Assignments for Genetics
Fall 2008
Assignments are listed by the assigned dates. Homework that is more than two weeks late will not be accepted. At times during the semester you will not have two weeks because all homework assigned prior to a midterm is due at the midterm.
Date Assignment
8/14
Read Chapter 1 in text and review vocabulary from first
lecture. You might start a list of definitions FOR YOURSELF of new words
you find in lecture and in the text. Can you define Allele? Chromosome?
Diploid? Genome? Mitosis?
Find a recent (within the last year) article or website on a behavior directly associated with a gene. Turn in a copy of the article, and a summary of the article (1/2 to 1 page typed).
8/19 Read Chapter 2 about Mendelian Inheritance. Do Chapter 1 Homework Problems C2,6,9,12,13,14 and E4,5 and Chapter 2 Homework Problems C1,2,3,4 and E4.
8/21 Do Chapter 2 problems C5-11, 13b, 14, 16a &b, and E6,7
8/26 Review basic cell structure and cell reproduction ("How Cells Divide" and then "mitosis vs. meiosis"). http://anthro.palomar.edu/biobasis/default.htm
Do Chapter 2 problems C18-21, 23,26,27,30,31,33,34 and E9,10
8/28 Find a recent (within the last year) article or website on the p53 (gene or protein) or Telomerase (gene or protein). Turn in a copy of the article and a summary of the article (1/2 to 1 page typed).
Do Chapter 2 E11,13,14 and Chapter 3 C1-4,15-17,21.
Review cell cycle and control!
http://www.cellsalive.com/cell_cycle.htm
Review the following terms: gene, allele, chromosome, genome, gene locus, haploid, diploid, biparental inheritance, sister chromatid, tetrad, crossing over, mitosis, meiosis.
9/2 Do Chapter 3 problems C8-12.
Check out this site
---Blood type: www.biology.arizona.edu/human_bio/human_bio.html
Here are two sites to back up our studies.
Basic Genetics:
http://anthro.palomar.edu/mendel/default.htm
Check Mendel's Genetics and do the quiz--as a form of study.
Also check out
Probability of
Inheritance and do the quiz.
9/4 Do chapter 3 problems C7,13,14,20,22A,B,D,23 and E1
Look at this meiosis and chromosome theory web sites for review!
http://www.biologie.uni-hamburg.de/b-online/e09/09b.htm
http://www.cellsalive.com/meiosis.htm
9/9 Do Chapter 3 problems C26-31 and E 7,9,10
When there is a mistake in meiosis, an individual may loose an arm of a chromosome or get an extra chromosome. Take a look at the site dealing with chromosomal abnormalities: Http://anthro.palomar.edu/abnormal/default.htm
9/11 Read Chapter 4 and do Chapter 4 problems c4,7,9,10,12,13,30 and E9.
Look at this site! It covers Mendel's first and second laws,
variations (co dominance and incomplete!), pleiotropy, epistasis, modifier
genes, penetrance, and expressivity.
http://www.ndsu.nodak.edu/instruct/mcclean/plsc431/mendel/mendel5.htm
Look at the Rn gene listed for horses on the websites. Is Roan dominant or recessive according to this site? http://en.wikipedia.org/wiki/Equine_coat_color_genetics
9/16
Go to
www.biology.arizona.edu/human_bio/human_bio.html
a. Pick
Human Gentics. Read through it and do 1, 4-11 in
the
problem set.
b. Pick Blood Types. Read through it and
do the problem set.
c. Pick
Color Blindness. Read through it and
do the Sex linked Inheritance problem set and the color
blindness problem set.
And this is another good site for Color blindness: www.biology.arizona.edu/human_bio/human_bio.html
9/23 FIRST TEST
Chapters 1-3
All homework for chapters 1-3 is due at the test.
9/25 Do chapter 4 problems C6,11,14-18 and E2,7,10
9/30 Do Chapter 4 problems C19-21,23-25,28,29 and E3,5,12
10/7 Do chapter 5 c1,3-10
10/13
Do Chapter 5 c11-14 and
E8
10/14 Do
Chapter 5 E11-18
10/21 Do Chapter 5 E19B,20-23
Here is a mapping problem you can do if you would like. I have worked it for you below.
Fine spines (s), smooth fruit (tu), and uniform fruit color (u) are three
recessive traits in cucumbers whose genes are linked on the same chromosome.
A cucumber plant heterozygous for all three traits is used in a test cross, and
the following progeny are produced from this test cross:
S
U Tu 2
s
u Tu 70
S
u Tu 21
s
u tu
4
S
U tu 82
s
U tu 21
s
U Tu 13
S
u tu 17
230
a) Determine the order of these genes on the chromosome.
b) Calculate the map distance between the genes.
c) Determine the coefficient of coincidence and the interference among
these genes.
d) List the genes found on each chromosome in the parents used in the test
cross.
Try this problem yourself. If you get stuck or want to check your answer, look at mine below.
The most common types with 70 and 82 are the parental types. Let's answer D first. The heterozygous parent had one chromosome with S,U and tu (from the type with 82) and s,u and Tu (from the type with 70). That makes that parent heterozygous for all 3 traits as was stated.
Next, let's figure out the order. Find the double crossovers! The
are least common types-those types with 2 and 4. The type with 2 has a
phenotype of S,U, and TU. This almost matches the S,U,tu chromosome
of the heterozygous parent but tu is off. Look at the type with 4
individuals. It has s,u, and tu. Again it almost matches a parental
type (the type with 70) but the Tu is off. This means that the Tu is in
the middle of S and U. S------Tu-------U is our order. This
make the heterozygous parent ( let's call this parent mom for easy reference)
look like this:
S----tu-----U
s----Tu----u
Now look for single crossovers. 21 and 21 ought to make a pair and the 17 and 13 ought to be the other pair but it doesn't hurt to double check. One set with 21 is s, U, tu or s tu U in the proper order. Look at Mom's top chromosome. This matches except for the S so this chromosome is a result of a single crossover between S and Tu. The other set of 21 has S, u,Tu or, in the correct order, S Tu u. This looks like the second product of the same crossover between S and Tu! Good. So how far apart are S and Tu? We add up the two groups produced by the crossover and the two groups produced by the double crossovers and divide the total by the number of F1- like this(21+21+2+4)/230= 48/230=.2087 So 20.9% recombination between S and Tu; they are 20.9 map units apart.
What about the other crossover? It must be between Tu and U. There are 13 s U Tu or, in the proper order, s Tu U. Look back at Mom's chromosomes and note how this phenotype matches the bottom chromosome except for the U so this represents a crossover between Tu and U. The other product from the crossover, of which there are 17, is S u tu or S tu u. This looks like Mom's top chromosome, except for the U. What is the distance between Tu and U? Add up the number of single crossovers at this position and the double crossovers (that have a crossover in both positions- between S and Tu as well as Tu and U) and divide this total by the number of individuals in this generation. (17+13+2+4)/230 = 36/230 = .157 or 15.7%. So the distance is 15.7 map units.
In conclusion, our map looks like this: S------20.9mu---------Tu----15.7mu-----U. What about coefficient of coincidence? We saw (2+4)/230 = 6/230 = .0261 or 2.6% for double recombinants and we expected .157 x .209 = .0328 or 3.3%. Observed/expected is 2.6/3.3 = .788. We got less than expected and, as expected, the coefficient is less than 1 so we had some positive interference.
Go to
http://anthro.palomar.edu/biobasis/default.htm
and pick "Recombination and Linkage" and read up to the "Why Sex?" title.
Do problems 5. and the following 2 problems.
1. In silkmoths, red eyes (re) and white-banded wing (wb) are encoded
by two mutant alleles that are recessive to those that produce wild-type traints
(re+ and wb+); these two genes are on the same chromosome. A moth
homozygous for red eyes and white-banded wings is crossed with a moth homozygous
for the wild-type traits. the F1 have normal eyes and normal wings.
The F1 are crossed with moths that have red eyes and white-banded wings in a
test cross. the progeny of this test cross are:
wild-type eyes and wings
418
red eyes, wild-type wings
19
wild-type eyes, white-banded wings 16
red eyes and white-banded wings
426
a. What is the genetic distance between the genes for red eyes and
white-banded wings?
b. What phenotypic proportions would be expected if the genes for the red eyes
and white-banded wings were located on different chromosomes?
2. Waxy endosperm (WX), shrunken endosperm (sh), and yellow seedling
(v) are encoded by three recessive genes in corn that are linked on Chromosome
5. A corn plant homozygous for all recessive alleles is crosses with a
plant homozygous for all the dominant alleles. The resulting F1 are then
crossed with a plant homozygous for the recessive alleles in a thre-point test
cross. The progeny of the testcross are:
wx sh
V 87
WX SH v
97
WX SH V
3479
WX sh v
280
wx SH v
1531
wx SH V
292
WX sh V
1515
wx sh
v 3478
a. Determine the order of these genes.
b. Calculate the map distances between the genes.
c. Is there interference? If so what type?
10/23 Read
Chapters 6 &7. Do Chapter 6 problems C.2,3 and E.1,4,7,8 and Chapter 7
C.3,4,6.
10/28 Do Chapter
6 C.1,14 and E.3 and Chapter 7 C.1,7,8,10,15,16.
Check out the use of mitochondrial DNA to identify Anastasia, the Czar and
Czarina from 1918 execution.
http://www.mhhe.com/biosci/genbio/life/articles/article26.mhtml
10/30
Do Chapter 7 E.4,5,11,12
Test 11/11 Tuesday
Midterm 2 --Chapters
4-7
All homework from
chapters 6 & 7 can be turned in at the test without being late.
11/20 Read Chapter 8 about monosomy and trisomy in humans. Do Chapter 8 problems C.2,3,12,17,18, 20-25, 30, 32, 35.
Read chapter 25. Do Chapter 25 problems C.1-7,13, 16, 18
and E.2 (show your work!),4, 9,16,19
11/25 From this point on you do not need to turn in your homework---but you still need to do it!
Do the following 3 problems.
1. In a plant, height varies from 6 cm to 36 cm. When 6 cm and 36cm plants are crossed, all plants are 21 cm. In the F2 generation, a continuous range of heights was observed. Most were around 21 cm, and 3 of 200 were as short as 6 cm parent. a. What mode of inheritance is illustrated, and how many gene pairs are involved? b. How much does each additive allele contribute to height?
2. An inbred strain of plants has a mean height of 34 cm. A second strain of the same species from a different geographical region also has a mean height of 34 cm. When plants from the two strains are crossed together, the F1 plants are the same height as the parent plants. However, the F2 generations shows a wide range of heights; the majority are like P1 and F1 plants, but approximately 8 of 2000 are only 18 cm high, and about 8 of 2000 are 50 cm high.
What mode of inheritance is occurring here?
How many gene pairs are involved?
How much does each gene contribute to plant height. Explain.
Indicate possible genotypes for the original P1 parents and the F1 plants that could account for these results. Explain.
Indicate two possible genotypes that could account for F2 plants that are 26 cm high. If possible make #1 true breeding and #2 not true breeding. If not possible, list two 26 cm genotypes and explain why you cant have true and not true breeding.
#1 #2
Look at Pre-Darwin: http://anthro.palomar.edu/evolve.htm
Read it and do the quiz to check yourself.
Go to
http://anthro.palomar.edu/evolve/default.htm
a.
Pick Darwin and Natural Selection. Read through it and
do the
problem
set.
b.
Read Evidence of Evolution. Watch the movie
Isn’t evolution just
a
theory?
Go to
http://anthro.palomar.edu/biobasis/default.htm
Pick Recombination and Linkage. Go to the bottom of this section to find
Red
Queen, read the background information, and then watch the movie.
A basic fossil site to look at is
http://pubs.usgs.gov/gip/fossils/succession.html
Class Reports --to
be done in lab the last few weeks of lab.
Prepare to give a ten minute power point talk on the heritable disease.
Include characteristics of the disease, cause of the disease, frequency of the
disease, genetic testing for the disease, inheritance pattern of the disease,
and treatment of the disease. 3 references (scientific journal
articles) are required.
11/27 Check out the following web site for review of Mendelian genetics: http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch12expl.htm
Read chapter 24 about quantitative genetics.
Do problems 24E.2,3,4A. Also do 1-3 on http://nitro.biosci.arizona.edu/courses/EEB182/handouts/popgen.htm
Do the following problems.
1. If a population is not in equilibrium, what are the five possible reasons for this. Apply these reasons to the sickle cell hemoglobin population and suggest the probable outcomes.
2. Tay-Sachs disease is caused by loss-of-function mutations in a gene on chromosome 15 that encodes a lysosomal enzyme. Tay-Sachs is inherited as an autosomal recessive condition. Among Ashkenazi Jews of central European ancestry, about 1 in 3600 children is born with the disease. What fraction of the individuals in this population are carriers?
3. A farmer plants transgenic BT corn that is genetically modified to produce its own insecticide. Of the corn borer larvae feeding on these Bt corn plants, only 25% survive unless they have at least one copy of the dominant B allele that confers resistance to the Bt insecticide. When the farmer first plants Bt corn, the frequency of the B allele is .04. What will the frequency of the resistant allele be after one generation of corn borers fed on Bt corn?
4. Looking at sickle cell hemoglobin in a population, the genotypic frequencies are AA 75.6%, AS 24.2% , SS 0.2%. Determine whether the data represent a population in Hardy-Weinberg equilibrium.
12/2 Do the following 5 problems
Assuming Hardy-Weinberg equilibrium.....
1. The frequency of the recessive homozygote genotype is 0.16. What is the percentage of individuals homozygous for the dominant allele?
2. Allele B is dominant and produces white wool. Allele b is recessive and produces black wool. In a population of 900 sheep, 891 are white and 9 are black. What are the allelic frequencies?
3. Given the frequency of two alleles in a gene pool are 0.1 (R) and 0.9 (r), what is the percentage in the population of heterozygous individuals? What is the percentage of homozygous recessive individuals?
4. Among 11,335 people, the following blood types were obtained:
5,150 O
4,791 A
1,032 B
362 AB
Calculate the frequencies for the
three alleles.
5. The frequency of Tasters is .83. What proportion of the tasters might expect some non-taster children? What is the likelihood that 2 tasters will have a non-taster child?
Final and Third Midterm --Chapters 8,24,25 ---
Thursday
December 11th
9:30-11:30
Future work.
Also do 1-3 on http://nitro.biosci.arizona.edu/courses/EEB182/handouts/popgen.htmREVIEW problems What are Mendel's postulates? What is sex-linked? sex limited?
Do problems 25.. Read Chapters 5 &6 in evolution text. Do the following question for homework.
#1 q2=.25 If Waa=.7, WAa=1, and WAA=1, what kind of selection is occurring? Directional? Stabilizing? Disruptive? What will q be after 2 generations?
REVIEW
Here is another site for you to use as resource material for Genetic equilibrium--Hardy Weinberg:
http://arapaho.nsuok.edu/~smitho/Population%20problems%20with%20solutions.pdf
REVIEW
Take a look at this web site on evolution and Hardy-Weinberg. http://www.users.csbsju.edu/~wlambert/bio115/topics/4.5modsynth.html
Check out speciation: http://www.santarosa.edu/lifesciences2/ensatina2.htm
REVIEW 24.