Mendelelian Genetics

Июль 21, 2022

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Биология
Mendelelian Genetics

Содержание

2. Gregor Mendel (1822-1884) Responsible for the Laws governing Inheritance of Traits. copyright cmassengale
3. Gregor Johann Mendel Austrian monk Studied the inheritance of traits in pea plants. Developed the laws
4. Gregor Johann Mendel Between 1856 and 1863, Mendel cultivated and tested some 28,000 pea plants. He
5. Site of Gregor Mendel’s experimental garden in the Czech Republic. copyright cmassengale
6. Mendel stated that physical traits are inherited as “particles”. Mendel did not know that the “particles”
7. Genetic Terminology Trait - any characteristic that can be passed from parent to offspring. Heredity -
8. Types of Genetic Crosses Monohybrid cross - cross involving a single trait e.g. flower color. Dihybrid
9. Punnett Square Used to help solve genetics problems copyright cmassengale
10. copyright cmassengale
11. Designers - “Genes” Alleles - two forms of a gene (dominant & recessive). Dominant - stronger
12. Genotype - gene combination for a trait. (e.g. RR, Rr, rr) Phenotype - the physical feature
13. Genotype & Phenotype in Flowers Genotype of alleles: R = red flower r = yellow flower
14. Genotypes Homozygous genotype - gene combination involving 2 dominant or 2 recessive genes (e.g. RR or
15. Genes and Environment Determine Characteristics copyright cmassengale
16. Mendel’s Pea Plant Experiments copyright cmassengale
17. Why peas, Pisum sativum? Can be grown in a small area. Produce lots of offspring. Produce
18. Reproduction in Flowering Plants Pollen contains sperm Produced by the stamen. Ovary contains eggs found inside
19. Mendel’s Experimental Methods Mendel hand-pollinated flowers using a paintbrush He could snip the stamens to prevent
20. How Mendel Began Mendel produced pure strains by allowing the plants to self-pollinate for several generations.
21. EightTraits of Pea Plant Seed shape --- Round (R) or Wrinkled (r) Seed Color ---- Yellow
22. copyright cmassengale
23. copyright cmassengale
24. Mendel’s Experimental Results copyright cmassengale
25. Did the observed ratio match the theoretical ratio? The theoretical or expected ratio of plants producing
26. Generation “Gap” Parental P1 Generation = the parental generation in a breeding experiment. F1 generation =
27. Following the Generations Cross 2 Pure Plants TT x tt Results in all Hybrids Tt Cross
28. Monohybrid Crosses copyright cmassengale
29. Trait: Seed Shape Alleles: R – Round r – Wrinkled Cross: Round seeds x Wrinkled seeds
30. P1 Monohybrid Cross Review Homozygous dominant x Homozygous recessive Offspring all Heterozygous (hybrids) Offspring called F1
31. Trait: Seed Shape Alleles: R – Round r – Wrinkled Cross: Round seeds x Round seeds
32. F1 Monohybrid Cross Review Heterozygous x heterozygous Offspring: 25% Homozygous dominant RR 50% Heterozygous Rr 25%
33. What Do the Peas Look Like? copyright cmassengale
34. …And Now the Test Cross Mendel then crossed a pure & a hybrid from his F2
35. Trait: Seed Shape Alleles: R – Round r – Wrinkled Cross: Round seeds x Round seeds
36. Trait: Seed Shape Alleles: R – Round r – Wrinkled Cross: Wrinkled seeds x Round seeds
37. F2 Monohybrid Cross Review Homozygous x heterozygous (hybrid) Offspring: 50% Homozygous RR or rr 50% Heterozygous
38. Practice Your Crosses Work the P1, F1, and both F2 Crosses for each of the other
39. Mendel’s Laws copyright cmassengale
40. Results of Monohybrid Crosses Inheritable factors or genes are responsible for all heritable characteristics. Phenotype is
41. Law of Dominance In a cross of parents that are pure for contrasting traits, only one
42. Law of Dominance copyright cmassengale
43. Law of Segregation During the formation of gametes (eggs or sperm), the two alleles responsible for
44. Applying the Law of Segregation copyright cmassengale
45. Law of Independent Assortment Alleles for different traits are distributed to sex cells (& offspring) independently
46. Dihybrid Cross A breeding experiment that tracks the inheritance of two traits. Mendel’s “Law of Independent
47. Question: How many gametes will be produced for the following allele arrangements? Remember: 2n (n =
48. Answer: 1. RrYy: 2n = 22 = 4 gametes RY Ry rY ry 2. AaBbCCDd: 2n
49. Dihybrid Cross Traits: Seed shape & Seed color Alleles: R round r wrinkled Y yellow y
50. Dihybrid Cross copyright cmassengale
51. Dihybrid Cross copyright cmassengale
52. Dihybrid Cross Round/Yellow: 9 Round/green: 3 wrinkled/Yellow: 3 wrinkled/green: 1 9:3:3:1 copyright cmassengale
53. Test Cross A mating between an individual of unknown genotype and a homozygous recessive individual. Example:
54. Test Cross Possible results: copyright cmassengale
55. Summary of Mendel’s laws copyright cmassengale
56. Incomplete Dominance and Codominance copyright cmassengale
57. Incomplete Dominance F1 hybrids have an appearance somewhat in between the phenotypes of the two parental
58. Incomplete Dominance r copyright cmassengale
59. Incomplete Dominance copyright cmassengale
60. Codominance Two alleles are expressed (multiple alleles) in heterozygous individuals. Example: blood type 1. type A
61. Codominance Problem Example: homozygous male Type B (IBIB) x heterozygous female Type A (IAi) copyright cmassengale
62. Another Codominance Problem Example: male Type O (ii) x female type AB (IAIB) copyright cmassengale
63. Codominance Question: If a boy has a blood type O and his sister has blood type
64. Codominance Answer: Parents: genotypes = IAi and IBi phenotypes = A and B copyright cmassengale
65. Sex-linked Traits Traits (genes) located on the sex chromosomes. Sex chromosomes are X and Y XX
66. Sex-linked Traits Sex Chromosomes Example: Eye color in fruit flies copyright cmassengale
67. Sex-linked Trait Problem Example: Eye color in fruit flies (red-eyed male) x (white-eyed female) XRY x
68. Sex-linked Trait Solution: 50% red eyed female 50% white eyed male copyright cmassengale
69. Female Carriers copyright cmassengale
70. Genetic Practice Problems copyright cmassengale
71. Breed the P1 generation tall (TT) x dwarf (tt) pea plants copyright cmassengale
72. Solution: tall (TT) vs. dwarf (tt) pea plants copyright cmassengale
73. Breed the F1 generation tall (Tt) vs. tall (Tt) pea plants copyright cmassengale
75. Скачать презентацию

