1. PATTERNS OF INHERITANCE
Chapter 11

2. Pre-Mendel’s Theories
Blending Hypothesis: when parents with different traits have offspring, they will always show a blending of the traits
Spontaneous generation: Non-living matter giving rise to living matter
Homunculus: The little man inside the sperm

4. Mendel’s experiments with pea plants
Particulate hypothesis: Parents pass on to their offspring separate and distinct factors (genes) that are responsible for inherited traits
Gene: factors pass on from parents to offspring. Sequence of DNA that determines a trait
Trait: a specific characteristic of an individual
Genetics: the study of heredity

5. https://www.youtube.com/watch?v=hf9XlqXcal0 3:00
10:00

6. Mendel’s experiments started with
True-breeding plants: when self- fertilized, a true-breeding plant produces offspring identical in appearance to itself generation after generation

7. Cross-fertilization, sperm from the pollen of one flower fertilizes the eggs in the flower of a different plant

8. the offspring of two different true-breeding varieties are called hybrids.

9. Monohybrid cross: pairing in which the parent plants differ in only one (mono) character.

11. HUMAN KARYOTYPE
A display of all the 46
chromosomes of an
Individual.

12. 9.5 page 2

13. Genus species (organism) NUMBER OF CHROMOSOMES
Homo sapiens (human)______________________________46
Mus musculus (house mouse)_________________________40
Drosophila melanogaster (fruit fly)_____________________8
Caenorhabditis elegans (microscopic roundworm)_________12
Saccharomyces cerevisiae (budding yeast) ______________32
Arabidopsis thaliana (plant in the mustard family) ________10
Xenopus laevis (South African clawed frog)______________36
Canis familiaris (domestic dog)________________________78
Gallus gallus (chicken) ______________________________28
Zea mays (corn or maize)____________________________20
Muntiacus reevesi (the Chinese muntjac, a deer) _________23
Muntiacus muntjac (its native american cousin) __________6
Myrmecia pilosula (an ant) ___________________________2
Parascaris equorum var. univalens (parasitic roundworm)___2
Cambarus clarkii (crayfish)___________________________200
Equisetum arvense (field horsetail, a plant)______________216

14. Horsetail

15. Mendel’s principle of segregation
There are alternative forms of factors (genes) called alleles.
For each character, an organism has two alleles for the gene controlling that character, one from each parent. Homozygous = same alleles Heterozygous = different alleles

16. Principle of segregation (cont.)
When only one of the two different alleles in an heterozygous individual appears to affect the trait, that allele is called the dominant allele. The allele that does not appear to affect the trait is called the recessive allele
The two alleles for a character segregate (separate) during the formation of gametes (sex cells). Each gamete carries only one allele of each character (Principle of segregation)

17. Phenotype refers to the observable trait (purple flowers)
Genotype refers to the combination of alleles (PP)
Phenotypic ratio: ratio of plants with purple flowers to those with white flowers (3 purple : 1 white)
Genotypic ratio: ratio of possible combinations of alleles (1 PP : 2 Pp : 1 pp)

18. Phenotype refers to the observable trait (purple flowers)
Genotype refers to the combination of alleles (Pp)

19. Phenotypic ratio: ratio of plants with purple flowers to those with white flowers (3 purple : 1 white)
Genotypic ratio: ratio of possible combinations of alleles (1 PP : 2 Pp : 1 pp)

20. Probability and Punnett Squares
Punnett Square: Diagram
used to show the probability
of a genetic cross
Probability: Chance of
Something happening

21. How can you find out the genotype of an individual showing the dominant trait?

22. TESTCROSS
In a testcross, an individual of unknown genotype, but dominant phenotype is crossed with a homozygous recessive individual

24. crossing of organisms differing in two characters
DIHYBRID CROSS
crossing of organisms differing in two characters

26. Possible allele combinations from a heterozygous dihybrid for round an yellow seed
R r Y y

27. DHYBRID CROSS

28. Principle of Independent Assortment
During gamete formation in an F2 cross, a particular allele for one character can be paired with either allele of another character

