Assignments for Genetics
Spring 2010
Assignments are listed by the assigned dates.
Homework is due one week after the assigned date--late homework will not be accepted.
At times during the semester you will not
have one week because all homework assigned prior to a midterm is due at the midterm.
Date Assignment
1/12
Read Chapter 1 in text and review vocabulary from first
lecture. You might start a list of definitions FOR YOURSELF of new words
you hear in lecture and read in the text. Can you define Allele? Chromosome?
Diploid? Genome? Mitosis?
Find a recently published (since 2004) 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, double spaced).
1/14 Read to p. 24 in Chapter 2 about Mendelian Inheritance. Do Chapter 1 Homework Problems C2,6,9,12,13,14 and E4 and Chapter 2 Homework Problems C1-4, 7-10 . Please show your work for the homework problems. You do not have to type your work on the problems.
Go out to this website and go through "WHAT IS
HEREDITY" and "WHAT IS A TRAIT":
http://learn.genetics.utah.edu/content/begin/traits/blood/
1/19 Do
Chapter 2 problems C5,11, 13, 14, 16a &b, and E4,6,7.
This talks about Mendel and simple inheritance.
http://www.brooklyn.cuny.edu/bc/ahp/MGInv/MGI.Intro.html
Review probability and do the 5 problems at
http://www.mathgoodies.com/lessons/vol6/intro_probability.html
You don't have to turn in these 5 problems.
Review ABO bloods types - the markers, genes, and
enzymes:
http://learn.genetics.utah.edu/content/begin/traits/blood/
Here is a site to back up our studies.
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.
You don't have to turn in the quizes.
1/21 Review basic cell structure and cell reproduction by looking at "How Cells Divide" and "mitosis vs. meiosis" at http://anthro.palomar.edu/biobasis/default.htm
Do Chapter 2 problems C18-21, 23,26,27,30,31,33,34 and E9,10
Review
cell cycle and control:
http://www.cellsalive.com/cell_cycle.htm
1/26 Do Chapter 2 E11,13,14 and Chapter 3 C1-4,15-17.
This is a good site which defines chromosomes: http://learn.genetics.utah.edu/content/begin/traits/
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
Check out this site ---Blood type: www.biology.arizona.edu/human_bio/human_bio.html
Here is a good review website for traits and their
inheritance:
http://learn.genetics.utah.edu/content/begin/traits/
1/28 Do Chapter 3 problems C7-14,20,21.
2/2 Do chapter 3 problems C22A,B,D,23,26-31 and E1,7,9,10
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
2/4
Go to
www.biology.arizona.edu/human_bio/human_bio.html
Pick Human
Genetics and then take a look at sections 1,3,4,8,9,
and 14.
Take a look at sex chromosome abnormalities................
Http://anthro.palomar.edu/abnormal/default.htm
2/9 Read Chapter 4 and do Chapter 4 problems C4,7,9,10,12,13,30 & 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? Is the gray gene pleotropic? http://en.wikipedia.org/wiki/Equine_coat_color_genetics
2/11 Look up pleiotropy, p. 86. Remember the Manx trait in cats? Here is a site that explains and gives examples of pleiotropy: http://www.nature.com/scitable/topicpage/Pleiotropy-One-Gene-Can-Affect-Multiple-Traits-569
Note that Protenor and Lygaeus Systems of Sex Determination are covered in Chapter 3, starting with p. 62. Conjugation is covered in Chapter 8-- p.135-142.
Read top right paragraph on p. 79 with bold words "temperature-sensitive allele". Remember temperature can determine sex in turtles, some snakes and some lizards.
Read p. 81-84 about sex-linked, sex limited, and sex influenced traits.
Do chapter 4 problems C14-19,21,23,29 and E3
Do the following problems
A. In Drosophila, an X-linked recessive mutation, scalloped (sd), causes irregular wing margins. Diagram the F1 and F2 results if (a) a scalloped female is crossed with a normal male; (b) if a scalloped male is crossed with a normal female. Compare the results with those that would be obtained if the scalloped gene were autosomal.
B. A husband and wife have normal vision, although both of their fathers are red-green color-blind, an inherited X-linked recessive condition. What is the probability that their first child will (a) be a son? (b) a normal daughter? (c) a color-blind son? (d) a color blind daughter?
C. While vermilion is
X-linked and recessive in drosphila and causes the eye color to be bright red, brown is an
autosomal recessive mutation that causes the eye color to be brown. Flies
carrying both mutations loose all pigmentation and are white eyed. Predict
the F1 and F2 results of the following crosses:
(a) vermilion
females X brown males
(b) brown females X vermilion males
(c) white females X wild-type males
Read about Lyon's hypothesis starting on page 165.
The following problems do not have to be turned in but you should be able to answer them.
1A. Repeat cross (a), from above problem A (9/17 assignment), if the organism, an insect, has the protenor system of sex determination.
1B. Repeat cross (a) and (b) from problem A (9/17) with birds and the ZZ/ZW system
2. How many barr bodies
will the XXY drosophila have in each cell?
the XXY human/mammal ?
3. Which is the heterogametic sex in flies? Define the term and explain your answer.
4. When cows have twin calves of unlike sex (fraternal twins), the female twin is usually sterile and has masculinized reproductive organs. This calf is referred to as a freemartin. In cows, twins may share a common placenta and thus fetal circulation. Predict why a freemartin develops.
5. What is the sex of an XXY individual in
drosophila? In humans? What is the sex of an X individual in
drosophila? In humans? Explain.
6. Which is the heterogametic sex in chickens? Define the term and explain your answer.
Go to
www.biology.arizona.edu/human_bio/human_bio.html
Pick
Color Blindness. Read through it and
do the Sex-linked Inheritance problem set and the color
blindness problem set. You don't have to
turn these questions in!
And this is another good site for
Color blindness:
www.biology.arizona.edu/human_bio/human_bio.html
TEST 1 Thursday 2/18 on the material above!
Remember all homework assigned to this point is due at the
test. No phones allowed.
2/23 Do chapter 4 problems C6,11,20,24,25,28 and E2,5,7,10.12
Try a couple of problems with multiple genes and epistasis--you don't need to turn them in.
1. Pigment in mouse fur is only produced when the
C allele is present. Individuals of the cc genotype are white. If
color is present, it may be determined by the A, a alleles. The A_
genotypes
result in agouti color, while aa results in black coats.
a. What F1 and F2 genotypic and phenotypic
ratios are obtained from a cross between AACC and
aacc mice?
b. In three crosses between different agouti
females of unknown genotypes and aacc males, the
following phenotypic ratios were
obtained:
cross 1: 8
agouti, 8 white cross 2: 9 agouti, 10 black cross
3: 4 agouti, 5 black, 10 white
What are the genotypes of the 3 females?
2. In some plants a red pigment, cyanidin, is synthesized from a colorless precursor. The addition of a hydroxyl group (OH-) to the cyanidin molecule causes it to become purple. In a cross between two randomly selected purple plants, the following results were obtained: 94 purple, 31 red, 43 white. How many genes are involved in the determination of these flower colors? Which genotypic combinations produce which phenotypes? Diagram the purple X purple cross.
3. Eye color of the Oriental fruit fly is determined by
a number of genes. A fly having wild-type eyes is crossed with a yellow
eyed fly. All the F1 flies from this cross have wild-type eyes. When
the F1 are interbred, 9/16 of the F2 have wildtype eyes, 3/16 have amethyst
eyes, and 4/16 have yellow eyes.
a. Give the genotypes for all flies
in the P, F1, and F2 generations.
b. Does epistasis account for eye
color in these flies? If so, which gene is epistatic and which is
hypostatic
(affected by another gene)?
4. A variety of opium poppy
having lacerate leaves was crossed with a variety that has normal leaves.
All the F1 had lacerate leaves. Two F1 plants were interbred to produce
F2. Of the F2, 249 had lacerate leaves and 16 had normal leaves.
