Name___________________________Course___________________
Problem Set #4: Eukaryotic Chromosome Structure, Mitosis,
Cell Cycle, Meiosis & Genetics
1. _________________ - condensed regions within the chromosome that are responsible
for the accurate segregation of the replicated chromosome during mitosis and meiosis
2. _______________ - the location where spindle fiber attachment occurs, consists of protein and DNA
3. _______________- the region of DNA at the end of linear eukaryotic chromosome; required for the
replication and stability of the chromosome
4. Each chromosome is made of two __________________________ tied together at the ______________
by the ________________________.
The Cell Cycle (Chapter 12)
1. Mitosis and cytokinesis distributes identical sets of ____________ to daughter cells.
2. (Pg. 216) In eukaryotic cells the DNA organizes in to "threads" called ____________.
3. Humans have _____ chromosomes or _____ pair of chromosomes. Human gametes have ______
chromosomes
4. (Fig. 12.3) A duplicated chromosome is made up of two _______________ which are held together at a
narrow region called the ______________.
5. Chromosomes consist of _______ coiled or wound around special proteins called ____________
6. What is the difference between a sister chromatid and a daughter chromosome?
7. In the typical cell cycle about how much time (%) is devoted to mitosis? ________________
8. What happens during the "M" phase of the cell cycle?
_________________________________________________ What do you think would be happening during
a G0 phase?
9. (Fig. 12.5) When do DNA (chromosomes) duplicate?
MATCHING – STAGES OF MITOSIS
10.
11.
12.
13.
_____
_____
_____
_____
CHOICES:
Chromosomes form and migrate to the cell’s equator
Cytokinesis occurs
Chromosomes move towards the poles
microtubules attach to the kinetochores
A. Prophase
C. anaphase
B. metaphase
D. telophase
14. The spindle apparatus is composed of ____________ that are thought to be involved in what process
?__________
15. Explain how cytokinesis differs between animal and plant cells.
16. (Fig. 12.10) Prokaryotes divide by a process called
17. (Fig. 12.14) How does M-phase promoting factor (MPF) promote mitosis?
Why does MPF fluctuate during the cell cycle?
18. (Fig. 12.17) What term is used to describe what this cancer is doing by spreading cells through the body?
The cell cycle consist of alternating phases of _____________ and ________________. How cell division
(and thus tissue growth) is controlled is very complex. The following terms are some of the features that are
important in regulation, and places where errors can lead to cancer. Cancer is a disease where regulation of
the cell cycle goes away and normal cell growth and behavior is lost.
Cdk (cyclin dependent kinase, adds phosphate to a protein), along with___________, are major control
switches for the cell cycle, causing the cell to move from G1 to S or G2 to M.
CdK and cyclins, make up the _____________________. It triggers progression through the cell cycle.
_______________is a protein that functions to block the cell cycle if the DNA is damaged. If the damage is
severe this protein can cause apoptosis (cell death). This protein increases in damaged cells. This allows time
to repair DNA by blocking the cell cycle. A mutation of this protein is the most frequent mutation leading to
cancer. An extreme case of this is Li Fraumeni syndrome, where a genetic a defect in this protein leads to a
high frequency of cancer in affected individuals.
___________is a protein that binds to cyclin and cdk blocking entry into S phase. Recent research (Nature
Medicine 3, 152 (1997)) suggests that breast cancer prognosis is determined by this protein levels. Reduced
levels of this protein predict a poor outcome for breast cancer patients.
Mitosis
Mitosis is nuclear division plus cytokinesis, and produces two identical daughter cells during prophase,
metaphase, anaphase, and telophase. Interphase is often included in discussions of mitosis, but interphase is
technically not part of mitosis, but rather encompasses stages G1, S, and G2 of the cell cycle.
Mitotic Stage
Activity
Prophase
Metaphase
Anaphase
Teleophase
Cytokinesis
Draw each phase of Mitosis:
Meiosis and Sexual Reproduction (Chapter 13)
1. How does asexual reproduction differ from sexual reproduction? Why do you thing sexual reproduction
evolved?
2. (Pg. 236) How do somatic tissues vary from germ line tissues?
3. When sex cells (sperm & egg) come together the process is called ______________.
4. Compare Fig. 12.5 (a) with Fig. (c) How do the two life cycles differ? How are they the same
5. (Fig. 13.7) What happens in prophase I of meiosis that doesn’t happen in mitosis?
___________________________
6. Use Fig. 13.7 to answer the following. Are homologous chromosomes the same or different colors?
How many chromosomes are in each cell under going mitosis or meiosis?_______
In meiosis II one of the blue chromatids has a piece of a red chromatid while the red chromatid has a
piece of the blue. What happened in meiosis I ? __________ What happens during anaphase II? and how
many cells are produced?
