chapter 11 -- basic genetics. inheritance gregor mendel 1822-1884

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Chapter 11 -- Basic Genetics

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Page 1: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Chapter 11 -- Basic Genetics

Page 2: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Inheritance

Page 3: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Gregor Mendel

1822-1884

Page 4: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Mendel’s pea garden in Brno

Page 5: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Verhandlungen des naturforschenden Vereines in Brünn. Brünn: Vereines, 1865.

Mendel’s paper

Page 6: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Why did Mendel choose peas?

Page 7: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Mendel’s Peas

Page 8: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Two Characters

Seed Coat

Flower color

Page 9: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Two traits per character

Rough

Smooth

Page 10: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Two traits per character

Purple flowers

White flowers

Page 11: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Traits are alternative forms of characters

white or purple

smooth or rough

Page 12: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

“Brother Mendel! We grow tired of peas!”

Page 13: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
Page 14: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Controlling the mating

Page 15: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

No question as to parentage of offspring

Page 16: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Compare

Page 17: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

• 1. Start with true breeding plants.

• 2. Cross alternative forms among these true-breeders.

Mendel’s experimental design

Page 18: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

P Generation

(true-breedingparents)

F1 Generation

(hybrids)

F2 Generation

Purpleflowers

Whiteflowers

All plants hadpurple flowers

Page 19: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
Page 20: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

• 3. Allowed progeny (F1) to self-fertilize and examined offspring

• 4. Count the number of offspring of each type

Mendel’s experimental design

Page 21: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

P Generation

(true-breedingparents)

F1 Generation

(hybrids)

F2 Generation

Purpleflowers

Whiteflowers

All plants hadpurple flowers

Page 22: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

• Monohybrid crosses: examining one trait at a time

What Mendel found-monohybrid crosses

Page 23: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

P Generation

(true-breedingparents)

F1 Generation

(hybrids)

F2 Generation

Purpleflowers

Whiteflowers

All plants hadpurple flowers

Monohybrid Cross

Page 24: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

What Mendel found F1 generation

P Generation

(true-breedingparents)

F1 Generation

(hybrids)

Purpleflowers

Whiteflowers

All plants hadpurple flowers

Page 25: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

P Generation

(true-breedingparents)

F1 Generation

(hybrids)

F2 Generation

Purpleflowers

Whiteflowers

All plants hadpurple flowers

F1 x F1

Page 26: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

F1 x F1

F2: purple and white

705 purple flowered plants

224 white flowered plants

3:1 ratio

What Mendel found F2 generation

Page 27: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

F1 Generation

(hybrids)All plants hadpurple flowers

F2 Generation

705 purple

224 white

3:1 ratio

Page 28: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Mendel’s 7 pea traits

Page 29: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

1. Alternative versions of genes lead to variations in inherited characters. Alternative versions are called alleles

2. Each individual receives 2 alleles.– homozygotes: 2 copies of identical allele– heterozygotes: two different alleles

Mendel’s model

Page 30: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

3. In heterozygotes only the dominant form of allele will be expressed.– genotype: alleles present– phenotype: physical appearance

4. Alleles segregate from one another into gametes (Law of segregation)

Mendel’s model

Page 31: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Allele for purple flowers

Homologouspair ofchromosomes

Allele for white flowers

Locus for flower-color gene

Chromosomes, genes and alleles ……..

Page 32: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Genes control characters

e.g., flower color

Page 33: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Genes control characters

Traits are alternative forms of characters

e.g., white or purple

Page 34: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Traits are alternative forms of characters

Alleles are alternative forms of a gene

Genes control characters

Page 35: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
Page 36: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Human Chromosomes

Page 37: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Genes

Alleles

and

Page 38: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Variation within a population

Page 39: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

• Capital letter for dominant allele; lower case letter for recessive allele

Example flower color:

P = dominant allele

p = recessive allele

Mendel used symbols to interpret results

Page 40: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Phenotype: purple

Genotype: PP or Pp

Page 41: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Phenotype: white

Genotype: pp

Page 42: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Phenotype

Purple

Purple3

Purple

Genotype

PP(homozygous

Pp(heterozygous

Pp(heterozygous

pp(homozygous

1

2

1

Ratio 1:2:1

White

Ratio 3:1

1

Page 43: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Cross plant with unknown genotype with homozygous recessive

The testcross

Page 44: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

The Punnett square

Reginald C. Punnett

Page 45: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
Page 46: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

PP x ppp p

P

P

Pp Pp

Pp Pp

Page 47: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Dominant phenotype,unknown genotype:

PP or Pp?

If PP,then all offspring

purple:

p p

P

P

Pp Pp

Pp Pp

If Pp,then 1

2 offspring purpleand 1

2 offspring white:

p p

P

Ppp pp

Pp Pp

Recessive phenotype,known genotype:

pp

The testcross

Page 48: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Different types of Inheritance

Page 49: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Dominant - Recessive

Page 50: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

purplePp

PP

white pp

Page 51: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Incomplete Dominance

Page 52: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Incomplete dominanceWhen alleles are not fully dominant or

fully recessive in heterozygotes

Page 53: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Multiple Alleles: ABO Blood Group

Codominance No single allele is dominantEach allele has its own effect.

Page 54: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Codominance

Page 55: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

• Type A: adds galactosamine– IAIA, IAi

• Type B: adds galactose– IBIB, IBi

• Type AB: adds galactosamine and galactose– IAIB

• Type O: no sugar added– ii

Multiple Alleles: ABO Blood Group

Page 56: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

ABO Blood Groups

Page 57: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Pleiotropic EffectsOne allele have multiple effects

Page 58: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Environmental effects

Page 59: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

THE CHROMOSOMAL BASIS OF INHERITANCE

Page 60: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Chromosomes and Mendelian Inheritance

Page 61: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Allele for purple flowers

Homologouspair ofchromosomes

Allele for white flowers

Locus for flower-color gene

Chromosomes, genes and alleles ……..

and loci

Page 62: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Thomas Hunt Morgan (1866 – 1945)

Drosophila

Page 63: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
Page 64: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Human Chromosomes

Page 65: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Sex Linkage

XXfemale

XY

male

Page 66: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Human sex chromosomes

Page 67: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Color blindness

Sex Linked traitsMale pattern baldness

Page 68: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Chromosomal problems

Page 69: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Chromosomal problems

Page 70: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
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Page 73: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Klinefelter syndrone

Page 74: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Recessive genes can be carried without being expressed

Page 75: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Queen Victoria and hemophilia

Page 76: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
Page 77: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884

Sickle cell anemia

Page 78: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
Page 79: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
Page 80: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884
Page 81: Chapter 11 -- Basic Genetics. Inheritance Gregor Mendel 1822-1884