Mendelian Laws of Inheritance PDF

Mendelian Laws of Inheritance General Biology 2 1/2 Science, Technology, Engineering, and Mathematics *What traits run in your family? *What did you inherit from your parents? *What makes your family distinct from other families? 2 How well do you resemble...

Mendelian Laws of Inheritance General Biology 2 1/2 Science, Technology, Engineering, and Mathematics *What traits run in your family? *What did you inherit from your parents? *What makes your family distinct from other families? 2 How well do you resemble your siblings? Do you share the same facial features and complexion? 3 Some of you may have inherited a widow’s peak and the ability to roll your tongue from your either or both of your parents, while some of you may lack these genetic traits. 4 Inheritance may also involve more complex traits such as the intelligence quotient level or IQ level. From whom do you think you inherited your natural intelligence? 5 How did the experiments of Gregor Mendel lay the foundation for the study of transmission genetics? 6  Learning Competency At the end of the lesson, you should be able to do the following: Predict genotypes and phenotypes of parents and offspring using the laws of inheritance (STEM_BIO11/12-IIIa-b-1). 7  Learning Objectives At the end of the lesson, you should be able to do the following: Explain the foundations and development of Mendelian genetics. Describe and apply the Mendelian laws of inheritance. 8  Introduction to Inheritance Looking at yourself in the mirror... 9  Introduction to Inheritance...have you ever wondered how you have inherited your biological traits from your parents? 10  Introduction to Inheritance...have you ever wondered how you have inherited your biological traits from your parents? 11 Introduction to Inheritance Genetics answers most of our inquiries about how traits are transmitted from parents to their children. 12  Introduction to Inheritance Genetics The word GENETIC comes from the Greek word ”genetikos”, which comes from the word genesis meaning “origin“. 13 Introduction to Inheritance Genetics Heredity Variation 14 Introduction to Inheritance Genetics Heredity Variation 15 Introduction to Inheritance Genetics Heredity Variation 16 Introduction to Inheritance Genetics Heredity Variation 17  Introduction to Inheritance Molecular genetics Cytogenetics Branches of Genetics Transmission genetics Population genetics 18  Introduction to Inheritance Molecular genetics deals Cytogenetics with DNA and gene expression and regulation. Branches of Genetics Transmission genetics Population genetics 19 Molecular Genetics 20  Introduction to Inheritance Molecular genetics Cytogenetics deals with chromosome structure and behavior during cell Branches division. of Genetics Transmission genetics Population genetics 21 Cytogenetics 22  Introduction to Inheritance Molecular genetics Cytogenetics Branches of Genetics Transmission genetics deals with different patterns of inheritance. Population genetics 23 Transmission Genetics 24  Introduction to Inheritance Transmission genetics, also called classical genetics, is the oldest subdiscipline of genetics. It attempts to predict outcomes of reproduction. 25  Introduction to Inheritance Molecular genetics Cytogenetics Branches of Genetics Population genetics deals with how forces of evolution influence genes in Transmission genetics populations. 26 Population Genetics 27 Brief Background of Gregor Mendel Farm Father of Tender Genetics Augustinian Beekeeper Academician Monk 28 Brief Background of Gregor Mendel Mendel took the path to priesthood when he entered Augustinian monastery of St. Thomas and became monk. This is also where he performed his pea plant studies. 29  Pea Plant Hybridization Mendel chose the legumes garden peas or Pisum sativum for his hybridization experiments. 30 Pea Plant Hybridization 31 Pea Plant Hybridization What makes peas ideal for genetic studies? 32 Pea Plant Hybridization They What makes exhibit peas ideal for genetic vigorous studies? growth. 33 Pea Plant Hybridization They can self- fertilize. They What makes exhibit peas ideal for genetic vigorous studies? growth. 34 Pea Plant Hybridization They can self- fertilize. They What makes exhibit They can peas ideal for genetic vigorous cross- studies? growth. fertilize. 35 36 37  Challenges faced by Mendel Pangenesis Previous Notions Homunculus of Inheritance theory Blending theory 38  Challenges faced by Mendel Previous Notions of Inheritance Pangenesis Homunculus theory Blending theory 39  Challenges faced by Mendel Previous Notions of Inheritance Pangenesis Homunculus theory Pangenesis was the belief that Blending seeds are produced in different theory organs and will later on gather to form the offspring. 