LG 1 Mendelian Inheritance PDF

LG 1.1 MENDELIAN INHERITANCE & HEREDITY Biology 2: Fundamentals of Biology II, SY. 2024-2025 October 16, 2024  Desired Learning Competencies Relate the process of meiosis to Mendel’s laws of inheritance. Illustrate how the outcomes of breeding/cro...

LG 1.1 MENDELIAN INHERITANCE & HEREDITY Biology 2: Fundamentals of Biology II, SY. 2024-2025 October 16, 2024  Desired Learning Competencies Relate the process of meiosis to Mendel’s laws of inheritance. Illustrate how the outcomes of breeding/crosses are governed by probability rules. Apply the rules of addition and multiplication in predicting the outcomes of genetic crosses. Define the following terms: genes, alleles, dominant, recessive, phenotype, genotype, homozygous, heterozygous, trait, character and homologous chromosomes.  OUTLINE I. Genetics II. Principles Of Inheritance 1. Law of Dominance 2. Law of Segregation 3. Law of Independent Assortment C Y S L A L E C A S R B O B E H L R C G N Y P E H I S G E P E A D R B G M A I N R Y S U T E F E L C O  What is Genetics? branch of biology that deals with the study of heredity and variation in organisms. Heredity- passing of traits Variation- forms of the trait https://www.vectorstock.com/royalty-free-vectors/heredity-vectors https://eschooltoday.com/science/genetics/what-is-genetic-variation.html Gene - physical unit of heredity which controls specific trait - occupies a specific chromosomal locus Allele - forms of the gene ➔ Dominant - expressed when at LEAST one allele is inherited (heterozygous condition) ◆ represented by UPPERCASE letters ➔ Recessive - expressed when both alleles are inherited (1 from each parent). ◆ represented by lowercase letters The case of peas: 1. What gene can be represented in the figure? 2. What alleles can you see? Genotype: specific allelic constitution of one or Phenotype: observable limited number of genes properties that are genetically controlled 2 dominant alleles ➔ Homozygous dominant - with two seed shape: dominant alleles (RR) 1 dominant allele round ➔ Heterozygous - with a dominant and recessive allele (Rr). NO dominant allele ➔ Recessive - with two recessive alleles wrinkled (rr) Character: an observable & Trait: any detectable inheritable phenotypic phenotypic variation of a attribute particular inherited character Eye color Coat color Fingernail shape variation in human eye color variation in mice coat color variations in fingernail shape  Tell whether it is a: 1. Character or Trait? a. yellow seed, green seed b. Petal color Concept Check 2. Genotype or Phenotype? c. homozygous brown eyes d. Reticulate leaf venation Who is Gregor Johann Mendel? Austrian Monk, born in Czech Republic in 1822 University of Vienna - studied botany and learned the Scientific Method Worked with pure lines of peas for eight years Prior to Mendel, heredity was regarded as a "blending" process and the offspring were Image: Gregor Mendel, Mendel's Principles of Heredity: A Defense by Bateson, William; Spicoli from Fast Times at Ridgemont High essentially a "dilution"of the different parental characteristics. Established the 3 Principles of Inheritance in 1866 published work: Experiments in Plant Hybridization  Principles of Inheritance Mendel's Laws of Inheritance: I. Law of Dominance II. Law of Segregation III. Law of Independent Assortment Image: Gregor Mendel, Mendel's Principles of Heredity: A Defense by Bateson, William; Spicoli from Fast Times at Ridgemont High  I. Mendel’s Law of _________ When pure breeding parents for contrasting traits are crossed, only one form of the trait will appear in the next generation. Parental Generation: GG x gg green yellow Offspring that are heterozygous for the trait (genotype) will express only the dominant trait in the phenotype.  1. Based on the true breeding cross of green and yellow seed parents below, which trait is dominant? Concept Check 2. What are the genotype of the parents and offsprings? Use letter R.  II. Mendel’s Law of ________ Alternative versions of genes (alleles) result in variations in inherited characteristics. For each character, an organism inherits 2 alleles (one from each parent). The alleles for each character segregate (separate) during gamete production (Recall Anaphase I). Alleles for a trait are recombined at fertilization, becoming genotype for the traits of the offspring.  