1408 Genetics Problems 2015
Name __________________________ Date __________
For each correctly conducted genetics problem, the value is 3 points. Maximum credit is 20 points.
All Punnett Squares must be shown for deriving the answer.
Turn in the problems, worked on this paper or an attached sheet. Show your work!!!
1. In humans, the allele for albinism (a) is recessive to the allele for normal pigmentation (A).
A normally pigmented woman whose father is an albino marries an albino man whose parents are normal. They have three children, two normal and one albino.
Give the genotypes for each person in the above scenario. Use the Punnett Square to prove your answer.
The woman _____________
Her Father ______________
The albino man __________
His Mother _____________
His Father ______________
3 children ____, ____, ____
Incomplete Dominance is an intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. Each allele is expressed in the heterozygous genotype producing an intermediate phenotype.
For example, in certain snapdragon flowers, the gene R codes for red flowers while its allele R’ codes for white flowers. The RR genotype produces red flowers, R’R’ produces white and heterozygous RR’ produces pink flowers.
Codominance occurs when two alleles are equally dominant, it is characterized by full expression of both alleles and both appear in a phenotype. The roan cow is the result of a heterozygous expression of colored and white hairs from the parents.
2. In four o’clock flowers the gene R codes for red flowers and its allele R’ codes for white flowers. The genotype RR produce red flowers R’R’ results in white and the heterozygous condition RR’ produces pink flowers. What type of dominance is this? Give the genotypic and phenotypic ratios of the offspring of a cross between a white and pink flowering four o’clock.
3. Give the genotypic and phenotypic ratios of the offspring of a cross between two pink flowering four o’clock plants.
4. In cocker spaniels, black coat color (B) is dominant over red (b), and solid color (S) is dominant over
spotted (s). If BbSs were crossed with Bbss, give the phenotype ratio for the offspring of this dihybrid cross. Show your work.
MULTIPLE ALLELES INHERITANCE – Characteristics determined by Multiple Allele Inheritance are determined by more than two alleles of the same gene in the general population, although any one individual only has a single pair of genes (2 alleles) for the characteristic.
For example ABO blood groupings are determined by three alleles of the same gene. The allele IA produce a type A antigen on the surface of the red blood cell, IB produces the type B antigen and the allele i does not code for any antigen. The genotypes IAIA and IAi produce type A blood, IBIB and IBi produce type B, IAIB produces type AB and ii produces type O blood. Remember that in ABO blood groupings the alleles for type A and type B are codominant. IA and IB are co-dominant genes so that the combination IA IB produces the AB blood type.
5. Knowing what you do about the ABO blood types (M ultiple Allele Inheritance ). .
Can each of these parents produce the given child? Show your work for each cross.
Parent Child Yes/No
a) A x AB B ______
b) A x O A ______
c) A x B O ______
d) A x A AB ______
e) B x B O ______
f) AB x AB A ______
X-LINKED INHERITANCE – The genes for X-linked characteristics are located on the X chromosome only,
thus females have two genes for each X-linked characteristic while males have only one.
As a result X-linked recessive characteristics appear more often in males than females.
In cats coat color is determined by one pair of X-linked alleles. The gene XB codes for black coat while its allele Xb produces yellow coat. In females the heterozygous condition XBXb results in a calico coat (female).
6. A calico cat (female) is mated with a yellow cat. Give the genotypic and the phenotypic ratios for the expected offspring. The interaction between XB and Xb to produce calico is an example of ____ inheritance.
6. (2 points) A yellow female cat is mated with a black male. Give the genotypic and phenotypic ratios for the offspring
Answer this following question.
1. Observe an ice cube. This is water in a solid form, so it has a high structural order. This means that the molecules cannot move very much and are in a fixed position. The temperature of the ice is zero degrees celcius. As a result, the entropy of the system is low.
2. Allow the ice to melt at room temperature. What is the state of molecules in the liquid water now? How did the energy transfer take place? Is the entropy of the system higher or lower? Why?
3. If you were to heat the melted water to its boiling point, what would happen to the entropy of the system?
4. Describe the structure and complementary base pairing of DNA.
5. Explain how single nucleotide changes can have vastly different effects on protein function.
6. In the past 25 years, we have learned a lot about DNA, and are now able to manipulate genes. Plants are genetically modified to possess desirable traits such as resistance to disease and to grow with less water and fertilizer. There are even certain Idaho potatoes that all grow to the same size, so McDonald’s french fries are the same length! Human genes are inserted into bacteria to inexpensively produce drugs that treat diseases. Soon, non-life threatening cosmetic changes will be available for those who can afford them.Conduct an internet search to find an interesting example of genetic engineering. Then, summarize what you discovered. Next, respond to at least one other student’s findings.