BIO2010 Exam #3: Chapters 12, 14, 15
Chapter 12: Mendel’s Experiments and Heredity
Learning Outcomes:
1. Students will be able to explain Mendel’s experiments.**
2. Students will be able to describe the expected outcomes of a monohybrid cross involving
dominant and recessive alleles.
3. Students will be able to apply the sum and product rules to calculate probabilities.
4. Students will be able to explain the use of a test cross.
5. Students will be able to explain relationship between phenotype and genotype.
6. Students will be able to construct a Punnett square for a monohybrid cross and a dihybrid
cross.
7. Students will be able to identify the non-Mendelian inheritance patterns.
Definitions:
1. Allele: Alternative version of a gene
2. Gene: Unit of inheritance passed from parent to child; consists of a specific nucleotide
sequence
3. Phenotype: Appearance or observable characteristic of an organism, which is determined
by the genotype. You can physically see this characteristics
4. Genotype: A set of alleles present in an organism, that determine the phenotype. The
genetic makeup of a phenotype
5. Dominant allele: Trait which confers the same physical appearance whether an
individual has two copies of the trait or one copy of the dominant trait and one copy of
the recessive trait
6. Recessive allele: Trait that appears “latent” or non-expressed when the individual also
carries a dominant trait for that same characteristic; when present as two identical copies,
the recessive trait is expressed
7. Monohybrid cross: Performed between two parents who are heterozygous (meaning
they each carry two different alleles).
8. Dihybrid cross: Two parents are heterozygous for two separate characteristics (genes)
a. Offspring have 16 possible genotypes and 4 possible phenotypes
b. Demonstrates the law of independent assortment
9. Incomplete dominance: Heterozygotes display an intermediate phenotype (they blend)
10. Codominance: Both alleles are expressed in the heterozygotes
11. Sex-linked trait: Ex. Red green color blindness in humans
12. Heterozygous: Having two different alleles for a trait
a. Bb
13. Homozygous: Having two identical alleles for a trait
a. BB, bb
14. Hemizygous: Males are hemizygous = the allele is always expressed
, 15. Law of independent assortment: Genes do not influence each other with regard to
sorting of alleles into gametes; every possible combination of alleles is equally likely to
occur
16. Law of segregation: Paired unit factors (i.e genes) segregate equally into gametes such
that offspring have an equal likelihood of inheriting any combination of factors
17. Sex-linked: Any gene on a sex chromosome.
18. Test cross: Cross between a dominant expressing individual with an unknown genotype
and a homozygous recessive individual; the offspring phenotypes indicate whether the
unknown parent is heterozygous or homozygous for the dominant trait.
19. Trait: Variation in the physical appearance of a heritable characteristic
20. Punnett square: Visual representation of a cross between two individuals in which the
gametes of each individual are denoted along the top and side of a grid, respectively, and
the possible zygotic genotypes are recombined at each box in the grid.
Questions/Discussion:
1. What is the difference between a chromosome, a gene and an allele?
a. Chromosome: Found in the nucleus; carries genetic information in the form of a
gene
b. Gene: Unit of inheritance passed from parent to child; consists of a specific
nucleotide sequence
c. Allele: Alternative version of a gene
2. Explain the terms homozygous and heterozygous.
a. Heterozygous: Having two different alleles for a trait
i. Bb
b. Homozygous: Having two identical alleles for a trait
i. BB, bb
3. Make sure you can work genetics problems and determine the resulting genotype
and phenotype ratios.
4. What is the difference between a phenotype and a genotype?
a. Phenotype is what traits you can see in an organism (eye color, hair color) and
genotype is the genetic makeup.
Chapter 14: DNA Structure and Function
Learning Outcomes:
1. Students will understand the experiments that helped identify DNA as the genetic
material.
