Chapter 11 Learning Curve
The second meiotic division resembles mitosis because:
- chromosomes decondense during telophase II.- sister chromatids are separated during anaphase II to become the chromosomes of the daughter cells.- microtubules attach from opposite directions to the centromere of each sister chromatid pair.- the daughter cells have the same number of chromosomes as the parent cells.
What would happen to the daughter cells if the G2 phase of the parent cell is shortened?
The cells would be smaller than normal.
Why are the X and Y chromosomes not considered homologous?
They do not carry the same set of genes.
What is the function of histone proteins?
to package DNA in eukaryotic chromosomes
A proto-oncogene is a "normal" gene that, if mutated, can become an oncogene and lead to a cell becoming cancerous.
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
An example of second-division nondisjunction is when sister chromatids fail to separate during anaphase of meiotic cell division.
ture
What protein forms the contractile ring during cytokinesis in animal cells?
actin
During what step in meiosis do homologous chromosomes separate?
anaphase 1
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
The process of cell division in a prokaryotic cell is called:
binary fission.
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
Non-sister chromatids are:
copies of homologs but not fully identical chromosomes.
In a person with the genotype XXY, we can tell that nondisjunction must have taken place in the mother and not the father.
false
Which of the following are part of the process of binary fission in prokaryotes?
formation of a new cell wall
A human cell with a total of 23 chromosomes is:
haploid
At which stage of the cell cycle could you see sister chromatids with a microscope?
m
Reproduction by mitotic cell division:
results in two daughter cells that are genetically identical.
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:
s phase
During meiosis I:
sister chromatids are not separated.
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.
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.
A cell that is not actively dividing is in what phase of the cell cycle?
G0
Which statement regarding the S cyclin-CDK complex is true?
It ensures that DNA is not replicated multiple times.
Which statement regarding the cell cycle is true?
It has three cell cycle checkpoints.It is regulated by cyclins and CDKs.Different levels of cyclins are observed at different cell cycle stages.It can be "paused" by the action of p53
How many chromosome pairs are there in a normal human genome?
23
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?
An intact cancer cell is necessary to cause cancer. A large protein may cause cancer. Cancer may be caused by bacteria.
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.
Would genetic recombination result if crossing over occurred between sister chromatids?
No, because sister chromatids are genetically identical or nearly identical.
Which of the following statements about viruses are true?
None of the other answer options is correct.
Crossing over occurs during which step in meiosis?
Prophase I
Replication of DNA in a eukaryote occurs during which phase of the cell cycle?
S phase
How must spindle microtubules attach to chromosomes during prometaphase of meiosis I?
Spindle microtubules from one pole must attach to both kinetochores in a pair of sister chromatids.
What important difference is there between meiosis in males and females? Refer to the figure shown. Click to view full size.
The division of cytoplasm differs between males and females.
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.