Name: Row Unit 8 - Chapter 11 - Mendelian Genetics and Meiosis Advance Organizer Topic: Mendelian Genetics and Meiosis 1. Objectives (What should I be able to do?) a. Summarize the outcomes of Gregor Mendel's experiments. b. Distinguish between the laws and principles of inheritance: dominance, segregation, and independent assortment. c. Use probability and Punnett squares to predict genotypes and phenotypes. d. Explore modes of inheritance: sex-linkage, codominance, crossing over, incomplete dominance, and multiple alleles. e. Compare and contrast mitosis and meiosis. f. Analyze the meiotic maintenance of constant chromosome number from one generation to the next. --------------------------------------------------------------------- 2. Key Vocabulary genetics true-breeding trait hybrid gene allele segregation gamete fertilization probability Punnett square homozygous heterozygous phenotype genotype codominance independent assortment incomplete dominance multiple alleles polygenic traits homologous diploid haploid meiosis tetrad crossing over gene map --------------------------------------------------------------------- 3. Essential Questions (What should I be able to answer?) a. Who was Gregor Mendel and why is his work central to the study of genetics? b. How are traits passed from generation to generation? c. How are recessive traits passed down generations? d. How is meiosis similar to mitosis? How is it different? e. Why is meiosis an essential process for species adaptation in changing environments? --------------------------------------------------------------------- 4. Assessments and Schedule Assignment/Class Work Date Trait Inventory Activity January 5 Notes & Practice over Mendelian Genetics and Meiosis January 6-8 Chapter 11 Vocabulary January 8 (due) Bikini Bottom Genetics Worksheets January 12 (due) Genetics Packet January 13-14 (due Jan 14) Genetics Lab - Smiley Baby January 14 (due Jan 15) Study Guide January 15 Jeopardy Review January 19 Unit 8 Test January 20
Notes 1. Who was Gregor Mendel and why is his work central to the study of genetics? Before Mendel - idea of blended inheritance - offspring have traits intermediate between parental traits - does not account for variation or species diversity Gregor Mendel - Monk, scientist, and mathematician in the mid-1800s. Conducted a statistical study of pea plants in the monastery s garden to develop new color variations (hybridization). Studied one trait at a time (one variable!) which allowed him to produce accurate results. He is considered the father of genetics" due to his study of traits and inheritance. Terms - a. genetics - study of heredity b. trait - specific characteristic (plant height, seed color) c. hybrid - offspring of two parents with different traits 2. How are traits passed from generation to generation through Mendelian inheritance? Terms - a. gene - chemical factors that determine traits b. allele - different forms of a gene (most genes have 2 alleles - 1 from each parent) c. genotype - genetic makeup of a trait (genotype = genetic) d. phenotype - outward physical expression of a trait (phenotype = physical) e. heterozygous - has 2 different alleles for the same trait f. homozygous - has 2 identical alleles for the same trait g. Punnett square - diagram that shows possible outcomes of genetic crosses
3. What are the types of inheritance and how can they be studied mathematically? a. Dominant - Recessive (one allele is dominant over the other) Example 1: In peas, seeds may be either round (R) or wrinkled (r). If two plants heterozygous round were crossed, what is the probability of any offspring being homozygous round? 25% If a homozygous round plant was crossed with a homozygous wrinkled plant, what is the probability of any offspring being homozygous wrinkled? 0%
b. Incomplete Dominance (neither allele is dominant - they blend) Name: Row: Example 2: A red flowering plant (RR) and a white flowering plant (WW) produce offspring that are pink. What are the genotypes of the parents? RR, WW What are the possible genotypes of the offspring? 100% RW What would be the phenotypic possibilities of a cross between two pink flowering plants? 25% Red, 50% Pink, 25% White
c. Codominance (both alleles show up at the same time) Name: Row: Example 3: A white cow and a red bull produce offspring that are roan. What are the genotypes of the parents? What are the possible genotypes of a cross between a red bull & a white cow? 100% RW What are the possible phenotypes of a cross between a roan cow and a roan bull? 25% Red, 50% Roan, 25% White d. Multiple Alleles - more than 2 alleles for a gene within a population Example 4: Coat color in rabbits is determined by a single gene that has at least 4 different alleles. Different combinations of alleles produce 4 different colors of rabbits: C = full color C ch = chinchilla C h = Himalayan c = albino What allele combinations could each color of rabbit have? Full color: CC, Cc ch, Cc h, Cc Himalayan: c h c, c h c h Chinchilla: c ch c h, c ch c ch, c ch c Albino: cc
If a chinchilla rabbit was crossed with a full color rabbit, what allele combinations are possible? See me for answer If an albino rabbit was crossed with a himalayan rabbit, what allele combinations are possible? See me for answer 4. How are traits passed on at the chromosomal level? Terms - a. meiosis - division of cells that produces a gamete gamete - sex cell produced through meiosis (egg or sperm) b. homologous - each chromosome from the male parent has a corresponding chromosome from the female parent c. diploid (2N) - cell that contains both sets of homologous chromosomes (somatic or body cell) d. haploid (N) - cell that contains a single set of chromosomes from either the male or female parent (sex cell) Male = sperm Female = egg
Meiosis: - Reduces the number of chromosomes per cell by half. - In meiosis, a cell undergoes the same steps as mitosis, but it is repeated to reduce the number of chromosomes to half the original cell. - In meiosis I, each chromosome pairs with its corresponding homologous chromosome to form a tetrad (4 chromatids). As the chromosomes pair up, they exchange portions of their chromatids through crossing - over - Meiosis results in four haploid (N) daughter cells. e. segregation - separation of alleles during gamete formation f. independent assortment - when genes for different traits segregate independently of one another and do not influence each other s inheritance g. gene linkage - some genes are next to each other on a chromosome, and are often inherited together h. gene map - shows the relative location of genes on a chromosome
5. How can mitosis and meiosis be compared? Why is meiosis an essential process for adaptation of species in changing environments? Mitosis Meiosis No crossing over Crossing over One cell division Two cell divisions 2 daughter cells 4 daughters cells Diploid cells (2n) Haploid cells (n) Identical daughter cells Not identical daughter cells Produces somatic cells Produces sex cells (gametes)