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Biology Notes Genetics Part 4 Pages 177-191
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Standards ____ Describe the process of meiosis including independent assortment and crossing over. Explain how reduction division results in the formation haploid gametes or spores ____ Use Mendel’s laws of segregation and independent assortment to analyze patterns of inheritance ____ Discuss observed inheritance patterns caused by various modes on inheritance, including dominant, recessive, co-dominant, sex-linked, polygenic, and multiple alleles 5.4 5.6 5.7
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Essential Question How do genes influence the variety of 1.
organisms that exist? 1.
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Heredity = any _____ that is passed down from _______ to offspring
Trait = a specific characteristic that is _________ e.g. Genetics = the scientific study of ________ trait parent inherited hair color, eye color, height, weight, shoe size heredity
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A. Gregor Mendel Mendel was an ________ scientist who is considered the father of modern _________ Before Mendel, there was the _________ hypothesis that explained how people looked Austrian genetics blending
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In the 1860’s, Mendel studied ____ plants
pea plants reproduced ________ but they are ____ pollinating meaning the flower contains both the _____ and the _______ when pea plant true ______, they make plants _________ to the parents pea sexually self egg sperm breed identical
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Mendel cross _________ the pea plants
In his notes, the ____ generation is the parental generation, the ___ was the first _____ generation, and the ____ was the second _____ generation. hybrid = the offspring of crosses between parents with _________ traits pollinated P F1 filial F2 filial different
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Mendel studied ___ traits for pea plants
7 pea plant traits: 7 seed shape, seed color, pod shape, pod color, seed coat color, flower position, plant height
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II. Mendel’s Laws: Law of Dominance = when __ alleles in a gene pair are different, __ allele is dominant and the other allele is _________ Gene = part of a chromosome that determines a ______________________ Allele = different versions of a _____ for the same ____ e.g. 2 1 recessive trait (hair color, eye color) gene trait red hair vs. blond hair green eyes vs. blue eyes
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DIAGRAM:
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for any trait, a person always has ___ alleles; one from _____ and one from ____
dominant = those alleles that are considered ______ and are _____ when in a gene pair represented by a _______ letter e.g. recessive = those alleles that are not _________ if the dominant ______ is present represented by a __________ letter used to abbreviate the _________ allele 2 mom dad strong seen capital Black = B Tall = T observed allele lowercase dominant white = b short = t
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homozygous = organisms that have __ identical alleles for the same trait
e.g. heterozygous = organisms that have _________ alleles for the same trait 2 BB bb TT tt different Bb Tt
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genotype = the genetic make-up of an __________
phenotype = what is physically _________ in an organism organism BB bb TT tt Bb Tt observed Black white Tall short Black Tall
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B. Law of Segregation = during meiosis, each pair of alleles separates into different _____________________ DIAGRAM: resulted in being able to _______ what offspring ______ look like gametes (egg & sperm) predict could
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Punnett square = a diagram that shows the ________ combinations that might result from a genetic ___________ monohybrid cross = cross involving only ___ trait Steps for forming a Punnett square: 1. make a ____ showing dominant and __________ alleles 2. determine the _______ in the gametes of the ________ possible combination 1 key recessive alleles parents
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3. place the alleles from ____ on top and the alleles from _____ on the side 4. combine the alleles in the ______ 5. determine the __________ and phenotypes of the offspring inside the boxes Example: dad mom boxes genotypes Mom = Bb Dad = BB B = Black b = white B B BB B BB b Bb Bb Genotypes = ½ BB ½ Bb Phenotypes = 4/4 Black
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Aa aa Aa Aa Aa
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Probability = the use of ________ or ratios to predict the likelihood of an event’s occurrence
used to predict the __________ and phenotypes of offspring in breeding experiments e.g. What is the probability of black fur in Bb x Bb in rabbits where B= black fur and b = white fur? fractions genotypes B b B = Black b = white B BB Bb Bb b bb ¾ black = 75%
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the probability that __ events will both happen is calculated by ___________ their separate probabilities e.g. What is the probability of black fur for 2 generations in rabbits for Bb x Bb where B= black fur and b= white fur? 2 multiplying 3/4 * 3/4 = 9/16
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C. Law of Independent Assortment = during meiosis, genes for different _______ sort randomly into different ________ this means that alleles are not ______ Mendel tested _____ shape and seed color Dihybrid cross = crosses involving only __ traits once the parent’s __________ are known, the most important step is to list all _________ gamete combinations for EACH _______ alleles gametes linked seed 2 genotypes possible parent
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e.g. What would be the outcome of the F2 generation if the parents (P) are RRGG x rrgg?
R = Round r = wrinkled G = Green g = yellow P = RRGG * rrgg F1 = RrGg (self pollinate) = RrGg * RrGg possible gametes: RG Rg rG rg
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RG Rg rG rg RG RRGG RRGg RrGG RrGg Rg RRGg RRgg RrGg Rrgg rG RrGG RrGg rrGG rrGg rg RrGg Rrgg rrGg rrgg 9 = R_G_ round, green 3 = R_gg round, yellow 3 = rrG_ wrinkled, green 1 = rrgg wrinkled, yellow
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