II. Mendel’s Law of ________ One type of Alternative versions of genes (alleles) gamete can result in variations in inherited be produced: characteristics. R For each character, an organism inherits 2 alleles (one from each parent). The alleles for each character segregate (separate) during gamete production (Recall Anaphase I). Alleles for a trait are recombined at fertilization, becoming genotype for the traits of the offspring.  II. Mendel’s Law of ________ Alternative versions of genes (alleles) result in variations in inherited characteristics. For each character, an organism inherits 2 How alleles (one from each parent). many types of The alleles for each character segregate gametes for one (separate) during gamete production (Recall parent? Anaphase I). Alleles for a trait are recombined at fertilization, becoming genotype for the traits of the offspring.  II. Mendel’s Law of ________ Alternative versions of genes (alleles) result in variations in inherited characteristics. For each character, an organism inherits 2 2 types: alleles (one from each parent). R r The alleles for each character segregate (separate) during gamete production (Recall Anaphase I). Alleles for a trait are recombined at fertilization, becoming genotype for the traits of the offspring.  Suppose a male parent has this genotype, AaBb Concept a. How many types of gametes can be Check produced? b. What is the chance of getting Ab sperm?  III. Mendel’s Law of ________ Alleles for two or more different genes are distributed to sex cells (& offspring) independently Diagram of how the genes exchange according to of one another. segregation or independent assortment during meiosis and how this translates into Mendel's laws. Recall Metaphase I Paternal RR rr Maternal YY yy  Recall: Product Rule of Probability - “AND” Rule where - the probability of two or more independent events occurring together is equal to the product of their individual probabilities Example: What is the probability of getting a pea plant with yellow pods (gg) from a cross of individuals that are both heterozygous for green pods?  Recall: Product Rule of Probability Visual representation using Punnett square:  Recall: Sum Rule of Probability - “OR” Rule where - the probability of either of two such mutually exclusive events occurring is the sum of their individual probabilities Example: What is the probability of getting a pea plant with green pods (Gg) from a cross of heterozygous individuals for pod color?  Recall: Sum Rule of Probability Visual representation using Punnett square:  In a cross between parents that both have round seeds (Rr) and green pods (Gg), a. What is the probability of getting an Concept offspring that is recessive to both Check traits? b. What is the probability producing offspring that is heterozygous (RrGg) for both traits?  LG 1.2 MENDELIAN INHERITANCE & HEREDITY Biology 2: Fundamentals of Biology II, SY. 2024-2025 October 16 and 21, 2024  Desired Learning Competencies Predict the expected phenotypic and genotypic ratios in the filial (F) generations of a monohybrid cross with complete dominance Solve problems involving monohybrid and dihybrid crosses using the Punnett square and forked line methods. Predict outcomes of a variety of test crosses  OUTLINE I. Three Methods of Solving Crosses 1. Punnett Square 2. Fork line method 3. Modified fork line method II. Dihybrid Cross  REVIEW 1. ____________ genotype: Both recessive alleles must be present (rr). 2. ___________ genotype: At least one dominant allele is present (R-). ___ ___ ___ ___ Character: Tongue Rolling Being able to roll your tongue is a dominant phenotype. 1. Harry: Being able to roll your tongue is the dominant trait (phenotype). Q: How would we represent the genotype of the ___ ___ homozygous dominant? 2. Hermione: Not being able to roll your tongue is the recessive Q: Would “Harriet” be able (phenotype). to roll her tongue? Q: What would be the recessive genotype?  