Genotypes, Phenotypes, Genetics, Oh my!

Transcription

1 Genotypes, Phenotypes, Genetics, Oh my! GEMS November 4, 2017

2 Definitions: 1. Traits are characteristics you inherit from your parents. 2. A gene carries information (DNA) that determines your traits. 3. Alleles are different variations of a gene. There are 2 alleles for every gene. 4. Genotype is the 2 alleles for a gene that represents a specific trait. Ex) The genotype Bb represents hair 5. Homozygous: the alleles are the same for a particular trait Ex) BB, bb 6. Heterozygous: the alleles are different for a particular trait Ex) Bb 7. Phenotype is the observable characteristic of a specific trait resulting from its genotype. Ex) Blonde hair is the phenotype observed determined by genotype Bb 8. A dominant trait hides the recessive trait in the phenotype of an individual. A capital letter represents the dominant form in an allele. 9. A recessive trait describes a trait that is covered over (or dominated) by another form of that trait and seems to disappear. A lowercase letter represents the recessive form in an allele.

3 Punnett squares The Punnett square is a way of working out what the possible genotype and phenotype offspring of two parents will be. We use two letters to represent the genotype. A capital letter represents the dominant allele and a lowercase letter is the abbreviation for the recessive allele. In the example on the left, B=dominant, blue and b= recessive red. Understanding your definitions! Answer the following questions based on the information above and Fig. 1. (Answers on last page) 1. What is the trait? 2. What are the alleles? 3. What are the 3 different genotypes of the offspring? 4. Which genotypes are homozygous? 5. Which genotypes are? 6. What are the phenotypes of each offspring?

4 How generate a Punnett square: 1. Put one letter (allele) above/ next to each box. It does not matter which parent s genotype goes on the top/side. 2. Fill in the boxes by copying the column & row letters down and across t Genotype= Phenotype=cannot taste PTC Homozygous Recessive t TT T Genotype=TT Phenotype=can taste PTC Homozygous Dominant T Fill in the boxes by copying the column & row le ers down & across into the empty spaces.

5 Practice filling in a Punnett square Fill in the Punnett square and use the results to answer the questions below. Genotype= Phenotype=cannot taste PTC Homozygous Recessive Genotype= Phenotype=can taste PTC Heterozygous Dominant Questions: 1. What are the phenotypes of each kid? 2. Which kids will be able to taste PTC? 3. Which kids will NOT be able to taste PTC?

6 Use Punnett squares to design a unicorn suncatcher 1. With a partner, pick one piece of paper from the cup labeled TRAITS. Write down the trait you & your partner picked below: TRAIT: 2. Look for the unicorn parent genotypes found on your table. Write down the genotypes for the unicorn parents of the trait you selected. Horn Mane Horn Mane Body Tail Body Hoof Hoof Tail Standing on 4 legs Standing on 2 legs GENOTYPE: GENOTYPE: 3. Your TA will give you an empty Punnett square on a piece of paper. With your partner, follow the directions on the paper and fill in the Punnett square for the trait you selected. Check you filled in your Punnet square correctly with your TA before going to the next step!!!!!!

7 4. Once your table has created all of the Punnett squares, pick one square from each trait cup and write down the genotype and phenotype below in the table below. PUT THE SQUARES BACK IN THE CORRECT CUP SO THE NEXT PERSON CAN PICK!!! Trait Genotype Phenotype Standing on 4 or 2 legs Body Hoof Tail Horn Mane 5. Once you ve finished selecting all traits, use the markers to create your unicorn suncatcher. Make sure your unicorn matches the phenotype!!! 6. Choose a piece of string so you can hang your suncatcher up! Answers Understanding your definitions! 1. What is the trait? 4. Which genotypes are homozygous? Color BB, BB 2. What are the alleles? 5. Which genotypes are? B and b Bb 3. What are the 3 different genotypes 6. What are the phenotypes of each of the offspring? offspring? Bb, BB, bb Bb=blue; BB=blue; bb=red