1862 / 1868 / 1880
Reading Guide 11.1-11.2
Pgs 308-315
Read the following pages and answer the questions below.
1. What is genetics?
2. Who was Gregor Mendel?
3. Define: Self-pollinating -
Describe the offspring that self-pollinating plants produce.
4. Define: Cross-pollination. -
Describe the offspring that result from cross-pollination
5. Define: Trait –
Gene -
Allele –
Pure-bred -
Hybrid -
6. Look at Figure 11-3 on page 310. Why was Mendel surprised when the offspring has the character of only one of the parents?
7. From his set of experiments, what two conclusions did Mendel draw?
8. Look at Figure 11-4 on page 311. Why aren’t any offspring in the F1 generation short? Why do these plants have an allele for shortness?
9. What are dominant and recessive and alleles?
10. What is segregation? What happens to alleles during segregation?
11. Using the letter A, which two combinations of alleles could produce a trait controlled by a dominant allele?
12. Using the letter A, what combination of alleles could produce a trait controlled by a recessive allele?
13. Explain how Mendel’s experiments would have been different if he had not worked with true-breeding plants?
14. One fourth of the plants resulting from a certain cross are expected to show a trait controlled by a recessive allele. If 675 plants resulting from the cross display a trait controlled by a dominant allele, how many plants will show the trait controlled by the recessive allele?
15. What is the probability and how is it used in genetics?
16. What is the probability that a tossed coin will come up tails twice in a row?
17. Define: Punnett Square -
Homozygous –
Heterozygous
Genotype-
Phenotype –
18. Give an example of two plants’ allele combinations that have different genotypes but produce the same phenotype.
19. Explain how two brown rabbits have white offspring.
I. History of Genetics
- Blending Concept of Inheritance:
1.Accepted before Mendel's experiments
2.Theory stated that ______
______
3.The appearance of red or white flowers again was consider instability in genetic material
4.Blending theory was of no help to Charles Darwin's theory of evolution
5.Blending theory did not ______
______
6.Particulate theory of Inheritance, proposed by Mendel, accounted for variation in a population generation after generation
7.Mendel's work ______
B. Gregor Mendel:
1.Austrian monk
2.Studied ______at the University of Vienna
3.Formulated ______
4.Did a statistical study of ______
5.Why peas, Pisum sativum?
a.
b.
c.Produce ______when allowed to self-pollinate several generations
d.Can be artificially cross-pollinate
GARDEN PEA
6. Mendel's Experiments:
a.Mendel studied ______
______
b.Mendel traced the inheritance of individual traits & kept careful records of numbers of offspring
c.He used ______
d.Mendel studied pea traits, ______
______
e.The dominant ______
______
______
f.Mendel's traits included:
(1.). Seed shape --- Round (R) or Wrinkled (r)
(2.). Seed Color ---- Yellow (Y) or Green (y)
(3.) Pod Shape --- Smooth (S) or wrinkled (s)
(4.) Pod Color --- Green (G) or Yellow (g)
(5.)Seed Coat Color --- Gray (G) or White (g)
(6.)Flower position --- Axial (A) or Terminal (a)
(7.)Plant Height --- Tall (T) or Short (t)
(8.)Flower color --- Purple (P) or white (p)
Dominant
Recessive
g.Mendel produced pure strains by ______
______
h.These strains were called the ______
i.Mendel cross-pollinated two strains and tracked each trait through two
generations (e.g. TT x tt )
Alleles - ______
P1 cross ______/ genotype -- ______
phenotype -- ______
genotypic ratio -- ______
Phenotypic ratio- ______
j.The offspring of this cross were all hybrids showing only the dominant trait & were called the First Filial or F1 generation
k.Mendel then crossed two of his F1 plants and tracked their traits; known as an F1 cross
Trait - ______Alleles - ______
F1 cross ______/ genotype -- ______
phenotype -- ______
genotypic ratio -- ______
Phenotypic ratio- ______
l.When 2 hybrids were crossed, ______of the offspring showed the dominant trait & ______showed the recessive trait; always a 3:1 ratio
m.The offspring of this cross were called the ______generation
n.Mendel then crossed a pure & a hybrid from his F2 generation; known as an F2 or test cross
Trait - Plant HeightAlleles - T tall, t short
F2 cross TT x Tt / F2 cross tt x Tt
T / t / T / t
T / TT / Tt / T / Tt / tt
T / TT / Tt / T / Tt / tt
genotype - TT, Tt / genotype - tt, Tt
Phenotype - Tall / phenotype - Tall & short
genotypic ratio- 1:1 / genotypic ratio- 1:1
Phenotypic ratio- all alike / phenotypic ratio- 1:1
o.50% (1/2) of the offspring in a test cross showed the same genotype of one parent & the other 50% showed the genotype of the other parent; always a 1:1 ratio
p.Mendel also crossed plants that differed ______(Dihybrid Crosses) such as seed shape & seed color
q.In the P1 cross, RRYY x rryy, all of the F1 offspring showed only the dominant form for both traits; all hybrids, RrYy
Traits: Seed Shape & Seed ColorAlleles:
P1 Cross: x
Ry / Genotype:
RY / RrYy
/ Phenotype:
Genotypic ratio:
Phenotypic ratio:
r.When Mendel crossed 2 hybrid plants (F1 cross), he got the following results
Traits: Seed Shape & Seed ColorAlleles: R round Y yellow
r wrinkled y green
F1 Cross: x
Genotypes / Genotypic Ratios / Phenotypes / Phenotypic Ratios
RRYY
RRYy
RrYY
RrYy
RRyy
Rryy
r rYY
r rYy
r ryy
7. Results of Mendel's Experiments:
a.Inheritable factors or ______
b.______
c.Eachtrait is based on ______,one from the mother and the other from the father
d.True-breedingindividuals are ______(both alleles are the same)
e.Law of Dominance states that ______
______
Trait: Pod ColorGenotypes: / Phenotype:
GG / Green Pod
Gg / Green Pod
Yellow Pod
Law of Dominance
______
______
______
______
______
f.Law of Segregation states that ______
______
RrR / R
g.Law of Independent Assortment states that ______
______
______
RrYyRY / Ry / rY / ry
Reading Guide 11.2/11.3
Pgs 316-321, 322, 328-329
Read the following pages and answer the questions below.
