LEQ: What did Mendel discover about the passing on of traits? 9.1 to 9.3

Early Misconceptions Lemark – proposed a theory of evolution based on the idea that acquired traits are inherited Lemark – proposed a theory of evolution based on the idea that acquired traits are inherited Lamark thought that organisms adapted to changes in their environment through altered behaviors. The behaviors lead to selective use or disuse of given structures causing them to increase or decrease in size. Lamark thought that organisms adapted to changes in their environment through altered behaviors. The behaviors lead to selective use or disuse of given structures causing them to increase or decrease in size. Lamark went on to claim that this acquired change was then passed on to the offspring. Lamark went on to claim that this acquired change was then passed on to the offspring.

Early Misconceptions Blended Inheritance – the traits of parents blend in the offspring Blended Inheritance – the traits of parents blend in the offspring

Gregor Mendel Father of Genetics – deduced the fundamental principles of inheritance Father of Genetics – deduced the fundamental principles of inheritance Published in 1866 – not recognized as important until long after his death Published in 1866 – not recognized as important until long after his death

Pea Plant Experiments Mendel used pea plants for his heredity experiments because… Mendel used pea plants for his heredity experiments because… Controlled breeding Controlled breeding Cheap Cheap Easy to grow and maintain Easy to grow and maintain Grow many in a small space Grow many in a small space Quick generation time Quick generation time 7 contrasting traits 7 contrasting traits

Fertilization in Pea Plants Self-fertilization Self-fertilization Pollen of one plant fertilizes the egg of the same plant Pollen of one plant fertilizes the egg of the same plant Cross-fertilization Cross-fertilization Pollen of one plant fertilizes the egg of a second plant Pollen of one plant fertilizes the egg of a second plant

True-breeding vs. Hybrid True-breeding True-breeding Organisms that when self- pollinated (or crossed with one of the same) produce an organism identical to self Organisms that when self- pollinated (or crossed with one of the same) produce an organism identical to self Hybrid Hybrid Offspring produced from crossing 2 dissimilar organisms Offspring produced from crossing 2 dissimilar organisms

Generations P – Parent Generation; the original cross P – Parent Generation; the original cross F1 – First Filial Generation; Offspring of the parent cross F1 – First Filial Generation; Offspring of the parent cross F2 – Second Filial Generation; Offspring of the F1 generation F2 – Second Filial Generation; Offspring of the F1 generation

Seven Characteristics

Monohybrid Crosses Genetic cross of individuals differing in one trait Genetic cross of individuals differing in one trait Trait – a characteristic that is inherited from parent to offspring; controlled by a gene Trait – a characteristic that is inherited from parent to offspring; controlled by a gene Examples: flower color, plant height, etc… Examples: flower color, plant height, etc… Punnett Square – diagram used to predict the possible outcome of a given cross Punnett Square – diagram used to predict the possible outcome of a given cross

Vocab… Allele – Allele – different forms of a gene different forms of a gene Example: flower color could be white or purple; plant height could be tall or short Example: flower color could be white or purple; plant height could be tall or short Homozygous Heterozygous Homozygous Heterozygous alleles are the samealleles are different alleles are the samealleles are different Dominant Dominant Allele that is expressed when it is present; represented using capitol letters Allele that is expressed when it is present; represented using capitol letters Recessive Recessive Allele that is only expressed in the absence of the dominant allele; represented using lower case of dominant letter Allele that is only expressed in the absence of the dominant allele; represented using lower case of dominant letter PhenotypeGenotype PhenotypeGenotype Physical appearance Genetic Make-up (the letters) Physical appearance Genetic Make-up (the letters)

Mendel’s Experiment

Mendel’s Law of Segregation A sperm or egg carries only 1 allele for each inherited trait because allele pairs separate from each other during the production of gametes A sperm or egg carries only 1 allele for each inherited trait because allele pairs separate from each other during the production of gametes When does segregation occur? When does segregation occur? Anaphase I of meiosis when homologous chromosomes are separated. Anaphase I of meiosis when homologous chromosomes are separated.

LEQ: How are Punnett Squares used to predict the outcomes of a cross? 4 boxes 4 boxes Define parents Define parents Aa X Aa Aa X Aa Define alleles Define alleles A = normal pigment A = normal pigment a = albino a = albino Possible alleles from one parent across the top Possible alleles from one parent across the top A or a A or a Possible alleles from 2 nd parent along the side Possible alleles from 2 nd parent along the side A or a A or a Fill in boxes bring letters down and across Fill in boxes bring letters down and across Give genotype and phenotype ratios Give genotype and phenotype ratios 1 AA: 2Aa: 1aa 1 AA: 2Aa: 1aa 3 normal: 1 albino 3 normal: 1 albino