1. Genetics
Chapter 11.1,11.2,11.3, and Chapter 14

2. Complex Inheritance Patterns
Incomplete Dominance—When one allele for a gene is not completely dominant over another allele. The hybrid displays an intermediate phenotype.
Ex: In snap dragons (flowers) the red allele is incompletely dominant over the white allele.
RR=red, WW=white, RW=pink

3. Incomplete Dominance

4. Complex Inheritance Patterns
Codominance—When both alleles for a gene are expressed. The hybrid displays both phenotypes.
Ex: In chickens the alleles for black and white feathers are codominant.
BB=black, WW=white, BW=speckled
(both b and w feathers)

5. Roan cattle display co dominance

6. Co dominance in humans
Sickle Cell Anemia—a human genetic disorder associated with codominance
Sickle cell is more common in people of African or Mediterranean decent
About 1/12 African Americans are heterozygous for the disorder
SS Normal blood cells
ss Sickle shaped red blood cells
Ss ½ normal red blood cells, ½ sickle cells

7. Red blood cells and Sickle cells

8. Complex Inheritance Patterns
Multiple alleles—when there are more than two possible alleles for a trait within a population. (Each individual still receives only two alleles for each trait.)
Ex: Human blood types

9. Human Blood Types 3 possible alleles: A, b and O Blood Types Genotypes
Can donate Blood to
Can receive blood from O OO
Eveeryone AB
everyone A
AA or AO
A, AB
A, O B
BB or BO
B, AB
B, O

10. Complex Inheritance Patterns
Polygenic Inheritance—when traits are controlled by many genes
Ex: AAbbCcddEeFFgg x AaBbCCDdEeFfGg
The genes can be on different chromosomes or the same chromosome (linked)
Traits controlled by polygenic inheritance have a wide variety of phenotypes
Ex: human skin color

11. Pedigree—a genetic family tree

12. Determining the sex of the offspring
Males have the sex chromosomes XY
Females have the sex chromosomes XX.
The female’s egg always has an X chromosome
50% of sperm have an X and the other 50% have a Y. (So it is the sperm that decide the sex of the offspring)

13. Determining the sex of the offspring

14. Complex Inheritance Patterns
Sex-linked traits—traits that are controlled by alleles located on the X chromosome.
(most sex-linked genetic disorders are recessive)
Females need two recessive alleles to exhibit the disorder
Males only need one recessive allele to exhibit the disorder
Examples: Hemophilia and Red-green colorblindness are fairly common sex-linked traits

15. Colorblindness Punnett Square
This is a cross between a “carrier” female and a normal male

16. Environmental Influences
Genes only determine potential
Environmental factors can determine whether genes are expressed
Internal factors—hormones, age
External factors—temperature, nutrition, light, chemicals, viruses

17. Environmental Influences
Nature vs. Nurture
(genetics) (environment)
Genes set the range/scale for a particular trait, and your environment determines the rest

18. Karyotyping Karyotype—a picture of an organism’s chromosomes
Karyotypes are used to diagnose genetic disorders like: *Monosomy (having only one copy of one type of chromosome)
*Trisomy (having three copies of one type of chromosome)
Ex: Trisomy 21, called Down Syndrome
XXY Syndrome, also called Klinefelter’s

19. Normal Female Karyotype

20. Normal Male Karyotype

21. Trisomy 21 Karyotype

22. Klinefelter's Karyotype

23. To review… Normal female – 22 pairs and 2 X chromosomes -> 23 pairs
Normal male – 22 pairs and an X and a Y - > 23 pairs
Down’s syndrome – trisomy 21
Klinefelter's – male with an extra x
Turner’s – female with only 1 X

24. DNA Technology
Cloning—producing cells or entire organisms that are genetically identical to the original.
Applications of cloning:
Creating stem cells to create new organs
Producing new organisms genetically identical to their parents
Using information from cloning to see what happens when certain genes are turned on or off

25. THE LAMB IS GENETICALY IDENTICAL TO SHEEP A
Cloning an organism
56 chrom
56 chrom
No DNA
In a lab
THE LAMB IS GENETICALY IDENTICAL TO SHEEP A

26. DNA Technology
Since ancient times humans have used selective breeding to obtain desired traits in plants and animals.
Inbreeding—when two closely related organisms are mated in order to maintain the desired traits in the offspring.
Inbreeding helps create “purebred” organisms that are homozygous for many traits.
Inbreeding is dangerous for the offspring because recessive genetic disorders are much more common in organisms that are homozygous for most of their traits.

27. DNA technology
Genetic Engineering—When scientists genetically modify the DNA of an organism to obtain desired traits.
Transgenic organisms—Organisms that have DNA from other species inserted into their genome
Ex: Plants with deep sea fish genes inserted to prevent crop damage by frost
Fish with inserted genes to make them grow year-round
Transgenic plants and animals have the potential to improve people’s diets worldwide

28. Alba, the albino rabbit with jellyfish gene

29. Transgenic Organisms Disadvantages of transgenic organisms:
Ethical questions: are we playing God?
We don’t know what would happen if these organisms were released into the wild and started breeding with the natural species. These new, genetically modified species could reproduce, spread, and do damage to the natural ecosystem.

30. DNA technology
Gel Electrophoresis—A technique that allows researchers to identify similarities and differences in the genomes (genes) of different organisms.

31. Gel Electrophoresis

32. DNA technology
DNA Fingerprinting—a technique in which scientists examine a person’s DNA. From your DNA bases scientists can determine if:
Two people are related
A suspect could have been involved in crime
A person carries a gene for a genetic disorder

33. DNA technology
Gene Therapy—a technique used by scientists to change the DNA in a person’s cells in order to cure genetic disorders. Scientists use genetically modified viruses to infect cells and change DNA.

34. Steps of gene therapy Steps:
1. Identify the faulty gene that causes the disease
2. Use restriction enzymes to cut out the normal gene from DNA
3. Splice the normal gene into viral DNA
4. Allow recombinant viruses to infect human cells.