29. Intermediate or incomplete inheritance Codominance Multiple alleles
Not all traits are inherited following the patterns found by Mendel in pea plants
Intermediate or incomplete inheritance
Codominance
Multiple alleles
Polygenic inheritance
Environment - Epigenetics
_dominance.html

30. Intermediate or Incomplete Inheritance
The heterozygotes have a phenotype that is intermediate between the phenotypes of the two homozygotes

31. condition in which both alleles for a gene are expressed when present (cattle: red, white, roan coat = codominant)
Codominance

32. Genetic Determination of Blood Type
Multiple Alleles -
Genetic Determination of Blood Type
For many genes several alleles exist in the population.
Multiple alleles control the character of blood type in humans.
There are six possible genotypes.
The alleles IA and IB exhibit codominance, meaning that a heterozygote expresses both traits.
Phenotype
(Blood type)
Genotypes O ii A
IA IA or IA i B
IB IB or IB i AB
IA IB

34. http://ww w.youtube .com/watc h?v=L06T JTMVkBo

36. Polygenic inheritance
When two or more genes affect a single character
In humans, height, eye and skin color have polygenic inheritance
Polygenic inheritance

37. The Environment - Epigenetics
Phenotype depends on environment as well as genes
Temperature affects fur color in Siamese cats
In humans
Nutrition affects built
Exposure to sun affects skin tone

38. Sex-Linked Genes (any gene located on sex chromosomes)
Bill Nye – Greatest Scientific Discoveries (genetics 3:40- 8:00)

39. HUMAN KARYOTYPE
A display of all the 46
chromosomes of an
Individual.

41. Morgan's monohybrid cross for fly eye color produced a 3 : 1 phenotypic ratio of red to white eyes in the F2 generation. However, none of the flies with white eyes were female.

42. Chromosome Theory of Inheritance
Genes are located on chromosomes
Behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns – chromosomes undergo segregation and independent assortment during meiosis

43. INDEPENDENT
ASSORTMENT OF
CHROMOSOMES
DURING GAMETE
FORMATION

44. Gene locus: location at which alleles of a gene reside on homologous chromosomes
Linked genes: genes that are located in the same region of a chromosome
Genetic linkage: tendency for the alleles on one chromosome to be inherited together. The closer two genes are on a chromosome, the greater the genetic linkage

46. Meiosis
Organisms that reproduce sexually have specialized cells called gametes (sex cells)
Gametes are the result of a type of cell division called meiosis

47. Diploid and haploid
Almost all human cells are diploid or containing two homologous sets of chromosomes
2n = 46
Eggs and sperm cells (gametes) are haploid or containing a single set of chromosomes
n = 23

48. MITOSIS

51. Meiosis

52. haploid egg and sperm
diploid zygote
In the human life cycle a haploid egg and sperm fuse and form a diploid zygote. Mitosis produces an embryo with numerous cells that continue to multiply and develop.

53. 2 diploid daughter cells
MEIOSIS
MITOSIS
Original diploid cell 2n 2n 2n
2 diploid daughter cells

54. Genetic variation is a result of two processes that occurs during meiosis:
Independent assortment of chromosomes, and
Crossing over

55. During metaphase I, the independent assortment of chromosomes that end up in the resulting cells occurs randomly

56. Crossing over: exchange of genetic material between homologous chromosomes during prophase I of meiosis

57. Genetic recombination: new combination of genetic information in a gamete as a result of crossing over during prophase I of meiosis

59. MITOSIS MEIOSIS TYPE OF CELL (that undergoes this division)
(pages 195, 200, & 201)
MITOSIS
MEIOSIS
TYPE OF CELL (that undergoes this division)
# OF CELL DIVISIONS
Starts/ends as diploid or haploid cell
# OF DAUGHTER CELLS
# OF CHROMOSOMES AFTER DIVISION
EXCHANGE OF DNA (Y/N)
UNIQUE OR IDENTICAL CELL AFTER DIVISION

60. Development of egg and sperm