Слайд 2

Gregor Mendel (1822-1884)
Responsible for the Laws governing Inheritance of Traits.
copyright cmassengale

Слайд 3

Gregor Johann Mendel
Austrian monk
Studied the inheritance of traits in pea plants.
Developed

the laws of inheritance.
Mendel's work was not recognized until the turn of the 20th century.

Слайд 4

Gregor Johann Mendel
Between 1856 and 1863, Mendel cultivated and tested some

28,000 pea plants.
He found that the plants' offspring retained traits of the parents.
Called the “Father of Genetics“.

Слайд 5

Site of Gregor Mendel’s experimental garden in the Czech Republic.
copyright cmassengale

Слайд 6

Mendel stated that physical traits are inherited as “particles”.
Mendel did not

know that the “particles” were actually Chromosomes & DNA.

Particulate Inheritance

Слайд 7

Genetic Terminology
Trait - any characteristic that can be passed from parent

to offspring.
Heredity - passing of traits from parent to offspring.
Genetics - study of heredity.

Слайд 8

Types of Genetic Crosses
Monohybrid cross - cross involving a single trait e.g.

flower color.
Dihybrid cross - cross involving two traits. e.g. flower color & plant height.

Слайд 9

Punnett Square
Used to help solve genetics problems
copyright cmassengale

Слайд 10

copyright cmassengale

Слайд 11

Designers - “Genes”
Alleles - two forms of a gene (dominant &

recessive).
Dominant - stronger of two genes expressed in the hybrid; represented by a capital letter (R).
Recessive - gene that shows up less often in a cross; represented by a lowercase letter (r).

