Red Cross Lifeguarding
Genetics WSU MBIOS/BIOL 301,
Exam 2, Dr. Julie Stanton, Spring Fall
Newest Solution
What is the difference between monozygotic and dizygotic twins? - ANS ✔✔ - Monozygotic: Identical
twins from the fertilization of one egg.
Dizygotic: Fraternal twins from the fertilization of two eggs.
What are the two forms of melanin? What colors do they produce? - ANS ✔✔ - Eumelanin: Yellow to
brown to black. Pheomelanin: Red
What is hair color determined by? - ANS ✔✔ - Total amount of melanin and
Relative amount of eumelanin and pheomelanin
Describe the Melanocortin-1 Receptor (MC1R) gene. - ANS ✔✔ - It effects the relative amounts of
melanin. Mutations can result in red hair.
MC1R is also found in the brain. Mutations are associated with resistance to local anesthetics. Red heads
are twice as likely to avoid dental treatment because of pain sensitivity.
Why/How to people have red hair. - ANS ✔✔ - They usually have two mutated copies of the MC1R gene.
This makes more pheomelanin than eumelanin.
Inheritance is generally recessive and if both parents pass on the mutated MC1R gene, the child is very
likely to be a red head.
1
, Red Cross Lifeguarding
What were the two major inheritance theories prior to Mendel? What was a "Homunculus?" - ANS ✔✔ -
Preformationism & Blending hypothesis.
Homunculus: Little man or women in sperm or eggs.
Define True-Breeding. - ANS ✔✔ - Every time they were crossed to themselves, the offspring had the
same traits.
What is the Law of Independent Assortment? What is its only major exception? - ANS ✔✔ - Two
different genes assort independently during gamete formation.
Major Exception: Linkage
Describe Wild-Type alleles. - ANS ✔✔ - It is the most prevalent in a population and tends to be
dominant.
It usually encodes a protein that is both functional and expressed in proper amounts.
Describe Mutant alleles. - ANS ✔✔ - Less prevalent in a population and tend to be recessive.
"Loss of Function" mutation encodes a protein that is either non-functional (due to "Null allele") or
made in lower amounts.
What is incomplete dominance? - ANS ✔✔ - Phenotype of heterozygote is intermediate.
This is because the heterozygote makes an intermediate level of protein.
It may go undetected to the naked eye (Ex. Under microscope, the heterozygous round/wrinkled pea
seed looks like an intermediate between homozygous dominant and recessive (level of starch))
What is codominance? - ANS ✔✔ - Two alleles are dominant. Both will be displayed in a heterozygote.
Ex. ABO Blood Type.
2
Genetics WSU MBIOS/BIOL 301,
Exam 2, Dr. Julie Stanton, Spring Fall
Newest Solution
What is the difference between monozygotic and dizygotic twins? - ANS ✔✔ - Monozygotic: Identical
twins from the fertilization of one egg.
Dizygotic: Fraternal twins from the fertilization of two eggs.
What are the two forms of melanin? What colors do they produce? - ANS ✔✔ - Eumelanin: Yellow to
brown to black. Pheomelanin: Red
What is hair color determined by? - ANS ✔✔ - Total amount of melanin and
Relative amount of eumelanin and pheomelanin
Describe the Melanocortin-1 Receptor (MC1R) gene. - ANS ✔✔ - It effects the relative amounts of
melanin. Mutations can result in red hair.
MC1R is also found in the brain. Mutations are associated with resistance to local anesthetics. Red heads
are twice as likely to avoid dental treatment because of pain sensitivity.
Why/How to people have red hair. - ANS ✔✔ - They usually have two mutated copies of the MC1R gene.
This makes more pheomelanin than eumelanin.
Inheritance is generally recessive and if both parents pass on the mutated MC1R gene, the child is very
likely to be a red head.
1
, Red Cross Lifeguarding
What were the two major inheritance theories prior to Mendel? What was a "Homunculus?" - ANS ✔✔ -
Preformationism & Blending hypothesis.
Homunculus: Little man or women in sperm or eggs.
Define True-Breeding. - ANS ✔✔ - Every time they were crossed to themselves, the offspring had the
same traits.
What is the Law of Independent Assortment? What is its only major exception? - ANS ✔✔ - Two
different genes assort independently during gamete formation.
Major Exception: Linkage
Describe Wild-Type alleles. - ANS ✔✔ - It is the most prevalent in a population and tends to be
dominant.
It usually encodes a protein that is both functional and expressed in proper amounts.
Describe Mutant alleles. - ANS ✔✔ - Less prevalent in a population and tend to be recessive.
"Loss of Function" mutation encodes a protein that is either non-functional (due to "Null allele") or
made in lower amounts.
What is incomplete dominance? - ANS ✔✔ - Phenotype of heterozygote is intermediate.
This is because the heterozygote makes an intermediate level of protein.
It may go undetected to the naked eye (Ex. Under microscope, the heterozygous round/wrinkled pea
seed looks like an intermediate between homozygous dominant and recessive (level of starch))
What is codominance? - ANS ✔✔ - Two alleles are dominant. Both will be displayed in a heterozygote.
Ex. ABO Blood Type.
2
