Infomercial True or false: if I miss more than two labs, it only counts off my lab grade

Infomercial

• True or false: if I miss more than two labs, it only counts off my lab grade.

Infomercial

• True or false: if I miss more than two labs, it only counts off my lab grade.– False. Automatic F for the course if more than

two labs are missed.

Infomercial



• Where are the study guides/outlines for each lecture and exam?

Infomercial



• Where are the study guides/outlines for each lecture and exam?– The study guides/outlines can be found at the

beginning of the slides for lecture.

Broad Course Objectives for Principles of HeredityStudents should be able to:• Explain Mendel’s principles of inheritance and apply these to problems of

inheritance• Describe the different forms of inheritance patterns and identify these in genetic data• Use and interpret probabilities and statistics in the gathering, predicting, and

analysis of genetic data• Describe various types of genetic crosses and indicate when/why they would be

used by a geneticist• Explain more complex modes of inheritance and how sex influences the inheritance

and expression of genes; use this information in predicting genetic outcomes and the analysis of genetic data

Necessary for understanding future material on:• Phenotypic and statistical differences between traits that assort independently vs.

two traits that co-segregate• Setting up genetic crosses for gene characterization and mapping, including Virtual

Flylab.• Pedigree analysis in Human Genetics.

Ch 3-Mendelian Genetics-Outline and Study Guide

Review terms: true-breeding, homozygous dominant, Homozygous recessive, Heterozygous, genotype, phenotype

Mendel’s discovery of genetic principlesMonohybrid crosses—studying one gene • Mendel discovers genetic principles using true-breeding pea plants• Mendel continually sees a 3:1 ratio of the dominant : recessive phenotypes• Genetic symbols for dominant and recessive, for genetic crosses• Predicting haploid gamete genotypes from the diploid parent• Using Punnett squares for predicting results of genetic matings (crosses)• Mendel’s Principle of Segregation • Cellular basis of Principle of Segregation (meiosis and creation of haploid

gametes)

Dihybrid crosses-studying two genes on different chromosomes• Genetic symbols for dihybrid crosses• Predicting haploid gamete genotypes from the diploid parent• Law of Independent Assortment• Cellular event in meiosis that is the basis of the Law of Independent Assortment • Difference between a monohybrid cross and a dihybrid cross?

Test Cross—how is a genetic test cross used to determine the genotype of an individual by looking at his/her children?

Ch 3—Outline and Study Guide, cont.

Using simple probability to predict inheritance• Branch and Fork method • Multiplicative probability—how often will two conditions

(e.g. blonde hair and blue eyes, or homozygous recessive) coincide in the same individual?

• Additive probability – how many total progeny will share this trait? (e.g. how many progeny will have blond hair?)

• Predicting frequency of phenotypes and genotypes from specific crosses

e.g.AaBb x AaBbaabb X AABBAABB x AaBB

• Using the chi-square distribution to determine if the observed data “fit” a particular hypothesis or prediction.

Gregor Mendel

Culver Pictures

The garden of the Augustinian Convent in Brno. This view is looking towards the entrance to the garden, with Mendlovonamesti, Mendel Square, beyond. In the shadows in front of the tree can just be seen part of the foundations of the greenhouse that Mendel used. His peas were planted in the beds against the building on the left. A MENDEL PHOTO-ESSAY –simonmawer.com

Traits of Pea Plant Studied by Mendel

Review of Genetic Terms

• True-breeding--• Genotype--• Phenotype--• Gene—• Allele—• Diploid--• Haploid—• Dominant--• Recessive—• Homozygous—• Heterozygous—

Mendel observes that the recessive trait “disappears” in the 2nd generation and reappears in the next



Studying different genes gave Mendel the same 3 to 1 ratio

705:224 3.15 to 1

651:207 3.14 to 1

6022:2001

5474:850

3.01 to 1

2.96 to 1

Adding genetic symbols to Mendel’s crosses

Mendel’s 1st Law—Principle of Segregation

Each physical trait of a diploid organism is determined by two factors. These two factors separate between the generations (meiosis and gametogenesis) and re-unite in the next generation (fertilization of egg and sperm).

Observation: the F2 generation shows all traits from the P0, even though the F1 parents do not show all traits.

Conclusion: the F1 must receive something that causes the “hidden” trait revealed in the F2, in addition to the trait that the F1 show. Therefore

Using Punnett Squares to predict the progeny from genetic crosses

Principle of Segregation is due to

diploid organisms creating haploid

gametes

Fig 3.11, Brooker

Metaphase

AnaphaseTelophase

Meiosis II

Meiosis IProphase

Haploid gametes

Heterozygous (Yy ) (yellow seed plant )

y

y

y

y y

y

yY Y

Y

Y

Y Y

Y

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Principle of Segregation: chromosome

view

Principle of Segregation is due to diploid organisms creating haploid gametes

Studying two genes on different chromosomes

Gene 1—seed shape, 5p19.2

Alleles:

Gene 2—seed color, 7q22.1

Alleles:

Mendel’s 2nd Law—Principle of Independent Assortment

Genes for different traits (e.g. eye color vs. hair color) segregate independently of one another during gametogenesis.

