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44 Cards in this Set

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Which molecules do not normally cross the nuclear membrane?
DNA
the nuclear envelope is continuos with the Golgi apparatus. True or false?
False
true or false? large proteins containing a nuclear localization signal bind to the nuclear pore and enter the nucleus without any expenditure of energy
False
a small protein (molecular weight = 25,000 daltons) is injected into a cell and observed in the nucleus a short time later. what type of transport has taken place?
passive transport
in experiments to test whether a protein can enter the nucleus, why would proteins be labeled with florescent molecules?
to make the proteins easy to see
Histones are nuclear proteins. two fusion proteins, each consisting of a different segment of histone linked to the same large cytoplasmic protein, are injected into a cell. a short time later, one fusion protein is found in the nucleus and the other is found in the cytoplasm? what conclusion can be drawn from these results? nucleoplasmin is a nuclear protein. this protein was divided into two segments and linked to the same large cytoplasmic protein, generating two fusion proteins. after injecting these fusion proteins into a cell, one of the proteins was found in the nucleus and the other in the cytoplasm. which of the following conclusion can be drawn from these results?
only one of the two fusion proteins possesses a nuclear localization signal. only one of the fusion proteins contains a nuclear localization signal.
pancreatic cells, which secrete a large amount of digestive enzymes, are labeled with radioactive leucine and then chased for several hours with nonradioactive leucine. photographic emulsions are prepared at different times during the chase. where would the black spots appear on an emulsion prepared 3 hours after the pulse?
exterior of the cell
what path does a protein in the secretory pathway take, starting from its site of synthesis?
rough er, golgi apparatus, secretory vesicles, plasma membrane
during a pulse-chase experiment, photographic emulsions were prepared at different times during the chase, and radioactive spots were detected at the following times and locations: 5 mintutes: rough ER. 10 minutes: golgi apparatus. 40 minutes: endosomes. 70 minutes: lysosomes. 140 minutes: lysosomes. what conclusion can be drawn?
the final destination of the proteins was lysosome
what scientific hypothesis can be tested by a pulse chase experiment?
movement of the molecules through a cell over time
true or false? proteins produced during the chase phase of a pulse chase experiment are labeled with radioactive material.
false
what is the first step in a pulse-chase experiment?
incubating cells with a labeled molecule
which event does not take place before the start of mitosis?
the nuclear envelope disintegrates
true or false? mitosis takes place during m phase, which is the longest phase of the cell cycle.
false
which term describes two recently replicated DNA strands that are joined together just before cell division?
sister chromatids
during which stage of mitosis are chromosomes lined up in the center of the cell?
metaphase
which stage of mitosis is characterized by the disintegration of mitotic spindles and the formation of two new nuclear membranes?
telophase
to which part of the centromere do mitotic spindle fibers attach during prometaphase?
kinetochore
during which substage of mitosis do sister chromatids break apart and start moving to opposite poles of the cell?
anaphase
what is the function of the S phase in the cell cycle?
synthesis of sister chromatids
the copying of chromosomes occurs during which phase in the cell cycle?
S phase
for the first several divisions of early frog embryos, cells proceed directly from the M phase to the S phase and back to the M phase without gaps. what is likely true about diving cells in early frog embryos?
the cells get smaller with each generation
True or false? The M phase is characterized by the replication and division of a cell's chromosomes.
Flase
If an organism normally has 34 chromosomes, how many molecules of DNA should there be in the G1 phase of the cell cycle?
34
Which of the following events would cause the cell cycle to arrest?
Poor nutrient conditions
What is the ploidy of organisms that have two sets of chromosomes?
2n
What information can not be obtained from an individual's karyotype?
The sequence of bases of a particular gene
True or false? A haploid organism has one pair of homologous chromosomes.
False
True or false? A haploid organism has one pair of homologous chromosomes.
False
If a cell has 24 chromosomes, how many chromosomes would each of its four daughter cells have after meiosis?
12
Which of the following statements about meiosis and mitosis is true?
Meiosis II is similar to mitosis in that sister chromatids of each chromosome separate.
Which structure is directly correlated with the production of genetic variability in the daughter cells produced during meiosis?
Chiasma
What is the composition of a tetrad at the beginning of prophase I?
One pair of homologous chromosomes
What is a nondisjunction?
An error in cell division that causes homologous chromosomes or sister chromatids to move to the same side of the dividing cell
When can nondisjunction occur? Choose the best answer.
All three answers are correct.
Which syndrome is characterized by the XO chromosome abnormality?
Turner syndrome
What kind of cell results when a diploid and a haploid gamete fuse during fertilization?
A triploid cell
Of the following chromosomal abnormalities, which type is most likely to be viable in humans?
Trisomy
If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n− 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred?
A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell.
If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n− 1 chromosomes, what type of error occurred?
A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell.
What kind of cell results when a diploid and a haploid gamete fuse during fertilization?
A triploid cell
Of the following chromosomal abnormalities, which type is most likely to be viable in humans?
Trisomy
If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n− 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred?
A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell.
If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n− 1 chromosomes, what type of error occurred?
A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell.