Chapter 9: The Cell Cycle

Assume that you are dealing with a species in which the number of chromosomes in each somatic cell is 14. How many sister chromatids are present in the early telophase of mitosis? None of the listed responses is correct. 14 28 0 7

0 There are no sister cells in telophase

A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle each contained 200 units of DNA. What would be the amount of DNA at G1 of the cell cycle in a daughter cell of one of these cells? 100 units Between 50 and 100 units 400 units 50 units 200 units

100 units

When not engaged in the processes leading to cell division, how many chromosomes from your mother are present in the nucleus of each of your somatic cells? 184 46 92 None of the listed responses is correct. 23

23

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? 23 or 46, depending on the portion of prophase examined 46 or 92, depending on the portion of prophase examined 23 92 46

92

If a human somatic cell is in metaphase, it has __________ chromatids. There is insufficient information to answer the question. 46 92 23 0

92

Down syndrome is characterized by cells having three copies of chromosome 21. As a somatic cell in an individual with Down syndrome prepares to enter mitosis, how many chromatids would be present in the cell's nucleus? ANSWER 92 46 94 98 23

94

What is the difference between a benign tumor and a malignant tumor? Benign tumors arise by transformation; malignant tumors do not. Cells of benign tumors do not metastasize; those of malignant tumors do. Benign tumors do not arise by transformation; malignant tumors do. Benign tumors will not kill you; malignant tumors will. Cells of benign tumors metastasize; those of malignant tumors do not.

Cells of benign tumors do not metastasize; those of malignant tumors do.

The complex of DNA and protein that makes up a eukaryotic chromosome is properly called __________. ANSWER actin a chromatid a centromere a centrosome chromatin

Chromatin

The cleavage furrow forms during which stage of mitosis and cell division of an animal cell? ANSWER Metaphase Telophase Cytokinesis Prophase Anaphase

Cytokineses

Which of the following does not occur during mitosis? ANSWER Alignment of chromosomes along the cell's equatorial plane Movement of chromosomes toward opposite poles of the cell Duplication of chromosomes Separation of chromatids Condensation of chromatin

Duplication of chromosomes

. A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in __________. G2 metaphase prophase G1

G1

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? M G2 G1 S cytokinesis

G1

Which of the following correctly matches a phase of the cell cycle with its description? S: immediately precedes cell division M: duplication of DNA G2: cell division G1: follows cell division All of the listed responses are correctly matched

G1: follows cell division

The cell cycle control systems of cancer cells differ from those of normal cells. Select the best explanation for this fact. Cancer cells are immortal. Genetic changes alter the function of the cancer cell's protein products. Cancer cells divide excessively and invade other tissues.

Genetic changes alter the function of the cancer cell's protein products.

Sister chromatids are __________. ANSWER identical copies of a chromosome held together by the centrioles found only in aberrant chromosomes present throughout the cell cycle the bacterial equivalent of eukaryotic chromosomes

Identical copies of a chromosome

You would know a dividing cell was a plant cell rather than an animal cell if you saw that __________. ANSWER it had microtubules it had formed a cell plate it had formed a cleavage furrow it had two pairs of centrioles during prophase chromatin was condensed into chromosomes visible through a microscope

It had formed a cell plate

Which of the following represents a mismatch or incorrect description? Telophase: nuclei form Metaphase: chromosomes line up on the equatorial plane Metaphase: the nuclear envelope disappears Anaphase: there is movement of the chromosomes toward opposite poles of the cell Prophase: chromatin becomes more tightly coiled

Metaphase: the nuclear envelope disappears

Which of the following processes does not occur in dividing bacteria? ANSWER Inward growth of the plasma membrane Separation of the origins of replication Replication of DNA Binary fission Mitosis

Mitosis

You would be unlikely to see which of the following human cells dividing? ANSWER Cancer cell Embryonic cell Cell of the intestinal lining Skin cell Nerve cell

Nerve cells

Chromosomes become visible during _____. prophase anaphase interphase metaphase prometaphase