Слайд 12

Genotype - gene combination for a trait. (e.g. RR, Rr, rr)

Phenotype - the physical feature resulting from a genotype. (e.g. red, white)

Слайд 13

Genotype & Phenotype in Flowers
Genotype of alleles: R = red flower r =

yellow flower
All genes occur in pairs, so 2 alleles affect a characteristic
Possible combinations are:

Genotypes RR Rr rr
Phenotypes RED RED YELLOW

Слайд 14

Genotypes
Homozygous genotype - gene combination involving 2 dominant or 2 recessive

genes (e.g. RR or rr); also called pure.
Heterozygous genotype - gene combination of one dominant & one recessive allele. (e.g. Rr); also called hybrid.

Слайд 15

Genes and Environment Determine Characteristics
copyright cmassengale

Слайд 16

Mendel’s Pea Plant Experiments
copyright cmassengale

Слайд 17

Why peas, Pisum sativum?
Can be grown in a small area.
Produce

lots of offspring.
Produce pure plants when allowed to self-pollinate. several generations
Can be artificially cross-pollinated.

Слайд 18

Reproduction in Flowering Plants
Pollen contains sperm
Produced by the stamen.
Ovary contains eggs
found

inside the flower.

Pollen carries sperm to the eggs for fertilization.
Self-fertilization can occur in the same flower.
Cross-fertilization can occur between flowers.

Слайд 19

Mendel’s Experimental Methods
Mendel hand-pollinated flowers using a paintbrush
He could snip the

stamens to prevent self-pollination.
Covered each flower with a cloth bag.
He traced traits through the several generations.

Слайд 20

How Mendel Began
Mendel produced pure strains by allowing the plants to

self-pollinate for several generations.

Слайд 21

EightTraits of Pea Plant
Seed shape --- Round (R) or Wrinkled (r)
Seed

Color ---- Yellow (Y) or Green (y)
Pod Shape --- Smooth (S) or Wrinkled (s)
Pod Color --- Green (G) or Yellow (g)
Seed Coat Color --- Gray (G) or White (g)
Flower position---Axial (A) or Terminal (a)
Plant Height --- Tall (T) or Short (t)
Flower color --- Purple (P) or White (p)

Слайд 22

copyright cmassengale

Слайд 23

copyright cmassengale

Слайд 24

Mendel’s Experimental Results
copyright cmassengale

Слайд 25

Did the observed ratio match the theoretical ratio?
The theoretical or expected

ratio of plants producing round or wrinkled seeds is 3 round :1 wrinkled.
Mendel’s observed ratio was 2.96:1
The discrepancy is due to statistical error.
The larger the sample the more nearly the results approximate to the theoretical ratio.

Слайд 26

Generation “Gap”
Parental P1 Generation = the parental generation in a breeding

experiment.
F1 generation = the first-generation offspring in a breeding experiment. (1st filial generation)
From breeding individuals from the P1 generation.
F2 generation = the second-generation offspring in a breeding experiment. (2nd filial generation)
From breeding individuals from the F1 generation.

Слайд 27

Following the Generations
Cross 2 Pure Plants TT x tt
Results in all Hybrids Tt
Cross

2 Hybrids get 3 Tall & 1 Short TT, Tt, tt.

Слайд 28

Monohybrid Crosses
copyright cmassengale

Слайд 29

Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Round seeds x

Wrinkled seeds
RR x rr

P1 Monohybrid Cross

Genotype: Rr
Phenotype: Round
Genotypic Ratio: All alike
Phenotypic Ratio: All alike

Слайд 30

P1 Monohybrid Cross Review
Homozygous dominant x Homozygous recessive
Offspring all Heterozygous (hybrids)
Offspring

called F1 generation
Genotypic & Phenotypic ratio is ALL ALIKE

Слайд 31

Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Round seeds x

Round seeds
Rr x Rr

F1 Monohybrid Cross

Genotype: RR, Rr, rr
Phenotype: Round & wrinkled
Gen. Ratio: 1:2:1
Phen. Ratio: 3:1

Слайд 32

F1 Monohybrid Cross Review
Heterozygous x heterozygous
Offspring: 25% Homozygous dominant RR 50% Heterozygous Rr 25%

Homozygous Recessive rr
Offspring called F2 generation
Genotypic ratio is 1:2:1
Phenotypic Ratio is 3:1

