Quinn CP Bio Name: __________________ Chapter 11: Introduction to Genetics 11-1: The Work of Gregor Mendel 1. Gregor Mendel’s Peas a. ____________ is the scientific study of __________________. b. Gregor Mendel was an Austrian ___________. His work was important to the understanding of heredity. c. Mendel carried out his work with ordinary _______________________. d. Mendel knew that: i. the male part of each flower produces ____________, (containing sperm). ii. the ____________ part of the flower produces egg cells. iii. During sexual reproduction, sperm and egg cells join in a process called ______________________. iv. Fertilization produces a new ________________. v. Pea flowers are ________-pollinating. vi. Sperm cells in pollen fertilize the egg cells in the ___________ flower. vii. The ___________ that are produced by self-pollination inherit all of their characteristics from the _________ plant that bore them. viii. Mendel had ___________-breeding pea plants that, if allowed to self-pollinate, would produce offspring _______________ to themselves. ix. Mendel wanted to produce seeds by joining male and female reproductive cells from _________ different plants. x. He cut away the pollen-bearing male parts of the plant and dusted the plant’s flower with pollen____________ from another plant. xi. This process is called ___________________________. xii. Mendel was able to produce seeds that had ______ different parents. 2. _____________ and Dominance a. A ____________ is a specific characteristic that varies from one individual to another. b. Mendel studied seven pea plant traits, each with two contrasting characters. i. He crossed plants with each of the seven contrasting characters and studied their ____________. ii. Each original pair of plants is the P (_____________) generation. iii. The offspring are called the ____, or “first filial,” generation. iv. The offspring of crosses between parents with different traits are called ______________. v. The F1 hybrid plants all had the character of only _______ of the ______________. Quinn CP Bio Name: __________________ c. Mendel's first conclusion was that ________________ inheritance is determined by factors that are passed from one ______________ to the next. d. Today, scientists call the factors that determine traits _____________. e. Each of the traits Mendel studied was controlled by one gene that occurred in two _____________________ forms that produced different characters for each ____________. f. The different forms of a gene are called _____________. g. Mendel’s second conclusion is called the principle of ______________. 3. What is the principle of dominance? a. The principle of dominance states that some alleles are dominant and others are _________________. b. An _______________ with a dominant allele for a trait will ___________ exhibit that form of the trait. c. An organism with the recessive allele for a trait will exhibit that form only when the dominant allele for that trait is ___________________. 4. ____________________ a. What happens during segregation? i. Mendel crossed the F1 generation with _____________ to produce the F2 (____________ filial) generation. ii. The traits controlled by recessive alleles reappeared in _______________ of the F2 plants. iii. Mendel assumed that a dominant allele had masked the corresponding recessive allele in the ________ generation. iv. The trait controlled by the ________________ allele showed up in some of the F2 plants. v. The reappearance of the trait controlled by the recessive allele indicated that at some point the allele for ______________ had been separated, or segregated, from the allele for ____________. vi. Mendel suggested that the alleles for tallness and shortness in the F1 plants ____________________ from each other during the formation of the sex cells, or gametes. vii. When each F1 plant flowers and produces _____________, the two alleles segregate from each other so that each gamete carries only a _______________ copy of each ____________. viii. Therefore, each F1 plant produces _______ types of gametes— those with the allele for tallness, and those with the allele for shortness. ix. Alleles ____________________ during gamete formation. 11-2: Probability and Punnett Squares 1. Genetics and __________________ a. How do geneticists use the principles of probability? b. The likelihood that a particular event will occur is called _____________. c. The principles of probability can be used to predict the outcomes of ___________________________. 2. Punnett Squares a. How do geneticists use Punnett squares? b. The __________ combinations that might result from a genetic cross can be determined by drawing a diagram known as a _______________ square. Quinn CP Bio Name: __________________ c. Punnett squares can be used to _____________ and compare the genetic variations that will result from a cross. d. A _____________ letter represents the dominant allele for tall. e. A lowercase letter represents the __________________ allele for short. f. In this example, i. T = _______ ii. ___ = short g. ______________ produced by each F1 parent are shown along the top and left side. h. Possible gene combinations for the F2 _____________ appear in the four boxes. i. Organisms that have two identical alleles for a particular trait are said to be ____________________. j. Organisms that have two ________________ alleles for the same trait are _____________________. k. Homozygous organisms are true- breeding for a particular _______. l. Heterozygous organisms are ____________ for a particular trait. m. All of the tall plants have the same phenotype, or _______________ characteristics. n. The tall plants _____________ have the same genotype, or genetic makeup. o. One third of the tall plants are _______, while two thirds of the tall plants are ______. p. The plants have different _______________ (TT and Tt), but they have the same ____________________ (tall). i. One fourth (1/4) of the F2 plants have _______ alleles for tallness (_____). ii. 2/4 or 1/2 have one allele for tall (___), and one for short (___). iii. One fourth (1/4) of the F2 have ______ alleles for short (tt). iv. Because the allele for tallness (T) is ________________ over the allele for shortness (t), 3/4 of the F2 plants should be tall. v. The ratio of tall plants (TT or Tt) to short (tt) plants is ____:____. vi. The predicted ratio showed up in Mendel’s experiments indicating that ___________________ did occur. 