2. Students will be able to state and explain Chargaff’s rule.
a. Helped scientists to establish the fact that there is always an equal amount of A=T
and G=C in a DNA molecule
3. Students will be able to describe the structure of DNA.
Chapter 12: Mendel’s Experiments and Heredity
Learning Outcomes:
1. Students will be able to explain Mendel’s experiments.**
2. Students will be able to describe the expected outcomes of a monohybrid cross involving
dominant and recessive alleles.
3. Students will be able to apply the sum and product rules to calculate probabilities.
4. Students will be able to explain the use of a test cross.
5. Students will be able to explain relationship between phenotype and genotype.
6. Students will be able to construct a Punnett square for a monohybrid cross and a dihybrid
cross.
7. Students will be able to identify the non-Mendelian inheritance patterns.
Definitions:
1. Allele: Alternative version of a gene
2. Gene: Unit of inheritance passed from parent to child; consists of a specific nucleotide
sequence
3. Phenotype: Appearance or observable characteristic of an organism, which is determined
by the genotype. You can physically see this characteristics
4. Genotype: A set of alleles present in an organism, that determine the phenotype. The
genetic makeup of a phenotype
5. Dominant allele: Trait which confers the same physical appearance whether an
individual has two copies of the trait or one copy of the dominant trait and one copy of
the recessive trait
6. Recessive allele: Trait that appears “latent” or non-expressed when the individual also
carries a dominant trait for that same characteristic; when present as two identical copies,
the recessive trait is expressed
7. Monohybrid cross: Performed between two parents who are heterozygous (meaning
they each carry two different alleles).
8. Dihybrid cross: Two parents are heterozygous for two separate characteristics (genes)
a. Offspring have 16 possible genotypes and 4 possible phenotypes
b. Demonstrates the law of independent assortment
9. Incomplete dominance: Heterozygotes display an intermediate phenotype (they blend)
10. Codominance: Both alleles are expressed in the heterozygotes
11. Sex-linked trait: Ex. Red green color blindness in humans
12. Heterozygous: Having two different alleles for a trait
a. Bb
13. Homozygous: Having two identical alleles for a trait
a. BB, bb
14. Hemizygous: Males are hemizygous = the allele is always expressed
, 15. Law of independent assortment: Genes do not influence each other with regard to
sorting of alleles into gametes; every possible combination of alleles is equally likely to
occur
16. Law of segregation: Paired unit factors (i.e genes) segregate equally into gametes such
that offspring have an equal likelihood of inheriting any combination of factors
17. Sex-linked: Any gene on a sex chromosome.
18. Test cross: Cross between a dominant expressing individual with an unknown genotype
and a homozygous recessive individual; the offspring phenotypes indicate whether the
unknown parent is heterozygous or homozygous for the dominant trait.
19. Trait: Variation in the physical appearance of a heritable characteristic
20. Punnett square: Visual representation of a cross between two individuals in which the
gametes of each individual are denoted along the top and side of a grid, respectively, and
the possible zygotic genotypes are recombined at each box in the grid.
Questions/Discussion:
1. What is the difference between a chromosome, a gene and an allele?
a. Chromosome: Found in the nucleus; carries genetic information in the form of a
gene
b. Gene: Unit of inheritance passed from parent to child; consists of a specific
nucleotide sequence
c. Allele: Alternative version of a gene
2. Explain the terms homozygous and heterozygous.
a. Heterozygous: Having two different alleles for a trait
i. Bb
b. Homozygous: Having two identical alleles for a trait
i. BB, bb
3. Make sure you can work genetics problems and determine the resulting genotype
and phenotype ratios.
4. What is the difference between a phenotype and a genotype?
a. Phenotype is what traits you can see in an organism (eye color, hair color) and
genotype is the genetic makeup.
Chapter 14: DNA Structure and Function
Learning Outcomes:
1. Students will understand the experiments that helped identify DNA as the genetic
material.
2. Students will be able to state and explain Chargaff’s rule.
a. Helped scientists to establish the fact that there is always an equal amount of A=T
and G=C in a DNA molecule
3. Students will be able to describe the structure of DNA.
