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CHAPTER 10.1. GENETICS DEVELOPED FROM CURIOSITY ABOUT INHERITANCE. THE BLENDING HYPOTHESIS OF INHERITANCE. Trait- a variation of a particular gene. TONGUE ROLLING. HITCHHIKERS THUMB. BENT PINKY. EARLOBES. WIDOW ’ S PEAK. DIMPLES. MID-DIGIT HAIR. THE BLENDING HYPOTHESIS OF INHERITANCE.
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CHAPTER 10.1 GENETICS DEVELOPED FROM CURIOSITY ABOUT INHERITANCE
THE BLENDING HYPOTHESIS OF INHERITANCE • Trait- a variation of a particular gene
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
MENDEL’S PLANT BREEDING EXPERIMENTS • Gregor Mendel- Austrian monk, gave rise to genetics, studied pea plants
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
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.
CHAPTER 10.2 MENDEL DISCOVERED THAT INHERITANCE FOLLOWS RULES OF CHANCE
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)
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)
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
MENDEL’S PRINCIPLE OF SEGREGATION • Test Cross- breed a homozygous recessive individual with a dominant phenotype
MENDEL’S PRINCIPLE OF SEGREGATION • Phenotype- an observable trait • Genotype- genetic makeup, combination of alleles
MENDEL’S PRINCIPLE OF INDEPENDENT ASSORTMENT • Dihybrid Cross- cross organisms differing in two characteristics, proves independent assortment
Predict the colors of the offspring of 2 true-breeding Mirabalis plants, one white, and one red.
MENDEL’S PRINCIPLE OF INDEPENDENT ASSORTMENT • Principle of Independent Assortment- alleles for genes are sorted independently of one another
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.
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
INTERMEDIATE INHERITANCE • Intermediate Inheritance- when a heterozygote has a phenotype between both homozygous parents • Also known as incompelte dominance
MULTIPLE ALLELES • When several alleles exist in a population • Example: Blood
MULTIPLE ALLELES • Codominance- when a heterozygote expresses both traits • IaIb • How is this different than intermediate inheritance?
POLYGENIC INHERITANCE • When two or more genes affect a single character
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
CHROMOSOME THEORY OF INHERITANCE • Chromosome Theory of Inheritance- genes are located on chromosomes, inheritance patterns are based on fertilization and meiosis
CHROMOSOME THEORY OF INHERITANCE • Gene Locus- the location of a trait on a chromosome
GENETIC LINKAGE AND CROSSING OVER • Genetic Linkage- the tendency for alleles to be inherited together
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
Why are some diseases more common in men than women? • Ex. Color blind • 8 % of males, • but only 0.5% females
Sex-Linked Traits in Human • Red/Green Colorblindness • Hemophilia