Download Genetics-Q4 2011

Genetics-Q4 2011
Courtney Chaplin
Bridget Jackson
Edward Turk
Joshua Guicherit
Punnett Squares
 The gene combinations that might result
from a genetic cross can be determined
by drawing a diagram known as a
punnett square.
 F1 and F2 crosses
Dihybrid Crosses
 A version of a punnett square used to
find the probability of the offspring’s traits
when crossing two independent alleles.
 Alleles are independently assorted. Ex:
Seed shape doesn’t determine a seed’s
color.
Dominant Traits
 Dominant Traits are represented by a
capital letter in a punnett square.
 They will always overrule the recessive
trait when they are present in a cross.
Recessive Traits
 Recessive traits are represented by a
lowercase letter in a punnett square.
 They will only be present if you have a
homozygous recessive genotype.
Homozygous Traits
 Homozygous traits are present when you
have two dominant traits or two recessive
traits. Ex: RR or rr
Heterozygous Traits
 Heterozygous traits are present when
there is one dominant trait and one
recessive trait. Ex: Rr
 In a heterozygous trait the dominant
allele always overrules the recessive
trait.
Genotype
 The genetic makeup of an organism.
 It determines your phenotype.
Phenotype
 The physical characteristics of an
organism.
 Determined by your genotype.
 You can’t tell the difference between a
homozygous dominant or a heterozygous
genotype in a phenotype.
Codominance
 Both alleles contribute to the phenotype.
 In chickens, the allele for black feathers
is codominant with the alleles for white
feathers meaning that heterozygous
chickens are speckled with black and
white feathers.
 White chicken+black chicken=
Incomplete Dominance
 When a heterozygous phenotype is
somewhere in between the homozygous
phenotypes.
 If a red flower mixes with a white flower
they will produce pink colored offspring.
Multiple Choice
1.
An uppercase letter on a Punnett square indicates:
a. Dominant Allele
b. Codominance
c. Recessive Allele
2. Which is homozygous?
a. AT
b. TA
c. TT
d. AA
e. Both c and d
3. T = tall t = short, a plant is Tt, is it tall or short?
a. tall
b. short
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4. If a white and red plant cross and they are in incomplete
dominance what color will the offspring be?
a. Red and White spots
b. Pink
c. White
d. Red
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5. If a white and a red plant cross and the alleles are
codominant what color will the offspring be?
a. Red and White Spots
b. Pink
c. Red
d. White
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6. The F1 generation is what?
a. The first children
b. The parents
c. The grandchildren
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7. What are multiple alleles?
a. A gene that has more than 2 alleles
b. A gene that has 1 allele
c. A gene with exactly 4 alleles
d. Doesn’t exist
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8. What are polygenic traits?
a. Multiple Alleles
b. Recessive
c. Traits controlled by 2 or more alleles
d. Traits controlled by exactly 4 alleles
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9. Are traits affected by the environment?
a. Yes, the environment gives organisms
characteristics
b. No, only by genes
c. By both the environment and genes
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10. What is genetics?
a. A scientific study of Mendel
b. A scientific study of probability
c. A scientific study of plants
d. A scientific study of heredity
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11. What happens during fertilization?
a. Male and female cells break apart
b. C and D
c. Male and female reproductive cells join
d. A embryo is produced
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12. What happens due to true-breeding?
a. Identical offspring
b. Different offspring
c. Small offspring
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13. What is a trait?
a. specific characteristic that varies in between organisms
b. specific characteristic that does not vary in between
organisms
c. the different forms of a gene
d. a characteristic
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14. What are alleles?
a. All the same genes
b. characteristics of the plant
c. A and C
d. the different forms of a gene
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15. What is gametes?
a. Identical offspring
b. Different offspring
c. Sex cells
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16. What is probability?
a. specific characteristic that varies in between organisms
b. the likelihood that a particular event will occur
c. the amount of money you get on payday
d. a characteristic
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17. Probability can predict what?
a. the outcome of genetic crosses
b. characteristics of the plant
c. A and B
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18. What is the difference between heterozygous and
homozygous?
a. one has Identical offspring
b. one has Different offspring
c. one has different alleles and one has the same alleles
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19. What is phenotype?
a. specific characteristic that varies in
between organisms
b. the likelihood that a particular event will
occur
c. a physical characteristic
d. a genetic characteristic
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20. What is genotype?
a. a physical characteristic
b. a genetic characteristic
c. A and B
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Answer Key!
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
A
E
A
B
A
A
A
C
C
D
11. B
12. A
13. A
14. D
15. C
16. B
17. C
18. C
19. C
20. D
Websites and other
Resources
 http://www.brightstorm.com/science/biolo
gy/mendelian-genetics/punnett-squares
 http://anthro.palomar.edu/mendel/
 California Prentice Hall Biology Book
 http://staff.jccc.net/pdecell/transgenetics/
probability.html
Good Luck!
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