GENETICS
Read chapters 14 and 15 in Campbell.
Key Terms:F1F2
Pdominant characteristic
recessive characteristiclocus (loci)
allelehomozygous
heterozygousgenotype
phenotypemonohybrid cross
test crosspartial dominance (incomplete dom.)
dihybrid crossepistasis
multiple allelesmutation
sickle cell anemiapleiotropic gene
sex chromosomeautosome
X chromosomeY chromosome
sex-linked characteristicBarr body
linked genescrossing-over
polytene chromosomestranslocation
duplicationdeletion
inversionnondisjunction
trisomypolyploid
Answer the following questions:
1.Explain Mendel's laws (Dominance, Independent Assortment , & Segregation). Relate each of these laws to chromosomal behavior during meiosis.
2.Differentiate between the two terms in each of the following pairs: dominant - recessive, allele - gene, F1 - F2, homozygous - heterozygous, phenotype - genotype, monohybrid - dihybrid.
3.Explain how incomplete dominance differs from complete dominance.
4.Use a Punnett square or the multiplication of probabilities to find the characteristic phenotypic ratios in the F2 generation of a cross involving two characters (dihybrid) in which the two genes are independent (not linked). Explain how gene interactions, such as those involving epistatic and modifier genes, could alter this ratio.
5.Explain why statistical analysis is a useful genetic tool.
6.List the possible genotypes of persons of each blood type (A, B, AB, and O) and explain the mode of inheritance. Then explain the importance of these blood types in giving blood transfusions; for example, explain why someone with type AB blood could not donate blood to a person with type O, while someone with type O blood could donate blood to someone with type AB.
7.Explain why most mutations are deleterious and how it is possible for a harmful recessive allele, even a lethal one, to persist in a population.
8.Differentiate between the terms sex chromosome and autosome, and explain the term sex-linked characteristic.
9.Explain how sex is determined genetically in human beings. Then discuss the pattern of inheritance of sex-linked characters, showing why recessive sex-linked characters are expressed more often in males than in females.
10.Use a Punnett square or the multiplication of probabilities to do problems involving sex linkage.
11.Explain the concept of linkage. Show how crossover frequencies are calculated and how they can be used to make chromosomal maps; then explain why the relative distances between genes on Drosophila chromosomal maps formulated from crossover data do not exactly match the corresponding distances on maps derived from salivary-chromosome studies, while the order of the genes on the chromosomes is the same in both.
12.Explain the process of nondisjunction and show how it affects the chromosomal composition of a cell.
13.Explain how translocations, deletions, duplications, and inversions alter chromosomal composition. Which of the above would you predict would have the most severe effect? The least severe effect? Explain.