Слайд 33

What Do the Peas Look Like?
copyright cmassengale

Слайд 34

…And Now the Test Cross
Mendel then crossed a pure & a

hybrid from his F2 generation
This is known as an F2 or test cross
There are two possible testcrosses: Homozygous dominant x Hybrid Homozygous recessive x Hybrid

Слайд 35

Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Round seeds x

Round seeds
RR x Rr

F2 Monohybrid Cross (1st)

Genotype: RR, Rr
Phenotype: Round
Genotypic Ratio: 1:1
Phenotypic Ratio: All alike

Слайд 36

Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Wrinkled seeds x

Round seeds
rr x Rr

F2 Monohybrid Cross (2nd)

Genotype: Rr, rr
Phenotype: Round & Wrinkled
G. Ratio: 1:1
P.Ratio: 1:1

Слайд 37

F2 Monohybrid Cross Review
Homozygous x heterozygous (hybrid)
Offspring: 50% Homozygous RR or rr 50%

Heterozygous Rr
Phenotypic Ratio is 1:1
Called Test Cross because the offspring have SAME genotype as parents.

Слайд 38

Practice Your Crosses
Work the P1, F1, and both F2 Crosses for

each of the other Seven Pea Plant Traits.

Слайд 39

Mendel’s Laws
copyright cmassengale

Слайд 40

Results of Monohybrid Crosses
Inheritable factors or genes are responsible for all

heritable characteristics.
Phenotype is based on Genotype.
Each trait is based on two genes, one from the mother and the other from the father.
True-breeding individuals are homozygous ( both alleles) are the same.

Слайд 41

Law of Dominance
In a cross of parents that are pure

for contrasting traits, only one form of the trait will appear in the next generation.
All the offspring will be heterozygous and express only the dominant trait.
RR x rr yields all Rr (round seeds)

Слайд 42

Law of Dominance
copyright cmassengale

Слайд 43

Law of Segregation
During the formation of gametes (eggs or sperm), the

two alleles responsible for a trait separate from each other.
Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring.

Слайд 44

Applying the Law of Segregation
copyright cmassengale

Слайд 45

Law of Independent Assortment
Alleles for different traits are distributed to

sex cells (& offspring) independently of one another.
This law can be illustrated using dihybrid crosses.

Слайд 46

Dihybrid Cross
A breeding experiment that tracks the inheritance of two traits.
Mendel’s

“Law of Independent Assortment”
a. Each pair of alleles segregates independently during gamete formation
b. Formula: 2n (n = # of heterozygotes)

Слайд 47

Question: How many gametes will be produced for the following allele arrangements?
Remember:

2n (n = # of heterozygotes)
1. RrYy
2. AaBbCCDd
3. MmNnOoPPQQRrssTtQq

Слайд 48

Answer:
1. RrYy: 2n = 22 = 4 gametes
RY Ry rY ry
2.

AaBbCCDd: 2n = 23 = 8 gametes
ABCD ABCd AbCD AbCd
aBCD aBCd abCD abCD
3. MmNnOoPPQQRrssTtQq: 2n = 26 = 64 gametes

Слайд 49

Dihybrid Cross
Traits: Seed shape & Seed color
Alleles: R round r wrinkled

Y yellow y green

RrYy x RrYy

RY Ry rY ry

All possible gamete combinations

Слайд 50

Dihybrid Cross
copyright cmassengale

Слайд 51

Dihybrid Cross
copyright cmassengale

Слайд 52

Dihybrid Cross
Round/Yellow: 9 Round/green: 3 wrinkled/Yellow: 3 wrinkled/green: 1
9:3:3:1
copyright cmassengale

Слайд 53

Test Cross
A mating between an individual of unknown genotype and a

homozygous recessive individual.
Example: bbC__ x bbcc
BB = brown eyes
Bb = brown eyes
bb = blue eyes
CC = curly hair
Cc = curly hair
cc = straight hair

Слайд 54

Test Cross
Possible results:
copyright cmassengale

Слайд 55

Summary of Mendel’s laws
copyright cmassengale

Слайд 56

Incomplete Dominance and Codominance
copyright cmassengale

Слайд 57

Incomplete Dominance
F1 hybrids have an appearance somewhat in between the phenotypes

of the two parental varieties.
Example: snapdragons (flower)
red (RR) x white (rr)
RR = red flower
rr = white flower