7. During mitosis a cell having 2n chromosomes how many chromosomes does each daughter cell have? ___
During meiosis? ______
8. (Pg. 242) Mitosis consists of _____ cell division(s) while meiosis consists of _____ division(s)
9. (Fig. 13.8) How does meiosis I anaphase differ from mitosis anaphase? Make sure you explain the role of the
kinetochore and centromere.
10. Define independent assortment in your own words.
11. (Pg. 245) In what three ways does sexual reproduction increase genetic variability
MATCHING – CHROMOSOME NUMBERS IN CELLS -------12. _____ Some plant cell contain 4 sets of chromosomes instead of 2
13. _____ Have homologous pairs of chromosomes
14. _____ Gametes
15. _____ Produced by meiosis
16 _____ Human cells with 23 pair of chromosomes
17. _____ Cells of a zygote
CHOICES A. Haploid cells
B. Diploid cells
C. Polyploid cells
Definitions: Genes, chromosomes, allele, genotype, phenotype, homozygous, heterozygous, Law of
Segregation, Independent Assortment, Incomplete Dominance
Law of Segregation
When Gregor Mendel performed cross-pollination between a true-breeding yellow pod plant and a truebreeding green pod plant, he noticed that all of the resulting offspring, F1 generation, were green. He
then allowed all of the green F1 plants to self-pollinate. He referred to these offspring as the F2
generation.
An Allele is an alternate form of a gene. An alleles are made up of one trait for a gene from each
parent. Alleles can be homozygous (dominant or recessive) or heterozygous. What are the alleles for a
True Breed Green Pod_________; a True Breed Yellow Pod______________; a heterozygous
Pod____________________ The genetic makeup of an organism is called ______________ while the
expressed physical trait of an organism is called the ______________________..
What is the geneotype of the true breed green pods___________
What is the geneotype of the true breed yellow pods___________
What is/are the geneotypes of all F1 generations______________
What is the ratio of F1___________________________________
What is the geneotype of the F1 green pod?________
What is the geneotype of the F2 pods_____________
What are the phenotypes of the F2_______________
What is the ratio of F2_________________________
From the above experiment Mendel formulated what is now known as Mendel's law of segregation. This
law states that allele pairs separate or segregate during gamete formation, and randomly unite at
fertilization. There are four main concepts involved in this idea. They are:
1. There are alternative forms for genes called alleles.
2. For each characteristic or trait organisms inherit two alternative forms of that gene, one
from each parent. These alternative forms of a gene are called alleles.
3. When gametes (sex cells) are produced, allele pairs separate or segregate leaving them
with a single allele for each trait.
4. When the two alleles of a pair are different, one is dominant and the other is recessive.
Mendel's Law of Independent Assortment
Mendel performed dihybrid crosses (mating of parent plants that differ in two traits) in plants that were
true-breeding for two traits. For example, a plant that had green pod color and yellow seed color was
cross-pollinated with a plant that had yellow pod color and green seeds. In this cross, the traits for
green pod color (GG) and yellow seed color (YY) are dominant. Yellow pod color (gg) and green seed
color (yy) are recessive.
F
(first)
O
(outside)
I
(inside)
L
(last)
G
G
Y
Y
G
g
Y
y
Using the Law of Segregation, identify all possible alleles of parent pods, then complete the dihybrid
cross. To identify all possible alleles for each parent, use F.O.I.L to multiply First and Inside, then First
and Last, then Outside and Inside, then Outside and Last.
F1
What are the F1 geneotypes by percentile?____________________________
F1 phenotypes___________________________________________________
What is the ratio for F1 offsprings____________________________________
F2: Cross two F1 generation to get F2s
What are the F2 geneotypes by percentile?_____________________________
F2 phenotypes___________________________________________________
What is the ratio for F2 offsprings____________________________________
Incomplete Dominance and Test Cross
Definition: Incomplete dominance is a form of intermediate inheritance in which heterozygous alleles are both expressed,
resulting in a combined phenotype
Which of the following is an example of incomplete dominance?
a. Crossing of an unknown trait of parent with an organism that is homozogous recessive for the trait
to obtain the genotype of the parent.
b. Crossing a homozogous red flower with a heterozygous white flower to get all heterozygous red
F1 flowers
c. Crossing a homozogous red flower with a homozogous white flower to get all pink F1 flowers
d. Crossing a homozogous red flower with a homozogous white flower to get all white f1 flowers
e. None of the above
Which of the following is an example of a test cross?
a. Crossing of an unknown trait of parent with an organism that is homozogous recessive for the trait
to obtain the genotype of the parent.
b. Crossing a homozogous red flower with a heterozygous white flower to get all heterozygous red
F1 flowers
c. Crossing a homozogous red flower with a homozogous white flower to get all pink F1 flowers
d. Crossing a homozogous red flower with a homozogous white flower to get all white f1 flowers
e. None of the above
Multiple Choices:
1.
