1. Genetics and Heredity

2. HEREDITY
The passing of traits from parents to offspring.

3. TRAIT 2 A characteristic of an organism
Examples include: height, skin color, eye color, freckles, nose shape, etc.
Traits are controlled by genes.
What traits did Mendel observe in pea plants? (p. 218)

4. GENETICS 26
Study of the passing on of characteristics from one organism to its offspring
Make sure #26 mentions Gregor Mendel! 1

9. GENE 4 3 10 The set of information that a controls a trait
It is a segment of DNA on a chromosome
Genes come in 2 forms (allele-forms of a gene):
a. DOMINANT: allele that will always be expressed (shown) in an offspring
Tries to PREVENT the expression of
recessive gene 3 10
What are some examples of alleles? (p. 221)
Which alleles on page 221 are DOMINANT?

10. 11
b. RECESSIVE: allele that will only be expressed if there are no dominant alleles present
Is prevented from showing up if there is a dominant allele present
Which alleles on page 221 are recessive?

11. Dominant & Recessive Example:
Eyecolor- Brown eyes are dominant and blue eyes are recessive.
A person can have a brown allele and a blue allele but still have brown eyes because the brown allele is dominant and hides the blue allele (it’s recessive).

12. Dominant & Recessive
Dominant alleles are represented with a capital letter. (Add this to Card #10)
Recessive alleles are represented with a lowercase letter. (Add this to Card #11)
R = Dominant
r = recessive
An organism is represented by two letters for each allele (or gene that comes from mom and dad)

13. Homozygous/Heterozygous (p. 230)9
Homozygous (purebred)-when a species has two identical (genes)alleles for a trait
Represented by the same 2 letters
Ex. BB (dominant) or bb (recessive)
Heterozygous (hybrid)-when a species has two different (genes) alleles for a trait
Represented by 2 different letters
Ex. Bb 8

14. Genotypes vs. Phenotypes (p. 230)24
Genotype- genes in an organism that are present
Ex. Bb, bb or BB (Add to #24)
Phenotype- an organism’s physical traits (or visible traits)
Ex. Brown eyes, brown hair (Add to #25) 25

15. Law of Dominance 12
This means if the two alleles are different, one usually wins out.
Think of sports. Dominance in sports means one team usually wins out.

16. Law of Independent Assortment13
Independent = by themselves
Assortment = how things are sorted out
This means if multiple traits get passed along, those alleles get sorted out each by themselves.
For example, getting one allele for one trait doesn’t mean you can only get a certain allele for another trait.

17. 14 Law of Segregation Segregation means separating.
When reproductive cells are made, all the pairs of alleles separate. Each gamete contains 1 allele for each trait.

18. MUTATION
Change in a gene’s information (like a change in instructions)

19. Mutations can be: HELPFUL HARMFUL
Examples include: Down’s syndrome, color blindness, albinism, sickle cell anemia
NEUTRAL

21. PUNNET SQUARE 15
A mathematical model used to predict the chances that offspring will inherit genes from their parents

22. SAMPLE PUNNET SQUARE

23. Practice problem #1
Predict the genotypes for the fur color of the offspring of a brown, heterozygous hamster and a white homozygous hamster. Brown is dominant and white is recessive.

25. Problem #2
Predict the gentoypes of the offspring of 2 white homozygous cows. Black is dominant over white.

26. #2

27. Problem #3
Predict the genotypes of the offspring of 2 gray heterozygous rats. Gray is dominant over white, which is recessive.

28. #3

29. Practice problem #4
What are the chances of having a girl or a boy baby?
How would you make a Punnett Square to show it?

30. #4

31. Pedigree Charts 7
Pedigree: a chart of the genetic history of a family over several generations
They are used to find out the probability of a child having a disorder or a certain trait in a family.

32. Symbols on a Pedigree
Female:
Male:

33. Connecting Pedigree Symbols:
Examples of connected symbols:
Married couple
Children

34. More symbols in a Ped. Chart:

35. Example of a ped. Chart:
What does a pedigree chart look like?

36. Interpreting a Ped. Chart:
1. Determine if the pedigree chart shows an autosomal or X-linked disease/disorder.
If one sex in the pedigree is affected, it is X-linked.
It is a 50/50 ration between sexes, the the disorder/disease is autosomal. Autosomal doesn’t affect just one sex.

37. Is it autosomal or X-linked?

38. Autosomal…why????

39. Interpreting Ped. Chart cont.
2. Determine whether the disorder is dominant or recessive.
If it is dominant, one of the parents must have the disorder/trait/disease.
It is is recessive, neither parent has to have the trait/disorder because they can be heterozygous (Bb).

40. Dominant or Recessive?

41. Dominant….why????

42. Dominant or Recessive???

43. Recessive…..why???

44. You are researching the inheritance of a red colored tongue in a lizard….
Is it autosomal or X-linked?
Is it dominant or recessive?