1. Genetic Inheritace

2. Important Vocab:
GENES: factors that are passed on by parents to offspring that determine the inheritance of traits.
Traits: a specific characteristic that varies from one individual to another.
The different forms of a gene are called alleles(ah-le-eels).

3. Important Vocab (Continued)
GENOTYPE – are the actual DNA coded genes or instructions that make you.
PHENOTYPE – The express or what the genotype looks like in the physical world. For short – What you look like.

4. Gregor Mendel’s Peas Genetics is the scientific study of heredity.
Gregor Mendel was an Austrian monk that studied the common garden pea and how various traits were inherited.
Mendel is considered the Father of Genetics, because of his discovery of the basic rules of genetic inheritance and the inheritance pattern of simple dominance.

5. Genes and Dominance
The principle of dominance states that some alleles are dominant and others are recessive.
Dominant alleles – Only need one for this form to show in the phenotype Possible Genotype – (DD or Dd)
Recessive – Need two alleles for this one to show in the phenotype Possible Genotype– (dd)

6. Segregation Principle of Segregation:
During the formation of GAMETES (sex cells) – Alleles are separated (segregated) into different resulting daughter cells.
**This is why some traits are some times said to skip a generation (recessive trait is hidden and then passed on)

7. Segregation Alleles separate during gamete formation.
During gamete formation, alleles segregate from each other so that each gamete carries only a single copy of each gene. Each F1 plant produces two types of gametes—those with the allele for tallness and those with the allele for shortness. The alleles are paired up again when gametes fuse during fertilization. The TT and Tt allele combinations produce tall pea plants; tt is the only allele combination that produces a short pea plant.

8. How genes work:
For every gene you have 2 copies of that gene. - 1 from mom and 1 from dad.
Since your mom and dad don’t necessarily have the same allele (version of the gene), there are different ways those two copies can interact.
These different ways are called Inheritance Patterns.

9. Inheritance Patterns

10. Simple Dominance AKA – Mendelian Genetics
Two alleles exist for the gene.
One allele is Dominant
One allele is recessive
For the dominant phenotype to show through, you only need to inherit 1 dominant allele.
For the recessive phenotype to show through, both of your alleles need to be recessive.

11. Simple Dominance

12. Incomplete Dominance
Incomplete Dominance: neither allele is dominant but combine and display a new trait that is a mixing of the two alleles
SYMBOLS USED
Two capital letters, one with an apostrophe to indicate the different allele that is involved
Ex. R (for the red allele) R’ (for the white allele)
RESULT for Heterozygous
- Blending of the two phenotypes (red + white = Pink)

13. Incomplete Dominance RR
R’R’
RR’
RR’ RR
RR’
R’R’

14. Codominance
Codominance: both alleles of a gene are dominant and the heterozygous phenotype has both traits equally expressed
SYMBOL:
Two capital letters: Use the first letter of one trait (B for Brown) and the first letter of the other trait (W for White)
RESULT of Heterozygous (BW)
Spotty/blotchy NO BLENDING!

15. Codominance

16. Codominance

17. Let’s Stop and Think…
Let’s say there are two alleles for the hair color trait- red and blue
What would be the resulting phenotype of a heterozygous pair if the alleles showed codominance?
A. Red
B. Blue
C. Purple
D. Red and Blue patches

18. Multiple Alleles
Multiple Alleles: the presence of more than two alleles for a genetic trait
Blood Type
Human blood type is governed by the presence of 3 different alleles: A B O
However, each person only has 2 of these 3 alleles in their DNA

19. ABO Blood Type
Blood types follow both Codominant and simple Dominant inheritance
A and B are codominant
A and B are both dominant over O
SYMBOLS USED
A allele = IA
B Allele = IB
O allele = i

20. Variation
The following patterns use the three already describe in different combinations due to either having more than 2 alleles, multiple genes, or are located on the sex chromosomes.

21. Multiple Alleles: Blood Type

22. Let’s stop and think…
What are the two allele combinations you can have for type A blood?
IAIA and IAi
What are the two allele combinations you can have for type B blood?
IBIB and IBi

23. Let’s Stop and Think…
What is the only allele combination you can have for type AB blood?
IAIB
What is the only allele combination you can have for type O blood? ii

24. Sex-Linked Traits genes which are carried only on the sex chromosomes
ex: red green color blindness
2:25 males
1:150 females

25. Sex-Linked Traits
DEFINITION: genes which are carried only on the sex chromosomes
Traits are usually not seen in women because it can be masked by another dominant gene on the other X-chromosome
Female – XBXb
Male – XbY **Note – Guys only have 1 copy**
EXAMPLE: Red – Green Color blindness

26. Color Blindness Test
Can you see the letters and numbers in these squares?

27. Polygenic Traits
In this pattern there are more than one gene responsible for a single trait
Makes it possible for many types of genotypes and phenotypes
Continuous variation
EXAMPLES: Height, Body shape, Skin tone

28. Polygenic
Example Skin Tone

29. Human Height Polygenic
It’s often hard to tell where a person might get their height from (short lady is the tall lady’s mother)