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?
B b b Bb bb
Objective:
To review heredity and probability b Bb bb

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

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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% r Rr rr r Rr rr

 Define genotype and phenotype
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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

 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
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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

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Scientific process
Living things
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What is life
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Characteristics of living things
Needs of living things
Classification
 Domain, kingdom, phyla, class, order, family, genus
Cell processes
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Cell parts (identify and function)
Chemical compounds in cells
Photosynthesis
Cellular respiration
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 Cell cycle
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Interphase
Mitosis
Cytokinesis
Genetics
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Mendel’s work
Probability
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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
W W
W WW W
W w Ww 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
R r
R RR Rr r Rr rr
 Genotypes
 RR, Rr, rr
 Phenotypes
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RR = Red
Rr = Red rr = white

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.
H c H c
H s H c H s H c H s
H c H c H c H c H c
 Genotypes
 H c H s
 H c H c
 Phenotypes
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H c H s =
Wavy hair
H c H c =
Curly hair