Give the genotypes for all of the plants in the P, F1, and F2 generations.
Explain how lacerate leaves are determined in the opium poppy.
2/25 Read Chapter 5 and do Chapter 5 C1,3-10 and E11,13
3/2 Do Chapter 5 C11-14 and E8,12,14,22
3/4 Do Chapter 5 E15-18,19B,20,21,23
Here is a mapping problem with 3 genes. 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.
3/9 Do Chapter 6 problems C.2,3 and E.1,4,7,8. Also, do the following 2 questions.
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?
3/11
Go to
http://anthro.palomar.edu/biobasis/default.htm
and pick "Recombination and Linkage" and read up to the "Why Sex?" title.
Read Chapter 7 and
do Chapter 7
C.1,3,4,6-8.
Pick up worksheet from Biology office (LH210) and complete for homework.
3/23
Do Chapter 7 C.10,15,16 and E.4,5,11,12.
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
Class Reports
--to
be done in lab the last few weeks of lab (4/13-27).
Prepare to give a ten minute power point talk on an heritable disease in
humans.
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.
Tentatively 3/25 MIDTERM 2-the end of Chapter 4 (codominance, incomplete dominance, lethal alleles, sex-linked inheritance, penetrance,)Chapter 5 p.100-117 (mapping), Chapter 6 p.133-142(conjugation, mapping), and Chapter 7 (extranuclear inheritance). All homework due at test.
Future Assignments
No more homework
will be turned in!!!
11/3 Read Chapter 8 about monosomy and trisomy in humans. Do Chapter 8 problems C.2,3,12,17,18, 20-25, 30, 32, 35.
11/5 Read chapter 25. Do Chapter 25 problems C.1-7,13, 16, 18 and E.2 (show your work!).
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
11/10 Do Chapter 25 problems E4,9,16,19.
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
11/19 Read chapter 24 about quantitative genetics.
Do problems 24.C.4,5,6,14, 25, E.24
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. Looking at sickle cell hemoglobin in a population, the genotypic frequencies are AA 75.6%, AS 24.2% , SS 0.2%. Determine p and q.
3. A group of 120 people leave the States to settle their own island, choosing to isolate themselves from the rest of the world. Five of the people are hh for hemophelia, 20 are Hh but wild type, and the rest are HH wild type. What is the value of P?
4. 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?
--Did it say recessive? so aa= 1/3600 = (freq of a) X (freq of a). So? Square root of 1/3600 is freq of a or q. And? 1- (freq of a)= freq of A = p. Who are the carriers? The heterozygotes or Aa and their frequency is 2pq.
11/24 Do problems 24E.2,3,4A,B. Also do 1-3 on http://nitro.biosci.arizona.edu/courses/EEB182/handouts/popgen.htm
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?
--- q= .16 so aa is q X q
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. If you have a fitness of 1 you are well fit-you make the max number of offspring. If you have a fitness of .5, you produce only 1/2 of the offspring as the individual with a fitness of 1 so you are not as fit. If fitness of aa=.7, Aa=1, and AA=1, what will happen over time?
-- will freq of a increase or decrease or stay the same?
Third Midterm --Chapters 8,24,25
and Darwin's Natural Selection
12/3
Check out the following web site for review of Mendelian genetics: http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch12expl.htm
4/30 Here is a review sheet to try.
Genetics Review Sheet Name_________________________
F1 checkered plain
F1 checkered plain
gGDDccAa X gGDdcCAa
s + b 660
s d + 17
s d b 192
+ d b 114
s + + 106
+ + + 198
+ d + 651
+ + b 12
a. What is the genotypic arrangement of the alleles of these genes on the X chromosomes of PARENTAL females? 2 points
b. Determine the correct sequence and construct a map of these genes on the X chromosome.
6 points
c. Is there positive or negative interference with crossing over? Explain. 3 points
Final
---
Thursday
Dec 10th
9:30-11:30