Chapter 11 LearningCurve
In human cells, at the end of mitosis and after cytokinesis, how many chromatids have moved into each daughter cell?
46
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.
Meiosis _____ is sometimes called reductional division because _____.
I; the number of chromosomes is reduced by half
Meiosis _____ is similar to mitosis in that _____ separate.
II; sister chromatids
What characteristics do you expect to observe with a microscope if you investigate the division of mitochondria and chloroplasts in eukaryotic cells?
circular DNA attached to the plasma membrane and binary fission
A human cell with a total of 23 chromosomes is:
haploid.
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 division of genetic material in a eukaryotic cell is called:
mitosis.
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
What type of gene is c-src (cellular-src)?
proto-oncogene
Reproduction by mitotic cell division:
results in two daughter cells that are genetically identical.
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 genes.
In which phase of mitosis does the nuclear envelope reform?
telophase
The centrosome is:
the microtubule organizing center for the mitotic spindle.
A proto-oncogene is a "normal" gene that, if mutated, can become an oncogene and lead to a cell becoming cancerous.
true
An example of second-division nondisjunction is when sister chromatids fail to separate during anaphase of meiotic cell division.
true
Nondisjunction can occur in both mitosis and meiosis.
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
Trisomy 21 (Down syndrome) is one of only a few examples of an autosomal trisomy in which the fetus develops to term and is born alive.
true
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.
Crossing over occurs during which step in meiosis?
Prophase I.
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 a research team does a detailed analysis of the DNA sequence of all three copies of chromosomes 21 from an individual with trisomy 21 (Down syndrome). They discover that each of the three chromosomes has a unique DNA sequence. Which of the answer choices is consistent with this observation?
The extra chromosome 21 resulted from first-division nondisjunction in one of the parents' gametes.
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
Which of the statements about viruses is true?
None of the other answer options is correct.
Cell division is regulated by:
All of these choices are correct.
How would the loss of p53 activity affect a cell?
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.
The prokaryotic protein FtsZ is evolutionarily related to eukaryotic tubulin. What does this mean?
All of these choices are correct.
What would happen if a pair of sister chromatids only connected to the mitotic spindle at one of their kinetochores?
All of these choices are correct.
Which are the functions of cyclins?
Cyclins activate kinases that regulate passage of cell cycle checkpoints.
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.
Which statement regarding tumor suppressors are true?
Mutations affecting tumor suppressors can contribute to the development of cancers.
Why are the X and Y chromosomes not considered homologous?
They do not carry the same set of genes.
How does meiosis generate genetic diversity?
both crossing over at prophase I and random alignment of homologs at metaphase I
A protein that has regular up-and-down pattern of abundance during the cell cycle and that triggers progress of the cell cycle by activating kinases is called a:
cyclin.
The division of the cell's cytoplasm in a eukaryotic cell is known as:
cytokinesis.
During meiosis I:
diploid cells become haploid.
Nondisjunction can only occur in the sex chromosomes and not the autosomes.
false
In mammals, females have two copies of the X chromosome, whereas males have only one copy. Dosage compensation (equalization of the numbers of each gene) is accomplished in mammals by:
females randomly inactivating one of the X chromosome in all cells.