BIO2 11_12 Q3 0101 PF FD Mendelian Laws of Inheritance PDF

Lesson 1.1 Mendelian Laws of Inheritance General Biology 1/2 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? How well do you resemble your sibling...

Lesson 1.1 Mendelian Laws of Inheritance General Biology 1/2 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? How well do you resemble your siblings? Do you share the same facial features and complexion? 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. 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? How did the experiments of Gregor Mendel lay the foundation for the study of transmission genetics? 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).  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.  Introduction to Inheritance Looking at yourself in the mirror...  Introduction to Inheritance...have you ever wondered how you have inherited your biological traits from your parents?  Introduction to Inheritance...have you ever wondered how you have inherited your biological traits from your parents? Introduction to Inheritance Genetics answers most of our inquiries about how traits are transmitted from parents to their children. Introduction to Inheritance Genetic s Variatio Heredity n Introduction to Inheritance Genetic s Variatio Heredity n Introduction to Inheritance Genetic s Variatio Heredity n Introduction to Inheritance Genetic s Variatio Heredity n  Introduction to Inheritance Molecular genetics Cytogenetics deals with DNA and gene expression and regulation. Branches of Genetics Transmission Population genetics genetics  Introduction to Inheritance Molecular genetics Cytogenetics Branches of Genetics Transmission Population genetics genetics  Introduction to Inheritance Molecular genetics Cytogenetics deals with chromosome structure and behavior during Branches cell division. of Genetics Transmission Population genetics genetics  Introduction to Inheritance Molecular genetics Cytogenetics Branches of Genetics Transmission genetics deals with different patterns of Population genetics inheritance.  Introduction to Inheritance Molecular genetics Cytogenetics Branches of Genetics Population genetics deals with how forces of evolution Transmission influence genes genetics in populations.  Introduction to Inheritance Transmission genetics, also called classical genetics, is the oldest subdiscipline of genetics. It attempts to predict outcomes of reproduction. Brief Background of Gregor Mendel Father Farm of Tender Genetic s Beekeep Augustinia Academici er n Monk an 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.  Pea Plant Hybridization Mendel chose the legumes garden peas or Pisum sativum for his hybridization experiments. Pea Plant Hybridization Pea Plant Hybridization What makes peas ideal for genetic studies? Pea Plant Hybridization They What exhibit makes peas ideal vigorou for genetic s studies? growth. Pea Plant Hybridization They can self- fertilize. They What exhibit makes peas ideal vigorou for genetic s studies? growth. Pea Plant Hybridization They can self- fertilize. They What exhibit They can makes peas ideal vigorou cross- for genetic s fertilize. studies? growth. Challenges faced by Mendel Pangenesis Previous Homunculus Notions of theory Inheritance Blending theory  Challenges faced by Mendel Previous Notions of Inheritance Pangenesis Homunculu s theory Blending theory  Challenges faced by Mendel Previous Notions of Inheritance Pangenesis Homunculu s theory Blending theory Pangenesis was the belief that seeds are produced in different organs and will later on gather to  Challenges faced by Mendel Previous Notions of Inheritance Pangenesis Homunculu s theory Blending theory The invention of the microscope made people believe that sperm cells bear a homunculus or little  Challenges faced by Mendel Previous Notions of Inheritance Pangenesis Homunculu s theory Blending theory The blending theory of inheritance states that traits of parents blend every generation of offspring.  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 What makes Pisum sativum an ideal model organism for genetic studies? 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 alternative 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: Tal Round- l seeded Review of Genetic Terminologies Let’s say that the given chromosomes give rise to the following observable traits: Tal Round- l seeded Phenotypes refer to the actual manifestation of genotypes into 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 How are the alleles of a gene transmitted from parents to offspring? Monohybrid Cross A monohybrid cross is a mating between two individuals involving one characteristic or one Monohybrid Cross In this example, the height of pea is involved. Monohybrid Cross In this example, the height of pea is involved. The parents have contrasting traits (i.e., tall and dwarf). 