Chapter 5 - Cell Division

Chapter 5 - Cell Division
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What forms the contractile ring in animal cells?
actin filaments
An organism has 8 pairs of chromosomes. If sperm and egg did not undergo meiosis, how many chromosomes would be present in a cell that resulted from the fusion of a sperm and egg?
32
The only haploid stage in the animal life cycle is the gamete.
True / False?
True
Technically, mitosis refers to nuclear division and NOT cytoplasmic division.
True / False?
True
You are looking at a cell under the microscope, and see what appears to be several "X" structures being pulled to each side of the cell. What stage of meiosis are you looking at?
anaphase I
One difference between spermatogenesis and oogenesis is
oogenesis stops at the second meiotic division and awaits fertilization by a sperm before finishing meiosis.
Growth factors that are transported through the blood play what role in the cell cycle?
an external signal to tell the cell whether or not to divide
In which stage of mitosis do the chromosomes line up in the center of the cell?
metaphase.
What is the difference between the chromosomes in a secondary spermatocyte and those in a spermatid?
the chromosomes in secondary spermatocytes consist of two chromatids, the ones in the spermatid consist of only one chromatid
In humans, the diploid number of chromosomes is
46.
The only function of apoptosis is to destroy healthy cells when they become damaged or infected.
True / False?
False
The formation of sperm gametes is termed
spermatogenesis.
During which phases of the cell cycle do the chromosomes look like "X"s?
prophase, metaphase
Centrioles are absolutely necessary to the process of mitosis in all organisms.
True / False?
False
Chromosomes are attached to the spindle fibers in order to move to and from the equator.
True / False?
True
It is the secondary oocyte and not the egg that the sperm fertilizes to form a diploid organism.
True / False?
True
During which stage of the cell cycle do the chromosomes duplicate?
interphase
If the diploid chromosome number is 16, the chromosome number of each gamete will be
8.
During what stage of mitosis does the nuclear envelope disappear and the chromosomes become distinct?
prophase
Synapsis occurs during what stage of meiosis?
prophase I
You are looking at chromosome 1 in a human being. Assuming there is no crossing over, what is the source of all the genes on this chromosome?
either the mother or father
Eukaryotic chromosomes are composed of
chromatin.
Which of the following is not a reason why two children born to the same parents [not identical twins] are unlikely to have the same genetic makeup?
A) Crossing over recombines portions of sister chromatids.
B) Fertilization provides a new pairing of chromosomes.
C) Each sperm or egg has a random assortment of chromosomes, half from each pair.
D) Chromosomes align themselves independently during meiosis I.
E) Since though they are produced at different times, all sperm will be genetically different from all other sperm.
E) Since though they are produced at different times, all sperm will be genetically different from all other sperm.
Microtubules found in spindle fibers are capable of assembling and disassembling.
True or False?
True
Which is NOT a correct association?
A) S stage-DNA synthesis
B) M stage-mitosis and cytokinesis
C) interphase-shortest stage of the cell cycle
D) G1 stage-cell grows in size and cell organelles increase in number
E) G2 stage-metabolic preparation for mitosis
C) interphase-shortest stage of the cell cycle
If a cell stops at the G1 checkpoint, this is most likely due to what problem?
There is DNA damage.
Without considering the variation provided by crossing-over, how much will two siblings from one set of parents vary from each other?
Siblings inherit essentially 50% of their genes from each parent, but two sibling offspring may share with each other from zero to 23 chromosomes in common from each parent and therefore vary widely from each other.
Which of the following is not true of the chromosomes in a cell undergoing mitosis?
A) They are highly compacted.
B) They are available for RNA synthesis.
C) They have histones bound to them.
D) They are found within the cell nucleus.
E) They are present in the diploid number.
B) They are available for RNA synthesis.
In plant cells, what is responsible for organizing the spindle?
centrosomes
Mitotic division is the normal process of cell reproduction to build and maintain the body of an organism, while meiosis takes place only in the formation of gametes for reproduction.
