OBJECTIVES 1. Explain how a combination of alleles OBJECTIVES 1. Explain how a combination of alleles for a gene can code for a specific trait. 2. Distinguish between dominant and recessive alleles. 3. Explain how genes and alleles are related to genotypes and phenotypes.

You will need a partner today, no exceptions. Find a Partner. Congratulations, you and your partner get to….

Reebops One partner must play the role of Dad and one partner must play the role of Mom. Find the baggie containing Mom’s Reebop’s chromosomes (Pink) and the baggie containing Dad’s Reebop chromosomes (Blue).  Partners will open the baggie that pertains to their role, take out the chromosomes and turn them face down. Do not mix them. Partners will sort each set of chromosomes into pairs of the same size (homologous pairs). You’re making a karyotype! *arrange in matching pairs from biggest to smallest.

Mom’s and Dad’s Karyotype should look something like this… Hint: if you are having trouble matching by size you can match by letter….more on this later 

Now randomly take one chromosome from each pair of Mum’s chromosomes and place in a pile. Randomly take one chromosome from each pair of Dad’s chromosomes and place in a pile. You have just formed gametes! Mixing the gametes like this is a model of meiosis – meiosis halves the number of chromosomes in the gametes so that when they combine at fertilization, the new organism has the correct total number.

Place all unused chromosomes back into the appropriate baggies.   Fertilize the female gamete with the male gamete by mixing your two piles together. This is now your selection of ‘baby genes’ (or your zygote chromosome set). You have now mixed half the chromosomes from each parent to make a new combination. Each parent donated half the total chromosome number (8) to make the final number (16).

Sort out the chromosomes of your new individual into homologous pairs. *(match by size or letters….Blue A with Pink A)   Write down the letter combinations you have obtained in the ‘genotype and phenotype table’ for your ‘baby Reebop’. For example, if the blue card (dad) provided a capital “A” and the pink card “mom” provided a lowercase “a”, then the genotype would be written as “Aa”. * It is customary in genetics to write the capital allele first. Why?

Use the ‘decoder key’ to decide what the characteristics (phenotype) of your baby Reebop will be based on your genotype description. For example, if the genotype is AA, the phenotype will be “2 antennae”. For example: antennae AA = 2 antennae Aa = 2 antennae aa = no antennae

Complete the rest of your data table along with your shopping list – you will need it tomorrow to build your baby Reebop!

Build your Reebop! Use toothpicks to join the body segments and the following items: antennae Pretzel sticks body segments large marshmallows tail pipe cleaners nose Colored marshmellows Leg # toothpicks eyes Jelly beans humps small marshmallows