Genetics The Science of Heredity Table of Contents

Genetics: The Science of Heredity Table of Contents Mendel’s Work Probability and Heredity The Cell and Inheritance The DNA Connection

Genetics: The Science of Heredity - Mendel’s Work Crossing Pea Plants Gregor Mendel crossed pea plants that had different traits. The illustrations show he did this.

Genetics: The Science of Heredity - Mendel’s Work Mendel’s Experiments In all of Mendel’s crosses, only one form of the trait appeared in the F 1 generation. However, in the F 2 generation, the “lost” form of the trait always reappeared in about one fourth of the plants.

Genetics: The Science of Heredity - Mendel’s Work Dominant and Recessive Alleles Mendel studied several traits in pea plants.

Genetics: The Science of Heredity - Mendel’s Work Outlining As you read, make an outline about Mendel’s work. Use the red headings for the main ideas and the blue headings for the supporting ideas. Mendel’s Work I. II. Mendel’s Experiments A. Crossing Pea Plants B. The F 1 Offspring C. The F 2 Offspring D. Experiments With Other Traits Dominant and Recessive Alleles A. Genes and Alleles B. Alleles in Mendel’s Crosses C. Symbols for Alleles D. Significance of Mendel’s Contribution

Genetics: The Science of Heredity - Mendel’s Work Data Sharing Lab Click the PHSchool. com button for an activity about sharing data for the Skills Lab Take a Class Survey.

Genetics: The Science of Heredity End of Section: Mendel’s Work

Genetics: The Science of Heredity - Probability and Heredity Percentages One way you can express a probability is as a percentage. A percentage (%) is a number compared to 100. For example, 50% means 50 out of 100. Suppose that 3 out of 5 tossed coins landed with heads up. Here’s how you can calculate what percent of the coins landed with heads up. 1. Write the comparison as a fraction. 3 out of 5 = 3/5 2. Multiply the fraction by 100% to express it as a percentage. 3/5 x 100%/1 = 60%

Genetics: The Science of Heredity - Probability and Heredity Percentages Practice Problem Suppose 3 out of 12 coins landed with tails up. How can you express this as a percent? 25%

Genetics: The Science of Heredity - Probability and Heredity A Punnett Square The diagrams show to make a Punnett square. In this cross, both parents are heterozygous for the trait of seed shape. R represents the dominant round allele, and r represents the recessive wrinkled allele.

Genetics: The Science of Heredity - Probability and Heredity Probability and Genetics In a genetic cross, the allele that each parent will pass on to its offspring is based on probability.

Genetics: The Science of Heredity - Probability and Heredity What Are the Genotypes? Mendel allowed several F 1 pea plants with yellow seeds to selfpollinate. The graph shows the approximate numbers of the F 2 offspring with yellow seeds and with green seeds.

Genetics: The Science of Heredity - Probability and Heredity What Are the Genotypes? Reading Graphs: How many F 2 offspring had yellow seeds? How many had green seeds? Yellow– 6, 000; green– 2, 000

Genetics: The Science of Heredity - Probability and Heredity What Are the Genotypes? Calculating: Use the information in the graph to calculate the total number of offspring that resulted from this cross. Then calculate the percentage of the offspring with yellow peas, and the percentage with green peas. 8, 000; 75% have yellow peas and 25% have green peas.

Genetics: The Science of Heredity - Probability and Heredity What Are the Genotypes? Inferring: Use the answers to Question 2 to infer the probable genotypes of the parent plants. (Hint: Construct Punnett squares with the possible genotypes of the parents. ) Both parents probably had the genotype Bb.

Genetics: The Science of Heredity - Probability and Heredity Phenotypes and Genotypes An organism’s phenotype is its physical appearance, or visible traits, and an organism’s genotype is its genetic makeup, or allele combinations.

Genetics: The Science of Heredity - Probability and Heredity Codominance In codominance, the alleles are neither dominant nor recessive. As a result, both alleles are expressed in the offspring.

