1. Complex Patterns of Inheritance
Chromosomes and Human Heredity

2. Advanced Genetics Fundamental genetics. Genetics Disorders
Dominant/Recessive traits
Incomplete Dominance
Codominance
Sex-Linked traits
Genetics Disorders
Recessive allele disorders
Dominant allele disorders
Codominant allele disorders
Sex-linked disorders
Chromosomal disorders

3. Genetic disorders
Most genetic disorders are caused by a single allele.
The allele could be either dominant or recessive.
The alleles could be carried on either autosomes or sex chromosomes.

4. Recessive Allele Disorder
A genetic disorder caused by a recessive allele does not show in a heterozygous individual.
The individual can still pass the trait on to his/her child.
Therefore this person is considered a carrier.
AA = Normal Aa = Carrier aa = Affected

5. Recessive genetic disorders
Tay-Sachs Disease
Caused by the absence of the enzymes responsible for breaking down fatty acids called gangliosides
Gangliosides accumulate in the brain, inflating brain nerve cells and causing mental deterioration.
Causes blindness, seizures and death in the early years of life

6. Recessive genetic disorders
Cystic Fibrosis
Affects the mucus- producing glands, digestive enzymes, and sweat glands
Causes a mucous build up in the lungs

7. Dominant genetic disorders
Huntington’s Disease
Causes a breakdown of the nervous tissue
Has an onset of approximately 20 years of age.
Achondroplasia
Genetic condition that causes small body size and limbs that are comparatively short.

8. Codominant disorders Sickle-Cell Disease
Normal red blood cell
Sickle-Cell Disease
Causes the red blood cells to become sickle shaped.
Could cause severe pain, cramping, and blood clotting.
Sickle cells

9. Sex-linked disorders Colorblindness Hemophilia
The person cannot distinguish between two colors, commonly red and green.
Hemophilia
Causes an inability to clot blood.

10. Chromosomal disorders
Down’s Syndrome
Caused by an extra 21st chromosome (Trisomy 21)
Turner’s Syndrome
Caused by a missing X chromosome (Monosomy X)
Klienfelter’s Syndrome
Caused by an extra X chromosome (XXY)

11. Karyotypes Genetic testing can be used to develop a karyotype
A karyotype is a lining up of all the homologous chromosomes from a cell
Images of chromosomes are stained during metaphase
It is used to look for major chromosome abnormalities:
Size of each chromosome
Number of chromosomes
* What is the sex of this child?
* Are there any abnormalities?

12. Karyotypes Turner’s Syndrome Down’s Syndrome
What is the sex of this child?
Are there any abnormalities?
What is the sex of this child?
Are there any abnormalities?
Turner’s Syndrome
Down’s Syndrome

13. Chromosomal Abnormalities
Some of the more serious genetic diseases are caused by a missing or extra chromosome.
This is due to complications during meiosis.
So what would happen if the sister chromatids didn’t separate?
* One cell would be missing a chromosome, and the other cell would have two chromosomes.
Remember meiosis…

14. nondisjunction Don’t Separate
Nondisjunction – when chromosomes don’t separate during meiosis.
This happens primarily during Meiosis II if the centromeres don’t break.
Don’t Separate

15. Fertilization
Results in Monosomy – Having one chromosome instead of a pair.
Could result in Turner’s Syndrome.

16. Fertilization
Results in Trisomy – Having 3 chromosomes instead of a pair
Could result in Down Syndrome

17. Basic Patterns of inheritance
Punnett squares allow us to determine the phenotypes and genotypes of future offspring.
However, this method only works if we know the particular genotypes we’re working with.
So how do we track a specific trait through a family, thus allowing us to use the punnett square method?
Pedigree - A diagram that traces the inheritance of a particular trait through several generations

18. Pedigrees Identical Twins Fraternal Twins
Inferring Genotypes - Knowing physical traits can determine what genes an individual is most likely to have.
Predicting Disorders - Record keeping helps scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and ascertain genotypes.

19. The Royal Family pedigree
* Tracking a trait using a Pedigree