3. Probabilities Predict Averages a. Probabilities predict the average ___________________ of a large number of events. b. Probability _____________ predict the precise outcome of an ______________ event. c. In genetics, the larger the number of ______________________, the closer the resulting numbers will get to ________________ values. Quinn CP Bio Name: __________________ 11-3: Exploring Mendelian Genetics 1. Independent Assortment a. What is the principle of independent assortment? b. To determine if the segregation of one __________ of alleles affects the segregation of another pair of alleles, Mendel performed a __________________ cross. 2. The _______-Factor Cross: F1 a. Mendel crossed __________-breeding plants that produced round ____________ peas (genotype RRYY) with true-breeding plants that produced ________________ green peas (genotype rryy). b. All of the F1 offspring produced round yellow peas (__________). c. The alleles for round (R) and yellow (Y) are ________________ over the alleles for wrinkled (r) and green (y). 3. The Two-Factor Cross:_______ a. Mendel crossed the heterozygous F1 _________ (RrYy) with each other to determine if the ___________ would segregate from each other in the F2 generation. i. RrYy × RrYy b. The Punnett square predicts a 9 : 3 : 3 :1 ratio in the F2 _________________. c. In Mendel’s experiment, the F2 generation produced the following: i. some seeds that were round and ___________ ii. some seeds that were wrinkled and ___________ iii. some seeds that were ____________ and green iv. some seeds that were _______________ and yellow d. The alleles for seed shape segregated independently of those for seed color. This principle is known as ___________________ assortment. e. Genes that segregate independently ______________ influence each other's inheritance. f. Mendel's experimental _____________ were very close to the 9 : 3 : 3 : 1 ratio predicted by the Punnett _____________. g. Mendel had discovered the principle of independent _______________. h. The principle of independent assortment states that ________ for different traits can segregate independently during the formation of gametes. i. Independent assortment helps account for the many genetic _________________ observed in plants, animals, and other organisms. 4. A Summary of Mendel's Principles a. Genes are passed from _______________ to their ________________. b. If two or more forms (______________) of the gene for a single trait exist, some forms of the gene may be dominant and others may be recessive. c. In most ________________ reproducing organisms, each adult has _____ copies of each gene. These genes are segregated from each other when gametes are formed. d. The alleles for different genes usually segregate __________________ of one another. Quinn CP Bio Name: __________________ 5. Beyond Dominant and Recessive Alleles a. What inheritance patterns exist aside from ____________ dominance? b. Some alleles are neither dominant nor recessive, and many traits are controlled by ____________________ alleles or multiple __________. 6. Incomplete Dominance a. When one allele is not completely dominant over another it is called ______________________________. b. In incomplete dominance, the heterozygous phenotype is ____________________ the two homozygous phenotypes. c. A cross between red (RR) and white (WW) four o’clock plants produces ___________-colored flowers (RW). 7. Codominance a. In _____________________, both alleles contribute to the phenotype. b. In certain varieties of chicken, the allele for _____________ feathers is codominant with the allele for _________ feathers. c. Heterozygous chickens are speckled with ____________ black and white feathers. The black and white colors do not blend to form a new color, but appear _________________. 8. Multiple Alleles a. Genes that are controlled by __________ than two alleles are said to have _________________ alleles. b. An _____________ can’t have more than two alleles. However, more than two possible alleles can exist in a ______________________. c. A rabbit's coat color is determined by a single gene that has at least four different alleles. 9. ________________ Traits a. Traits controlled by ______________ genes are said to be polygenic traits. b. Skin color in humans is a polygenic trait controlled by more than four different genes. 10. Applying Mendel's Principles a. Thomas Hunt Morgan used _________________ to advance the study of genetics. b. Morgan and others tested Mendel’s principles and learned that they applied to other ________________ as well as plants. c. Mendel’s principles can be used to study inheritance of ______________ traits and to calculate the probability of certain traits appearing in the next generation. 11. Genetics and the ___________________ a. Characteristics of any organism are determined by the interaction between ______________ and the environment. 11-4: Meiosis 1. Each organism must inherit a _______________ copy of every gene from each of its “________________.” 