Elodea Cells 400x Magnification cell wall cytoplasm nucleus Elodea Cells 400x Magnification

It all starts in the nucleus Introduction to Genes It all starts in the nucleus How do cells know what to do and how does a single cell become a full grown multicellular plant or animal?

How do your cells know what to do?

NUCLEUS Found in both plant and animal cells Control Center of the cell. “Brain” of the cell. Directs all of the cells activities But how?

DNA (found in the nucleus)

In most plant and animal cells, chromosomes come in pairs Instructions for determining cell structure and function are found in chromosomes inside the nucleus of the cell In most plant and animal cells, chromosomes come in pairs One from each parent Humans usually have 46 chromosomes in 23 pairs What about other species?

CHROMOSOMES Organism # of chromosomes per cell Humans 46 Cow 60 Chicken 78 Corn 20 Butterfly 80 Fruit Fly 8

CHROMOSOMES Karyotype

DNA: Deoxyribonucleic acid Chromosomes are made of DNA DNA forms a long winding shape called a helix. This helix has two main strands, so it is a double helix.

DNA: Deoxyribonucleic acid Scientists James Watson and Francis Crick created the double helix model that we know today DNA is made up of building block molecules represented by the letters A (adenine), T (thymine), G (guanine) and C (cystine) The order of these building blocks is what makes up our genetic code

GENES DNA contains segments called genes Most genes provide the cell with instructions for making proteins (using a code) This code consists of sequences of A, T, G and C Thus, genes control the cell’s activities and much of it’s structure

FROM GENES TO PROTEINS The Code: A always pairs with T C always pairs with G Each DNA molecule contains hundreds or thousands of genes Genes control many features such as hair and eye colour, food allergies, height Genes determine what kinds of proteins your cells can make which determines how your body functions and/or looks Environmental factors can play a role as well

Each protein is designed to carry out a specific job FROM GENES TO PROTEINS Each protein is designed to carry out a specific job Some examples include: Building parts of the body Couriers to carry materials throughout the body Transfer signals within the body Speed up chemical reactions within the body