Chapter 11 Cell Division
A researcher is studying phases of the cell cycle in a population of cells during which there is an increase in the DNA content. The stage is most likely:
S phase
What would happen to the daughter cells if the G2 phase of the parent cell is shortened?
The cells would be smaller than normal.
Suppose you analyze a time-lapse of a cell under a microscope and you observe what appears to be cross like structures within a bivalent. Which of the answer choices is an interpretation of this observation?
These structures represent crossing over between non-sister chromatids.
Why are the X and Y chromosomes not considered homologous?
They do not carry the same set of genes.
An example of second-division nondisjunction is when sister chromatids fail to separate during anaphase of meiotic cell division.
True
Construction of a karyotype from an image of stained chromosomes is a technique by which a researcher can see and count chromosomes.
True
Evidence exists (especially in dinoflagellates) that mitosis evolved from binary fission. For example, in certain eukaryotic cells during mitosis, DNA is attached to the membrane of the nucleus (much like a circular chromosome of a bacterium is attached to the plasma membrane).
True
The alignment of chromosomes at metaphase of meiosis II is most similar to the alignment of chromosomes during metaphase of mitosis.
True
The occurrence of nondisjunction during mitosis can result in the development of certain cancers; however, nondisjunction is often thought of in relation to meiosis and the development of certain trisomies.
True
Reproduction by mitotic cell division:
results in two daughter cells that are genetically identical.
What protein forms the contractile ring during cytokinesis in animal cells?
Actin
Muscle cells in the mammalian heart are multinucleate, meaning that multiple nuclei are present in the cytoplasm of individual large cells. Predict what is different about the cell cycle in a muscle cell.
Cytokinesis does not occur.
Which statement is true regarding binary fission?
DNA replication of the circular bacterial chromosome during binary fission is a bidirectional process, starting at one point but progressing in opposite directions.
Predict what would happen if crossing over between homologous chromosomes occurred as part of mitosis.
Daughter cells would not be genetically identical.
If you analyze the sequences of the two copies of any of the chromosomes shown in the karyotype, there would be slight sequence differences. What could account for the small differences between a few of the homologous chromosomes? Click to view full size.
Each homologous chromosome in a pair is from a different parent.
In mammals, females have two copies of the X chromosome, whereas males have only one copy. Dosage compensation (equalization of the numbers in each gene) is accomplished in mammals by:
Females randomly inactivating one of the X chromosome in all cells.
A phragmoplast functions to:
Form a new cell wall
A cell that is not actively dividing is in what phase of the cell cycle?
G0
If a human has a genotype XXXY, they would:
Have 2 inactivated X chromosomes and be male.
What is the role of the protein FtsZ in prokaryotes?
It forms a ring at the site of constriction.
What is the role of the protein FtsX in prokaryotes?
It forms a ring at the site of construction.
Homologous chromosomes separate from each other in:
Meiosis I
At the start of mitosis, how many sister chromatids are present in a human cell?
46
To visualize chromosomes, a picture of each can be arranged such that homologous chromosomes are aligned with each other and arranged as pairs in order of decreasing size. What is this called?
A Karyotype
Why don't plant cells use a contractile ring to divide their daughter cells?
A contractile ring can't "pinch" a cell wall.
During what step in meiosis do homologous chromosomes separate?
Anaphase I
Asexual reproduction occurs in:
Animal cells, plant cells, bacterial cells, unicellular eukaryotes
The microtubules that form the mitotic spindle extend out from the centrosome. Where would you expect to find the plus (fast-assembling) end of a spindle microtubule?
Away from the centrosome and toward the kinetochore
What cellular process(es) is/are responsible for the increase in protein content associated with the gap phases of the cell cycle?
Both transcription and translation
Why would a compound that interferes with bacterial cell wall synthesis be useful for treating a bacterial infection?
It would limit growth of the bacterial population through cell division.
A person has the genotype XXY. What syndrome does that person have and what sex is the person?
Klinefelter; male
At which stage of the cell cycle could you see sister chromatids with a microscope?
M
In which phase of mitosis do chromosomes condense?
Prophase
Replication of DNA in eukaryote occurs during which phase of the cell cycle?
S phase
Mitotic cell division is considered asexual because:
The daughter cells receive DNA from one parent cell, and the daughter cells are genetically identical.
What important difference is there between meiosis in males and females? Refer to the figure shown.
The division of cytoplasm differs between males and females.
Synapsis is best described as:
The pairing of homologous chromosomes in prophase I.
What would happen if a pair of sister chromatids only connected to the mitotic spindle at one of their kinetochores?
The sister chromatids would not separate. The chromosome would not line up properly at metaphase. One of the daughter cells would have an extra copy of that chromosome.