40  Challenges faced by Mendel Previous Notions of Inheritance Pangenesis Homunculus theory The invention of the microscope Blending theory made people believe that sperm cells bear a homunculus or little man. 41  Challenges faced by Mendel Previous Notions of Inheritance Pangenesis Homunculus theory The blending theory of Blending inheritance states that traits theory of parents blend every generation of offspring. 42 Rediscovery of Mendel’s Work Hugo de Vries Carl Correns Erich von (1848–1935) (1864–1933) Tschermak (1871–1962) Mendel’s paper, The Experiments on Plant Hybridization, was rediscovered independently by de Vries, Correns, and von Tschermak in 1900s. 43 What makes Pisum sativum an ideal model organism for genetic studies? 44 Review of Genetic Terminologies A chromosome consists of a DNA molecule, which serve as the repository of genetic information in cells. Review of Genetic Terminologies Our chromosomes occur in pairs called homologous chromosomes. Review of Genetic Terminologies Our chromosomes occur in pairs called homologous chromosomes. Paternal (from the father or male parent) Review of Genetic Terminologies Our chromosomes occur in pairs called homologous chromosomes. Paternal (from the father or male parent) Maternal (from the mother or female parent) Review of Genetic Terminologies A gene is the basic unit of heredity. It controls the expression of a biological characteristic. Review of Genetic Terminologies A gene is the basic unit of heredity. It controls the expression of a biological characteristic. A characteristic is a heritable feature of an organism. Review of Genetic Terminologies In our given example, the gene controls height of peas. Review of Genetic Terminologies Also, note that genes occur in pairs. Thus, a pair of genes control a particular characteristic. Review of Genetic Terminologies How about this gene pair? What does it control? Review of Genetic Terminologies How about this gene pair? What does it control? The highlighted gene controls seed shape in peas. Review of Genetic Terminologies Alleles are the alternativ e forms of a gene. Review of Genetic Terminologies Genotype refers to the set of alleles possessed by an organism. Review of Genetic Terminologies The genotype is homozygous if the alleles are identical. Review of Genetic Terminologies The genotype is heterozygous if the alleles are different. Review of Genetic Terminologies Let’s say that the given chromosomes give rise to the following observable traits: Tall Round-seeded Review of Genetic Terminologies Let’s say that the given chromosomes give rise to the following observable traits: Tall Round-seeded Phenotypes refer to the actual manifestation of genotypes into observable traits. Review of Genetic Terminologies If the phenotype for seed shape is round, then we can conclude that: Review of Genetic Terminologies If the phenotype for seed shape is round, then we can conclude that: The allele for round pea is the dominant allele. The allele for wrinkled pea is the recessive allele. Pea Plant Characters Gregor Mendel utilized seven characteristics of peas in his hybridization experiments. Each exists in two variants. 63 How are the alleles of a gene transmitted from parents to offspring? 64  Monohybrid Cross A monohybrid cross is a mating between two individuals involving one characteristic or one pair of contrasting traits. 65 Monohybrid Cross In this example, the height of pea is involved. 66 Monohybrid Cross In this example, the height of pea is involved. The parents have contrasting traits (i.e., tall and dwarf). 67 Monohybrid Cross In this example, the height of pea is involved. The parents have contrasting traits (i.e., tall and dwarf). Both parents must also be true- breeding or homozygous. 68 Monohybrid Cross P generation F1 generation F2 generation 69 Monohybrid Cross The parental generation P generation consists of the true- breeding initial parents. F1 generation F2 generation 70 Monohybrid Cross P generation The first filial generation F1 generation consists of the offspring of the P generation. F2 generation 71 Monohybrid Cross P generation F1 generation The second filial F2 generation generation consists of the offspring of F1 gen. 72  Monohybrid Cross Result 1: The dwarf trait disappeared in the F1 generation. 