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.  Monohybrid Cross P generation F1 generation F2 generation  Monohybrid Cross The parental P generation generation consists of the true- breeding initial parents. F1 generation F2 generation  Monohybrid Cross P generation The first filial F1 generation generation consists of the offspring of the P generation. F2 generation  Monohybrid Cross P generation F1 generation The second filial F2 generation generation consists of the offspring of F1 gen.  Monohybrid Cross Result 1: The dwarf trait disappeared in the F1 generation.  Monohybrid Cross P generatio Result 1: n The dwarf trait disappeared in the F1 generation. F1 generatio n  Monohybrid Cross P generatio Result 1: n The dwarf trait disappeared in the F1 generation. F1 Explanation: generatio Tall trait must be n dominant over the dwarf trait.  Monohybrid Cross Principle of Dominance In a heterozygous individual, one allele (dominant) completely masks the expression of the other allele (recessive). Monohybrid Cross Principle of Dominance If we assign letters to each allele : Monohybrid Cross Principle of Dominance If we assign letters to each allele : T - tall Monohybrid Cross Principle of Dominance If we assign letters to each allele : T - tall t - dwarf 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 : 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 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 - Tt - tall tall  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 - Tt - tt - tall tall dwarf  Monohybrid Cross Thus, we can have the genetic cross as follows:  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotype Genotypes s P generation F1 generation F2 generation  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotype Genotypes s P Tall × Dwarf generation F1 generation F2 generation  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotype Genotypes s P Tall × Dwarf TT × tt generation F1 generation F2 generation  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotype Genotypes s P Tall × Dwarf TT × tt generation Phenotypic Ratio Genotypic Ratio (PR): (GR): F1 generation F2 generation  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotype Genotypes s P Tall × Dwarf TT × tt generation Phenotypic Ratio Genotypic Ratio (PR): (GR): F1 100% or All generation Tall F2 generation  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotype Genotypes s P Tall × Dwarf TT × tt generation Phenotypic Ratio Genotypic Ratio (PR): (GR): F1 100% or All 100% or All Tt generation Tall F2 generation  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotype Genotypes s P Tall × Dwarf TT × tt generation Phenotypic Ratio Genotypic Ratio (PR): (GR): F1 100% or All 100% or All Tt generation Tall F2 3/4 Tall: 1/4 generation Dwarf  Monohybrid Cross Thus, we can have the genetic cross as follows: Phenotype Genotypes s P Tall × Dwarf TT × tt generation Phenotypic Ratio Genotypic Ratio (PR): (GR): F1 100% or All 100% or All Tt generation Tall F2 3/4 Tall: 1/4 1/4 TT: 2/4 Tt: generation Dwarf 1/4 tt  Monohybrid Cross Result 2: The phenotypes in the F2 generation occur in a ratio of 3:1.  Monohybrid Cross F1 generatio Result 2: n The phenotypes in the F2 generation occur in a ratio of 3:1. F2 generatio n  Monohybrid Cross F1 generatio Result 2: n The phenotypes in the F2 generation occur in a ratio of 3:1. F2 generatio n  Monohybrid Cross F1 generatio Result 2: n The phenotypes in the F2 generation occur in a ratio of 3:1. F2 Explanation: generatio The alleles are n segregating during gamete formation. Monohybrid Cross Law of Segregation The two alleles of a gene in an individual segregate or separate from each other during gamete formation. Monohybrid Cross Law of Segregation P generation cross F1 generation cross Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t proge ny  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t proge Tt Tt ny  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t proge Tt Tt Tt Tt ny  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t proge Tt Tt Tt Tt ny  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t T t T t proge Tt Tt Tt Tt ny  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t T t T t proge Tt Tt Tt Tt TT Tt ny  Monohybrid Cross Law of Segregation P generation cross F1 generation cross TT × tt Tt × Tt alleles T T t t T t T t proge Tt Tt Tt Tt TT Tt Tt tt ny  Punnett Square 1. Write the given. Let’s apply Punnett square 2. Write the to our P gen genotypes. cross. 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Dwa 2. Write the rf to our P gen genotypes. cross. 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Dwa 2. Write the to our P gen TT × rf tt genotypes. cross. 