Download Molecular Biology BIO 250

Genetics BIO 203
Test 3 Guide
Chapters 7, 8 & 9
Types of Questions:
Multiple-choice, matching, short answer, fill in the blanks, explain, work out problems,
label the diagrams
Chapter 7 Linkage & Chromosome Mapping
Chapter 8 Genetic Analysis & Mapping in Bacteria & Bacteriophages
Chapter 9 DNA Structure & Analysis
Chapter 7 Linkage & Chromosome Mapping
 Know what linkage is. How is the behavior of linked genes during meiosis different
from genes that Mendel studied? Which one of Mendel’s laws does not apply when two
genes are linked?
 How is genetic distance between two genes located on the same chromosome
calculated using linkage? Who discovered this method to find distance between two
genes? In which organism? Which chromosome?
 What is a linkage group? a map unit?
 Compare genetic map to a physical map. Give three differences
 How would you identify parental and recombinant gametes in two point crosses?
 What are double crossovers? Are they more or less frequent than single crossovers?
 Why is that as the distance between two genes increases, mapping estimates become
more inaccurate?
 Explain the role of mapping functions
 Know the meaning of the terms, interference, coefficient of coincidence. Under what
situation the interference can be negative value
 Who provided the physical evidence for genetic recombination by cytologically observing
corn chromosomes, how?
Chapter 8 Genetic Analysis & Mapping in Bacteria & Bacteriophages
 Know the structure of prokaryotes (bacteria) and advantages of using bacteria to
understand genetics and molecular biology
 Know the shapes of bacteria and their names
 Know the meaning of terms prototrophs and auxotrophs. Which one could be grown in
a minimum media?
 What are the growth phases of bacteria in liquid culture? Explain what is happening in
each phase.
 Know how recombination take place in bacteria through the three methods discussed.





Learn the three types of conjugation and which one could be used to make map of the
E. coli chromosome based on time.
What are plasmids and what role do they play in the survival/evolution of bacteria.
What are bacteriophages and how do they multiply inside host.
Learn the two life cycles of bacteriophages. (Lytic & Lysogenic)
Do bacteriphages undergo genetic recombination? Where does this take place?
Chapter 9 DNA Structure & Analysis
 What are the properties that should be present in genetic material
 Know the following:
 Discovery of DNA by Miescher
 Discovery of Chargaff
 Griffith’s Experiments on Transformation
 Discovery of DNA Structure by Franklin, Wilkins, Watson & Crick
 Composition of DNA & RNA (bases, nucleosides & nucleotides)
 Structure & Properties of DNA: Learn the names of sugars and bonds in DNA.
 Learn to label the C atoms in the sugars from 1’ to 5’
Sample questions:
1. Assume that a cross is made between AaBb and aabb plants and the offspring fall into
approximately equal numbers of the following groups: AaBb, Aabb, aaBb, aabb.
These results are consistent with the following circumstance:
A. independent assortment.
B. alternation of generations.
C. complete linkage.
D. incomplete dominance.
E. hemizygosity.
2. Bacteriophages engage in two interactive cycles with bacteria. What are these cycles?
A. lytic and lysogenic
B. insertion and replication
C. auxotrophic and prototrophic D. heteroduplex and homoduplex
E. negative and positive
3. The basic structure of a nucleotide includes the following components:
A. amino acids.
B. tryptophan and leucine.
C. base, sugar, and phosphate.
D. mRNA, rRNA, and tRNA.
E. phosphorus and sulfur.
4. Reverse transcriptase is an enzyme found in association with retroviral activity. It
has the property of
A. synthesis of DNA from an RNA template.
B. synthesis of RNA from a DNA template.
C. requiring no template.
D. translation.
E. reverse translation.
6. Phenotypically wild F1 female Drosophila, whose mothers had light eyes (lt) and wild
bristles and fathers had straw (stw) bristles and wild type eyes produced the
following offspring when crossed to homozygous light-straw males:
PHENOTYPE
Light/straw
Wild/wild
Light/wild
Wild/straw
NUMBER
22
18
990
970
Compute the map distance between the light and straw loci.
6. The genes for mahogany eyes and ebony body are approximately 25 map units apart on
chromosome III in Drosophila. Assume that a mahogany-eyed, (wild type-bodied)
female was mated to an ebony-bodied (wild type-eyed) male and the resulting F1
phenotypically wild type females were mated to mahogany, ebony males. Of 1000
offspring, what would be the expected phenotypes and in what numbers would they
be expected?
Mahogany eyes, wild type body =
Wild type eyes, ebony body =
Wild type eyes, wild type body =
Mahogany eyes, ebony body =
7. Assume that the genes for tan body and bare wings are 15 map units apart on
chromosome II in Drosophila. Assume also that a tan-bodied, bare-winged female was
mated to a wild type male and the resulting F1 phenotypically wild type females were
mated to tan-bodied, bare- winged males. Of 1000 offspring, what would be the
expected phenotypes and in what numbers would they be expected?
Wild/wild
Tan/bare
Tan/wild
Bare/wild
______
______
_______
_______
8. Compare and contrast bacteriophage lysis and lysogeny. Give three points
9. Jacob, Wollman, and others developed a linkage map of E. coli that is based on time.
What form of recombination is involved in generating a linkage map based on time?
10. Draw and label the typical phases of the bacterial growth cycle in liquid culture
medium. Explain what is happening in each phase.
11. Compare and contrast DNA & RNA – Give at least five points
12.
Distinguish between F+, F- , Hfr & F’ bacteria.
13. The percentage of adenine in a DNA sample was 20%, what would be the expected
percentages of the other nitrogenous bases in this DNA?
14. Chapter 7: Insights and solutions: Do problems 1 & 2