Reebops: a “model” organism for learning genetics

Do Now: Define the following OR draw a picture of each term Gene Allele Genotype vs. Phenotype Heterozygous vs. Homozygous Dominant vs. Recessive

Objectives SWBAT explain that sexual reproduction produces offspring that inherit half their DNA from each parent. SWBAT explain how genes are carried from parents to their offspring on chromosomes

What are Reebops? Reebops are imaginary animals made from marshmallows and other easily found materials You and your partner will be making a baby Reebop

Chromosomes in Humans Why do chromosomes come in pairs???? Because humans reproduce through sexual reproduction, they inherit half or 50% of their DNA from each parent. SO, they inherit 23 chromosomes from each parent. What if they mated ppt.?

What does a human baby look like? Because chromosomes carry genes, when the two sex cells meet and the chromosomes form pairs--the baby ends up with 2 alleles for each trait. DAD’S MOM’S

Parent Reebops Record phenotyppic observations of parent reebops on your paper

How to construct your baby Reebop? You will be given 7 sets of chromosomes in envelopes. Turn the chromosomes face down on the desks so no letters are showing. Sort them so that they are matched by length.

Chromosome Pairs Take 1 strip from the mother and 1 strip from the father. Make a new pile for your Reebop baby. Repeat for the rest of the strips. The pink pair of strips are the mother’s chromosomes. The blue pair of strips are the father’s chromosomes. Each individual strip is an allele. The baby Reebop’s alleles 

Congratulations!! It’s a… Reebop Each Reebop baby will have 14 chromosomes: 7 blue and 7 pink. Return the remaining alleles to the envelopes. Turn over your chromosomes to see what your baby will look like.

Reebop Worksheet Fill out the genotype and phenotype for your baby. Highlight each of your baby’s 7 traits in the “Key to Reebop Traits.” BUILD YOUR BABY REEBOP using the materials in the ziplock bags Draw your Reebop baby and one of your classmates Answer the Post-Lab Questions

You just conducted a Reebop breeding program. What were some of the observable differences between the parent Reebops and their babies? What were some of the observable differences between the babies? In other words, how did the phenotypes of the Reebops differ? Give students an opportunity to share some of their observations from the breeding activity. Instructor note: While phenotype may sometimes be defined as the outward appearance of an organism, phenotype is actually the complete expression of the genotype, be it at the morphological, anatomical, physiological, behavioral, or molecular level. For the purposes of this activity, morphological traits are the only part of the phenotype being considered.

How did the phenotypes of the Reebops differ? Antennae Tails Body segments Humps Eyes Legs Noses Note that the concepts of genotype and dominant and recessive traits will be discussed in the Reebop Ratios activity and PowerPoint. 1, 2, or no antennae Curly or straight tail 2 or 3 body segments 1, 2, or 3 green humps 2 or 3 eyes Blue or red legs Red, orange, or yellow nose

Quick-Think Time Think–Pair–Share How did the Reebop babies end up being different from their parents and from each other? Provide a minute for thinking and jotting down ideas. Ask students to share with a partner for another minute. Call on a few students to share their ideas with the class. You can vary the procedure by asking students to share their partner’s ideas rather than their own. After giving students a chance to share, continue with the next slides, connecting to various student ideas as you go.

Sources of Variation: Each Reebop parent has two copies of each chromosome in all of its body cells. A cell with two sets of chromosomes is diploid. Traits are determined by genes carried on chromosomes. Different forms of a gene for the same trait are called alleles. Both copies of a chromosome might carry the same allele or they might carry different alleles. Instructor Note: For the purposes of this discussion, we are not distinguishing between germline cells and somatic cells. The cells destined to produce sperm and eggs (germline) are set aside very early in embryonic life. There can be different forms of a gene as a result of mutations. Different forms of the gene are called alleles. A gene can consist of a variety of different forms, but only two forms are ever present in a diploid cell. Emphasize that because each parent has two alleles for each trait, and these alleles may differ from one another, much more genetic diversity is possible than if each parent had only one allele.