GENETICS DEVELOPED FROM CURIOSITY ABOUT INHERITANCE 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 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

GREGOR MENDEL

PEA PLANT CHARACTERISTICS

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.

MENDEL DISCOVERED THAT INHERITANCE FOLLOWS RULES OF CHANCE 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 Ended here

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

Andalusian chicken Not blenging hypothesis because reappear in f2 Stopped here

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? Ended here

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

Sex-linked Inheritance

Why are some diseases more common in men than women? Ex. Color blind 8 % of males, but only 0.5% females

Sex-Linked Traits Male and Female Y does not carry many genes

Sex-Linked Traits in Human Red/Green Colorblindness Hemophilia

1/10 males! Only 1/100 females

Hemophilia

Hemophilia Queen Victoria of England was a carrier 1819-1901

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.

Exit Ticket Would this person XH Xh have hemophilia? Is this male of female? Would person XHY have hemophilia? Is this male or female?

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

Sex-Linked Cross Cross a female that has normal vision with a male that is colorblind. What percent of their children will be colorblind?

Pedigree

Offspring: Shade in the trait expressed

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).