Chromosomes carry genes that determine traits like height and eye color. Humans have 22 chromosome pairs and two sex chromosomes that determine biological sex. Abnormalities in chromosomes can occur through changes in number, structure, or arrangement of chromosomes and genes. Examples of genetic disorders caused by recessive genes include sickle cell anemia and Tay-Sachs disease. Fragile X syndrome is a rare inherited disorder caused by a faulty X chromosome that progressively destroys neurons in the brain and spinal cord.

2. are thread-like molecules that carry
hereditary information for everything
from height to eye color. They carry
all of the information used to help a
cell grow, thrive, and reproduce.
Chromosomes are made up of DNA.
Segments of DNA in specific
patterns are called genes. Your
genes make you who you are.

3. Humans have 22 chromosome pairs and two sex
chromosomes. Females have two X chromosomes;
males have an X chromosome and a Y chromosome.

5. a. Abnormal number
b. Abnormal structure
c. Abnormal arrangement

6. 1. All ova (eggs) contain X
chromosomes
2. Sperm contain either X
or Y
3. XX = girl
4. XY = boy

7. 1. DOMINANT overpowers the
other (recessive) gene
2. Both parents have to have a
recessive gene for it to be
expressed in offspring
- Sickle Cell Anemia
- Tay Sachs

10. a rare inherited disorder that
progressively destroys nerve cells
(neurons) in the brain and spinal
cord.

11. 1. Occurs when the mother
carries a faulty gene
2. Sons have a 50% chance of
manifesting the disorder
3. Daughters become carriers