73  Monohybrid Cross P generation Result 1: The dwarf trait disappeared in the F1 generation. F1 generation 74  Monohybrid Cross P generation Result 1: The dwarf trait disappeared in the F1 generation. F1 generation Explanation: Tall trait must be dominant over the dwarf trait. 75  Monohybrid Cross Principle of Dominance In a heterozygous individual, one allele (dominant) completely masks the expression of the other allele (recessive). 76 Monohybrid Cross Principle of Dominance If we assign letters to each allele : 77 Monohybrid Cross Principle of Dominance If we assign letters to each allele : T - tall 78 Monohybrid Cross Principle of Dominance If we assign letters to each allele : T - tall t - dwarf 79 Monohybrid Cross Principle of Dominance If we assign letters to each allele : T - tall t - dwarf Thus, we will have the corresponding genotypes and phenotypes : 80 Monohybrid Cross Principle of Dominance If we assign letters to each allele : T - tall t - dwarf Thus, we will have the corresponding genotypes and phenotypes : TT - tall 81 Monohybrid Cross Principle of Dominance If we assign letters to each allele : T - tall t - dwarf Thus, we will have the corresponding genotypes and phenotypes : TT - tall Tt - tall 82  Monohybrid Cross Principle of Dominance If we assign letters to each allele : T - tall t - dwarf Thus, we will have the corresponding genotypes and phenotypes : TT - tall Tt - tall tt - dwarf 83  Monohybrid Cross Thus, we can have the genetic cross as follows: 84  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotypes Genotypes P generation F1 generation F2 generation 85  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotypes Genotypes P generation Tall × Dwarf F1 generation F2 generation 86  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotypes Genotypes P generation Tall × Dwarf TT × tt F1 generation F2 generation 87  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotypes Genotypes P generation Tall × Dwarf TT × tt Phenotypic Ratio (PR): Genotypic Ratio (GR): F1 generation F2 generation 88  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotypes Genotypes P generation Tall × Dwarf TT × tt Phenotypic Ratio (PR): Genotypic Ratio (GR): F1 generation 100% or All Tall F2 generation 89  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotypes Genotypes P generation Tall × Dwarf TT × tt Phenotypic Ratio (PR): Genotypic Ratio (GR): F1 generation 100% or All Tall 100% or All Tt F2 generation 90  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotypes Genotypes P generation Tall × Dwarf TT × tt Phenotypic Ratio (PR): Genotypic Ratio (GR): F1 generation 100% or All Tall 100% or All Tt F2 generation 3/4 Tall: 1/4 Dwarf 91  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotypes Genotypes P generation Tall × Dwarf TT × tt Phenotypic Ratio (PR): Genotypic Ratio (GR): F1 generation 100% or All Tall 100% or All Tt F2 generation 3/4 Tall: 1/4 Dwarf 1/4 TT: 2/4 Tt: 1/4 tt 92  Monohybrid Cross Result 2: The phenotypes in the F2 generation occur in a ratio of 3:1. 93  Monohybrid Cross F1 generation Result 2: The phenotypes in the F2 generation occur in a ratio of 3:1. F2 generation 94  Monohybrid Cross F1 generation Result 2: The phenotypes in the F2 generation occur in a ratio of 3:1. F2 generation 95  Monohybrid Cross F1 generation Result 2: The phenotypes in the F2 generation occur in a ratio of 3:1. F2 Explanation: generation The alleles are segregating during gamete formation. 96 Monohybrid Cross Law of Segregation The two alleles of a gene in an individual segregate or separate from each other during gamete formation. 97 Monohybrid Cross Law of Segregation P generation cross F1 generation cross 98 Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt 99  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles 100  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t 101  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t progeny 102  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t progeny Tt Tt 103  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t progeny Tt Tt Tt Tt 104  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t progeny Tt Tt Tt Tt 105  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t T t T t progeny Tt Tt Tt Tt 106  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t T t T t progeny Tt Tt Tt Tt TT Tt 107  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t T t T t progeny Tt Tt Tt Tt TT Tt Tt tt 108  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen 2. Write the genotypes. cross. 