1. Human Heredity and Genetic Disorders
Honors

2. Heredity
Sex chromosomes =they have genes that determine a persons sex.
Autosomes =no genes for sex determination.
Karyotype is a picture of all 46 human chromosomes grouped together in homologous pairs.
Heredity is the passing on of genetic traits (genes) from parents to offspring
Humans have alleles
(1 from mom/ 1 from dad)

3. Heredity (cont.) -2 copies(alleles) =3 types of dominance
Humans genes can show :
Complete dominance.
Ex. Brown Eyes hide Blue eyes
Incomplete dominance.
Ex. curly hair + straight hair=wavy hair
Codominance.
Ex. Type A blood + Type B blood = Type AB blood

4. ABO Blood Types Blood types are inherited
2 genes determine your over all blood type
Gene 1 has 3 possible alleles=A, B, or O
Gene 2 has 3 possible alleles=Rh- or Rh+
ABO- blood types controlled by 3 alleles
A. Allele codes for an A antigen (protein) on the surface
B. Allele codes for an B antigen (protein) on the surface
O. Allele codes for no antigen (protein) at all on surface

7. ABO Blood types (cont.)
Genotype Phenotype Blood transfusion AA AO BB BO OO AB

8. What is a genetic disorder?
A genetic disorder is a disease/disabling condition that is a result of mutations in DNA.
2 causes of genetic disorders:
Gene mutations
Chromosome mutations
A gene mutation is when DNA base sequence in a gene changes by inserting, deleting or substituting a base.

9. What is a genetic disorder? (cont.)
Ex.
Cystic fibrosis
Gene on chromosomes 7
Normal dominant allele makes a protien to transport chloride ions across cell.
Mutated recessive allele makes a protien that does not transport chloride ions across cell.
Results= mucus that clogs lungs and pancreas= shortened life expectance to early adulthood.

10. Sex linked genetic disorders
The X and Y chromosomes have genes for determining sex traits and some genes for non-sex traits
The X chromosome has more than 1000 genes and the Y chromosome has only 231
Most sex linked disorders are recessive and found on the X chromosome, not the Y chromosome
Males (XY) have just one X chromosome. So all X-linked disorder alleles are expressed in male, even recessive.

11. Sex linked genetic disorders(cont.)
Female XX Male XY
Sex-linked disorder examples:
colorblindness—
Results- Can’t see red/green or colors
Gene on X chromosome.
hemophilia-
Normal dominant gene produces protein that helps create platelets.
Mutated recessive gene produces damaged protein.
Results- doesn’t form properly clotting platelets

13. Sex Linked Genes (continued)
Males have only one X chromosome
They will ALWAYS inherit ANY genetic disorder found on the X chromosome even if it recessive.
Female must get 2 recessive x linked alleles to have disorder.

14. Red Green Color Blind Test

16. C= Normal vision (dominant) c = colorblind vision (recessive)
How Do we Write it?
C= Normal vision (dominant) c = colorblind vision (recessive)
XC = Normal Vision
Xc = Colorblind Vision

17. Female with regular vision; carries recessive gene for colorblindness (CARRIER)
Female colorblind, carries both recessive
Female normal vision, not carrier
Male, Normal vision
Male, Colorblind
XCXc
Xc Xc
XCXC
XCY
XcY

18. XHXh Xh Xh XHXH XHY XhY Female hemophilia, carries both recessive
X Linked Disorder-hemophilia (recessive). H=normal clotting. h=hemophilia <PRACTICE>
Female with regular blood clotting; carries recessive gene for hemophilia (CARRIER)
Female hemophilia, carries both recessive
Female normal blood clotting, not carrier
Male, Normal blood clotting
Male, hemophilia
XHXh
Xh Xh
XHXH
XHY
XhY

20. Chromosomal disorders
Chromosomes disorders result when a person is missing a chromosome or has an extra chromosome or if large part of chromosomes are deleted or added
Most chromosome mistake result in death of the baby before it is born
Common occurrence:
non-disjunction-chromosomes don’t correctly separate during meiosis.
This leads to sperm and egg containing more than 23 chromosomes or less.

21. Examples: Down syndrome= an extra 21st chromosome
Turner syndrome= having only X chromosome
Klinefelters syndrome= having extra X chromosomes XXY or XXXY

22. Non-Disjunction Video

24. Down Syndrome
People with Down Syndrome have 3 copies of chromosome 21.
For this reason, Down Syndrome is also called "Trisomy 21".
Down Syndrome is a genetic disorder caused by extra genetic material
can include mental retardation, eyes that slant upward, and heart defects.

27. Cri du chat Syndrome
Cri du chat is a rare syndrome caused by a deletion on chromosome 5.
The name of this syndrome is French for "cry of the cat," referring to the distinctive cry of children with this disorder.
low birth weight and may have respiratory problems.

29. Turner Syndrome
Women and girls with Turner Syndrome have only one X chromosome.
Girls with Turner Syndrome do not develop secondary sex characteristics

31. http://ib. berkeley. edu/courses/ib140/Intersexuality_files/image006

32. Klinefelter Syndrome Men and boys with Klinefelter Syndrome XXY
Often tall and usually do not develop secondary sex characteristics
May develop breast tissue