Genetics

Cell Theory: All living things are made up of cells Cells are the basic units of structure and function in living things New cells are produced from existing cells.

Benchmarks for Basic Genetics B4.1 Genetics and Inherited Traits B4.1B Explain that the information passed to offspring is transmitted by means of genes that are coded in DNA molecules. These genes contain the information for the production of proteins. B4.1c Differentiate between dominant, recessive, codominant, polygenic, and sex-linked traits. B4.1e Determine the genotype and phenotype of monohybrid crosses using a Punnett Square.

Who was Gregor Mendel Gregor Mendel was an Austrian monk born in 1822 in what is now known as the Czech Republic. He studied math and science at the University of Vienna. Mendel spent the next 14 years working in the monastery and teaching at the high school. In addition to teaching, Mendel was in charge of the monastery garden – where he would complete the genetic studies that made him famous!

Chapter 11 Genetics—the scientific study of heredity Started 1860’s in gardens of Austria by Gregor Mendel

Mendel—worked/experimented with pea plants He studied sciences and mathematics He was curious about patterns of heredity and was studying traits in generations of pea plants

He noticed color variations between generations: Purple flower crossed with white flower all purple flowers are produced or Tall with short all Tall But when he crossed the “new” purple flowers with themselves the white flower reappeared Or when he crossed the two “new” tall flowers the short reappeared

Mendel used a quantitative approach to figure out the mystery (measuring &counting)

Garden pea plant was used because: Easiest to grow Produces a large number of offspring Mature quickly Have their male and female parts enclosed in the same flower (so it could either self-pollinate or be controlled by transferring pollen from one flower to another (cross-pollination) 

Steps of Mendel's Experiment

Review Gregor Mendel studied seven different pea plant traits What is a trait? Answer: a specific characteristic such as seed color or plant height which varies from one individual to another

Traits Mendel Studied Can you give examples of some human traits?

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Mendel’s Proof F1 Generation (1st Generation) One of the Alleles Disappeared (short) Where did it go? Was it destroyed?

Mendel named every generation:. Starting generation – Mendel named every generation: Starting generation – P (parent) generation. The following offspring generation was called F1 - first generation (daughter generation), F2 - second filial generation, and so on.

3:1 Ratio of Mendel’s meant something.

Mendel Concluded: Parents transmit information about traits to their offspring (information was called “factors”) Each individual has 2 factors for each trait, one from each parent. The two factors may or may not have the same information.

3. Alleles—are the alternate forms of a factor P ~ Purple p ~ White

Key Terms: a. Homozygous—same information Ex. Same info for purple PP vs. pp b. Heterozygous—different information Ex. one for purple, one for white Pp

c. Dominant—expressed by a capital letter d. Recessive-- expressed by a lower case letter e. Genotype—are the different types of alleles an organism has Genetically what it looks like (PP,Pp, pp) f. Phenotype—physical appearance (Purple, White)

Here we crossed two peas which contained both tall and short information. Tt TT tt

Review _____ are the chemical factors that determine traits Answer: genes Remember: Each of the traits Mendel studied was controlled by one gene that occurred in two different forms What are the different forms of a gene called? Answer: alleles

4.One allele comes from female parent other allele from the father In heterozygous only the dominant trait is expressed (usually) Pp not pP Pp = Purple not Purple white Tt = Tall not Tall short

Mendel's Proof You cross pollinate two plants from the F1 Generation Mendel Performed An F1 Cross You cross pollinate two plants from the F1 Generation

The missing allele re-appears in the F2 Generation Mendel's Proof The missing allele re-appears in the F2 Generation

Mendel’s Proof Key Concept: When Each F1 Plant Flowers, The Two Alleles Are Segregated From Each Other So That The Gamete Carries Only A Single Copy Of Each Gene. Therefore, each F1 plant produces two types of gametes – one Tall and one Short.

A cross in which only one trait is studied is called monohybrid cross (usually both are heterozygous—Ex. Rr x Rr).