Download Genes and DNA

Genes and DNA
Genes are located on chromosomes, which are structures in the nucleus of the cell. Chromosomes are made
of protein and DNA (deoxyribonucleic acid).
Gene material does two things:
1. Supply instructions for processes in the cell
2. Must be able to be copied each time a cell divides
Facts about DNA:
1. Chemical record of all of your characteristics (acts like
a blueprint for your body).
2. Every cell in your body has DNA in it.
3. Everybody’s DNA is different, except for maybe twins.
DNA Structure:
4. DNA is in the shape of a double helix (like a twisted ladder)
5. Two sides of the “ladder” are made of alternating sugar and phosphate molecules
6. Each “step of the ladder” is made of a pair of nucleotide bases.
Four Nucleotide bases:
Adenine always pairs up with thymine.
Guanine always pairs up with cytosine.
Designer Genes
Selective breeding – organisms with certain desirable characteristics are mated to produce a new breed
For example: Many of the eggs you eat are the product of selective breeding because they came from a
chicken that was bred to produce a large amount of eggs
However, scientists now have the ability to produce desired characteristics in some organisms without
breeding. This can be done by genetic engineering.
Genetic Engineering – when scientists manipulate individual genes and transfer them from one organism to
another. (For example: Genetic Engineering made it possible to create a glowing plant by adding to it a gene
found in fireflies.)
Examples of Different Types of Genetic Engineering:
Cloning – copy the DNA if a living organism to grow a new genetically identical one
Genetically modified food - scientists insert carefully selected genes into a plant to give a better yield with
good characteristics. (For example: bigger squash, redder tomatoes or corn that doesn’t need pesticide.)
To see a 3D model of the cell go online to: http://personal.tmlp.com/Jimr57/tour/cell/cell.htm