1. Genetic and Environmental Foundation
We are made up of cells
Each cell has a nucleus
The nucleus contains chromosomes
There are 23 pairs of chromosomes
One chromosome is inherited from the mother and one from the father

2. Genetic Code
Each cell in your body contains chromosomes. Each chromosome contains a long molecule of DNA. Each DNA molecule contains many genes
Chromosomes are made up of a chemical substance called deoxyribonucleic acid (DNA)
A gene is a segment of DNA along the length of the chromosome
Genes can be of different lengths
The DNA can duplicate itself through a process called mitosis

3. The Sex Cells
There are two types of sex cells: male and female. The male sex cells are sperm, while the female sex cells are ovum.
Meiosis is the cell division process
When the sperm and ovum unite at conception, it results in a zygote

4. Determining whether it is a boy or girl
22 of the 23 pairs of chromosomes are matching pairs (this is known as autosomes-they are not sex chromosomes)
The 23rd pair consist of sex chromosomes
In females, this pair is called XX
In males it is called XY
The X is a large chromosome
The Y is a short chromosome
The sex of the new organism is determined by whether an the sperm is bearing an X or Y chromosome which fertilizes the ovum

5. Multiple Offspring
Twins are created when a zygote that has started to duplicate separates into two clusters of cells that develop into two individuals
These are called identical or monozygotic twins because they have the same genetic makeup

6. Chromosomal Abnormalities
Down syndrome is the most common chromosomal disorder
It occurs 1 out of every 770 live births
In 95% of the cases, it results a failure of the 21 pair of chromosomes to separate during meiosis
As a result, the individual receives three of these chromosomes rather than the normal two
The effects of Down syndrome include:
mental retardation,
memory and speech problems
Limited vocabulary
Slow motor development

7. Chromosomal Abnormalities
Individuals who are affected may have
distinct physical features
short, stocky build
A flattened face
A protruding tongue
Almond shaped eyes
Infants with down syndrome are often born with eye cataracts, hearing loss and heart and intestinal defects
Affected individuals who live past age 40 show symptoms of Alzheimer’s disease
The risk of bearing a child with down syndrome rises with maternal age

8. Matching Activity
The goal of this activity is to match the correct answer to the correct phrase.
On your tables you have a set of card with a sentence written on it.
Read each sentence and match each sentence to the correct word
You have three minutes to do this activity
After three minutes, we will go over each sentence and determine what the correct answer is.