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Genetics BIO 203
Test Guide
Test 1 – Chapters 1, 2 & 3
Types of Questions
Multiple-choice, matching, short answer, fill in the blanks, explain, work out problems
Chapter 1 Introduction to Genetics:
 What do we study in genetics? Give two very different definitions for genetics
 Know the meaning of terms, gene, chromosome, protein, mitosis, meiosis, karyotype,
diploid, haploid, autosome, sex-chromosome, gene map, locus
 What did Mendel discover on transmission of traits (in brief)
 What is chromosome theory of inheritance? What two individuals are credited with
this theory? What commonalities between genes and chromosomes led to his theory?
 What is the importance of mutations?
 Know the contributions of the following to the determination that genes are made of
DNA: Avery, MacLeod, and McCarty.
 Describe and distinguish between the structures of DNA and RNA. Know which bases
pair with one another and how many hydrogen bonds hold them together.
 Know the meaning of terms, nucleotide, base, antiparallel, deoxyribose, ribose,
transcription, translation, genetic code, restriction enzymes
 What is the central dogma of genetics?
 What do we mean by gene expression?
 What are some of the benefits of genetic engineering
 Know the basic criteria for selection of model organism for genetic study.
 Name two model organisms
Chapter 2 Mitosis & Meiosis
 Learn the structures of cells and their functions.
 Compare cell structure of animals vs. plants; Prokaryotes vs. Eukaryotes.
 What are homologous chromosomes? From where do the members of a homologous
pair come?
 Know the meaning of terms centromere, telomere, haploid number(n)
 Distinguish between metacentric, submetacentric, acrocentric, and telocentric
chromosomes. On what are these classifications based? Distinguish between the p
and q arms of a chromosome.
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Know the stages of the cell cycle. Be able to draw the cell cycle and list what occurs
at each stage. Know which part of the cell cycle that the cell spends most of its time.
When is DNA replicated in the cell cycle?
For Mitosis, list the stages in order. Know what happens at each stage. Know the
products of mitosis.
For Meiosis, know the products and what happens at each stage. Know which division
is a reductional division and which is an equational division and what these designations
mean. Know the number of chromosomes (n) at all stages of meiosis.
Compare and contrast mitosis and meiosis. Give at least three features of each.
Know the three different ways meiosis introduces genetic variation to create unique
gametes
Be able to calculate genetic variation created by independent assortment of
chromosomes and random fertilization for given species
When does synapsis occur? What is chiasmata formation? What is its function?
Chapter 3 Mendelian Genetics
 Define: gene, allele, genotype, phenotype, homozygous, heterozygous, dominant,
recessive
 Describe Mendel’s experimental approach. What organism did he use and why?
 Discuss Mendel’s results obtained from monohybrid and dihybrid crosses.
 Discuss the conclusions Mendel drew from his results, including the postulates of
segregation and independent assortment.
 Define and distinguish between the P1, F1, and F2 generations.
 Know the genotypic and phenotypic ratio you would expect from a monohybrid cross
and a dihybrid cross, where two genes are not linked on the same chromosome
 What is a testcross? What is the goal of performing a testcross? Know that the test
cross ratios for a monohybrid is considered 1:1 and a dihybrid 1:1:1:1
 Know the product law and the sum law and how to use them to solve probability
questions. (what we did in the lab is included)
 What is a X2 test? What is its purpose? Know how to carry out a X2 test (for both
monohybrid and dihybrid crosses)
 Pedigrees: Know the conventions and possible modes of inheritance for various
conditions.
 Be able to determine the mode of inheritance and give genotypes of individuals in
pedigrees (what we did in the lab is included). At this point we have covered only
autosomal recessive and autosomal dominant inheritance patterns
Go through How to solve genetic problems -by Harry Nickla - Chapters 1-3
Sample questions:
1. Homologous chromosomes are those that can be matched by virtue of their similar
structure and function within a nucleus. What chromosomes making up a genome do
not follow the same characteristics of homology?
2.
The horse (Equus caballus) has 32 pairs of chromosomes while the donkey (Equus
asinus) has 31 pairs of chromosomes. How many chromosomes would be expected in
the somatic tissue of a mule hybrid?
3.
In an unusual rodent, coat color may be either red or brown. Two red females are
crossed independently with the same brown male. In several litters resulting from
the cross with the male, female #1 produced 19 red offspring. In several litters
resulting from the cross with the male, female #2 produced 11 red offspring and 9
brown. Describe the pattern of inheritance of coat color in this animal, and suggest
the genotype of each of the parents.
4.
The house fly, Musca domestica, has a haploid chromosome number of 6. How many
sister chromatids should be present in a diploid, somatic, metaphase cell?
5.
Albinism, lack of pigmentation in humans, results from an autosomal recessive gene.
Two parents with normal pigmentation have an albino child.
6.
(a)
What is the probability that their next child will be normally pigmented?
(b)
What is the probability that their next child will be an albino boy?
(c)
What is the probability that their next four children will be albino?
Assume that an organism has a diploid chromosome number of six. Two
chromosomal pairs are telocentric and the third pair is metacentric. Assume that
the sex chromosomes are morphologically identical. Draw chromosomes as you
would expect them to appear at the
a. metaphase of mitosis
b. metaphase of meiosis I
c. metaphase of meiosis II
7.
In humans, there are over 8 million possible ways that chromosomes can line up
during metaphase I of meiosis. The common dog (Canis lupus familiaris) has 78
chromosomes. What is the number of possible ways that chromosomes can line up
during metaphase I? Why? Show your work.
8.
What conditions are likely to apply if the progeny from the cross AaBb X AaBb
appear in the 9:3:3:1 ratio?
(Answer: complete dominance, independent assortment, no gene interaction)
9.
Assume that a cross is made between a heterozygous tall pea plant and a
homozygous short pea plant. Fifty offspring are produced in the following
frequency:
30 = tall
20 = short
(a) What frequency of tall and short plants is expected?
(b) If one wanted to test the goodness of fit between the observed and expected
values, provide a statement of the null hypothesis.
(d) How many degrees of freedom are associated with this test of significance?
(c) Compute a Chi-square value associated with the appropriate test of
significance.
10.
Workout pedigree problems 21, 23 & 24 at the end of Chapter 3 in the textbook.
Determine the mode of inheritance and give genotypes of individuals.