1. Genes and Chromosomes

2. Gene Segment of DNA whose sequence codes for a specific product – Examples: physical trait, RNA, enzymes etc. Genes are located on chromosomes

3. Alleles Alternate forms of a gene Cause variations and diversity

4. Chromosomes Homologous chromosomes contain same genes but can have different alleles Humans have 44 autosomes and 2 sex chromosomes Female = XX; Male = XY Which parent determines the sex of the child?

5. Identifying and Studying Chromosomes Chromosome samples obtained (by amniocentesis for fetus) Chromosomes stained, photographed, cut out, matched up by size, shape, and banding patterns and arranged in order to form a karyotype Allows for determination of sex and chromosomal abnormalities

6. Karyotyping: Picture of an individual’s chromosome

7. Can you see the extra chromosome?....... This one shows an extra chromosome #21 – called trisomy 21. A person with this karyotype has Down’s Syndrome.