Transcript Probability Discussion - Faculty Homepages (homepage.smc.edu)

Probability and Pedigree
Practice Problems
Pick a card
Today

Practice probability problems

Practice will help in doing these types of questions.
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Any problems you do not have time to do, try doing later.
Practice
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1. Work on the probability problems on pages 14 and 1-5 of the lab manual
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2. Pedigrees and probability problems 1-28 and
1-30. These you may need to complete at
home.
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Please refer to Dr. Colavito’s homepage for
solutions.
Begin with page 1-4
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1.
– A) Probability of rolling a “5”= 1/6
– B) Probability of rolling an even number: 1/6 + 1/6 + 1/6 =
1/2
Problem 1 continued
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1c) 1/6 x 1/6 x1/6 = 1/216
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1d) 6x(1/216)=1/36
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1e) 1/216 x 6 = 1/36
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1f) 1 (any number) x 5/6 x 4/6 = 20/36= 5/9
Problem 2
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First identify the probabilities of selecting various
colors:
– Jar 1: P (y)= 1/5 P (G) = 4/5
– Jar 2 :P (O) = 2/5 P(G) 3/5
– Jar 3 :P (P) 1/10
P(G) 9/10
Problem 2
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A. 1/5 x 2/5 x 1/10 = 2/250 = 1/125
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B. 4/5 x 2/5 x 9/10 = 72/250
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C. 1-(probability of no green skittles, see part A.)= 11/125=124/125
Problem 2
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D. calculate all possible combinations for each container:
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(4/5 x 3/5 x 1/10) + (4/5 x 2/5 x 9/10) +
1/5 x 3/5 x 9/10) = 111/250
Problem 2
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E. (2/5 x 1/10 x 4/5) = 8/250= 4/125
Problem 3 Autosomal Dominant
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A. ¾
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B. 4!/3!1! (1/4)3 (3/4)1= 3/64
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C. ¼ x ¾ x/ ¾ = 9/64
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D. 1-(probability that all will have straight little fingers)=
1-(1/4) 3= 63/64
Problem 4: Autosomal Recessive
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A. 2/3
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B. 2/3
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Keep in mind the parents of Jessica and Jerry must be
heterozygous for in order to have a sibling that has CF.
Problem 4
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C. 2/3 x 2/3 x 1/4 = 1/9
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Remember to refer to your Punnett square
and you will see that with heterozygous
parents there is ¼ chance of cc.
Problem 4
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D. 3!/2!1! (1/9)2 (8/9)1 = 8/243
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E. 8/9 x 1/9 x 8/9 = 64/729
Problem 5: X linked recessive
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½ that Polly has the “d” allele
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½ x ¼ =1/8
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½ x 3/8 x 1/8 = 3/128
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5!/2!3! (1/8)2 (7/8) 3 = 3430/32768 =0.105
Pedigrees (page 1-26)
A. autosomal dominant
 B. X linked dominant
 C. X linked recessive
 D. autosomal recessive
 E. X-linked dominant
 F. Autosomal recessive
 G. Autosomal Dominant
 H. X-linked recessive
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Answers
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Check Dr. Colavito’s
homepage “study guide” to
check your answers.