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 109  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Tall × Dwarf 2. Write the genotypes. cross. 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 110  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Tall × Dwarf 2. Write the genotypes. cross. TT × tt 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 111  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Tall × Dwarf 2. Write the genotypes. cross. TT × tt 3. Identify the alleles. T T t t 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 112  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Tall × Dwarf 2. Write the genotypes. cross. TT × tt 3. Identify the alleles. T T t t 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 113  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Tall × Dwarf 2. Write the genotypes. cross. TT × tt 3. Identify the gametes. T T t t 4. Draw the square. T T 5. Distribute gametes. 6. Combine gametes. t 7. Determine phenotypes. t 8. Determine ratios. 114  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Tall × Dwarf 2. Write the genotypes. cross. TT × tt 3. Identify the alleles. T T t t 4. Draw the square. T T 5. Distribute alleles. 6. Combine alleles. t Tt Tt 7. Determine phenotypes. t Tt Tt 8. Determine ratios. 115  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Tall × Dwarf 2. Write the genotypes. cross. TT × tt 3. Identify the alleles. T T t t 4. Draw the square. T T 5. Distribute alleles. 6. Combine alleles. t Tt Tt (Tall) (Tall) 7. Determine phenotypes. t Tt Tt 8. Determine ratios. (Tall) (Tall) 116  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Tall × Dwarf 2. Write the genotypes. cross. TT × tt 3. Identify the alleles. T T t t 4. Draw the square. T T 5. Distribute alleles. 6. Combine alleles. t Tt Tt (Tall) GR: 100% Tt (Tall) 7. Determine phenotypes. PR: 100% Tall t Tt Tt 8. Determine ratios. (Tall) (Tall) 117  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen 2. Write the genotypes. cross. 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 118  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen Tall × Tall 2. Write the genotypes. cross. 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 119  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen Tall × Tall 2. Write the genotypes. cross. Tt × Tt 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 120  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen Tall × Tall 2. Write the genotypes. cross. Tt × Tt 3. Identify the alleles. T t T t 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 121  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen Tall × Tall 2. Write the genotypes. cross. Tt × Tt 3. Identify the alleles. T t T t 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 122  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen Tall × Tall 2. Write the genotypes. cross. Tt × Tt 3. Identify the alleles. T t T t 4. Draw the square. T t 5. Distribute alleles. 6. Combine alleles. T 7. Determine phenotypes. t 8. Determine ratios. 123  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen Tall × Tall 2. Write the genotypes. cross. Tt × Tt 3. Identify the alleles. T t T t 4. Draw the square. T t 5. Distribute alleles. 6. Combine alleles. T TT Tt 7. Determine phenotypes. t Tt tt 8. Determine ratios. 124  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen Tall × Tall 2. Write the genotypes. cross. Tt × Tt 3. Identify the alleles. T t T t 4. Draw the square. T t 5. Distribute alleles. 6. Combine alleles. T TT Tt (Tall) (Tall) 7. Determine phenotypes. t Tt tt 8. Determine ratios. (Tall) (Dwarf) 125  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen Tall × Tall 2. Write the genotypes. cross. Tt × Tt 3. Identify the alleles. T t T t 4. Draw the square. T t 5. Distribute alleles. GR: 6. Combine alleles. T TT Tt 1/4 TT: 2/4 Tt: 1/4 tt (Tall) (Tall) 7. Determine phenotypes. PR: t Tt tt 3/4 Tall: 1/4 Dwarf 8. Determine ratios. (Tall) (Dwarf) 126 Dihybrid Cross A dihybrid cross is a mating between two individuals involving two characteristics or two pairs of contrasting traits. 127 Dihybrid Cross 128 Dihybrid Cross In this example, the seed shape and seed color are involved. 129 Dihybrid Cross In this example, the seed shape and seed color are involved. Two pairs of contrasting traits are involved: round/wrinkled and yellow/green. 130 Dihybrid Cross In this example, the seed shape and seed color are involved. Two pairs of contrasting traits are involved: round/wrinkled and yellow/green. Both parents must also be true- breeding or homozygous. 