True or False?
True
The mitotic stage of cell division consists of
mitosis and cytokinesis.
If the total number of chromosomes in a cell is six, then after mitosis there will be
six chromosomes in each daughter cell.
The genes that code for the proteins of the signaling pathway could be classified as
proto-oncogenes.
You are examining a cell under the microscope that is undergoing cell division and cannot find any asters. What else would not be present in this cell?
a cleavage furrow
When does apoptosis occur?
during development
During which phase will homologous chromosomes separate?
anaphase I
There are two sets of caspases operating during apoptosis. Which statement does NOT correctly characterize the role of these caspases?
A) One set of caspases are called initators because they receive a signal to activate the second set.
B) One set of capsases are called executioners because they dismantle the cell.
C) Caspases can be unleashed by either internal or external signals.
D) Caspases are normally active during the entire cell cycle.
E) Caspases are responsible for the typical stages a cell goes through during apoptosis.
D) Caspases are normally active during the entire cell cycle.
The cell cycle consists of
mitosis and interphase.
During interphase,
hereditary material duplicates itself.
Which sequence of stages in mitosis is correct?
A) prophase, metaphase, interphase, telophase
B) metaphase, anaphase, prophase, telophase
C) anaphase, interphase, telophase, prophase
D) prophase, metaphase, anaphase, telophase
E) interphase, metaphase, prophase, anaphase
D) prophase, metaphase, anaphase, telophase
How does cell division differ between animal and plant cells?
The cell plate is the final partitioning of plant cells.
Which of the following descriptions does NOT occur during apoptosis?
A) cell rounds up
B) cells lose contact with neighbors
C) nucleus fragments
D) DNA is duplicated
E) plasma membrane develops blisters
D) DNA is duplicated
In some plants, the haploid stage is the dominant stage while in humans, the diploid stage is the dominant stage.
True or False?
True
Meiosis results in a change in chromosome number indicated by
2n to n.
We presume that meiosis evolved later than mitosis. What process would not have to evolve in cells undergoing meiosis in order to make this transition?
A) homologous chromosomes would have to pair up
B) an additional division would have to occur but without a second DNA replication
C) sister chromosomes do not separate at first anaphase; centromeres hold until second division
D) a method of lining up single chromosomes along the metaphase plate
E) fertilization processes to restore the diploid number in an organism
D) a method of lining up single chromosomes along the metaphase plate
The overall cell cycle is dramatically different for animals than for plant cells.
True or False?
False
The length of DNA in each chromosome is longer than the diameter of the animal cell.
True or False?
True
During mitosis, separation of the sister chromatids ensures that each daughter cell will receive two copies of each type of chromosome.
True or False?
False
Upon examination, a cell is found to have twice as much DNA as the normal diploid state but is no longer in the process of replicating the DNA. All of the DNA is found within a single nucleus. Which stage of the cell cycle is this cell in?
G2 phase
What is a potential outcome if one of your fathers gametes did not go through meiosis correctly and one of the chromosomes did not separate correctly?
You inherited a normal amount of genetic material from your mother but inherited an extra chromosome from your father. One of your pairs of chromosomes will not be homologous.
Which of the following best describes the role of histones?
A) Histones play a role in coding for hereditary features.
B) Histones make RNA synthesis possible.
C) Histones determine the structure of the chromosome.
D) Histones are not thought to play any role in the cell.
E) Histones determine the diploid number of chromosomes.
C) Histones determine the structure of the chromosome.
Meiosis differs from mitosis in that
it occurs only in the reproductive tissues that produce gametes.
During crossing-over,
chromatids exchange segments of genetic material.
What lines up at the metaphase plate during both metaphase I of meiosis and metaphase of mitosis?
homologous chromosomes for meiosis, each chromosome is composed of two sister chromatids for mitosis
The chromatids are held together at a region called the centromere.
True or False?
True
Which of the following proteins would you expect to be a coded for by a proto-oncogene?
