1/14/13 Bell Ringer Create a punnett square for this situation: In guinea pigs, the allele for black fur (B) is dominant over the allele for white fur (b). In a cross between a heterozygous black guinea pig (Bb) and a homozygous white guinea pig (bb), what is the probability that an offspring will have white fur? Objective: To review heredity and probability Bb b Bbbb b Bbbb

Agenda  Go over homework  Pg. 123 #1-3  Finals study guide  Review of Punnett Squares  Get started on homework

Homework pg. 123 #1-3  What is probability?  A number that describes how likely it is that an event will occur.  If you know the parents’ alleles for a trait, how can you use a Punnett square to predict the probable genotypes of the offspring?  A punnett square shows all the possible combinations of alleles that can result from a genetic cross.  A pea plant with round seeds has the genotype Rr. You cross this plant with a wrinkled-seed plant, genotype rr. What is the probability that the offspring will have wrinkled seeds? (Use a Punnett square to help with the prediction.)  50% Rr r Rrrr r Rrrr

 Define genotype and phenotype  Genotype – an organism’s genetic makeup  Phenotype – an organism’s physical appearance  Explain how two organisms can have the same phenotype but different genotypes. Give an example.  A heterozygous organism will have the same phenotype as an organism that is homozygous for a dominant allele. An example would be a tall pea plant can be either heterozygous or homozygous.  A pea plant has a tall stem. What are its possible genotypes?  TT or Tt  What is codominance? Give an example of codominant alleles and explain why they are codominant.  An inheritance pattern in which alleles for a trait are neither dominant nor recessive. For example, the alleles for black and white chicken feathers are codominant because both colors show.  What is the phenotype of a chicken with the genotype F B F W ?  Black and white feathers

Semester 1 Final  Schedule  This week:  Monday – Finals overview  Tuesday – Pass out study guide  Wednesday – Go over study guide  Thursday – Review Game/ Computer Lab  Friday – Review Game /Computer Lab

 Study Tips  Things to use:  Book  Composition Notebook  Any handouts, diagrams, foldables  Ms. Park’s science website  Videos online  You must study!  Building good study habits  Don’t calculate grade, just do your best!  Review each day  Test yourself

Study Guide  Scientific process  Living things  What is life  Characteristics of living things  Needs of living things  Classification  Domain, kingdom, phyla, class, order, family, genus  Cell processes  Cell parts (identify and function)  Chemical compounds in cells  Photosynthesis  Cellular respiration  Cell cycle  Interphase  Mitosis  Cytokinesis  Genetics  Mendel’s work  Probability  Punnett square  Finding percentage  Vocabulary words

Punnett Square Practice W = long whiskers w = short whiskers What percentage of offspring would be expected to have short whiskers from the cross of two long-whiskered seals, one that is homozygous dominant and one that is heterozygous ?  Homozygous = WW  Heterozygous = Ww WW W WWW w Ww

Punnett Square Practice R = Red flower r = white flower If two heterozygous red flowers are mixed, what are the possible phenotypes and genotypes that can occur? Heterozygous = Rr  Genotypes  RR, Rr, rr  Phenotypes  RR = Red  Rr = Red  rr = white Rr R RRRr r rr

Punnett Square Practice In humans, wavy hair (H c H s ) results by the co-dominant situation of curly hair (H c ) and straight hair (H s ). What are the possible results if a curly-haired man and wavy-haired woman have children.  Genotypes HcHsHcHs HcHcHcHc  Phenotypes  H c H s = Wavy hair  H c H c = Curly hair HcHc HcHc HsHs HcHsHcHs HcHsHcHs HcHc HcHcHcHc HcHcHcHc