Genetics: The Science of Heredity - Probability and Heredity Building Vocabulary After you read the section, reread the paragraphs that contain definitions of Key Terms. Use all the information you have learned to write a definition of each Key Term in your own words. Key Terms: Examples: probability homozygous An organisms Probability is that a number has two that identical describes alleles howfor likely a trait it isis that an said to be event homozygous. will occur. Punnett square heterozygous An. Punnett A organisms square that has is a two chart different that shows alleles all for thea trait is possible combinations heterozygous for that of trait. alleles that can result from a genetic cross. In codominance, the alleles are neither dominant nor An organism’s phenotype is its physical appearance, recessive. or visible traits. codominance phenotype genotype An organism’s genotype is its genetic makeup, or allele combinations.

Genetics: The Science of Heredity - Probability and Heredity Links on Probability and Genetics Click the Sci. Links button for links on probability and genetics.

Genetics: The Science of Heredity End of Section: Probability and Heredity

Genetics: The Science of Heredity - The Cell and Inheritance Meiosis During meiosis, the chromosome pairs separate and are distributed to two different cells. The resulting sex cells have only half as many chromosomes as the other cells in the organism.

Genetics: The Science of Heredity - The Cell and Inheritance Punnett Square A Punnett square is actually a way to show the events that occur at meiosis.

Genetics: The Science of Heredity - The Cell and Inheritance A Lineup of Genes Chromosomes are made up of many genes joined together like beads on a string. The chromosomes in a pair may have different alleles for some genes and the same allele for others.

Genetics: The Science of Heredity - The Cell and Inheritance Identifying Supporting Evidence As you read, identify the evidence that supports the hypothesis that genes are found on chromosomes. Write the evidence in a graphic organizer. Grasshoppers: 24 chromosomes in body cells, 12 in sex cells. Chromosomes are important in inheritance. Fertilized egg has 24 chromosomes. Alleles exist in pairs in organisms.

Genetics: The Science of Heredity - The Cell and Inheritance Links on Meiosis Click the Sci. Links button for links on meiosis.

Genetics: The Science of Heredity - The Cell and Inheritance Chromosomes Click the Video button to watch a movie about chromosomes.

Genetics: The Science of Heredity End of Section: The Cell and Inheritance

Genetics: The Science of Heredity - The DNA Connection The DNA Code Chromosomes are made of DNA. Each chromosome contains thousands of genes. The sequence of bases in a gene forms a code that tells the cell what protein to produce.

Genetics: The Science of Heredity - The DNA Connection How Cells Make Proteins During protein synthesis, the cell uses information from a gene on a chromosome to produce a specific protein.

Genetics: The Science of Heredity - The DNA Connection Protein Synthesis Activity Click the Active Art button to open a browser window and access Active Art about protein synthesis.

Genetics: The Science of Heredity - The DNA Connection Mutations can cause a cell to produce an incorrect protein during protein synthesis. As a result, the organism’s trait, or phenotype, may be different from what it normally would have been.

Genetics: The Science of Heredity - The DNA Connection Sequencing Sequence is the order in which the steps in a process occur. As you read, make a flowchart that shows protein synthesis. Put each step in the flowchart in the order in which it occurs. Protein Synthesis DNA provides code to form messenger RNA. Messenger RNA attaches to ribosome. Transfer RNA “reads” the messenger RNA. Amino acids are added to the growing protein.

Genetics: The Science of Heredity - The DNA Connection Protein Synthesis Click the Video button to watch a movie about protein synthesis.

Genetics: The Science of Heredity End of Section: The DNA Connection

Genetics: The Science of Heredity Graphic Organizer RNA includes Messenger RNA Transfer RNA functions to Copy the coded message from the DNA Carry the message to the ribosome in the cytoplasm Carry amino acids Add amino acids to the growing protein

Genetics: The Science of Heredity End of Section: Graphic Organizer