Podcast
Questions and Answers
What percentage of the gumballs are red?
What percentage of the gumballs are red?
The probability of getting two 5's when rolling a die is 1/36.
The probability of getting two 5's when rolling a die is 1/36.
True
What is the product rule of probability?
What is the product rule of probability?
The probability of independent events occurring together is the product of the probabilities of the individual events.
The probability of getting one green and one red gumball can happen in __ ways.
The probability of getting one green and one red gumball can happen in __ ways.
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Match the following probabilities with their combined outcomes:
Match the following probabilities with their combined outcomes:
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Using the sum rule, what is the probability of getting either two 5's or two 6's?
Using the sum rule, what is the probability of getting either two 5's or two 6's?
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Calculate the probability of getting a 5 on a single roll of a die.
Calculate the probability of getting a 5 on a single roll of a die.
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The probability of independent events occurring together is expressed as p(a __ b) = p(a) x p(b).
The probability of independent events occurring together is expressed as p(a __ b) = p(a) x p(b).
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Who is the TA for the Genetics class?
Who is the TA for the Genetics class?
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The Law of Independent Assortment states that alleles of different genes assort independently from one another during gamete formation.
The Law of Independent Assortment states that alleles of different genes assort independently from one another during gamete formation.
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What are the office hours for Hannah Kotek?
What are the office hours for Hannah Kotek?
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A test cross is performed by crossing a phenotypically dominant individual with a phenotypically ______________ individual.
A test cross is performed by crossing a phenotypically dominant individual with a phenotypically ______________ individual.
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Match the following concepts with their definitions:
Match the following concepts with their definitions:
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What is a key purpose of attending the TA office hours?
What is a key purpose of attending the TA office hours?
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The practice problems assigned will be graded.
The practice problems assigned will be graded.
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What type of problems will be assigned later for a grade?
What type of problems will be assigned later for a grade?
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Study Notes
Teaching Assistant Office Hours
- Office hours are held Monday-Wednesday evenings in FEA 141.
-
Genetics TAs:
- Monday: 6:00 PM - 8:00 PM - Hannah Kotek
- Tuesday: 6:00 PM - 8:00 PM - Hannah Kotek
- Wednesday: 6:00 PM - 8:00 PM - Ashley Lee
- Thursday: 6:00 PM - 8:00 PM - Ashley Lee
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Additional TA:
- Hannah Kotek
- Students can drop by for study tips, strategies, and other genetics assistance.
Mendelian Analysis & Probabilities
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Mendelian Analysis:
- Mendel's pea plant crosses
- Law of Segregation
- Law of Independent Assortment
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Probabilities Review:
- Product rule
- Sum rule
Practice Problems
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Chapter 3:
- Single-gene analysis problems: 4th edition (14, 15, 16, 17, 18, 19, 29, 30, 40); 5th-7th edition (14, 16, 17, 18, 20, 21, 31, 33, 43)
- Problems are provided to help with understanding the material
- No need to turn in the practice problems listed here
- A separate problem set will be assigned for a grade and cover material from multiple lectures (~10 problems)
Test Crosses
- Used to determine the genotype of a phenotypically dominant individual
- Cross with an individual with a known recessive phenotype
- Test for hidden recessive genes with homozygous recessive tester strain
- Phenotype of progeny from test cross indicates the genotype of the tested parent
Test Crosses (Continued)
- A test cross helps determine the alleles carried by the F1 parent.
- The recessive allele is solely contributed from the test-cross parent.
- The resulting phenotypes of the progeny indicate the F1 parent's genotype.
- Example: Yellow pea (F1): Is it YY or Yy? Cross it with a yy pea (test cross) to determine genotype.
Expected Results of a Test Cross
- Yellow peas are dominant to green peas
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Heterozygous Yellow Pea:
- Yy X yy (tester)
- Expect 50% Yy (yellow) and 50% yy (green) progeny
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Homozygous Yellow Pea:
- YY X yy (tester)
- Expect 100% Yy (yellow) and 0% yy (green) progeny
- Works for all 7 of Mendel's chosen traits (and many others)
Mendel Followed Two Genes at Once
- Consider two traits for pea color and shape:
- Y (yellow) and y (green)
- R (round) and r (wrinkled)
- Example problem involving a true breeding plant with round, green seeds crossed with a true breeding plant with wrinkled, yellow seeds.
Tracking Two Genes
- Pure-breeding parentals
- F1 are all RrYy (round, yellow)
- Observed 9:3:3:1 ratio in F2 generation (round yellow, round green, wrinkled yellow, wrinkled green)
Dihybrid Cross
- Parents are heterozygous for two traits
- Each dihybrid plant produces 4 gamete types
- Example: YyRr → YR, Yr, yR, yr (equal frequency)
Punnett Square of a Dihybrid Cross
- F1 produces 4 different gamete types in equal proportions
- Gametes combine at random to form zygotes
- Example Punnett square for a dihybrid cross of RrYy x RrYy
Mendel's Second Law
- Law of Independent Assortment:
- Segregation of alleles of two different genes is independent of each other
- Example: No bias towards yR or Yr in gametes
- Random fertilization of ovules by pollen
- No bias of gametes for fertilization
Dihybrid Test Cross
- F1 is heterozygous for both genes (e.g., YyRr) crossed with a homozygous recessive parent (yyrr)
- Result is a 1:1:1:1 phenotypic ratio (e.g., yellow round, yellow wrinkled, green round, green wrinkled).
Patterns of Segregation
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One gene (one trait):
- Monohybrid cross: 3:1 (F2)
- Test cross of F1, 1:1
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Two genes (two traits):
- Dihybrid cross: 9:3:3:1 (F2)
- Test cross of F1, 1:1:1:1
Some Genetic Vocabulary
- Progeny: Offspring, children, results of reproduction
- Gametes: Sperm and egg; carry half the genetic information of the parent; haploid
- Zygote: Results from fusion of gametes; diploid
- Haploid: One copy of each chromosome/gene (in animals, only in gametes)
- Diploid: Two copies of each chromosome/gene (in animals, all other cells)
- Homozygous: Having two identical copies of a gene
- Heterozygous: Having two different versions of a gene
- Gene: Discrete unit of inheritance, determines protein expression
- Segments of DNA: One gene is part of a chromosome, on chromosome has many genes
- Alleles: Different forms of a specific gene
- Genotype: The alleles carried by an individual for a gene or set of genes
- Phenotype: The appearance (expression) of the alleles for a gene or set of genes
- Mutation: A heritable change in a gene, resulting in a new allele (most allele variation in genetics)
- Wild type: Standard allele, the most common allele found in the wild
- Variant allele: New allele, mutant allele
Probability
- Probability of an outcome = (# of times event is expected to happen) / (# of opportunities (trials)).
- Example: Probability of a red gum ball from a mixture of 60 red and 40 green gum balls; 60/(60+40) = 0.6
Product Rule
- Probability of independent events occurring together is the product of individual event probabilities.
- Example: Chance of getting a 5 on two dice rolls (1/6 x 1/6 = 1/36)
Sum Rule
- Probability of either of two mutually exclusive events occurring is the sum of individual probabilities.
- Example: Chance of rolling a 5 or 6 on two dice rolls
Using Both Product and Sum Rules
- Combining probability concepts for more complicated situations.
- Example: Calculating the probability of getting one green and one red gum ball when buying two from a mixture
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Description
Test your understanding of Mendelian analysis and probabilities with this quiz focused on single-gene analysis problems. Review key concepts from chapter 3 and practice your problem-solving skills. This quiz provides an opportunity to reinforce your knowledge in genetics.