2. Gametes are formed by a process that separates the two sets of genes so that each gamete ends up with just ___________ set. 3. Chromosome Number a. All organisms have _________________ numbers of chromosomes. b. A body cell in an adult fruit fly has _________ chromosomes: 4 from the fruit fly's _____________ parent, and ____ from its female parent. c. These two sets of chromosomes are _____________________. Quinn CP Bio Name: __________________ d. Each of the 4 chromosomes that came from the male parent has a corresponding _______________________ from the female parent. e. A cell that contains both sets of homologous chromosomes is said to be _______________. f. The number of chromosomes in a diploid cell is sometimes represented by the symbol __________. g. For Drosophila, the diploid number is _______, which can be written as 2N=8. h. The gametes of sexually reproducing organisms contain only a _____________ set of chromosomes, and therefore only a single set of ___________. i. These cells are haploid. Haploid cells are represented by the symbol _____. j. For Drosophila, the haploid number is 4, which can be written as ___. 4. Phases of _____________ a. What happens during the process of meiosis? b. Meiosis is a process of reduction division in which the number of chromosomes per cell is cut in ____________ through the separation of homologous chromosomes in a diploid cell. c. Meiosis involves _________ divisions, meiosis ___ and meiosis ____. d. By the end of meiosis II, the diploid cell that entered meiosis has become ____ haploid cells. Meiosis I Interphase I Prophase I Metaphase I Anaphase I Telophase I 5. Interphase I a. Cells undergo a round of _______ replication, forming duplicate chromosomes. 6. Prophase I a. Each chromosome ________ with its corresponding homologous chromosome to form a _________. b. There are 4 ____________ in a tetrad. c. When homologous chromosomes form tetrads in meiosis I, they ___________ portions of their chromatids in a process called crossing _________. d. Crossing-over produces ________ combinations of alleles. 7. Metaphase I a. _____________ fibers attach to the chromosomes. 8. Telophase I and ________________ a. Nuclear ____________ form. b. The cell separates into _______ cells. c. The two cells produced by meiosis I have chromosomes and alleles that are _____________ from each other and from the diploid cell that entered meiosis I. Quinn CP Bio Name: __________________ 9. Meiosis II a. The two cells produced by ____________________ now enter a second meiotic division. b. Unlike meiosis I, ___________ cell goes through chromosome replication. c. Each of the cell’s chromosomes has 2 __________________. Telophase I and Prophase II Metaphase II Anaphase II Telophase II and Cytokinesis Cytokinesis 10. Prophase II a. Meiosis I results in _______ haploid (N) daughter ________, each with ______ the number of chromosomes as the original cell. 11. Metaphase II a. The chromosomes line up in the ___________ of cell. 12. Anaphase II a. The sister chromatids __________ and move toward opposite ends of the cell. 13. Telophase II and Cytokinesis a. Meiosis II results in ____ haploid (N) daughter cells 14. Gamete Formation a. In ____________ animals, meiosis results in four equal-sized gametes called _________. b. In many ___________ animals, only ______ egg results from meiosis. The other three cells, called polar bodies, are usually ______ involved in reproduction. 15. Comparing Mitosis and Meiosis a. How is meiosis different from mitosis? b. _____________ results in the production of two genetically ___________ diploid cells. Meiosis produces four genetically ___________ haploid cells. c. Mitosis i. Cells produced by mitosis have the ________ number of chromosomes and alleles as the original cell. ii. Mitosis allows an organism to __________ and ____________ cells. iii. Some organisms reproduce _______________ by mitosis. d. Meiosis i. Cells produced by meiosis have _____________ the number of chromosomes as the parent cell. ii. These cells are genetically ________________ from the diploid cell and from each other. Quinn CP Bio Name: __________________ iii. Meiosis is how sexually-reproducing organisms produce _________________. 11-5: Linkage and Gene Maps 1. Gene ______________ a. What structures actually assort independently? b. Thomas Hunt Morgan’s research on fruit flies led him to the principle of ______________. c. Morgan discovered that many of the more than 50 Drosophila genes he had identified appeared to be “linked” ______________. d. They seemed to violate the principle of __________________ assortment. e. Morgan and his associates _______________ the linked genes into _____ linkage groups. f. Each linkage group assorted independently but all the genes in one group were inherited _________________. g. Each chromosome is actually a group of linked genes. h. Morgan concluded that Mendel’s principle of independent assortment still holds true. i. Chromosomes assort independently, __________ individual genes. 2. Gene ___________ a. ______________-over during meiosis sometimes _______________ genes that had been on the same chromosomes onto homologous chromosomes. b. Crossover events occasionally separate and ________________ linked genes and produce new combinations of alleles. c. Alfred Sturtevant, a student of Morgan, reasoned that the ____________ apart two genes were, the ______________________ they were to be separated by a crossover in meiosis. d. Recombination frequencies can be used to determine the distance between genes. e. Sturtevant created a gene map showing the relative ______________ of each known gene on one of the Drosophila chromosomes. f. If two genes are ____________ together, the recombination frequency between them should be _______________, since crossovers are rare. g. If they are __________________, recombination rates between them should be ____________.
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