Слайд 58

Incomplete Dominance
r
copyright cmassengale

Слайд 59

Incomplete Dominance
copyright cmassengale

Слайд 60

Codominance
Two alleles are expressed (multiple alleles) in heterozygous individuals.
Example: blood type
1. type

A = IAIA or IAi
2. type B = IBIB or IBi
3. type AB = IAIB
4. type O = ii

Слайд 61

Codominance Problem
Example: homozygous male Type B (IBIB)
x heterozygous female Type A (IAi)
copyright

cmassengale

Слайд 62

Another Codominance Problem
Example: male Type O (ii) x female type AB

(IAIB)

Слайд 63

Codominance
Question: If a boy has a blood type O and his sister

has blood type AB, what are the genotypes and phenotypes of their parents?
type O (ii) X type AB (IAIB)
boy girl

Слайд 64

Codominance
Answer:
Parents:
genotypes = IAi and IBi
phenotypes = A and B
copyright cmassengale

Слайд 65

Sex-linked Traits
Traits (genes) located on the sex chromosomes.
Sex chromosomes are X

and Y
XX genotype for females
XY genotype for males
Many sex-linked traits carried on X chromosome.

Слайд 66

Sex-linked Traits
Sex Chromosomes
Example: Eye color in fruit flies
copyright cmassengale

Слайд 67

Sex-linked Trait Problem
Example: Eye color in fruit flies
(red-eyed male) x

(white-eyed female) XRY x XrXr
Remember: the Y chromosome in males does not carry traits.
RR = red eyed
Rr = red eyed
rr = white eyed
XY = male
XX = female

Слайд 68

Sex-linked Trait Solution:
50% red eyed female
50% white eyed male
copyright cmassengale

Слайд 69

Female Carriers
copyright cmassengale

Слайд 70

Genetic Practice Problems
copyright cmassengale

Слайд 71

Breed the P1 generation
tall (TT) x dwarf (tt) pea plants
copyright cmassengale

Слайд 72

Solution:
tall (TT) vs. dwarf (tt) pea plants
copyright cmassengale

Слайд 73

Mendelelian Genetics

Содержание

Gregor Mendel (1822-1884)Responsible for the Laws governing Inheritance of Traits.copyright cmassengale

Gregor Johann MendelAustrian monkStudied the inheritance of traits in pea plants.Developed

Gregor Johann MendelBetween 1856 and 1863, Mendel cultivated and tested some

Site of Gregor Mendel’s experimental garden in the Czech Republic.copyright cmassengale

Mendel stated that physical traits are inherited as “particles”.Mendel did not

Genetic TerminologyTrait - any characteristic that can be passed from parent

Types of Genetic CrossesMonohybrid cross - cross involving a single trait e.g.

Punnett SquareUsed to help solve genetics problemscopyright cmassengale

copyright cmassengale

Designers - “Genes”Alleles - two forms of a gene (dominant &

Genotype - gene combination for a trait. (e.g. RR, Rr, rr)

Genotype & Phenotype in FlowersGenotype of alleles: R = red flower r =

GenotypesHomozygous genotype - gene combination involving 2 dominant or 2 recessive

Genes and Environment Determine Characteristics copyright cmassengale

Mendel’s Pea Plant Experimentscopyright cmassengale

Why peas, Pisum sativum?Can be grown in a small area. Produce

Reproduction in Flowering PlantsPollen contains spermProduced by the stamen.Ovary contains eggsfound

Mendel’s Experimental MethodsMendel hand-pollinated flowers using a paintbrushHe could snip the

How Mendel BeganMendel produced pure strains by allowing the plants to

EightTraits of Pea PlantSeed shape --- Round (R) or Wrinkled (r)Seed

copyright cmassengale

copyright cmassengale

Mendel’s Experimental Resultscopyright cmassengale

Did the observed ratio match the theoretical ratio?The theoretical or expected

Generation “Gap”Parental P1 Generation = the parental generation in a breeding

Following the GenerationsCross 2 Pure Plants TT x ttResults in all Hybrids TtCross

Monohybrid Crossescopyright cmassengale

Trait: Seed ShapeAlleles: R – Round r – WrinkledCross: Round seeds x

P1 Monohybrid Cross ReviewHomozygous dominant x Homozygous recessiveOffspring all Heterozygous (hybrids)Offspring

