 3m of DNA coiled and packaged. In each chromosome there are little sections called genes. Genes determine what we look like and each gene in each chromosome controle a specific thing. for exapmle the colour of our eyes, the color of our hair, if we have hairy or non hairy legs.

There is a really awesome slide show on this website but I dont know how to put it on so here's the link: http://learn.genetics.utah.edu/units/basics/tour/

A feature who's appearance is determined by inheritance is called a trait. The actual object which is inherited is called a //gene//. Genes determine the appearance of traits. That's a bit confusing. In any group of humans there will be differences in features such as skin colour, eye colour, height, foot size, hair curliness/colour, etc. When these differences are caused by environment (e.g. sun tanning) or by actions (e.g. hair curling) they are classifyed as **__aquried variation.__** Differences which are determined by what we receive from our parents at coneption are classifyed as **__inherited variation__** (e.g. eye shape, body shapes, ear lobe attatched of free etc). Here are some definitions that involve genetics:
 * Genetics** is the study of how genes are inherited and expressed in plants, animals and human beings.


 * aquired variation-** differences causes by the environment or by actions
 * inherited variation-**differences determined by what we recieve at conception
 * gene-** the object we inherit which determines a trait,its a section of DNA,approximately 40,000 genes are in your DNA
 * trait-** a feature whos appearance is determined by inheritance
 * genetics-**the study of how genes are inherited and expressed
 * chromosome-** structure in nucleus consisting of a long string of genes,DNA is tightly packed with chromosomes{DNA 3 meters long}
 * asexual reproduction-** production of identicle offspring by a single parent
 * sexual reproduction-** production of varying offspring by two parents
 * gamete-** special sex cells used to combine genes
 * egg-** a large immoble female gamete
 * sperm-** a small mobile male gamete
 * pollen-** produced by flowers that contain sperm
 * pollenation-** act of transferring pollen from male to female organs
 * fertilisation-** fusing of egg and sperms
 * zygote-** the first cell formed when a sperm fertilises the egg
 * mitosis-** cell division which produces two identicle body cells
 * embryo-** early form of an organism when organs are reconisable
 * meiosis-** cell devision which produces four varying gametes
 * Allel-** The coding for a particular characteristic
 * X and Y-** Sex Chromosome
 * GenoType-** One of the choices a gene can take
 * Phenotype-** The visible outcome for a characteristic