The Inheritance of Biological Traits Instructional Approach(s): The teacher should review the essential question and the standards that align to the essential question

Let’s Review… Cell/Nucleus Chromosome DNA Gene Instructional Approach(s): Review with students the information on the slide. Cell/Nucleus Chromosome DNA Gene

Sexual Reproduction and Heredity Instructional Approach(s): Present information in the slide. Humans have 46 total chromosomes in 23 pairs. One chromosome of each pair comes from each parent.

Each set of Genes codes for a different trait Chromosomes Each set of Genes codes for a different trait Instructional Approach(s): Review the information in the slide.

The various forms of the same gene are called Alleles. Chromosome Pair BOX 2 From Mom From Dad While both chromosomes have the same genes, they can have different forms of these genes. Gene for making Earwax Gene for Eye Color For example, in the chromosome to the left one form of the gene for eye color will give you blue eyes and the other form will give you brown eyes. Instructional Approach(s): Present information in slide. Have student fill in vocabulary on notes sheet. The various forms of the same gene are called Alleles.

Alleles are usually represented by letters. Instructional Approach(s): Present information in the slide.

Phenotype BOXES 3, 9, 15, 21 An organism’s phenotype describes the physical characteristics that can be observed. Instructional Approach(s): Present information in the slide. Students will fill in vocabulary. View video clip.

Genotype BOXES 4, 10, 16, 22 An organism’s genotype describes the actual genes an organism has. Your genotype is not always obvious from your phenotype. Instructional Approach(s): Present information in the slide. Students will fill in vocabulary.

How can you wear your mom and dad’s genes at the same time? Transition slide.

Alleles, Phenotype and Genotype Instructional Approach(s): See resources for a possible demonstration to do prior to introducing Dominant and Recessive

Sometimes your genes contain information that is not expressed in your phenotype. Instructional Approach(s): Present information in the slide. Emphasize the allele not expressed in the phenotype

[represented by a Capital Letter] A Dominant allele is one that is expressed in the phenotype even if only one copy is present in the genotype [represented by a Capital Letter] BOXES 5, 11, 17 Instructional Approach(s): Present information in the slide. Students will fill in vocabulary.

A Recessive allele is one that is expressed in the phenotype only when two copies of it are present [represented by a lower case Letter] BOX 6, 18, 24 Instructional Approach(s): Present information in the slide. Students will fill in vocabulary.

If one chromosome in the pair contains a dominant allele and the other contains a recessive allele, the dominant allele will be expressed in your phenotype. Instructional Approach(s): Present information in the slide.

Alleles that have the same form of the same gene [two capital or two lower case letters] are called Homozygous. BOX 8 Instructional Approach(s): Present information in the slide. Students will fill in vocabulary.

Alleles that have two different forms of the same gene [a capital and a lower case letter] are called Heterozygous. BOX 14 Instructional Approach(s): Present information in the slide. Students will fill in vocabulary.

Instructional Approach(s): Present information in the slide.

How does the combination of parent alleles affect offspring? Instructional Approach(s): Present information in slide. Student will fill in notes sheet. A Punnett Square is used to show the possible combination of genes.

A Punnett Square is used to illustrate how a parent’s alleles might combine in offspring. Instructional Approach(s):Present information in slide.

Let’s Look at this Example Instructional Approach(s): Present information in the slide. Go through the process of how each part of the Punnett square is derived. Dd Dd d

What percent of the offspring will have a double tail? 2 out of 4 squares have a double tail = 50% What percent of the offspring will have a normal tail? 2 out of 4 squares have a normal tail = 50% Instructional Approach(s): Present information in the slide, showing how results inside the square obtained. Demonstrate calculation of probabilities. Dd Dd d

Bb and bb Rusty (bb) Bb 50% 50% With a seat partner, examine the following Punnett Square where B is dominant for brown eyes and b is recessive for blue eyes. 1. Identify the parent alleles. Bb and bb 2. Which parent’s alleles are homozygous? Rusty (bb) 3. Identify the heterozygous alleles? Bb 4. What percent of Rusty and Carrie’s offspring will have Brown eyes? Instructional Approach(s): Have students turn to a partner and discuss the questions on the slide. Partners can be determined by the students or the teacher can provide more specific directions such as turn to the person directly in front/behind you or to the right/left of you, etc. It may be necessary to have a group of three if you have an uneven number of students. Do not allow more than 2-3 minutes of discussion time. The teacher should be walking around listening and redirecting discussions as needed. When ready, the teacher can ask groups or the class each question and click the mouse to reveal the answer. 50% 5. What percent of Rusty and Carrie’s offspring will have Blue eyes? 50%

Selective Breeding is the process of selecting and breeding parent organisms to pass on particular trait to offspring. Instructional Approach(s): Have students fill in notes sheet.

Instructional Approach(s): Present information in the slide Instructional Approach(s): Present information in the slide. Students may use this as an example to fill in their notes sheet, or discuss other examples with an elbow partner.

Combination of Genes Differences or variations in DNA are what make one organism different from another Sometimes there are accidental changes in DNA. These changes can then be passed to offspring Mutations are any changes in DNA Instructional Approach(s): Prior to showing the first bullet, you may want to do the Mutation Introduction demonstration. Fill in notes sheet.

Pedigree A pedigree is a tool geneticists use to trace genetic traits through a family. Parents Instructional Approach(s): Present information in the slide. Discuss the key (noting that the particular trait is not specifically identified) and trace the trait through the pedigree. Generation 1 Generation 2