Trait: Seed ShapeAlleles: R – Round r – WrinkledCross: Round seeds x

F1 Monohybrid Cross ReviewHeterozygous x heterozygousOffspring: 25% Homozygous dominant RR 50% Heterozygous Rr 25%

What Do the Peas Look Like?copyright cmassengale

…And Now the Test CrossMendel then crossed a pure & a

Trait: Seed ShapeAlleles: R – Round r – WrinkledCross: Round seeds x

Trait: Seed ShapeAlleles: R – Round r – WrinkledCross: Wrinkled seeds x

F2 Monohybrid Cross ReviewHomozygous x heterozygous (hybrid)Offspring: 50% Homozygous RR or rr 50%

Practice Your CrossesWork the P1, F1, and both F2 Crosses for

Mendel’s Lawscopyright cmassengale

Results of Monohybrid CrossesInheritable factors or genes are responsible for all

Law of Dominance In a cross of parents that are pure

Law of Dominancecopyright cmassengale

Law of SegregationDuring the formation of gametes (eggs or sperm), the

Applying the Law of Segregationcopyright cmassengale

Law of Independent Assortment Alleles for different traits are distributed to

Dihybrid CrossA breeding experiment that tracks the inheritance of two traits.Mendel’s

Question: How many gametes will be produced for the following allele arrangements? Remember:

Answer:1. RrYy: 2n = 22 = 4 gametes RY Ry rY ry2.

Dihybrid CrossTraits: Seed shape & Seed colorAlleles: R round r wrinkled

Dihybrid Crosscopyright cmassengale

Dihybrid Crosscopyright cmassengale

Dihybrid CrossRound/Yellow: 9 Round/green: 3 wrinkled/Yellow: 3 wrinkled/green: 19:3:3:1copyright cmassengale

Test CrossA mating between an individual of unknown genotype and a

Test CrossPossible results:copyright cmassengale

Summary of Mendel’s lawscopyright cmassengale

Incomplete Dominance and Codominancecopyright cmassengale

Incomplete DominanceF1 hybrids have an appearance somewhat in between the phenotypes

Incomplete Dominancercopyright cmassengale

Incomplete Dominancecopyright cmassengale

CodominanceTwo alleles are expressed (multiple alleles) in heterozygous individuals.Example: blood type 1. type

Codominance ProblemExample: homozygous male Type B (IBIB) x heterozygous female Type A (IAi)copyright

Another Codominance ProblemExample: male Type O (ii) x female type AB

CodominanceQuestion: If a boy has a blood type O and his sister

CodominanceAnswer:Parents:genotypes = IAi and IBiphenotypes = A and Bcopyright cmassengale

Sex-linked TraitsTraits (genes) located on the sex chromosomes.Sex chromosomes are X

Sex-linked TraitsSex ChromosomesExample: Eye color in fruit fliescopyright cmassengale

Sex-linked Trait ProblemExample: Eye color in fruit flies (red-eyed male) x

Sex-linked Trait Solution:50% red eyed female50% white eyed malecopyright cmassengale

Female Carrierscopyright cmassengale

Genetic Practice Problemscopyright cmassengale

Breed the P1 generationtall (TT) x dwarf (tt) pea plantscopyright cmassengale

Solution:tall (TT) vs. dwarf (tt) pea plantscopyright cmassengale

Breed the F1 generationtall (Tt) vs. tall (Tt) pea plantscopyright cmassengale

Похожие презентации

Gregor Mendel (1822-1884)
Responsible for the Laws governing Inheritance of Traits.
copyright cmassengale

Gregor Johann Mendel
Austrian monk
Studied the inheritance of traits in pea plants.
Developed

Gregor Johann Mendel
Between 1856 and 1863, Mendel cultivated and tested some

Site of Gregor Mendel’s experimental garden in the Czech Republic.
copyright cmassengale

Mendel stated that physical traits are inherited as “particles”.
Mendel did not

Genetic Terminology
Trait - any characteristic that can be passed from parent

Types of Genetic Crosses
Monohybrid cross - cross involving a single trait e.g.

