1. Human Genetics
Biology

2. Human Chromosomes Karyotype
Picture of chromosomes arranged in pairs
Autosomes – 44 chromosomes that everyone has no matter what sex they are
Sex chromosomes – 2 chromosomes that determine sex
Females = XX, Males = XY

3. How is sex determined? Meiotic division
Eggs = 22 autosomes, 1 sex chromosome (X)
Sperm = 22 autosomes, 1 sex chromosome (X or Y)
Human genetic disorders can exist within the autosomes (chromosome pairs 1-22) or the sex chromosomes (chromosome pair 23)
Meiotic division

4. Human Genetic Disorders
Changes in autosomal chromosomes

5. Ways genetic disorders happen:
Changes can happen in a DNA sequence within an individual chromosome
-substitution: one nucleotide base is substituted for another
-insertion: an extra base pair not normally present is added to the code.
-deletion: a base pair is subtracted from the normal code

6. Example: Sickle Cell Anemia
Recessive gene on chromosome 11
Results in mutated hemoglobin (protein that allows red blood cells to carry oxygen)
Red blood cells are misshapen (like sickles)
Common in African Americans

7. Changes can happen to a whole chromosome
multiple/missing chromosomes: caused by possession of too many or not enough chromosomes
nondisjunction: failure of chromosome pairs to separate properly during cell division
translocation: small parts of chromosomes break and rejoin other chromosomes

9. Example: Trisomy 18 Edward’s Syndrome 99 Balloons:
Most die before birth; those born die within 2 months
Heart abnormalities
Difficulty breathing
Small in size
99 Balloons:

10. Human Genetic Disorders
Changes in sex chromosomes

11. Sex Chromosome Abnormalities
X-linked (previously covered in class)
Chromosomal abnormalities on the 23rd pair of chromosomes
Jacob’s Syndrome

12. Male Sex Chromosome Abnormalities
Klinefelter Syndrome
Males with 2 X chromosomes (XXY)
Tend to be overweight, tall
Some feminine traits (breasts, higher pitched voice)
Sperm count is low
Hormone injections can help

13. The Human Genome Project
Sequence all the DNA in a human cell
Find out what protein that DNA codes for
Better understand human genetics and how our DNA works
Cure diseases?

14. Gene Therapy
With Human Genome Project, we understand what our genes do
With gene therapy, we can try to fix them
Cure genetic diseases
Replace faulty genes with the correct one
Cells begin to produce the proper protein and disease is cured!