1. Inheritance & Human Genetic Patterns
Chapter 12-13

2. WHY?? Thomas Hunt Morgan Early 1900’s
Used fruit flies, Drosophila melanogaster to identify genetic patterns.
Observed that only male fruit flies had white eyes
WHY??

3. Linkage groups A group of genes located on one chromosome.
These genes are usually inherited together.
Example:
Fruit flies have 4 pairs of chromosomes & four linkage groups.
How many linkage groups do humans have?

4. Sex Determination Sex Chromosomes Autosomes X & Y
Located in 23rd position (human)
XX – female
XY - male
Autosomes
All other chromosomes

5. Sex Linkage
Traits that are linked to sex chromosomes.

6. Gene Maps
Show the relative locations of each known gene on an organisms’ chromosome.

7. Mutations Change in DNA Germ cell mutation Somatic cell mutation
Occurs in gametes
Do no affect the organism
May be passed on offspring
Somatic cell mutation
Occurs in body cells
Not passed to offspring
LETHAL MUTATIONS: cause death usually before birth

8. Gene mutations
Involve a single nitrogen base or larger segment of DNA.
Point Mutations
Substitution, addition, or removal of a single nitrogen base
Mutagen
Environmental factor that damages DNA
Ex. Carcinogens, tobacco, tars, UV radiation

9. Chromosome Mutations Deletion Inversion Loss of a piece of chromosome
Chromosome section breaks off & reattaches in reverse orientation.

10. Chromosome Mutations cont…
Translocation
Chromosome section breaks off & reattaches to another, non-homologous chromosome
Nondisjunction
Failure of a chromosome to separate during meiosis.

11. Results of Nondisjunction
Monosomy
Zygote with 45 chromosomes
Turners Syndrome (XO)
Trisomy
Zygote with 47 chromosomes
Down Syndrome (Trisomy 21)
Klinefelters Syndrome (XXY)

12. Trisomy 21

13. Genetic Traits & Disorders
Single Allele Traits (dominant)
Huntington’s Disease, Achondroplasia (Dwarfism), Cataracts, Polydactyly
Single Allele Traits (recessive)
Albinism, PKU, Cystic Fibrosis, Hereditary deafness, Sickle cell anemia

14. Genetic Traits continued…
X-linked Traits
Colorblindness, hemophilia, muscular dystrophy, ichthyosis simplex
Multiple Allele Traits
Blood Types
Polygenic Traits
Skin, hair, & eye color; foot size, nose length, height
Sex-influenced Traits
Male pattern baldness

15. Detecting Human Genetic Disorders
Genetic Screening
Examination of person’s genetic makeup
Genetic Counseling
Amniocentesis
Removal of amniotic fluid from mother
Chorionic Villi Sampling
Villi contain same genetic makeup of fetus

16. Continued… Karyotype Ultrasound Pedigree
Picture of an organisms’ chromosomes
Ultrasound
Bouncing sound waves off fetus to create an image
Pedigree
Family record that shows how traits are inherited over several generations

17. Pedigree

18. DNA Technology Genetic Engineering Uses of DNA Technology
Used to identify genes for specific traits
Transfer genes for a specific trait from one organism to another organism.
Uses of DNA Technology
Cure diseases
Treat genetic disorders
Improve good crops

19. Transplanting Genes Isolate a gene (ex. Insulin)
Produce recombinant DNA
A combination of DNA from 2 or more sources.
Clone DNA
Allow bacteria time to reproduce
Transgenic animal: A host organism receiving recombinant DNA

20. The Human Genome Project
Goals:
To determine the nucleotide sequence of the entire human genome (approx. 3 billion nucleotide pairs or 100,000 genes)
To map the location of every gene.

21. Gene Therapy
Treating a disorder by introducing a gene into a cell or by correcting a gene defect in a cell’s genome.