1. Ch. 14 The Human Genome

2. Ch. 14 Outline 14-1: Human Heredity Human Chromosomes Human Traits
Human Genes
From Gene to Molecule

3. Ch. 14 Outline 14-2: Human Chromosomes 14-3: Human Molecular Genetics
Human Genes and Chromosomes
Sex-linked Genes
X-Chromosome Inactivation
Chromosomal Disorders
14-3: Human Molecular Genetics
Human DNA Analysis
The Human Genome Project
Gene Therapy
Ethical Issues in Human Genetics

4. Human Chromosomes Karyotypes:
A picture of chromosomes arranged by homologous pairs
Humans have 23 pairs (46 total) chromosomes.
Two of the 46 chromosomes are called sex chromosome because they determine and individual’s sex.
In Human’s:
Female –
Male –

5. Human Chromsomes
Autosomes: the remaining 44 chromosomes. They do not determine the sex of the organism.
All Human egg cells carry a single X chromosome.
Half of all sperm cells carry an X chromosome and half carry the Y.
This is why the ratio of males to females is 50/50.

6. Human Traits
Scientists use a pedigree chart to help study how a trait is passed from one generation to the next.
Pedigree: chart that shows the relationships within a family.

7. How to read a pedigree A circle represents a female.
A square represents a male.
A horizontal line connecting a male and female represents a marriage.
A vertical line and a bracket connect the parents to their children.
A half-shaded circle or square indicates that a person is a carrier of the trait.
A circle or square that is not shaded indicates that a person neither expresses the trait nor is a carrier of the trait.
A completely shaded circle or square indicates that a person expresses the trait.

8. Pedigrees
These Charts are used to infer the genotypes of family members. They can reveal if traits are sex-linked, dominant or recessive.

9. Human Genes Blood Group Genes
Knowing a person’s blood group is important during transfusions.
Two blood groups:
Rh groups
ABO groups

10. The Rh Blood Group
The Rh blood group is determined by a single gene with two alleles: Positive and negative
Rh+ is dominant to Rh-
The Rh factor is named after the Rhesus Monkey where the factor was first isolated
Very important for females to know during pregnancies.

11. ABO Blood Groups There are three alleles for the ABO Blood Group:
IA, IB, I
“i” is the recessive allele. ii  type O blood
IAIB are codominant  type AB blood
IAIA or IAi  type A Blood
IBIB or IBi  type B Blood

12. ABO Blood Groups Safe Transfusions Phenotype Antigen on (Blood Type
Red Blood Cell
Genotype To
From

13. Antigens and Blood

14. Disorders in Humans Genetic Disorders may be caused by:
Recessive Alleles
Ex. CF, PKU, Tay-Sachs
Dominant Alleles
Huntington’s Disease
Codominant Alleles
Sickle Cell Anemia

15. Concept Map Autosomol Disorders caused by Recessive alleles
Dominant alleles
Codominant alleles
include
include
include
Albinism
Galactosemia
Tay-Sachs disease
Huntington’s disease
Sickle cell disease
Cystic fibrosis
Phenylketonuria
Achondroplasia
Hypercholes-
terolemia

16. Sex-Linked Genes
Sex-linked genes: Genes Located on the sex chromosomes
Many genes are located on the X chromosome
Sex-linked disorders are caused by genes on the X or Y chromosome
Colorblindness, Hemophilia

17. X-Chromosome Inactivation
Females have two X chromosomes but males only have one. How do females cells “adjust” to having an extra X if males can survive with just one?
One of the X chromosomes in female cells are randomly switched off. Those are called Barr bodies.

18. Chromosomal Disorders
Nondisjunction: failure of chromosomes to separate correctly in meiosis
This leads to an abnormal number of chromosomes in gametes
Ex: Down Syndrome (3 copies of chromosome 21  “trisomy”)

19. Homologous chromosomes fail to separate
Nondisjunction
Homologous chromosomes fail to separate
Meiosis I:
Nondisjunction
Meiosis II

20. The Human Genome Project
A research project to sequence (identify in order) all the bases in Human DNA ~3.2 BILLION pairs!
Some discoveries:
A large amount of DNA does not code for proteins
Humans only have 30,000-40,000 genes (scientists expected 100,000)

21. The Human Genome Project Website
Really interesting Information about the Human Genome Project. It might help you understand stuff better.
EDUCATE YOURSELF!

22. Gene Therapy
Information about the human genome might be used to cure genetic disorders though the use of gene therapy.
Gene therapy: the process of changing a gene that causes a genetic disorder
It replaces the faulty gene with a normal, working gene

23. Ethical Issues
If Human cells can be manipulated to cure disease, should biologists try to engineer people with specific traits?
What will happen to the human species if we design our own bodies?
Should we clone humans?