131 Dihybrid Cross In this example, the seed shape and seed color are involved. Two pairs of contrasting traits are involved: round/wrinkled and yellow/green. Both parents must also be true- breeding or homozygous. All of the offspring in F1 have round and yellow seeds due to dominance. 132  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen 2. Assign alleles. cross. 3. Write genotypes. 4. Identify the alleles. 5. Draw the square. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 133  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Round, yellow × Wrinkled, green 2. Assign alleles. cross. 3. Write genotypes. 4. Identify the alleles. 5. Draw the square. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 134  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Round, yellow × Wrinkled, green 2. Assign alleles. cross. 3. Write genotypes. 4. Identify the alleles. 5. Draw the square. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 135  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Round, yellow × Wrinkled, green 2. Assign alleles. cross. 3. Write genotypes. Seed shape: 4. Identify the alleles. Round seed is dominant over wrinkled seed. 5. Draw the square. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 136  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Round, yellow × Wrinkled, green 2. Assign alleles. cross. 3. Write genotypes. Seed shape: 4. Identify the alleles. Round seed is dominant over wrinkled seed. 5. Draw the square. R - round r - wrinkled 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios. 137  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Round, yellow × Wrinkled, green 2. Assign alleles. cross. 3. Write genotypes. Seed shape: 4. Identify the alleles. Round seed is dominant over wrinkled seed. 5. Draw the square. R - round r - wrinkled 6. Combine alleles. Seed color: 7. Determine phenotypes. Yellow seed is dominant over green seed. 8. Determine ratios. 138  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Round, yellow × Wrinkled, green 2. Assign alleles. cross. 3. Write genotypes. Seed shape: 4. Identify the alleles. Round seed is dominant over wrinkled seed. 5. Draw the square. R - round r - wrinkled 6. Combine alleles. Seed color: 7. Determine phenotypes. Yellow seed is dominant over green seed. 8. Determine ratios. Y - yellow y - green 139  Punnett Square 1. Write the given. Let’s apply Punnett square to our P gen Round, yellow × Wrinkled, green 2. Assign alleles. cross. 3. Write genotypes. Seed shape: 4. Identify the alleles. Round seed is dominant over wrinkled seed. 5. Draw the square. R - round r - wrinkled 6. Combine alleles. Seed color: 7. Determine phenotypes. Yellow seed is dominant over green seed. 8. Determine ratios. Y - yellow y - green 140  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Wrinkled, green square to our P gen 2. Assign alleles. cross. RRYY × rryy 3. Write genotypes. 4. Identify the alleles. 5. Draw the square. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Wrinkled, green square to our P gen 2. Assign alleles. cross. RRYY × rryy 3. Write genotypes. R r Y y 4. Identify the alleles. 5. Draw the square. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Wrinkled, green square to our P gen 2. Assign alleles. cross. RRYY × rryy 3. Write genotypes. R r Y y 4. Identify the gametes. R R 5. Draw the square. Y Y r 6. Combine alleles. y 7. Determine phenotypes. r 8. Determine ratios. y  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Wrinkled, green square to our P gen 2. Assign alleles. cross. RRYY × rryy 3. Write genotypes. R r Y y 4. Identify the alleles. R R 5. Draw the square. Y Y r RrYy RrYy 6. Combine alleles. y 7. Determine phenotypes. r RrYy RrYy 8. Determine ratios. y  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Wrinkled, green square to our P gen 2. Assign alleles. cross. RRYY × rryy 3. Write genotypes. R r Y y 4. Identify the alleles. R R 5. Draw the square. Y Y r RrYy RrYy 6. Combine alleles. y (round, yellow) (round, yellow) 7. Determine phenotypes. r RrYy RrYy 8. Determine ratios. y (round, yellow) (round, yellow)  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Wrinkled, green square to our P gen 2. Assign alleles. cross. RRYY × rryy 3. Write genotypes. R r Y y 4. Identify the alleles. R R 5. Draw the square. Y Y r RrYy RrYy GR: 6. Combine alleles. 100% RrYy y (round, yellow) (round, yellow) 7. Determine phenotypes. PR: r RrYy RrYy 100% round, 8. Determine ratios. y (round, yellow) (round, yellow) yellow  Punnett Square 1. Write the given. Let’s apply Punnett square to our F1 gen 2. Write genotypes. cross. 