Meiosis review

1. Meiosis review • What is a mutation? In terms of DNA, amino acids, and proteins, what is a possible outcome when a mutation occurs? • What is the difference between meiosis and mitosis? • Describe how mutations are possible during meiosis and give an example • Describe how mutations are possible during mitosis and give an example

2. Twins a study of genome of 19 identical twins (Casselman 2008) Some genomes differed from one twin to the other For example, one twin was missing some genes that showed a risk of leukemia, which he had. The other twin was not missing these genes and did not have leukemia. DNA in each identical twin changes over time from environmental factors. Study of 40 pairs of twins in Europe; the youngest set of twins was 3, and the oldest pair was 74.  Results from blood tests showed the youngest set of twins had the most identical genomes and the oldest set had the least identical. (Wagner 2012)

3. Objective 6: Punnett Squares You should be able to: • Identify or state(level 1-2) • Define or Describe (3-4) • Explain or discuss (5-6) • How to make a Punnet Square • The outcome of a Punnet square • Mendel and his work

4. Vocabulary • trait • procreate • GregorMendel • Punnett squares • dominant • recessive • phenotype • genotype • homozygous • heterozygous • allele • cross • pure breed • hybrid • expressed

5. Genetic possibilites What are the possible traits an offspring can inherit from their parents?

6. Punnett Squares A Punnett square is diagram that is used to predict the genotype (genes) and phenotype (looks) of an offspring The person who invented Punnett squares (1908) and further studied Mendel's theories was named Reginald Punnett. Therefore the Punnett square was named after him.

7. Mendel‘s work Traits • Phenotypes – what the offspring looks like • Genotypes - the genetic description of the gene = the letters that represent the genes

8. Mendel‘s work Gene: flower color Allele: white

9. Homozygous & Heterozygous • Homozygous(aka pure breed): the letters or alleles are exactly the same on both chromosomes (TT or tt) • The base pairs are the same in both genes • Heterozygous (aka hybrid): • the letters or alleles are different (Tt) on each chromosome are different • The base pairs are different on each chromosome in the pair

10. Dominant & Recessive • Dominant trait – allele is always expressed • At least one of the chromsomes carries the dominant allele • Written as a capital letter • Recessive trait– only expressed when both chromosomes have the same allele • Written as a lower case letter

11. How to Draw a Punnett Square • Rules: • Tt = one gene • T = allele • Capital = dominant • Lowercase = recessive • Phenotype = looks • Genotype = gene letters • Homozygous = same letter (tt) • Heterozygous – different (Tt) • T = tall & t = short T t T t x

12. Rules: • Tt = one gene • T = allele • Capital = dominant • Lowercase = recessive • Phenotype = looks • Genotype = gene letters • Homozygous = same letter (tt) • Heterozygous – different (Tt) • T = tall • t = short • Tt x tt

13. Which traits do you think are dominant?

14. How to use Punnett Squares • http://www.youtube.com/watch?v=d4izVAkhMPQ&feature=related (Punnett square) • http://www.athro.com/evo/gen/punexam.html (quiz)

15. bibliography Casselman, Anne. "Identical Twins' Genes Are Not Identical: Scientific American."Science News, Articles and Information | Scientific American. 3 Apr. 2008. Web. 22 Jan. 2012. <http://www.scientificamerican.com/article.cfm?id=identical-twins-genes-are-not-identical>. Wagner, Holly. "Identical Twins May Have More Differences Than Meet The Eye."OSU Research News Index Page. 7 July 2005. Web. 22 Jan. 2012. <http://researchnews.osu.edu/archive/identwin.htm>.