Heredity

Mav Mark 10/11/11 In pea plants, purple flowers (P) are dominant over white (p). A purple flowered plant pollinates a white flowered plant. As a result, two purple flowered plants and one white flowered plant are produced. Using a Punnett square, show how these results are possible.

Mav Mark 10/12/11 In pea plants, yellow peas (Y) are dominant over green peas (y). Use a Punnett square to predict the phenotypes and genotype that result from a heterozygous (Yy) pea plant and homozygous recessive (yy) pea plant.

Mav Mark 10/13/11 What biological process produces sex cells? How do sex cells differ from body cells? Explain why it is necessary to make sex cells through a process separate from mitosis.

Mav Mark 10/14/11 1.Physical appearance of traits 2.Inherited combination of alleles 3.Process that produces sex cells 4.Process through which bacteria reproduce 5.The chances that an event will occur A.Probability B.Genotype C.Binary Fission D.Phenotype E.Meiosis

Mav Mark 10/17/11 Define a genetic disorder. What can cause a genetic disorder? Are genetic disorders typically the result of dominant or recessive genes? Give an example of a genetic disorder.

Mav Mark 10/18/11 Here is a pedigree for an inherited lung disease. Provide the genotypes of each of the individuals marked with lower case letters. Determine if they are male or female.

Mav Mark 10/19/11 Compare and contrast hybrid and purebred organisms.

Mav Mark 10/20/10 1.Two forms of the same gene 2.Each allele has its own degree of influence 3.Structure of DNA 4.Process produces sex cells 5.Mutation in these cells can be passed down to offspring A.Meiosis B.Double Helix C.Alleles D.Sex Cells E.Body Cells F.Incomplete Dominance

Mav Mark 10/21/10 Test Day! Clear Desk except for sheet of notebook paper and a pencil.

I. What is Genetics? Genetics is the study of genes Heredity is the passing of traits from a parent to an offspring

II. Gregor Mendel Gregor Mendel is the “Father of Genetics” He spent 7 years researching the inheritance patterns of pea plants

Mendel used pea plants because –They reproduce quickly –They could self-pollinate –They had several different traits (7) Height, Flower Color, Seed Texture, etc. Mendel’s work was successful because he studied one trait at a time!!! A. The Pea Plants

B. The Experiments First we need to know a few important terms Self-pollinate- one plant- fertilizes its own flowers Cross-pollinate- two plants- pollen from one fertilizes the other P1 (parent) – original plant F1 (offspring) – 1 st generation after the parents F2 (offspring) – 2 nd generation after the parents

1. The 1 st Experiment – Cross Pollination Mendel made sure to begin with purebred plants –Example: Tall always makes tall, Purple flowers produced purple flowers Mendel cross-pollinated the purebred plants to see what would happen –Example: Tall X Short = ?

2. The Results P1 (Tall) X P1 (short) = F1 (All Tall) He concluded that tall is a dominant trait and short is a recessive trait: –Dominant: more likely to appear; represented by capital letters (T) –Recessive: usually hidden; represented by lower-case letters (t)

3. The 2 nd Experiment Mendel allowed his new plants to self-pollinate He noticed the short trait reappeared

4. His Conclusions After years of research, Mendel found that: –Information for traits were located on genes –Each parent contributes this information to its offspring –Traits are not connected (Tall plants don’t always have purple flowers)

III. Chromosomes and Genes Genes control particular hereditary traits Genes are located ON chromosomes An allele is a form of a gene –Two alleles = 1 gene –One is from mom; one is from dad

IV. Genetic Crosses Genotype- is an organism’s genetic make- up; represented by letters (TT, Tt, tt) Phenotype- is a physical description of the organism; Tall or short Homozygous- When both alleles of a gene are the same; TT or tt Heterozygous- When the alleles of a gene are different; Tt

A. The Punnett Square Developed by Rudolph Punnett Makes genetic predictions a lot easier!

Examples 1. What offspring would result if a plant that is homozygous dominant for height is crossed with a plant that is homozygous recessive for height?

Examples 2. What offspring would result if a plant that is homozygous recessive for flower color is crossed with a plant that is heterozygous for flower color?

Examples 3. What offspring would result if a plant that is heterozygous for seed texture is crossed with another plant that is heterozygous for seed texture?

V. Incomplete Dominance When one trait is not completely dominant over another. The result is a combined phenotype. –Ex. Snap dragons: Red X White = Pink

VI. Codominance Occurs when both alleles for a gene are expressed equally. –Ex. Blood Type

VII. Probability Probability is the mathematical likelihood that something is the case or will happen May be expressed as a fraction or as a percentage –Ex. Flipping a coin ½ chance of coin landing on heads and ½ chance of coin landing on tails 50% chance of coin landing on heads and 50% chance of coin landing on tails