A) a growth factor receptor
B) a DNA repair protein
C) a protein involved with the G1 checkpoint
D) a caspase
E) a DNA replication protein
A) a growth factor receptor
Which is NOT a correct association?
A) cytokinesis-division of the cytoplasm
B) centromere-point where sister chromatids remain attached
C) haploid-one of each chromosome
D) sister chromatids-two identical chromosome strands still attached at the centromere
E) mitosis-when a cell duplicates and then divides twice to reduce chromosome number by half
E) mitosis - when a cell duplicates and then divides twice to reduce chromosome number by half
Which of the following statements is NOT true about oogenesis in humans?
A) It occurs in the ovary.
B) The egg will contain 23 chromosomes.
C) Four equal size daughter cells will form.
D) Three nonfunctional polar bodies will form.
E) Once started, it will not necessarily go to completion.
C) Four equal size daughter cells will form
Which of the following is NOT true concerning the checkpoints in the cell cycle?
A) Mitosis stops if chromosomes are not properly aligned.
B) Mitosis will not occur if DNA is damaged or not replicated.
C) If DNA is damaged, apoptosis may occur.
D) The first checkpoint is located in the S phase of interphase.
E) Cyclins must be present at certain stages to advance to the next stage.
D) The first checkpoint is located in the S phase of interphase.
Following a cut or scrape, which process repairs your skin?
Mitosis
Which of the following is not involved in the regulation of the cell cycle?
A) cyclins
B) internal and external signals
C) growth factors
D) check points
E) caspases
E) Caspases
What lines up at the metaphase plate during metaphase II of meiosis and metaphase of mitosis?
each chromosome composed of two sister chromatids at both
Would it be possible to observe crossing-over between sister chromatids? Why or why not?
No. Since they are genetically identical you could not tell the difference without labeling the chromatids.
Replication of the DNA for meiosis occurs between telophase I and prophase II.
True or False?
False
Which of the below is the correct sequence for the cell cycle?
A) S-M-G1-G2
B) S-M-G2-G1
C) S-G1-G1-M
D) S-G2-M-G1
E) S-G1-M-G2
S-G2-M-G1
Which of the following are genetically identical?
A) both members of a pair of chromosomes
B) sister chromatids
C) the mother's and the father's chromosomes
D) the mother's and her child's chromosomes
E) the father's and his child's chromosomes
B) sister chromatids
Which of the following events would be controlled by an external signal?
A) Cell division.
B) Prophase proceeds into metaphase.
C) The chromosomes align at the equatorial plane before the cell begins anaphase.
D) All of the DNA is copied before the cell enters into the G2 phase.
E) All of these are controlled by an external signal.
A) Cell division
The second meiotic division is essentially a mitotic division except for the fact that the cells produced are
haploid
Which type of genes, if abnormally activated such that the protein is always present and active, can result in cancer
proto-oncogenes
You are examining a cell under the microscope and see what appear to be four sister chromatids bound together and remnants of the nuclear envelope. What stage of meiosis are you looking at?
prophase I
The nuclear membrane reappears in mitosis during
telophase.
If a crayfish has 200 total chromosomes in its body cells (not ovaries or testes)
they would consist of 100 pairs with one of each pair from the father, one of each pair from the mother.
A basic difference between spermatogenesis and oogenesis is that in oogenesis
one functional egg is produced.
During what stage of meiosis do sister chromatids separate from each other?
anaphase II
Homologous chromosome are genetically identical to each other.
True or False?
False
Which of the following best characterizes apoptosis?
A) Apoptosis is bad for an organism.
B) The stages of apoptosis are different in each cell type.
C) Apoptosis happens accidentally to healthy cells.
D) Apoptosis plays a normal role in development and cancer prevention.
E) Apoptosis results in our going from a fertilized egg to trillions of cells.
D) Apoptosis plays a normal role in development and cancer prevention.
Crossing-over is the only factor that is responsible for the variation that exists between offspring of one set of parents.
True/False?
False