Being able to roll your tongue is a dominant 3 Methods of phenotype. Solving Crosses Harry: Being able to roll your tongue is the I. Punnett Square dominant trait. II. Fork line method* Hermione: Not being able to roll your tongue is III. Modified fork the recessive. line method* *for dihybrid cross and up Q: Would “Harriet” be able to roll her tongue?  Procedure 1. Create a key showing which trait/s is dominant or recessive. R - tongue roller r - non-tongue roller 2. Identify the phenotypes, genotypes , and gametes of the parents. P1 RR x rr tongue roller non tongue roller Gametes: R r  Procedure 3. Calculate using any of the 3 4. Determine the relative methods: proportions of the a. Punnett Square genotypes and phenotypes of the R R offspring. Genotypic ratio: r Rr Rr 100% Rr Phenotypic ratio: 100% tongue roller r Rr Rr ★ Harriet will be tongue roller  Figuring Out Patterns of Inheritance The trait of bent little finger is dominant (B): DAVID (the BabyDaddy): - dominant phenotype (whose parent is recessive) - Q: What is David’s genotype? David’s Genotype: TAMI (the BabyMama): - Recessive phenotype - Q: What is my genotype? Tami’s Genotype: LEO (the BabyBaby): - Dominant phenotype [bent finger] - Q: What is Leo’s genotype? Image: Bent Little Finger” (B - ), David & Leo Port  Determine the genotypic and phenotypic ratio of the following: Concept a. AA x AA b. AA x aa Check c. AA x Aa d. Aa x Aa e. Aa x aa f. aa x aa  Dihybrid Cross a cross between two individuals with two observed traits that are controlled by two distinct genes. Example: A pea plant with yellow and round seeds is crossed with a plant that has green and wrinkled seeds. If the resulting offspring of the initial (F1) cross is self-fertilized, what is the genotypic and phenotypic ratios of the F2 offspring?  Dihybrid Cross Given: yellow (Y) > green (y) round (R) > wrinkled (r) P1 YYRR x yyrr BOARD yellow, round green, wrinkled DEMONSTRATION: Gametes: YR yr a. Punnett Square F1 YyRr (self fertilized) b. Fork Line Method c. Modified Method P2 YyRr x YyRr yellow, round green, wrinkled Gametes: ? ?  Dihybrid Cross a. Punnett Square *for class convention, use fraction form in genotypic and phenotypic ratios not in LOWEST term, otherwise stated.  Dihybrid Cross b. Fork Line Method  Dihybrid Cross c. Modified Fork Line Method  In a cross between a black and white guinea pig, all members of the F1 generation is Practice black. The F2 generation is made up of approximately ¾ black and ¼ white. Diagram Problems the cross, identify the genotypes and phenotypes of the P1, F1, and F2 generations.  Albinism in humans is inherited as a simple Practice recessive trait. Determine the genotypes of the parents and offspring when two Problems non-albino (normal) parents have five children, four normal and one albino.  Cleft chin in humans is inherited as a dominant trait while albinism is recessive. Determine the Practice probability of an albino child with cleft chin from Problems an albino man with smooth chin and normal woman with cleft chin, whose mother is albino with smooth chin.  In horses, the coat color black is dominant (B) over chestnut (b) while trotting gait is Assignment dominant (T) over the pacing gait (t). If a homozygous black pacer is mated to a chestnut, heterozygous trotter, what will be the probabilities having a black pacer in F1 generation?  If pure breeding tall plant with yellow seed crossed with a short plant with green seed (tall>short; yellow>green), a. What are the genotypic and phenotypic Practice Assignment ratio of the F1 generation? (Note: Dominant traits: tall plant with yellow Problems seeds) b. If the F1 generation is self fertilized, what will be the genotypic and phenotypic ratio of F2 generation?  REMINDERS Oct 23 - FA 1: Problem Set on Mendelian Genetics  References Klug, W.S., Cummings, M.R., Spencer, C.A and Palladino, M.A. (2012) Concepts of Genetics. 10th ed. California: Person Education Inc. Campbell, Reece, Urry, Cain, Wesserman, Minorsky and Jackson (2015) Biology: A Global Approach. 10th edition. USA: Pearson Education Ltd. Learning Guides in Biology 2 Edited* and Prepared by: Reviewed by: sgd. Angel C. Palabrica Jerile Mae E. Casimiro SST I SST-III / AUH, Biology Date: October 15, 2024 Date: Oct 15. 2024 * Edited from Biology 2 PPT from Casimiro and Viz (2023)