Prophase

In a human skin cell that is going through the cell cycle, when do the centrosomes separate? S phase Metaphase Anaphase Prophase G2 phase

Prophase

Which of the following is true of kinetochores? They are sites at which microtubules attach to chromosomes. They are the primary centromere structures that maintain the attachment of the sister chromatids prior to mitosis. They interdigitate at the cell's equator and then move apart, causing the cell to elongate. They are located at the center of the centrosome; their function is to organize tubulin into elongated bundles called spindle fibers. They attach to the ring of actin along the cytoplasmic surface of the plasma membrane, causing the actin to contract to form the cleavage furrow.

They are sites at which microtubules attach to chromosomes

What is true of all cancers? They are inherited. They have escaped normal cell cycle controls. They are caused by chemical carcinogens.

They have escaped normal cell cycle controls.

Why is it difficult to observe individual chromosomes with a light microscope during interphase? They have uncoiled to form long, thin strands. They leave the nucleus and are dispersed to other parts of the cell. The spindle must move them to the metaphase plate before they become visible. The DNA has not been replicated yet. Sister chromatids do not pair up until division starts.

They have uncoiled to form long, thin strands.

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely __________. a plant cell in metaphase a plant cell in the process of cytokinesis an animal cell in the process of cytokinesis a bacterial cell dividing

a plant cell in the process of cytokinesis

The function of mitosis and cytokinesis is to produce daughter cells that __________ have the same number of chromosomes as the parent cell but unique genetic content have a random assortment of maternal and paternal chromosomes are genetically identical to the parent cell None of the listed responses is correct. have the same number of chromatids as the parent cell had chromosomes

are genetically identical to the parent cell

The function of mitosis and cytokinesis is to produce daughter cells that __________. ANSWER have the same number of chromosomes as the parent cell but unique genetic content have a random assortment of maternal and paternal chromosomes are genetically identical to the parent cell None of the listed responses is correct. have the same number of chromatids as the parent cell had chromosomes

are genetically identical to the parent cell

A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in the cells doubled __________. between anaphase and telophase between prophase and anaphase between the G2 phase and prophase between the G1 and G2 phases during the M phase of the cell cycle

between the G1 and G2 phases

During interphase, the genetic material of a typical eukaryotic cell is __________. ANSWER dispersed in the nucleus as long strands of chromatin transported through the nuclear pores dispersed in the cytoplasm as long strands of chromatin attached to microtubule spindle fibers condensed, and the chromosomes are often visible under the light microscope

dispersed in the nucleus as long strands of chromatin

Cytokinesis refers to __________. ANSWER alignment of chromosomes movement of sister chromatids to opposite ends of the cell duplication of the cell's chromosomes division of the nucleus division of the cytoplasm

division of the cytoplasm

Observations of cancer cells in culture support the hypothesis that cancer cells __________. ANSWER exhibit anchorage dependence All of the listed responses are correct. spend the majority of their time in the G0 phase do not exhibit density-dependent inhibition produce molecules that inhibit the growth factors

do not exhibit density-dependent inhibition

Tissue culture experiments with PDGF demonstrate that without this substance __________. bacterial cells will not proliferate animal cells are unable to attach to the substratum various kinases are unable to bind to cyclin fibroblasts fail to divide cells divide in an uncontrolled fashion, confirming PDGF's role as a cell division inhibitor

fibroblasts fail to divide

During binary fission of a bacterium, __________. origins of replication move apart a small daughter cell buds from a large parent cell chromosomes are separated through attachment to a mitotic spindle genetic material is acquired from another bacterium the nuclear envelope fragments

origins of replication move apart

Spindle fibers attach to kinetochores during _____. telophase interphase metaphase prometaphase anaphase

prometaphase

One event occurring during prophase is __________. ANSWER the alignment of chromosomes in a single plane separation of sister chromatids the synthesis of a new nuclear envelope the beginning of the formation of a mitotic spindle cytokinesis

the beginning of the formation of a mitotic spindle