1. What does the principle of independent assortment state? Describe what this means in your own words.
2. A genetic cross is done with an FfJj and an FFJj allele combination. Draw the resulting Punnett square.
3. Break the word down. What does a polygenic trait mean?
4. Describe each of the following: Incomplete dominance
Codominance
Multiple Alleles
Polygenic Traits
5. What is the difference between incomplete dominance and codominance?
6. Use the pie chart on page 320 to answer the following questions:
a. Which blood type makes up the greatest percentage of the U.S. population?
b. What percentage of the total U.S. population has a positive Rh factor? What percentage has a negative Rh factor?
c. Which blood type can be used for transfusion into the largest percentage of individuals? Which type has the smallest percentage of possible donors available?
d. Could a person with O positive blood have two parents with O negative blood? Could that person have a daughter with AB positive blood? Explain both of your answers.
7. What is the relationship between the environment and phenotype?
What might the result of an exceptionally hot spring on wing pigmentation in the western white butterfly?
8. Of the careers listed on page 322, which do you find most interesting? Explain.
9. What is meant by gene linkage (pg. 328-329)?
If two genes are on the same chromosome but usually assort independently, what does that tell you about how close together they are?
C. Other Patterns of Inheritance:
1. Incomplete dominance ______
______
a. Flower color in snapdragons shows incomplete dominance whenever a red flower is crossed with a white flower to produce pink flowers
b. It’s like mixing paints, red + white will make pink. Red doesn’t totally block (dominate) the pink, instead there’s incomplete dominance, and we end up with something in-between.
c. The key is to recognize incomplete dominance. There are two ways to do this:
(1.)______
(2).______
d. Example: In a carnation field there are red carnations and white carnations. What would be the possible phenotype of a cross between a red carnation and a whit carnation where red flower color shows incomplete dominance over white flower color?
e. What would be the possible phenotypes for a cross between a red carnation and a pink carnation where red flower color shows incomplete dominance over white flower color?
f. What are the possible phenotypes of a cross between two pink carnations where red flower color shows incomplete dominance over white flower color?
2. Codominance - ______
______
______
a. For example a red and white flower that are crossed will give you a red and white spotted flower.
b. A common phenotype used in codominance questions is roan coat color in cattle. Cattle can be all red (RR), white (WW) or roan (RW- red and white hairs mixed together).
c. What is the chance that a cow with roan coat color and a bull with red coat color will produce a calf with red coat color where red coat color is codominate to white coat color?
d. A cross between a black cat and a tan cat produces a tabby pattern (black an tan fur together). What pattern of inheritance does this illustrate? What percent of kitten would have tan fur if a tabby cat is crossed with a black cat?
3. Sex-Linked Crosses ______
______
a. Representations of the trait:
b. What is the chance that a bald man and a normal woman will have a child that will go bald? What is the chance that one of their sons will go bald? Where baldness is a sex-linked trait.
c. What is the chance that a colorblind mother and a normal father will produce colorblind children? Colorblind sons? Colorblind daughters?
4. Multiple Alleles:In some populations, ______may determine a trait such as in ABO Blood type
a. Alleles: There are three alleles: ______
A & B are dominant, while O is recessive
Genotype / Phenotypeii / Type O
IAi / Type A
IAIA / Type A
IBi / Type B
IBIB / Type B
IAIB / TypeAB
a. What is the chance that a person with blood type A and a person with blood type O will produce a child with blood type O?
5. . ______occurs whenever many variations in the resulting phenotypes such as in hair, skin, & eye color
6. The expression of a gene is also influenced by ______(example: seasonal change in fur color)
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