1. & Human Heredity January 6th/7th, 2008
The Human Genome
& Human Heredity
January 6th/7th, 2008

2. Human Chromosomes 46 total (23 from mom and 23 from dad)

3. Key Terms Sex Chromosomes – two of the 46 total
chromosomes. Determine whether a baby
will be a boy or a girl.
If a baby gets an X from its mom and a Y from its dad, it will be a boy.
If a baby gets an X from its mom and an X from its dad, it will be a girl.
Autosomal Chromosomes – the remaining
44 chromosomes. Where most of your
inherited traits come from.

4. Different Types Of Inheritance
Sex Linked Inheritance- applies specifically to genes located on the X chromosome.
Females – because they have two X chromosomes – are more likely to be carries and not show defective trait. This is because they would need the mutated gene on both chromosomes.
Males – because they only have one X chromosome – are more likely to express the disease. This is because there are really no genes on the Y chromosome to cover the effects of the abnormal X chromosome.

5. Sex Linked Inheritance- ex. Color blindness.
Male (XY) are more likely to be affected and show the trait because they only have one X chromosome.
Males can pass gene only to daughters. Why?

6. Practice
How is color blindness transmitted?

7. Different Types Of Inheritance
Sex Linked Inheritance- w

8. Are You Color Blind?
25. Everyone should see this.
29. People who are RED/GREEN color blind will not see anything.

9. Are You Color Blind?
45. People who are color blind will not see anything.
56. Even people who are color blind should see this.

10. Some Autosomal Disorders in Humans
Type of Disorder
Disorder
Major Symptoms
Disorders caused by
Albinism
Lack of pigment in skin, hair, and eyes.
recessive alleles
Cystic fibrosis
Excess mucus in lungs, digestive tract, liver; increased susceptibility to infections.
Galactosemia
Accumulation of galactose (a sugar) in tissues; mental retardation; eye and liver damage.
Phenylketomuria (PKU)
Accumulation of phenlalanine in tissues; lack of normal skin pigment; mental retardation.
Tay-Sachs disease
Lipid accumulation in brain cells; mental deficiency; blindness; death in early childhood
Achondroplasia
Dwarfism (one form)
dominant alleles
Huntington disease
Mental deterioration and uncontrollable movements; symptoms usually appear in middle age
Hypercholesterolemia
Excess cholesterol in blood; heart disease
Disorders caused by codominant alleles
Sickle cell disease
Misshapen, or sickled, read blood cells; damage to many tissues

11. Practice: Human Inherited Disorders
Autosomal Dominant and Autosomal Recessive Traits
In autosomal recessively inherited disorders, do heterozygotes (also called “carriers”) show the genetic disorder? Why or why not?
In a recessive disorder, what is the probability of an offspring having the disorder when two carriers mate? Prove it.
What are two examples of recessive inherited disorders? Briefly explain the symptoms of each of the disorders.
Why are males more likely to have a recessive disorder than females?
What are the chances two carriers of Huntington’s disease will pass the trait to their offspring? Prove it.

12. Nondisjunction
Normally Chromosome pairs are pulled to opposite ends during Anaphase I and II. Nondisjunction is when chromosomes do not properly separate. Gametes with the wrong number of chromosomes usually do not survive.

13. A few exceptions… Down’s syndrome-Trisomy 21 (47 chromosomes)
Turner syndrome X 0 (45 chromosomes)
Klinefelter;s syndrome – XXX (47 chromosomes)

14. Activity: Looking at Karyotypes
Questions to answer:
Circle the sex chromosomes.
Male or Female? _____
Normal or Abnormal? _________
If abnormal, circle the abnormality and tell what disease is present.

15. Activity: Looking at Karyotypes
Questions to answer:
Circle the sex chromosomes.
Male or Female? _____
Normal or Abnormal? _________
If abnormal, circle the abnormality and tell what disease is present.

