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Genetics

Genetics. Genotypes, Phenotypes, Punnett Squares, and Karyotypes. Genotypes. Genotypes are the specific combinations of the genes you get from your dad and mom. They are written as a combination of 2 letters (cases where there are more than 2 exist). Understanding Genotypes.

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Genetics

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  1. Genetics Genotypes, Phenotypes, Punnett Squares, and Karyotypes.

  2. Genotypes • Genotypes are the specific combinations of the genes you get from your dad and mom. • They are written as a combination of 2 letters (cases where there are more than 2 exist)

  3. Understanding Genotypes Anytime a capital letter is present, it represents a dominant gene. Dominant means overpowering. Anytime a lower-case letter is present, it represents a recessive gene. Recessive is understood to be weaker.

  4. Genotype Examples Gene for hair type can look like this. F - dominant gene (carries gene for straight hair) f - recessive gene (carries gene for curly hair) Possible Genotypes: FF (2 dominants) Ff (1 of each) ff (2 recessives)

  5. Phenotypes Phenotypes are the characteristics that a person shows. They are based on the two letter combination of letters (genotype)

  6. Phenotype Examples No Freckles is a dominant trait Freckles is a recessive trait Genotype: FF -> Phenotype: No Freckles Genotype: ff -> Phenotype: Freckles Genotype: Ff -> Phenotype: No Freckles Genotype: fF -> Phenotype: No Freckles

  7. Paper Activity. You are going to get strips of paper. Some are colors, some are clear. Follow the directions on the wall to complete the activity.

  8. Punnett Squares • Punnett Squares are tools that we use to try to predict what genotypes are possible when two people have children. • A punnett square can tell us what percent chance two people have of having a child with a certain phenotype (characteristic)

  9. Setting Up a Punnett Square. • Make a square • Draw a vertical line cutting the square in half. • Draw a horizontal line cutting the square in half. • You should have 4 equally sized squares.

  10. Setting Up a Punnett Square Mom f F • Put Dad’s Genotype (two letters) on the side. 1 in front of each row.) • Put Mom’s Genotype(2 letters) on top. 1 on top of each column. F DAD f

  11. Setting Up a Punnett Square • Fill in each box with the gene from dad. F f

  12. Setting Up a Punnett Square f F • Fill in each box with a gene from mom

  13. Setting Up a Punnett Square MOM F f F D AD f

  14. In this case, you have three possible combinations. • FF - No Freckles • Ff - No Freckles, but carries gene for freckles (f) • Ff - freckles

  15. What chance do these two people have of having a child that cannot roll his/her tongue? Rolling tongue is a dominant = Shaded (capital letters) Non rolling tongue is recessive = Nonshaded (lower-case letters) Dad Mom Mom’s Geno: tt Mom’s Pheno: Can not roll Dad’s Geno: TT Dad’s Pheno: Can roll

  16. What chance do these two people have of having a child that cannot roll his/her tongue? Rolling tongue is a dominant = Shaded (capital letters) Non rolling tongue is recessive = Nonshaded (lower-case letters) Dad Mom Mom’s Geno: tt Mom’s Pheno: Can not roll Dad’s Geno: Tt Dad’s Pheno: Can roll

  17. What chance do these two people have of having a child that cannot roll his/her tongue? Rolling tongue is a dominant = Shaded (capital letters) Non rolling tongue is recessive = Nonshaded (lower-case letters) Dad Mom Mom’s Geno: TT Mom’s Pheno: Can roll Dad’s Geno: Tt Dad’s Pheno: Can roll

  18. Try These Punnet Squares and answer the ?’s for each.

  19. Karyotypes • A Karyotype is a picture of all your chromosomes nicely paired and organized so that a genetic counselor can identify any possible conditions. • A normal karyotype would contain 46 total chromosomes or 23 pairs of chromosomes…all labeled.

  20. Karyotype Info • It costs a lot of money to have a karyotype done. • Most people that get one are people concerned that their child will have a certain condition • A karyotype is made early in the pregnancy. • A karyotype can give parents and doctors time to prepare (specialists on hand a birth, additional screening done after birth, etc).

  21. How to make a karyotype • Take a picture of all your chromosomes • Cut out all the chromosomes • Pair them up based on length and banding pattern (sometimes where the centromere is located) - think of a bar code.

  22. Karyotype Activity #1

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