GCSE EDEXCEL BIOLOGY GENETICS

GCSE EDEXCEL BIOLOGY GENETICS

HideShow resource information
  • Created by: Hugo
  • Created on: 28-02-10 23:50
Preview of GCSE EDEXCEL BIOLOGY GENETICS

First 305 words of the document:

Genetics
There are two types of variation; Discontinuous and Continuous.
Continuous are things like, height and weight etc.
Discontinuous are whether you can roll your tongue or not, what type of blood you have. There are
groups to be fitted into.
There are two ways which influence why we are like we are.
Genetic ­ We inherit characteristics from our parents in the form of genes. Genes are instructions
found on chromosomes in the cell.
Environment ­ Things which eat little are smaller. Amount of light, shelter and overcrowding all
affect the way in which an organism develops.
Mitosis
Long threads of DNA coil. Emerge as double strands known as chromosomes.
Protein Fibres grow from the centriole, forming a lattice work of spindles.
Nuclear membrane disintegrates.
Spindle from each centriole attaches itself to a chromosome.
Spindle pulls each chromatin away (tug of war motion) to the opposite holes.
Nuclear membranes reform around the two sets of chromosomes.
Nuclei and cytoplasm separate forming two new cells.
Meiosis
The DNA coiled makes a pair with another one; one from father one from mother.
Nuclear membrane disappears.
Spindle fibres pull the homologues apart.
Genetic deck is cut in two.
4 unique sets of chromosomes created.
Called haploid cells, most turn to sperm and eggs.
Boy ­ XY
Girl ­ XX
Humans have a diploid number of 46 (46 Chromosomes)
Homozygous Dominant - TT
Homozygous Recessive ­ tt
Heterozygous ­ Tt
Cystic Fibrosis ­ It's recessive. People with only one copy of this gene are the carriers and do not
have the disease. People with two copies of this gene suffer the disease. The lungs clog up because
the mucus becomes too thick.

Other pages in this set

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »