What is this crazy woman talking about?! Just in Time What is this crazy woman talking about?!

Inheriting Traits Heredity-The passing of traits from parent to offspring. Genes located on chromosomes control traits. Alleles-Different forms of a trait that make up a gene pair. Genetics-The study of how traits are inherited through interactions of alleles.

How alleles work Each chromosome has alleles for each trait of the organism. During meiosis, chromosome pairs separate. This results in every sex cell having one chromosome with one allele for each trait. When the zygote is formed, it gets one set of alleles from the mother and one set from the father.

Mendel-The Father of Genetics He was an Austrian monk that studied math and science but became a gardener. In 1856, he began experimenting with pea plants and the correlation between flower color and seed type. He used the scientific method in what was the first recorded study of how traits pass from one generation to the next.

Mendel-The Father of Genetics He was the first to study one trait through several generations. He was also the first to use the mathematics of probability to explain heredity. The use of math in plant science wasn’t widely accepted, and Mendel’s work was “lost” for many years. In 1900, three independent scientists all came to to same conclusions as Mendel, after discovering his research.

Mendel-The Father of Genetics He was the first to study one trait through several generations. He was also the first to use the mathematics of probability to explain heredity. The use of math in plant science wasn’t widely accepted, and Mendel’s work was “lost” for many years. In 1900, three independent scientists all came to to same conclusions as Mendel, after discovering his research.

Dominant and Recessive Factors Instead of letting pollination happen naturally, Mendel pollinated his plants by hand. He would cross-pollinate purebred tall plants with purebred short plants. The offspring created by the cross were all tall plants. He called the tall form dominant because of its ability to cover up the short form. He called the short form recessive because it seemed to disappear Today we call these dominant and recessive alleles.

Using Probability to Make Predictions Probability helps you predict the chance that something will happen. Mendel use probability to make predictions. What made his predictions so accurate is that he studied nearly 30,000 plants over 8 years. This greatly increased his chances of seeing a repeatable pattern. Valid scientific conclusions need to be based on results that can be duplicated.

Punnett Squares These are tools used in Mendelian genetics to predict the offspring of a cross without having to perform the cross. Letters are used to represent dominant (uppercase) and recessive (lowercase) alleles. The letters are a code for the genotype, genetic makeup, of the organism. The phenotype, the way the organism looks/behaves, is the result of the genotype.

Easy way to remember what means what Phenotype P for physical As in the stuff you can see on the outside Genotype G for gene or genetics As in the stuff in DNA

Alleles Determine Traits Organisms have at least 2 alleles for every trait they possess. If the alleles are the same, it is referred to as homozygous. Ex: T T would be homozygous dominant Ex: t t would be homozygous recessive If the alleles are different, it is referred to as heterozygous. Ex: T t would be heterozygous dominant All of the hybrids Mendel produced were T t

Principles of Heredity Traits are controlled by alleles on chromosomes An allele’s effect is dominant or recessive When a pair of chromosomes separates during meiosis, the different alleles for a trait move into separate sex cells. (aka Independent Assortment)

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Gender Determination A female has two X chromosomes (XX). A male has one X and one Y chromosome (XY). When a sperm fertilizes an egg, the zygote that is formed will have one sex chromosome from the mother and one from the father.