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Dwa 2. Write the to our P gen TT × rf tt genotypes. cross. T T t t 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Dwa 2. Write the to our P gen TT × rf tt genotypes. cross. T T t t 3. Identify the alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Dwa 2. Write the to our P gen TT × rf tt genotypes. cross. T T t t 3. Identify the gametes. 4. Draw the square. T T 5. Distribute gametes. 6. Combine t gametes. 7. Determine phenotypes. t 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Dwa 2. Write the to our P gen TT × rf tt genotypes. cross. T T t t 3. Identify the alleles. 4. Draw the square. T T 5. Distribute alleles. Tt Tt 6. Combine alleles. t 7. Determine phenotypes. t Tt Tt 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Dwa 2. Write the to our P gen TT × rf tt genotypes. cross. T T t t 3. Identify the alleles. 4. Draw the square. T T 5. Distribute alleles. Tt Tt 6. Combine alleles. t (Tall) (Tall) 7. Determine phenotypes. t Tt Tt 8. Determine ratios. (Tall) (Tall)  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Dwa 2. Write the to our P gen TT × rf tt genotypes. cross. T T t t 3. Identify the alleles. 4. Draw the square. T T 5. Distribute alleles. Tt Tt 6. Combine alleles. t GR: 100% Tt (Tall) (Tall) 7. Determine PR: 100% phenotypes. t Tt Tt (Tall) (Tall) Tall 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square 2. Write the to our F1 gen genotypes. 3. Identify the cross. alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Tall 2. Write the to our F1 gen genotypes. 3. Identify the cross. alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Tall 2. Write the to our F1 gen Tt × Tt genotypes. 3. Identify the cross. alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Tall 2. Write the to our F1 gen Tt × Tt genotypes. 3. Identify the cross. T t T t alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Tall 2. Write the to our F1 gen Tt × Tt genotypes. 3. Identify the cross. T t T t alleles. 4. Draw the square. 5. Distribute alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Tall 2. Write the to our F1 gen Tt × Tt genotypes. 3. Identify the cross. T t T t alleles. 4. Draw the square. T t 5. Distribute alleles. 6. Combine alleles. T 7. Determine phenotypes. t 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Tall 2. Write the to our F1 gen Tt × Tt genotypes. 3. Identify the cross. T t T t alleles. 4. Draw the square. T t 5. Distribute alleles. TT Tt 6. Combine alleles. T 7. Determine phenotypes. t Tt tt 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Tall 2. Write the to our F1 gen Tt × Tt genotypes. 3. Identify the cross. T t T t alleles. 4. Draw the square. T t 5. Distribute alleles. TT Tt 6. Combine alleles. T (Tall) (Tall) 7. Determine phenotypes. t Tt tt 8. Determine ratios. (Tall) (Dwarf)  Punnett Square 1. Write the given. Let’s apply Punnett square Tall × Tall 2. Write the to our F1 gen Tt × Tt genotypes. 3. Identify the cross. T t T t alleles. 4. Draw the square. T t 5. Distribute alleles. GR: TT Tt 6. Combine alleles. T 1/4 TT: 2/4 Tt: (Tall) (Tall) 1/4 tt 7. Determine PR: phenotypes. t Tt tt 3/4 Tall: 1/4 8. Determine ratios. (Tall) (Dwarf) Dwarf Dihybrid Cross A dihybrid cross is a mating between two individuals involving two characteristics or two pairs of Dihybrid Cross Dihybrid Cross In this example, the seed shape and seed color are involved. 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. 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. 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.  Punnett Square 1. Write the given. Let’s apply Punnett square 2. Assign alleles. to our P gen cross. 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 square Round, yellow × Wrinkle d, 2. Assign alleles. to our P gen green cross. 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 square Round, yellow × Wrinkle d, 2. Assign alleles. to our P gen green cross. 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 square Round, yellow × Wrinkle d, 2. Assign alleles. to our P gen green cross. Seed shape: 3. Write genotypes. 4. Identify the Round seed is dominant over alleles. wrinkled seed. 5. Draw the square. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Round, yellow × Wrinkle d, 2. Assign alleles. to our P gen green cross. Seed shape: 3. Write genotypes. 4. Identify the Round seed is dominant over alleles. wrinkled seed. 5. Draw the square. R - r - wrinkled round 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Round, yellow × Wrinkle d, 2. Assign alleles. to our P gen green cross. Seed shape: 3. Write genotypes. 4. Identify the Round seed is dominant over alleles. wrinkled seed. 5. Draw the square. R - r - wrinkled round 6. Combine alleles. Seed color: 7. Determine Yellow seed is dominant over green phenotypes. seed. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Punnett square Round, yellow × Wrinkle d, 2. Assign alleles. to our P gen green cross. Seed shape: 3. Write genotypes. 