1. Fundamentals of Genetics
Chapter 11

2. Genetics The scientific study of heredity.
Trait: a characteristic that can be passed from parent to offspring.
Traits usually come in different forms. (i.e. Blue or brown eyes, tall or short, etc.)

10. Alleles Different forms of a gene. For example Blue or brown eyes.
Blue = one allele.
Brown = a different allele.

11. Genes Sections of a chromosome that code for a trait. For example
Brown or blonde hair.
Fish have fins, dogs have legs.
Six fingers or five.

12. Dominant vs. Recessive Alleles
When both a dominant and a recessive allele are present…
Dominant allele: can be seen (expressed).
Recessive allele: cannot be seen but is still present and may be seen in later generations.

13. Genotype and Phenotype
Genotype: the genetic makeup of an organism. (What genes does it have?) Phenotype: The outward expression of a trait. (What you can see.) Bb or BB or bb = genotype Brown Brown Blue = phenotype

14. Homozygous vs. Heterozygous
Homozygous: Same form of the gene from both parents.
Homozygous recessive: bb or rr
Homozygous dominant: BB or RR
Heterozygous: Different forms of the gene from each parent.
For example: Bb or Rr

15. Mendel’s Laws of Genetics
Law of Segregation: Gene pairs separate when gametes form.
Law of Independent Assortment: Genes separation is random and independent.
Law of Dominance: A dominant allele will be seen and the recessive allele will be hidden.

16. What makes us unique? Sexual Reproduction Crossing over Mutations
Genes from both parents
Crossing over
Swapping genes
Mutations
Random changes in genetic makeup
Recombinations

17. Crossing-Over

18. Meiosis
Meiosis I

19. Meiosis II Meiosis II Prophase II Metaphase II Anaphase II
Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

20. Gregor Mendel (1822-1884) 1860’s did experiments with pea plants.
Conducted experiments that established modern genetics.

21. Gregor Mendel
Chose peas because they had seven traits that were unusual.
Each trait only had two forms.
Tall or short
Purple or white
Yellow or green

22. Purebred Mendel’s peas could self-fertilize.
Purebred: the offspring receives the same trait from both parents.
Hybrid: the offspring receives different forms of the trait from each parent.

23. Principles of Dominance
Section 11-1
P Generation
F1 Generation
F2 Generation
Tall
Short
Tall
Tall
Tall
Tall
Tall
Short

24. Mendel’s Seven F1 Crosses on Pea Plants
Seed Shape
Seed Color
Seed Coat
Color
Pod
Shape
Pod Color
Flower Position
Plant Height
Round
Yellow
Gray
Smooth
Green
Axial
Tall
Wrinkled
Green
White
Constricted
Yellow
Terminal
Short
Round
Yellow
Gray
Smooth
Green
Axial
Tall

25. Chromosomal Theory of Heredity
States that the material of inheritance is carried by genes on the chromosomes.
Walter S. Sutton proposed the theory in 1903.

26. What are the chances? Can be expressed as… Fractions: 1/3
Percentages: 33%
Ratios: 1:2

27. Punnett Squares Show the probabilities… are not guaranteed.
Monohybrid Cross: studying one trait at a time.
Dihybrid Cross: studying two traits at a time.
Test Cross: a monohybrid cross in which one of the parents is homozygous recessive. This cross reveals hidden alleles.

28. Monohybrid Cross Tt
Parent 1 T t T T T T t
Parent 2 TT T T T T t

29. Probabilities P(1) x P(2) x P(3) = Total Probability Example Tt x TT
Hh x hh
Ww x Ww
What the chance of having offspring with the following genotype Tthhww

30. TtGg ttGg Dihybrid Cross Parent 1 T G T g t G t g t G T t G G TtGg

31. rr Test Cross r r RR R R r R r Rr ? ? r ? r Parent 1
Homozygous recessive r r
Parent 2 RR R R r R r or
Can roll
Can roll Rr ? ? r ? r
Tongue Roller
Can roll
Can roll

32. Autosome and Sex-Linked
Autosomal- Genes or traits found on any chromosome except sex chromosome
Sex-Linked- genes or traits found on the sex chromosomes

33. Figure 14-13 Colorblindness
Section 14-2
Father
(normal vision)
Normal vision
Colorblind
Male
Female
Daughter
(normal vision)
Son
(normal vision)
Mother (carrier)
Daughter
(carrier)
Son
(colorblind)

41. Exceptions to the dominant recessive rule.
Incomplete Dominance: offspring show an intermediate form of the trait.
Codominance: offspring show both forms of the trait.
Polygenic Traits: traits that are controlled by two or more genes.
Multiple Alleles: three or more alleles control a trait.
Pleiotropy: one gene affects more than one trait.

42. Examples of the exceptions...
Incomplete Dominance: red and white colored flowers have offspring with pink flowers.
Codominance: Human blood type (A, B, AB, O).
Polygenic Traits: Human eye color.
Multiple Alleles: Human hair color.
Pleiotropy: Sickle-cell anemia disease.

43. Incomplete Dominance in Four O’Clock Flowers

44. Blood Groups Safe Transfusions Phenotype Antigen on (Blood Type
Red Blood Cell
Genotype To
From

45. Pedigree A chart that shows how a trait is inherited within a family.
Carriers
Phenotype Bb bb Bb Bb Bb bb Bb
Genotype bb

46. Pedigree Figure 14-3 A Pedigree Section 14-1
A circle represents a female.
A square represents a male.
A horizontal line connecting a male and female represents a marriage.
A vertical line and a bracket connect the parents to their children.
A half-shaded circle or square indicates that a person is a carrier of the trait.
A circle or square that is not shaded indicates that a person neither expresses the trait nor is a carrier of the trait.
A completely shaded circle or square indicates that a person expresses the trait.

47. Identifying types of inheritance by pedigree charts
Autosomal-trait appears in both sexes
X-linked-trait appears in only one sex
Dominant- no carriers are shown
Recessive- carriers are present
Four types
Autosomal dominant, autosomal recessive, x-linked dominant, x-linked recessive

52. The Cause of Cystic Fibrosis
Chromosome # 7
CFTR gene
The most common allele that causes cystic fibrosis is missing 3 DNA bases. As a result, the amino acid phenylalanine is missing from the CFTR protein.
Normal CFTR is a chloride ion channel in cell membranes. Abnormal CFTR cannot be transported to the cell membrane.
The cells in the person’s airways are unable to transport chloride ions. As a result, the airways become clogged with a thick mucus.

53. Genes can react to the environment
Body temperature causes a rabbit to have black or white fur.
Soil acidity determines blue or pink flowers.
Japanese goby fish will change from female to male and back again.
Human height.

54. Gene Therapy Bone marrow cell Normal hemoglobin gene Nucleus
Chromosomes
Bone marrow
Genetically engineered virus