Punnett Square
Used to help solve genetics problems
copyright cmassengale

Designers - “Genes”
Alleles - two forms of a gene (dominant &

Genotype & Phenotype in Flowers
Genotype of alleles: R = red flower r =

Genotypes
Homozygous genotype - gene combination involving 2 dominant or 2 recessive

Genes and Environment Determine Characteristics
copyright cmassengale

Mendel’s Pea Plant Experiments
copyright cmassengale

Why peas, Pisum sativum?
Can be grown in a small area.
Produce

Reproduction in Flowering Plants
Pollen contains sperm
Produced by the stamen.
Ovary contains eggs
found

Mendel’s Experimental Methods
Mendel hand-pollinated flowers using a paintbrush
He could snip the

How Mendel Began
Mendel produced pure strains by allowing the plants to

EightTraits of Pea Plant
Seed shape --- Round (R) or Wrinkled (r)
Seed

Mendel’s Experimental Results
copyright cmassengale

Did the observed ratio match the theoretical ratio?
The theoretical or expected

Generation “Gap”
Parental P1 Generation = the parental generation in a breeding

Following the Generations
Cross 2 Pure Plants TT x tt
Results in all Hybrids Tt
Cross

Monohybrid Crosses
copyright cmassengale

Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Round seeds x

P1 Monohybrid Cross Review
Homozygous dominant x Homozygous recessive
Offspring all Heterozygous (hybrids)
Offspring

Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Round seeds x

F1 Monohybrid Cross Review
Heterozygous x heterozygous
Offspring: 25% Homozygous dominant RR 50% Heterozygous Rr 25%

What Do the Peas Look Like?
copyright cmassengale

…And Now the Test Cross
Mendel then crossed a pure & a

Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Round seeds x

Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Wrinkled seeds x

F2 Monohybrid Cross Review
Homozygous x heterozygous (hybrid)
Offspring: 50% Homozygous RR or rr 50%

Practice Your Crosses
Work the P1, F1, and both F2 Crosses for

Mendel’s Laws
copyright cmassengale

Results of Monohybrid Crosses
Inheritable factors or genes are responsible for all

Law of Dominance
In a cross of parents that are pure

Law of Dominance
copyright cmassengale

Law of Segregation
During the formation of gametes (eggs or sperm), the

Applying the Law of Segregation
copyright cmassengale

Law of Independent Assortment
Alleles for different traits are distributed to

Dihybrid Cross
A breeding experiment that tracks the inheritance of two traits.
Mendel’s

Question: How many gametes will be produced for the following allele arrangements?
Remember:

Answer:
1. RrYy: 2n = 22 = 4 gametes
RY Ry rY ry
2.

Dihybrid Cross
Traits: Seed shape & Seed color
Alleles: R round r wrinkled

Dihybrid Cross
copyright cmassengale

Dihybrid Cross
copyright cmassengale

Dihybrid Cross
Round/Yellow: 9 Round/green: 3 wrinkled/Yellow: 3 wrinkled/green: 1
9:3:3:1
copyright cmassengale

Test Cross
A mating between an individual of unknown genotype and a

Test Cross
Possible results:
copyright cmassengale

Summary of Mendel’s laws
copyright cmassengale

Incomplete Dominance and Codominance
copyright cmassengale

Incomplete Dominance
F1 hybrids have an appearance somewhat in between the phenotypes

Incomplete Dominance
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Incomplete Dominance
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Codominance
Two alleles are expressed (multiple alleles) in heterozygous individuals.
Example: blood type
1. type

Codominance Problem
Example: homozygous male Type B (IBIB)
x heterozygous female Type A (IAi)
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Another Codominance Problem
Example: male Type O (ii) x female type AB

Codominance
Question: If a boy has a blood type O and his sister

Codominance
Answer:
Parents:
genotypes = IAi and IBi
phenotypes = A and B
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Sex-linked Traits
Traits (genes) located on the sex chromosomes.
Sex chromosomes are X

Sex-linked Traits
Sex Chromosomes
Example: Eye color in fruit flies
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Sex-linked Trait Problem
Example: Eye color in fruit flies
(red-eyed male) x

Sex-linked Trait Solution:
50% red eyed female
50% white eyed male
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Female Carriers
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Genetic Practice Problems
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Breed the P1 generation
tall (TT) x dwarf (tt) pea plants
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Solution:
tall (TT) vs. dwarf (tt) pea plants
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Breed the F1 generation
tall (Tt) vs. tall (Tt) pea plants
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