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GENETICS DEVELOPED FROM CURIOSITY ABOUT INHERITANCE
CHAPTER 10.1 GENETICS DEVELOPED FROM CURIOSITY ABOUT INHERITANCE
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THE BLENDING HYPOTHESIS OF INHERITANCE
Trait- a variation of a particular gene
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TONGUE ROLLING
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HITCHHIKERS THUMB
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BENT PINKY
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EARLOBES
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WIDOW’S PEAK
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DIMPLES
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MID-DIGIT HAIR
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THE BLENDING HYPOTHESIS OF INHERITANCE
Blending Hypothesis- early 1800’s, offspring would appear as a blending of parental traits Example: Purple flower X White Flower = Pink Flower ACTUALITY: Purple flower DISPROVED
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MENDEL’S PLANT BREEDING EXPERIMENTS
Gregor Mendel- Austrian monk, gave rise to genetics, studied pea plants
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GREGOR MENDEL
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PEA PLANT CHARACTERISTICS
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MENDEL’S PLANT BREEDING EXPERIMENTS
Genetics- the study of heredity True Breed- when a plant is crossed with itself, it ALWAYS produces identical offspring Cross-fertilization- sperm from the pollen of one flower fertilizes the eggs in the flower of a different plant
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Class Work 1. Explain how Mendel's particulate hypothesis is different from the blending hypothesis of inheritance. 2. What is the difference between self-fertilization and cross-fertilization? 3. Describe a pattern of inheritance that the blending hypothesis fails to explain.
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MENDEL DISCOVERED THAT INHERITANCE FOLLOWS RULES OF CHANCE
CHAPTER 10.2 MENDEL DISCOVERED THAT INHERITANCE FOLLOWS RULES OF CHANCE
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MENDEL’S PRINCIPLE OF SEGREGATION
Hybrid- an individual with two different alleles Hh Pure Breed (true breed)- an individual with two of the same alleles hh or HH Allele- alternate forms of a gene (letters)
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MENDEL’S PRINCIPLE OF SEGREGATION
Homozygous- when two alleles are the same HH or hh Heterozygous- when two alleles are different Hh Dominant- apparent, capital letter (H) Recessive- masked, lower case letter (h)
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MENDEL’S PRINCIPLE OF SEGREGATION
Principle of Segregation- when two alleles separate during the formation of gametes Punnett Square- a tool to predict the possible outcomes
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MENDEL’S PRINCIPLE OF SEGREGATION
Test Cross- breed a homozygous recessive individual with a dominant phenotype
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MENDEL’S PRINCIPLE OF SEGREGATION
Phenotype- an observable trait Genotype- genetic makeup, combination of alleles Ended here
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MENDEL’S PRINCIPLE OF INDEPENDENT ASSORTMENT
Dihybrid Cross- cross organisms differing in two characteristics, proves independent assortment
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Predict the colors of the offspring of 2 true-breeding Mirabalis plants, one white, and one red.
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MENDEL’S PRINCIPLE OF INDEPENDENT ASSORTMENT
Principle of Independent Assortment- alleles for genes are sorted independently of one another
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Class Work 1. What are the two possible gametes produced by a plant that has the genotype Aa? Give the probability of each type of gamete. 2. Use a Punnett square to predict the genotypes produced if the plant in Question 1 is self-fertilized. Calculate the probability of each outcome. 3. List all the possible genotypes of a pea plant with purple flowers and round seeds. 4. List the four possible allele combinations in the gametes of a plant with genotype PpWw.
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CHAPTER 10.3/10.4/10.5 THERE ARE MANY VARIATIONS OF INHERITANCE PATTERNS/MEIOSIS EXPLAINS MENDEL’S PRINCIPLE/SEX-LINKED TRAITS HAVE UNIQUE INHERITANCE PATTERNS
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INTERMEDIATE INHERITANCE
Intermediate Inheritance- when a heterozygote has a phenotype between both homozygous parents Also known as incompelte dominance
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Andalusian chicken Not blenging hypothesis because reappear in f2 Stopped here
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MULTIPLE ALLELES When several alleles exist in a population
Example: Blood
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MULTIPLE ALLELES Codominance- when a heterozygote expresses both traits IaIb How is this different than intermediate inheritance? Ended here
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POLYGENIC INHERITANCE
When two or more genes affect a single character
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IMPORTANCE OF ENVIRONMENT
Leaves vary in size, shape, and greenness from year to year depending on exposure to wind and sunlight Nutrition/Exercise influence on height, body build, and skin color Temperature and fur Siamese Cats
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CHROMOSOME THEORY OF INHERITANCE
Chromosome Theory of Inheritance- genes are located on chromosomes, inheritance patterns are based on fertilization and meiosis
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CHROMOSOME THEORY OF INHERITANCE
Gene Locus- the location of a trait on a chromosome
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GENETIC LINKAGE AND CROSSING OVER
Genetic Linkage- the tendency for alleles to be inherited together
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SEX-LINKED GENES Sex-linked gene- genes located on a sex chromosome
In humans sex linked genes are on the X chromosome (most of the time) Why do you think? Men: XY Women: XX
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Sex-linked Inheritance
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Why are some diseases more common in men than women?
Ex. Color blind 8 % of males, but only 0.5% females
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Sex-Linked Traits Male and Female
Y does not carry many genes
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Sex-Linked Traits in Human
Red/Green Colorblindness Hemophilia
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1/10 males! Only 1/100 females
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Hemophilia
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Hemophilia Queen Victoria of England was a carrier
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XBXb Carrier Female (normal) XbXb Disorder female
XBXB Normal Female XBXb Carrier Female (normal) XbXb Disorder female ( you need two copies of the gene in females to express) XBY Normal male XbY Disorder male Why do you think sex linked traits effect men more than women? Males only need one copy of the recessive allele to show the trait.
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Exit Ticket Would this person XH Xh have hemophilia? Is this male of female? Would person XHY have hemophilia? Is this male or female?
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Sex- Linked Cross If a mother who is a carrier for Hemophilia has a child with a father who has normal blood? What percent of the children will have Hemophilia? What percent of the boys? Stopped here
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Sex-Linked Cross Cross a female that has normal vision with a male that is colorblind. What percent of their children will be colorblind?
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Pedigree
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Offspring: Shade in the trait expressed
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Problems with Chromosome Number
Monosomy – only one of a particular type of chromosome (2n -1) Trisomy – having three of a particular type of chromosome (2n + 1) Polyploidy – having more than two sets of chromosomes; triploids (3n = 3 of each type of chromosome), tetraploids (4n = 4 of each type of chromosome).
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