1. Chapter 27 Human Genetics
27.1 Role of Chromosomes
27.2 Human Traits
27. 3 Genetic Disorders

2. 27.1 Role of Chromosomes Chromosome number
How to tell the chromosome number
Sex Determination

3. Human Chromosomes Each sperm or egg has 23 chromosomes
Each body cell has 23 pairs or 46 chromosomes
Different organisms have different numbers of chromosomes

4. # body cell chromosome pairs
Chromosome Numbers
Organism
# body chromosomes
# body cell chromosome pairs
# sex cell chromosomes
Red Clover 12 6
Pea 14 7
Cat 38 19
Rabbit 44 22
Human 46 23

5. Amniocentesis

6. Amniocenteses Dr.’s analyze the amniotic fluid of an unborn baby
Able to count the number of chromosomes
Look for genetic disorders

7. Karyotype Complete set of all chromosomes of a cell of an organism
Arranged and displayed : in pairs, ordered by size.

9. Determining Sex Determined by male sperm
Female eggs carry only X chromosomes
Male sperm can be X or Y
Genotype Male: XY
Genotype Female: XX