4. Identify the Round seed is dominant over alleles. wrinkled seed. 5. Draw the square. R - r - wrinkled round 6. Combine alleles. Seed color: 7. Determine Yellow seed is dominant over green phenotypes. seed. 8. Determine ratios. Y - y - green yellow  Punnett Square 1. Write the given. Let’s apply Punnett square Round, yellow × Wrinkle d, 2. Assign alleles. to our P gen green cross. Seed shape: 3. Write genotypes. 4. Identify the Round seed is dominant over alleles. wrinkled seed. 5. Draw the square. R - r - wrinkled round 6. Combine alleles. Seed color: 7. Determine Yellow seed is dominant over green phenotypes. seed. 8. Determine ratios. Y - y - green yellow  Punnett Square 1. Write the given. Let’s apply Round, yellow × Wrinkle d, Punnett square 2. Assign alleles. to our P gen green RRYY × rryy cross. 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 Round, yellow × Wrinkle d, Punnett square 2. Assign alleles. to our P gen green RRYY × rryy cross. 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 Round, yellow × Wrinkle d, Punnett square 2. Assign alleles. to our P gen green RRYY × rryy cross. 3. Write genotypes. R r Y y 4. Identify the R R gametes. 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 Round, yellow × Wrinkle d, Punnett square 2. Assign alleles. to our P gen green RRYY × rryy cross. 3. Write genotypes. R r Y y 4. Identify the R R alleles. 5. Draw the square. Y Y r RrYy RrYy 6. Combine alleles. y 7. Determine r RrYy RrYy phenotypes. 8. Determine ratios. y  Punnett Square 1. Write the given. Let’s apply Round, yellow × Wrinkle d, Punnett square 2. Assign alleles. to our P gen green RRYY × rryy cross. 3. Write genotypes. R r Y y 4. Identify the R R alleles. 5. Draw the square. Y Y r RrYy RrYy 6. Combine alleles. (round, (round, y 7. Determine yellow) yellow) phenotypes. r RrYy RrYy 8. Determine ratios. y (round, (round,  Punnett Square 1. Write the given. Let’s apply Round, yellow × Wrinkle d, Punnett square 2. Assign alleles. to our P gen green RRYY × rryy cross. 3. Write genotypes. R r Y y 4. Identify the R R alleles. 5. Draw the square. Y Y r RrYy RrYy GR: 6. Combine alleles. (round, (round, 100% y yellow) yellow) RrYy 7. Determine r PR: phenotypes. RrYy RrYy 100% 8. Determine ratios. y (round, (round, round,  Punnett Square 1. Write the given. Let’s apply Punnett square 2. Write genotypes. to our F1 gen 3. Identify the alleles. cross. 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 Round, yellow × Round, yellow Punnett square 2. Write genotypes. to our F1 gen 3. Identify the alleles. cross. 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 Round, yellow × Round, yellow Punnett square 2. Write genotypes. to our F1 gen 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 Round, yellow × Round, yellow Punnett square 2. Write genotypes. to our F1 gen cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching 4. Draw the square. technique. 5. Distribute the alleles. 6. Combine alleles. 7. Determine phenotypes. 8. Determine ratios.  Punnett Square 1. Write the given. Let’s apply Round, yellow × Round, yellow Punnett square 2. Write genotypes. to our F1 gen 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 Round, yellow × Round, yellow Punnett square 2. Write genotypes. to our F1 gen cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. Rr Yy 5. Distribute the Y alleles. R 6. Combine alleles. y 7. Determine Y phenotypes. r 8. Determine ratios. y  Punnett Square 1. Write the given. Let’s apply Round, yellow × Round, yellow Punnett square 2. Write genotypes. to our F1 gen cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. Rr Yy 5. Distribute the Y alleles. R 6. Combine alleles. y 7. Determine Y phenotypes. r 8. Determine ratios. y  Punnett Square 1. Write the given. Let’s apply Round, yellow × Round, yellow Punnett square 2. Write genotypes. to our F1 gen cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. Rr Yy R 5. Distribute the Y Y alleles. R R 6. Combine alleles. y y r 7. Determine Y Y phenotypes. r 8. Determine ratios. r y y  Punnett Square 1. Write the given. Let’s apply Round, yellow × Round, yellow Punnett square 2. Write genotypes. to our F1 gen cross. RrYy × RrYy 3. Identify the alleles. TIP: Use the branching technique. 4. Draw the square. Rr Yy R 5. Distribute the Y Y Thus, the alleles. R R genotype 6. Combine alleles. y y RrYy has r four 7. Determine Y Y phenotypes. possible r r 8. Determine ratios. y gametes. 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 r phenotypes. 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. RRYy RRyy RrYy Rryy R y 5. Distribute the alleles. RrYY RrYy rrYY rrYy r 6. Combine alleles. Y RrYy Rryy rrYy rryy 7. Determine r phenotypes. 