The cytoplasmic division in plants must be facilitated by a mechanism called
a. cleavage furrow formation
b. spindle equator formation
c. spindle plate formation
d. cell plate formation
e. a & d
2.
What is a major feature of prophase in mitosis?
a. Chromosomes condense
b. Crossing-over between homologous chromosomes
c. Nuclear envelope breaks up
d. a & c
e. All of the above
3.
In which stage in interphase does the DNA replication take place?
a. G1
b. G2
c. S
d. G1 & S
e. G1 & G2
4.
When all chromosomes line up at the spindle equator, it is referred as the stage(s) of
a. Metaphase
b. Anaphase
c. Anaphase I
d. Anaphase II
e. None of the above
5.
The cells that make up our body, and usually have a diploid chromosome number, are
known as
a. Sex cells
b. Germ cells
c. Diploid cells
d. Prokaryotic cells
e. Somatic cells
6.
Meiosis only occurs in
a. Somatic cells
b. Germ cells
c. Animal cells
d. Plant cells
e. Prokaryotic cells
7.
Sister chromatids break apart in which of the following stages?
a. Metaphase
b. Anaphase
c. Anaphase I
d. Anaphase II
e. a & d
8.
A different molecular form of the same gene is known as a/an
a. phenotype
b. genotype
c. allele
d. homologous pair
e. sister chromatids pair
9.
Crossing-over can be found in the stage of
a. Prophase I
b. Prophase II
c. Interphase
d. Anaphase I
e. Anaphase II
10.
Which of the following organelles is/are important during the stage of metaphase?
a. Mitochondrion
b. Ribosome
c. Centrioles
d. Golgi Apparatus
e. All of the above
11.
Which of the following process will result in a reduction of the chromosome number by
half?
a. Mitosis
b. Meiosis
c. Cytoplasmic division
d. DNA replication
e. Fertilization
12.
The gamete usually has a ___________ chromosome number.
a. haploid
b. diploid
c. triploid
d. tetraploid
e. polyploidy
13.
Which of the following best describe the term “crossing over”?
a. An exchange of information between two sister chromatids
b. A molecular interaction between two sister chromatids
c. A molecular interaction between two non-sister chromatids
d. A separation of two sister chromatids
e. None of the above
14.
There are DNA replications during the stage(s) of
a. interphase prior to mitosis
b. interphase prior to meiosis I
c. interphase between meiosis I and meiosis II
d. a & b
e. All of the above
15.
Sexual reproduction requires all of the following except
a. meiosis
b. mitosis
c. gamete formation
d. fertilization
e. None of the above
Genetics crosses
1. In sheep, white (W) is dominant to black w. Give the F-2 phenotypic and genotypic ratios
resulting from the cross of a pure-breeding white ram with a pure-breeding black ewe.
2. If you found a white sheep and wanted to determine its genotype, what color animal would
you cross it to and why?
3. In peas yellow seed color is dominant to green. Make the following crosses and give the
phenotypes a. a green with a green, b. A heterozygous yellow with a heterozygous yellow.
and c. A heterozygous yellow with a green
4. If d is dominant in dwarfism, give the genotypes of the parents that produce 3/4 tall plants
and ¼ dwarf plants among their progeny.
5. In rabbits, black (B) is dominant to brown b, and spotted coat S is dominant to solid coat s.
Give the genotypes of the parents if a black, spotted male is crossed with a brown, solid
female and all the offspring are black and spotted.
6. In cattle, having horns p is recessive to hornless or polled P. Coat color is controlled by
incompletely dominant genes RR for red, R'R' for white and RR' for roan (reddish brown with
gray spots). If two heterozygous roan -polled cattle are mated, what kinds of offspring are
expected?
7. Color-blindness c is a sex-linked recessive trait, while normal color vision C is dominant.
a). If two normal-visioned parents have a color-blind son, what are the parents genotypes?
b). what are the chances that their daughter will be color-blind?
8. In humans, deafness can be the result of a recessive allele affecting the middle ear (dd =
deaf) or another recessive allele (ee = deaf) that affects the inner ear. Suppose two deaf
parents have a child that can hear. Give the genotypes of all three individuals.
9. In carnations, red or white phenotypes are dependent on homozygous genotypes, while the
heterozygotes are pink. Give the F-1 and F-2 genotypic and phenotypic ratios expected
from a cross: red x white.
10. Migraine headaches and High blood pressure are thought to be inherited as dominate
traits. If a man who suffers from migraines and is heterozygous for high blood pressure is
mated to a woman who is heterozygous for migraines and high blood pressure, what
probability of their children will have migraines and high blood pressure?