Ψ The Beginnings of life
• The name for a human reproductive cell is gamete, they are either sperm or ovum.
• When a sperm & ovum fuse a living cell called a zygote is formed.
Ψ The genetic code
• The genetic code is a sequence of chemical compounds (called bases) that is held within DNA molecules & directs development, behavior & form.
• The basic unit of genetic instruction is the gene, which is a discrete segment of a chromosome (gene carrier).
• Genes can have several variations (alleles).
• A karyotype portrays a person's 46 chromosomes (23 pairs).
• Sex is determined by the 23rd chromosome pair; XY is male, XX is female.
• The human genome is like a blueprint for creating humans. Your genome contains all the
genetic (gene) information needed to create you, & to determine how your cells function throughout your whole life. Every one of your body cells, contains a copy of your genome. The human genome contains about 25,000 genes.