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. RRYy RRyy RrYy Rryy R round, round, round, round, y yellow green yellow green 5. Distribute the alleles. RrYY RrYy rrYY rrYy r round, round, wrinkled wrinkled 6. Combine alleles. Y yellow yellow yellow yellow RrYy Rryy rrYy rryy 7. Determine r round, round, wrinkled wrinkled, phenotypes. 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. RRYy RRyy RrYy Rryy R round, round, round, round, y yellow green yellow green 5. Distribute the alleles. RrYY RrYy rrYY rrYy r round, round, wrinkled wrinkled 6. Combine alleles. Y yellow yellow yellow yellow RrYy Rryy rrYy rryy 7. Determine r round, round, wrinkled wrinkled, phenotypes. 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 6. Combine alleles. Ratio: 7. Determine 9/16 round, 3/16 wrinkled, phenotypes. yellow yellow 8. Determine ratios.  Dihybrid Cross Result 2: The phenotypes in the F2 generation occur in a ratio of 9:3:3:1  Dihybrid Cross Result 2: The phenotypes in the F2 generation occur in a ratio of 9:3:3:1  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.  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. Is the law of segregation still applicable when two genes are already involved? Why do you think so?  Laws of Inheritance and Gametogenesis Both laws of inheritance operate during the Anaphase I of meiosis during gamete formation. How is the separation of homologous chromosomes relevant to the laws of inheritance?  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?  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. Try It! Nickson cultivated two different plants. The first plant is recessive for trait A, while the second plant is homozygous dominant for trait B and heterozygous for trait C. What are the allele combinations that can be produced by his first and second plants?  Let’s Practice! In pea plants, axial inflorescence is dominant over terminal inflorescence. If Laiza crossed a parent plant that is heterozygous for inflorescence to another plant with terminal inflorescence, what are the genotypic and phenotypic ratios of the offspring?  Let’s Practice! In pea plants, axial inflorescence is dominant over terminal inflorescence. If Laiza crossed a parent plant that is heterozygous for inflorescence to another plant with terminal inflorescence, what are the genotypic and phenotypic ratios of the offspring? The genotypic ratio of the cross is 1/2 AA: 1/2 aa. The phenotypic ratio is 1/2 axial: 1/2 terminal. Try It! If a parent pea plant that is hybrid for flower color is crossed with a plant that is true-breeding for violet flowers, what are the genotypic and phenotypic ratios of the F1 generation? Note that having violet flowers is dominant over having white flowers.  Let’s Practice! In pea plants, round seeds are dominant over wrinkled seeds, while the tall trait is dominant over the dwarf trait. If you cross two plants that are both heterozygous for seed shape but homozygous dominant for height, what are the expected genotypic and phenotypic ratios of the offspring?  Let’s Practice! In pea plants, round seeds are dominant over wrinkled seeds, while the tall trait is dominant over the dwarf trait. If you cross two plants that are both heterozygous for seed shape but homozygous dominant for height, what are the expected genotypic and phenotypic ratios of the offspring? The genotypic ratio of the offspring of the cross is 1/4 AABB: 2/4 AaBB: 1/4 aaBB. The phenotypic ratio is 3/4 round tall: 1/4 wrinkled tall. Try It! Gene A codes for seed color, where having yellow seed is dominant over having a green seed. Gene B codes for pod shape, where the smooth pod is dominant over the constricted pod. Given the cross AaBB × AABb, what is the genotypic and phenotypic ratio of the offspring?  Check Your Understanding Determine the accuracy of each of the following statements. Write true if the statement is correct and false if otherwise. 1. If the genes for seed shape and height of peas are independently assorting, then they highly influence the inheritance of each other. 2. The F2 generation is the offspring of the P generation. 3. Both the laws of inheritance operate during the first  Check Your Understanding Provide what is asked in each of the following items. 1. What are the alleles produced by an individual with genotype NN? 2. What are the alleles produced by an individual with genotype Bb? 3. What are the alleles produced by an individual with genotype Mmnn?  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.  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.  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  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.  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.  Let’s Sum It Up! Transmission genetics serves as the pioneer field in genetics. 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? 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. 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.