3. Identify the alleles. 4. Draw the square. 5. Distribute the alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Round, yellow square to our F1 gen 2. Write genotypes. cross. 3. Identify the alleles. 4. Draw the square. 5. Distribute the alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Round, yellow square to our F1 gen 2. Write genotypes. cross. RrYy × RrYy 3. Identify the alleles. 4. Draw the square. 5. Distribute the alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Round, yellow square to our F1 gen 2. Write genotypes. cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. 5. Distribute the alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Round, yellow square to our F1 gen 2. Write genotypes. cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. Rr Yy 5. Distribute the alleles. R 6. Combine alleles. 7. Determine phenotypes. r 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Round, yellow square to our F1 gen 2. Write genotypes. cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. Rr Yy 5. Distribute the alleles. Y R 6. Combine alleles. y 7. Determine phenotypes. Y r 8. Determine ratios. y  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Round, yellow square to our F1 gen 2. Write genotypes. cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. Rr Yy 5. Distribute the alleles. Y R 6. Combine alleles. y 7. Determine phenotypes. Y r 8. Determine ratios. y  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Round, yellow square to our F1 gen 2. Write genotypes. cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. Rr Yy R 5. Distribute the alleles. Y Y R R 6. Combine alleles. y y r 7. Determine phenotypes. Y Y r r 8. Determine ratios. y y  Punnett Square 1. Write the given. Let’s apply Punnett Round, yellow × Round, yellow square to our F1 gen 2. Write genotypes. cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. Rr Yy R 5. Distribute the alleles. Y Y Thus, the R R genotype 6. Combine alleles. y y RrYy has r four possible 7. Determine phenotypes. Y Y gametes. r r 8. Determine ratios. y y  Punnett Square 1. Write the given. RrYy × RrYy 2. Write genotypes. 3. Identify the alleles. 4. Draw the square. 5. Distribute the alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. RrYy × RrYy R R r r 2. Write genotypes. Y y Y y R 3. Identify the alleles. Y 4. Draw the square. R y 5. Distribute the alleles. r 6. Combine alleles. Y 7. Determine phenotypes. r y 8. Determine ratios.  Punnett Square 1. Write the given. RrYy × RrYy R R r r 2. Write genotypes. Y y Y y R RRYY RRYy RrYY RrYy 3. Identify the alleles. Y 4. Draw the square. R RRYy RRyy RrYy Rryy y 5. Distribute the alleles. r RrYY RrYy rrYY rrYy 6. Combine alleles. Y 7. Determine phenotypes. r RrYy Rryy rrYy rryy y 8. Determine ratios.  Punnett Square 1. Write the given. RrYy × RrYy R R r r 2. Write genotypes. Y y Y y R RRYY RRYy RrYY RrYy 3. Identify the alleles. Y round, round, round, round, yellow yellow yellow yellow 4. Draw the square. R RRYy RRyy RrYy Rryy round, round, round, round, y 5. Distribute the alleles. yellow green yellow green r RrYY RrYy rrYY rrYy 6. Combine alleles. round, round, wrinkled wrinkled Y yellow yellow yellow yellow 7. Determine phenotypes. r RrYy Rryy rrYy rryy round, round, wrinkled wrinkled, y yellow green yellow green 8. Determine ratios.  Punnett Square 1. Write the given. RrYy × RrYy R R r r 2. Write genotypes. Y y Y y R RRYY RRYy RrYY RrYy 3. Identify the alleles. Y round, round, round, round, yellow yellow yellow yellow 4. Draw the square. R RRYy RRyy RrYy Rryy round, round, round, round, y 5. Distribute the alleles. yellow green yellow green r RrYY RrYy rrYY rrYy 6. Combine alleles. round, round, wrinkled wrinkled Y yellow yellow yellow yellow 7. Determine phenotypes. r RrYy Rryy rrYy rryy round, round, wrinkled wrinkled, y yellow green yellow green 8. Determine ratios.  Punnett Square 1. Write the given. RrYy × RrYy 2. Write genotypes. Genotypic Ratio: 3. Identify the alleles. 1/16 RRYY 2/16 RrYY 1/16 rrYY 4. Draw the square. 2/16 RRYy 4/16 RrYy 2/16 rrYy 1/16 RRyy 2/16 Rryy 1/16 rryy 5. Distribute the alleles. Phenotypic Ratio: 6. Combine alleles. 7. Determine phenotypes. 9/16 round, yellow 3/16 wrinkled, yellow 3/16 round, green 1/16 wrinkled, green 8. Determine ratios.  Dihybrid Cross Result 2: The phenotypes in the F2 generation occur in a ratio of 9:3:3:1 162  Dihybrid Cross Result 2: The phenotypes in the F2 generation occur in a ratio of 9:3:3:1 163  Dihybrid Cross Result 2: The phenotypes in the F2 generation occur in a ratio of 9:3:3:1 Explanation: The genes for seed shape and color are independently assorting. 