Chapter 11 Learning Curve
In human cells, at the end of mitosis and after cytokinesis, how many chromatids have moved into each daughter cell?
46
Why don't plant cells use a contractile ring to divide their daughter cells?
A contractile ring can't "pinch" a cell wall.
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.
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.
Polar bodies are:
haploid.
A malignant cancer differs from a benign tumor in that:
malignant cancers invade surrounding tissue and benign cancers do not.
The assembly of what cytoskeletal structures are initiated by the M cyclin-CDK complex?
microtubules
One of the important cell cycle checkpoints occurs during M phase. It inhibits progression to anaphase until all of the chromosome kinetochores are correctly attached to microtubules of the spindle apparatus. If anaphase of mitosis occurred when the kinetochore microtubule connected to only one of the two spindle poles but not the other, what could result?
nondisjunction
Nondisjunction results when:
pairs of chromosomes fail to separate during anaphase.
Several years ago, a man noticed a small mole on his wrist. Years later, the mole grew in size and the man was diagnosed as having metastatic melanoma. This was likely the result of:
several mutations affecting proto-oncogenes and/or tumor suppressor gene
Second-division nondisjunction occurs when:
sister chromatids fail to separate during anaphase II
Synapsis is best described as:
the pairing of homologous chromosomes in prophase I.
What is the function of histone proteins?
to package DNA in eukaryotic chromosomes
An example of second-division nondisjunction is when sister chromatids fail to separate during anaphase of meiotic cell division.
true
The alignment of chromosomes at metaphase of meiosis II is most similar to the alignment of chromosomes during metaphase of mitosis.
true
Which of the answer choices is an accurate statement that accounts for why women with the genotype XXX are not phenotypically different from an XX female?
Only one X chromosome is active in each cell, regardless of how many X chromosomes there are in a cell.
A woman has her genome sequenced and finds that she carries a mutation in p53. Will she develop cancer?
Possibly; this mutation is likely to predispose her to developing certain types of cancer
A researcher is studying phases of the cell cycle in a population of cells during which there is an increase in the DNA content. This stage is most likely: Please choose the correct answer from the following choices, and then select the submit answer button. Answer choicesmitosis.
S phase.
Which statement represents a misconception about sister chromatids?
Sister chromatids are formed when the prokaryotic circular chromosome attaches at the plasma membrane.
Suppose a research team does a detailed analysis of the DNA sequence of all three copies of chromosome 21 from an individual with trisomy 21 (Down syndrome). They discover that two of the three chromosomes are essentially identical in sequence, whereas the third chromosome has a significant number of sequence differences. Which of the answer choices is consistent with this observation?
The extra chromosome 21 resulted from second-division nondisjunction in one of the parents' gametes.
A gene associated with promoting normal cell division is called:
a proto-oncogene.
What type of protein is being activated by the G1 /S cyclin-CDK complex to promote the expression of histone genes?
a transcription factor
In which phase of mitosis do spindle microtubules shorten?
anaphase
A couple has a baby that only has one X chromosome and no Y chromosome. This could have occurred because: Please choose the correct answer from the following choices, and then select the submit answer button. Answer choicesthere was nondisjunction of homologous chromosomes in meiosis I in the mother. Meiosis in the father was normal.All of these choices are correct.there was nondisjunction of the sister chromatids in meiosis II in the mother. Meiosis in the father was normal.there was nondisjunction of sister chromatids in meiosis II of the father. Meiosis in the mother was normal.there was nondisjunction of the paired X and Y chromosomes in meiosis I in the father. Meiosis in the mother was normal.
All of these choices are correct.
Asexual reproduction occurs in: All of these choices are correct. animal cells. plant cells. bacterial cells. unicellular eukaryotes.
All of these choices are correct.
How would the loss of p53 activity affect a cell? All of these choices are correct. DNA damage could accumulate. CDK activity would not be appropriately regulated. The G1 /S checkpoint would not be functional.
All of these choices are correct.
Recall the experiments of Peyton Rous and his colleagues. If he had found that filtered cancer cell extract could not cause cancer when injected into healthy animals, what could he have deduced? All of these choices are correct. An intact cancer cell is necessary to cause cancer. A large protein may cause cancer. Cancer may be caused by bacteria.
All of these choices are correct.
What properties are associated with a malignant cancer? All of these choices are correct. It invades surrounding tissue. It is metastatic. It is fast growing.
All of these choices are correct.
Suppose you are observing some cells with a microscope, and you see a cell that appears to be dividing. You can see that as the cell starts to pinch in half, the DNA seems to be attached to the plasma membrane via a membrane protein. On further analysis, you find that this organism's DNA is circular - that is, it consists of a closed loop. What can you conclude about this organism and its mode of cell division?
It is a prokaryote that is dividing by binary fission.
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.
At which stage of the cell cycle could you see sister chromatids with a microscope?
M
Which of the answer choices is a characteristic of meiotic cell division?
Meiotic cell division results in halving the number of chromosomes.
A researcher is evaluating the expression of p53 in cells she is culturing in the laboratory. She notices that in a small group of cells, high levels of phosphorylated p53 occur in the nuclei. What can she deduce about these cells?
These cells likely contain damaged DNA.
What happens to CDKs in the absence of cyclins?
They are inactive.
Why are the X and Y chromosomes not considered homologous?
They do not carry the same set of genes.
Which of the answer choices is true about gametes?
They fuse to form a new organism during fertilization.
The process of cell division in a prokaryotic cell is called:
binary fission.
How does meiosis generate genetic diversity?
both crossing over at prophase I and random alignment of homologs at metaphase I
A _____ is an enzyme that adds phosphate groups to other proteins. If this enzyme is only active when bound to a specific protein that fluctuates in concentration in synchrony with the cell cycle, then it is a _____.
cyclin; cyclin-dependent kinase
A zygote is:
diploid.
Nondisjunction can only occur in the sex chromosomes and not the autosomes.
false
Which of the answer choices is part of the process of binary fission in prokaryotes?
formation of a new cell wall
