1. Patterns of Inheritance
Chapter 10

2. Blending Hypothesis of Inheritance
Blending hypothesis (1800s)
Early explanation of how offspring inherit trait from both parents
Example: if a red flower plant crossed with a yellow flower, the offspring would be orange
Later discarded

3. Gregor Mendel Austrian monk Father of Genetics (study of heredity)
Said parents pass on to their offspring separate and distinct genes
Studied 7 characteristics in pea plants

4. True breeding plants Cross fertilization
A true plant will show the same physical appearance generation after generation after self-fertilization
Cross fertilization
The sperm from the pollen of one true flower fertilizes the eggs in the flower of a different plant

5. Mendel's Experiments
Cross-fertilized 2 true-breeding plants each with contrasting traits (i.e. white and purple flowers)
What color of flowers do you think the offspring plants were?

6. Mendels’s Principle of Segregation
P generation
Parental plants (purebred and true breeding)
F1 generation ( F for filial “son”)
Hybrid offspring
Hybrids
The offspring of 2 different true-breeding varieties
F2 generation
When F1 self-fertilize or fertilize each other

7. Monohybrid Cross Monohybrid cross
Cross fertilization in which only one physical characteristic is considered
In Mendel's cross, all F1 were purple but ¼ of F2 were white

8. There are alternative forms of genes which determine physical appearances
Allele is the term
Example: Flower color can be white or purple

9. For each characteristic, an organism has 2 alleles for genes controlling the physical appearances (one from each parent)
If 2 alleles are the same= homozygous
If 2 alleles are different =heterozygous

10. Dominant alleles determine the physical appearance in a heterozygous individual.
Recessive allele is the other allele that does not affect the physical appearance
Capital letter represents dominant allele : P
Lower case letter represents recessive allele: p

11. Phenotype is the physical appearance Genotype is the genetic makeup
Possible genotype are PP, Pp, pp.

12. The two alleles for a character segregate (separate) during meiosis so that each gamete carries only one allele for each character, known as principle of segregation.

14. Dihybrid Cross: a cross that shows the possible offspring for two traits
Coat Texture: R: Rough r: Smooth
Fur Color: B: Black b: White

15. Intermediate Dominance/ Incomplete Dominance
Heterozygotes have a phenotype intermediate between the phenotypes of the two homozygote
This is referred to as INCOMPLETE DOMINANCE
Rules: (example: snapdragon flowers)
Capital/lower case letters not used
Instead, a C for “color” is paired with a superscript R for “red” and W for “white”
CR CR is red and CW CW is white
CR CW is pink

17. Multiple alleles
Heterozygote express the distinct traits of both alleles
Example: Human blood system
A, B, AB, or o
The letters are antigens found on the surface of red blood cells
Red blood cells may be coated with one protein (A), the other (B), both (AB), or neither (O)
There are six possible genotype combinations

18. ABO blood type is a genetic example of multiple alleles.
There are three alleles in the gene pool for ABO blood type. IA IB i

19. IA codes for protein A
IB codes for protein B
i codes for neither protein A nor protein B.

20. Within this multiple allele pool the gene interactions illustrate both simple dominance as well as co-dominance.
Remember each individual has only two alleles for each trait even if there are multiple alleles in the gene pool.
IAIA
both code for A type blood
IAi

21. Phenotype
Genotype
Protein on RBC (antigen)
Antibodies in the blood plasma
Type A
IA IA and
IA i A b
Type B
IB IB and
IB i B a
Type AB
IA IB
A and B
Type O ii
a and b

22. ABO Blood System
Antibodies (proteins) also found in the blood serum that attacks foreign antigens
Blood A has antibody Anti-B
Blood B has antibody Anti-A
Blood AB has no antibody
Blood O has Antibody Anti A and B
Blood O is the universal donor
Blood AB can receive any blood type

23. Rh Factor Rh positive (Rh +) has protein in blood
Rh negative (Rh -) has no protein in blood
Rh+ is dominant

24. Some of us have it, some of us don't
Some of us have it, some of us don't. If it is present, the blood is Rh positive, if not it's Rh negative. So, for example, some people in group A will have it, and will therefore be classed as A+ (or A positive). While the ones that don't, are A- (or A negative). And so it goes for groups B, AB and O.
85% of the population is Rh positive, the other 15% of the population is running around with Rh negative blood.

25. Do you know which blood group you belong to?
According to above blood grouping systems, you can belong to either of following 8 blood groups:
Do you know which blood group you belong to?

26.                                                                            
A person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies.
A person with Rh+ blood can receive blood from a person with Rh- blood without any problems.

27. Definition
Some traits are determined by the combined effect of two or more pairs of alleles. These traits are called polygenic traits.
Each pair of alleles adds something to the resulting phenotype.
Other names for polygenic traits are multi-factorial traits, or quantitative traits.

28. Polygenic traits are continuous
Because so many alleles contribute to the final phenotype, a variety of phenotypes can occur!
For example, height is a polygenic trait.

29. Polygenic Traits are Continuos
When dealing with polygenic traits that are only controlled by two pairs of alleles, we can complete Punnett squares to determine the genotypes and phenotypes of the F1 generation.

30. Blood Typing Blood Type Anti-a Sera Anti-b Sera A Clumping No clumpingAB O

32. Sex-linked genes
The eggs contain a single X chromosome and sperm contain either an X or a Y
Sex of the offspring depends on whether the sperm that fertilizes the egg has an X or a Y
Any gene located on a sex chromosome (X) is called a sex-linked gene
Most are found on the X (2,000) and few on the Y (24)

33. Sex-linked traits Written as a XRXr for heterozygous.
Y chromosome carries no allele and the phenotype is dependant upon the woman’s allele
Therefore, males carry one allele for a sex-linked trait.

34. Sex-linked disorders Red-green blindness
Hemophilia (inability of blood to clot)