16. Activity: Looking at Karyotypes
Questions to answer:
Circle the sex chromosomes.
Male or Female? _____
Normal or Abnormal? _________
If abnormal, circle the abnormality and tell what disease is present.

17. Activity: Looking at Karyotypes
Questions to answer:
Circle the sex chromosomes.
Male or Female? _____
Normal or Abnormal? _________
If abnormal, circle the abnormality and tell what disease is present.

18. Home Work: Genetic Practice
In fruit flies, normal wings (W) are dominant to dumpy wings (w). Two normal-winged flies were mated and produced 298 normal-winged and 100 dumpy-winged flies. What were the parents’ genotypes?
Hemophilia is an X-linked trait. A normal male person has children with a normal female who carries the hemophilia allele. What is the probability their offspring will have hemophilia? What is the probability their daughters will have hemophilia? What is the probability their sons will have hemophilia?
Color-blindness is an X-linked trait. A male who is colorblind mates with a normal female. What is the probability their offspring will have color-blindness? What is the probability their daughters will have color-blindness? What is the probability their sons will have color-blindness?
In fruit-flies, white eyes are a recessive X-linked trait. If a male mates with a female and the offspring came up as follows, what were the parents’ genotypes?
Male, White-Eyed 98
Male, Red-Eyed 102
Female, White-Eyed 99
Female, White-Eyed 101

19. Pedigrees
January 8th/9th, 2008

20. Human Traits Pedigree – a chart that shows the relationships
within a family.
A square represents a male.
A circle represents a female.
A vertical line and a bracket connect the parents to their children.
A circle or square that is not shaded indicates that a person does not express the trait.
A horizontal line connecting a male and a female represents a marriage.
A shaded circle or square indicates that a person expresses the trait.

21. In humans, dimples (D) is dominant to no dimples (d)
In humans, dimples (D) is dominant to no dimples (d). Complete the pedigree below. For each individual, list the possible genotypes and the phenotype of each. dd Dd no
dimples
dimples Dd DD Dd Dd dd Dd Dd
dimples
dimples no
dimples
dimples
dimples
dimples Dd DD Dd DD Dd DD dd dd Dd no
dimples no
dimples
dimples
dimples
dimples
dimples

22. Problem Solving: Using a Pedigree
Introduction:
Imagine that you are a genetic counselor. The pedigree shown illustrates the inheritance of albinism – a condition in which a person’s skin, hair, and eyes lack normal coloring – in three generations of a family. A couple from the family has come to you for advice about how the trait is inherited. Your task is to determine whether the allele for albinism is dominant or recessive.
Question to be answered:
Based on your analysis of the pedigree, is albinism caused by a dominant or recessive allele and how do you know?

23. Procedure:
Inside each circle or square on the pedigree below, label each person with his or her phenotype: normal pigmented skin (NP) or albino (A). Then, inside each circle or square, write down each individual’s possible genotype.
Male
Female
Albino
Normal
pigmented skin

24. Extra Credit
Office Hour Work – Blood Types

25. Blood Groups
Multiple Alleles- More than just two forms of a gene. Much more realistic but much more complicated. Ex. Blood types 3 alleles IA,IB,i

26. Sample Blood type crosses.
Directions: Cross the requested parents on the following pages. For each cross, list genotypes and genotype ratios; phenotypes, and phenotype ratios.
Type A mom with a Type O Dad.
Genotypes Genotype Ratios
Phenotypes Phenotype Ratios
Genotypes Genotype Ratios
Phenotypes Phenotype Ratios

27. Type AB mom with a Type B Dad.
Genotypes Genotype Ratios
Phenotypes Phenotype Ratios
Genotypes Genotype Ratios
Phenotypes Phenotype Ratios

28. Type B mom with a Type A Dad.
Genotypes Genotype Ratios
Phenotypes Phenotype Ratios
Genotypes Genotype Ratios
Phenotypes Phenotype Ratios
Genotypes Genotype Ratios
Phenotypes Phenotype Ratios
Genotypes Genotype Ratios
Phenotypes Phenotype Ratios