164  Dihybrid Cross Law of Independent Assortment The alleles from different genes are sorted into the gametes independently of each other. Thus, the inheritance of these two genes become independent. 165 Is the law of segregation still applicable when two genes are already involved? Why do you think so? 166  Laws of Inheritance and Gametogenesis Both laws of inheritance operate during the Anaphase I of meiosis during gamete formation. 167 How is the separation of homologous chromosomes relevant to the laws of inheritance? 168  Let’s Practice! Brylle is fond of growing crops in his garden. One of the crops that he cultivates is the garden pea (Pisum sativum). One strain of his pea plants is heterozygous for flower colors, with genotype Mm. Another strain of his peas has smooth pods and axial flowers with genotype AaBB. What are the alleles produced by each of these two plants with respect to the indicated characteristics? 169  Let’s Practice! Brylle is fond of growing crops in his garden. One of the crops that he cultivates is the garden pea (Pisum sativum). One strain of his pea plants is heterozygous for flower colors, with genotype Mm. Another strain of his peas has smooth pods and axial flowers with genotype AaBB. What are the alleles produced by each of these two plants with respect to the indicated characteristics? Plant 1 (Mm) produces gametes with alleles M and m, while Plant 2 (AaBB) produces gametes with allele combinations AB and aB. 170  Let’s Sum It Up! Genetics is the study of inheritance and variation in organisms. It has various subdisciplines. Transmission genetics is the one that is particularly concerned about the mechanisms or patterns of inheritance. 172  Let’s Sum It Up! Gregor Mendel is the father of genetics. He performed experiments on garden pea or Pisum sativum. This led him to formulate the laws of inheritance in his publication, Experiments on Plant Hybrids. 173  Let’s Sum It Up! Different genes control the expression of the characteristics of organisms. Each gene exists in alternative forms called alleles. In terms of expression, genes can either be dominant or recessive. According to the principle of dominance of Mendel, in a heterozygous individual, the dominant allele tends to mask the expression of the recessive allele. 174  Let’s Sum It Up! Mendel’s monohybrid cross reveals the law of segregation. According to this law, the alleles segregate during gametogenesis. This explains the characteristic 3:1 phenotypic ratio of F2 in monohybrid crosses. 175  Let’s Sum It Up! Mendel’s dihybrid cross reveals the law of independent assortment. According to this law, allele pairs from different genes separate independently during gamete formation. This explains the characteristics ratio of 9:3:3:1 of F2 of dihybrid crosses. 176  Let’s Sum It Up! Transmission genetics serves as the pioneer field in genetics. 177 Challenge Yourself You crossed two true-breeding lines of violet-flowered and white- flowered peas. Is it possible to establish a true-breeding line of the genotype found in the offspring of your cross? Why or why not? 178 Photo Credits Slide 4: Woman with widow's peak, cropped by Kdhondt is licensed under CC BY-SA 4.0 via Wikimedia Commons. Slide 4: Rolled tongue flikr, cropped, by Gideon Tsang from Austin, USA is licensed under CC BY-SA 2.0 via Wikimedia Commons. Slides 17 to 21: India - Chennai - busy T. Nagar market 1 (3059480968) by McKay Savage from London, UK, cropped, adjusted is licensed under CC BY 2.0 via Wikimedia Commons. Slide 24: StThomasAbbeyBrno by No machine-readable author provided, Parmesan~commonswiki assumed (based on copyright claims) is licensed under CC BY-SA 3.0 via Wikimedia Commons. Slides 25 to 30: Starr 081009-0043 Pisum sativum var. Macrocarpum by Forest & Kim Starr is licensed under CC BY 3.0 via Wikimedia Commons. Slide 25: Pisum sativum flowers J1 by Jamain is licensed under CC BY-SA 3.0 via Wikimedia Commons. 179 Bibliography Brooker, J. Concepts of Genetics (1st ed.). New York, USA: McGraw-Hill Companies Inc., 2012. Klug, W.S, and Cummings, M.R. Concepts of genetics (6th ed). Upper Saddle River, N.J: Prentice-Hall. 2003. Pierce, B. Genetics: a conceptual approach (8th ed). New York: W.H. Freeman. 2012. Reece J., Taylor M., Simon E., and Dickey J. Campbell Biology: Concepts and Connections (7th ed.). Boston: Benjamin Cummings/Pearson. 2011. Snustad, D.P., and Simmons, M.J. Principles of Genetics (6th ed.). Hoboken, NJ: Wiley. 2012. 180