Exception—when genes are closely linked on the same chromosome, then original alleles tend to segregate together in next generation.

Chromosome basis for a dihybrid individual

Gene 1—seed shape, 5p19.2 Gene 2—seed color, 7q22.1

Draw diploid karyotype for an RrYy individual:

Draw haploid karyotypes for the gametes coming from this

individual:

Draw haploid genotypes for the gametes coming from this individual:

Fig 3.12, Brooker2 ry : :

YyRr genotype y

y

y

y y

y

yy

y

Y

YY

Y

YY

Y

YY

r

r

r R

R

y

R

R r

r

Y

r

rr

r

y

r

R

RR

R

Y

R

Yy

rR

r

RR

2 RY 2 Ry 2 rY

Meiosis II

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Chromosome Basis of Principle of Independent Assortment

Meiosis I(two possiblearrangementsin metaphase)

Large chromosome and small c’some segregate independently of one another:

“Big Red” can co-segregate with “little red”

OR

“Big Red” can co-segregate with“little blue”

From the cross Aa x Aa:

• What is the probability that a child will be Aa or aA?

• What is the probability that a child will have at least one allele a?

• Assume that A codes for the “wildtype” phenotype. What is the probability that a child will be wildtype?

Branch and Fork Method

Practice predicting the genotypes of the progeny

• Assume that the gene with the alleles R/r (R=round, r=wrinkled) is on a different chromosome than the gene with the alleles for Y/y (Y= yellow, y = green)

• Use Punnett Squares or the Branch and Fork method if you need to

• Give proportions of each genotype

• Give associated phenotype

1.) RR x rr

2.) Rr x rr

3.) Rr x Rr

4.) RR x Rr

5.) RRyy x rrYY

6.) RrYy x RrYy

7.) RRYy x RrYy

8.) RrYy x rrYy

Which one is the monohybrid cross? The dihybrid cross?

1.) RR x rr

2.) Rr x rr

3.) Rr x Rr

4.) RR x Rr

5.) RRyy x rrYY

6.) RrYy x RrYy

7.) RRYy x RrYy

8.) RrYy x rrYy

Use the Branch and Fork method to determine the

genotypic ratios of the progeny from crosses 6-8

1.) RR x rr

2.) Rr x rr

3.) Rr x Rr

4.) RR x Rr

5.) RRyy x rrYY

6.) RrYy x RrYy

7.) RRYy x RrYy

8.) RrYy x rrYy

What is the probability of getting a progeny of “RrYY”

from each of crosses 5 -8?

1.) RR x rr

2.) Rr x rr

3.) Rr x Rr

4.) RR x Rr

5.) RRyy x rrYY

6.) RrYy x RrYy

7.) RRYy x RrYy

8.) RrYy x rrYy

What is the probability of getting yellow progeny from

crosses 5-8?

5.) RRyy x rrYY—100% yellow progeny

6.) RrYy x RrYy—75% yellow progeny

7.) RRYy x RrYy—75% yellow progeny

8.) RrYy x rrYy –75% yellow progeny

What is the probability of getting a yellow progeny from

crosses 5-8?

1.) RR x rr

2.) Rr x rr

3.) Rr x Rr

4.) RR x Rr

5.) RRyy x rrYY

6.) RrYy x RrYy

7.) RRYy x RrYy

8.) RrYy x rrYy

What is the probability of getting wrinkled, yellow

progeny from crosses 5-8?

Short hair in rabbits (S) is dominant over long hair (s). The following crosses are carried out, producing the progeny shown. Give all possible genotypes of parents in each cross.

a.) P0--short x short F1--4 short and 2 long

b.) P0--Short x long F1--12 short

c.) P0--Short x long F1--3 short and 1 long,

d.) P0--long and long F1--2 long.

Test Cross

You are given a pea plant with smooth seeds that are yellow. You know that smooth is dominant to wrinkled, and yellow is dominant to green. How can you determine the exact genotype of this pea plant?

Hairlessness in American rat terriers is recessive to the presence of hair. Suppose that you have 3 rat terriers with hair. You perform test crosses on these dogs and get the following among their puppies:

Dog 1 Dog 2 Dog 3

3 hairless 1 hairless 0 hairless

4 hair 4 hair 6 hair

What are the genotype of the test-crossed dogs with hair?

Dog 1: Hh; Dog 2: Hh, Dog 3: most likely HH [technically need to see 30 of its progeny for definitive answer]

Individuals of the Round Yellow phenotype were test crossed. Give the expected phenotype ratios of progeny for each of the possible individuals:

1.) RrYy x rryy

2.) RRYy x rryy

3.) RrYY x rryy

4.) RRYY x rryy

Round is dominant to wrinkled; yellow is dominant to green.

1.) RrYy x rryy 1:1:1:1 2.) RRYy x rryy ½ round yellow, ½ round green 3.) RrYY x rryy ½ round yellow, ½ wrinkled yellow 4.) RRYY x rryy all round yellow

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Infomercial True or false: if I miss more than two labs, it only counts off my lab grade