AP Bio Chapter 12-13

checkpoint

a control point in the cell cycle where stop and go-ahead signals can regulate the cycle

somatic cell

any cell in a multicellular organism except a sperm or egg or their precursors

cleavage

(1) The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane.

Transformation

1) The conversion of a normal animal cell to a cancerous cell. 2) A change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of a different species, transformation results in horizontal gene transfer.

growth factor

1) a protein that must be present in the extracellular environment for the growth and normal development of certain types of cells. 2) a local regulator that acts on nearby cells to stimulate cell proliferation and differentiation.

malignant tumor

A cancerous tumor containing cells that have significant genetic and cellular changes and are capable of invading and surviving in new sites. Malignant tumors can impair the functions of one or more organs.

chromosome

A cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. each chromosome consists of one very long DNA molecule and associated proteins. (A bacterial chromosome usually consists of a single circular DNA molecule and associated proteins. It is found in the nucleoid region, which isn't membrane bounded.)

cell plate

A membrane-bounded, flattened sac located at the midline of a dividing plant cell, inside which the new cell wall forms during cytokinesis.

G0 phase

A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly.

centromere

In a duplicated chromosome, the region on each sister chromatid where they are most closely attached to each other by proteins that bind to specific DNA sequences; this close attachment causes a constriction in the condensed chromosome. (An uncondensed, unduplicated chromosome has a single centromere, identified by its DNA sequence.)

MPF

Maturation-promoting factor (or M-phase-promoting factor); a protein complex required for a cell to progress from late interphase to mitosis. The active form consists of cyclin and a protein kinase.

cytokinesis

The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II.

interphase

The period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interphase often accounts for about 90% of the cell cycle.

cell division

The reproduction of cells.

G2 phase

The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.

metaphase

The third stage of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate.

cyclin

a cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulating the cell cycle

cell cycle control system

a cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinates key events in the cell cycle.

gamete

a haploid reproductive cell, such as an egg or sperm. gametes unite during sexual reproduction to produce a diploid zygote.

benign tumor

a mass of abnormal cells with specific genetic and cellular changes such that the cells are not capable of surviving at a new site and generally remain at the site of the tumor's origin.

binary fission

a method of asexual reproduction by division in half; in prokaryotes, binary fission does not involve mitosis, but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process

mitosis

a process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei.

cyclin-dependent kinases (Cdk)

a protein kinase that is active only when attached to a particular cyclin

aster

a radial array of short microtubules that extends from each centrosome toward the plasma membrane in an animal cell undergoing mitosis.

kinetochore

a structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle

centrosome

a structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. a centrosome has two centrioles

How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n 5 8)? a) 16 b) 8 c) 4 d) 2 e) 32

a) 16

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 a) G1. b) prophase. c) anaphase. d) metaphase. e) G2.

a) G1

"Cytokinesis" refers to _____. a) division of the cytoplasm b) movement of a cell from one place to another c) division of the nucleus d) reduction in the number of chromosomes e) division of the entire cell

a) division of the cytoplasm

Observations of cancer cells in culture support the hypothesis that cancer cells _____. a) do not exhibit density-dependent inhibition b) spend the majority of their time in the G0 phase c) exhibit anchorage dependence d) produce molecules that inhibit the growth factors required for cell division e) All of the listed responses are correct

a) do not exhibit density-dependent inhibition

Tissue culture experiments with PDGF demonstrate that without this substance _____. a) fibroblasts fail to divide b) cells divide in an uncontrolled fashion, confirming PDGF's role as a cell division inhibitor c) bacterial cells lose their resistance to antibiotics d) the various kinases, such as MPF, are unable to bind to cyclin e) animal cells are unable to attach to the substratum

a) fibroblasts fail to divide

At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell? a) metaphase b) prophase c) interphase d) telophase e) anaphase

a) metaphase

Which of the following processes does NOT occur in dividing bacteria? a) mitosis b) binary fission c) replication of DNA d) inward growth of the plasma membrane e) separation of the origins of replication

a) mitosis

Which life cycle stage is found in plants but not animals? a) multicellular haploid b) zygote c) unicellular diploid d) gamete e) multicellular diploid

a) multicellular haploid

In a human skin cell that is going through the cell cycle, when do the centrosomes separate? a) prophase b) S phase c) metaphase d) anaphase e) G2 phase

a) prophase

In telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in _____. a) prophase b) S phase c) anaphase d) interphase e) metaphase

a) prophase

If we continued to follow the cell lineage from question 5, then the DNA content of a single cell at metaphase of meiosis II would be a) x. b) 0.25x. c) 0.5x. d) 4x. e) 2x.

a) x.

mitotic spindle

an assemblage of microtubules and associated proteins that is involved in the movement of chromosomes during mitosis.

metaphase plate

an imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located.

cell cycle

an ordered sequence of events in the life of a cell, form its origin in the division of a parent cell until its own division into two. The eukaryotic cell cycle is composed of interphase and M phase.

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? a) 14 b) 0 c) 7 d) 28 e) None of the listed responses is correct.

b) 0

During what phase in the cell cycle would you find the most DNA per cell? a) S b) G2 c) S1 d) G1 e) prophase II

b) G2

The region of a chromosome holding the two double strands of replicated DNA together is called _____. a) a centriole b) a centromere c) chromatin d) an aster e) a chromatid

b) a centromere

During which stage of the cell cycle do sister chromatids separate? a) metaphase b) anaphase c) prophase d) G2 phase e) G1 phase

b) anaphase

The phase of mitosis during which the chromosomes move toward separate poles of the cell is _____. a) telophase b) anaphase c) prometaphase d) metaphase e) prophase

b) anaphase

The function of the mitotic cell cycle is to produce daughter cells that _____. a) have the same number of chromatids as the parent cell had chromosomes b) are genetically identical to the parent cell (assuming no mutation has occurred) c) have the same number of chromosomes as the parent cell but not the same genetic content d) have a random assortment of maternal and paternal chromosomes e) None of the listed responses is correct.

b) are genetically identical to the parent cell (assuming no mutation has occurred)

Chromatids are _____. a) the bacterial equivalent of eukaryotic chromosomes b) identical copies of each other if they are part of the same chromosome c) found only in aberrant chromosomes d) composed of RNA e) held together by the centrioles

b) identical copies of each other if they are part of the same chromosome

You would know a dividing cell was a plant cell rather than an animal cell if you saw that _____. a) it had formed a cleavage furrow b) it had formed a cell plate c) the nucleolus was visible during metaphase d) it had microtubules e) it had two pairs of centrioles during prophase

b) it had formed a cell plate

Homologous chromosomes move toward opposite poles of a dividing cell during a) meiosis II. b) meiosis I. c) mitosis. d) fertilization. e) binary fission.

b) meiosis I.

Which of the following represents a mismatch or incorrect description? a) metaphase: chromosomes line up on the equatorial plane b) metaphase: the nuclear envelope disappears c) prophase: chromosomes become more tightly coiled d) anaphase: there is movement of the chromosomes to the poles e) telophase: chromosomes become more extended

b) metaphase: the nuclear envelope disappears

Which of the following does not occur during mitosis? a) separation of sister chromatids b) replication of the DNA c) separation of the spindle poles d) condensation of the chromosomes e) spindle formation

b) replication of the DNA

Meiosis II is similar to mitosis in that a) homologous chromosomes synapse. b) sister chromatids separate during anaphase. c) the chromosome number is reduced. d) the daughter cells are diploid. e) DNA replicates before the division.

b) sister chromatids separate during anaphase.

DNA replication occurs in _____. a) metaphase of meiosis only b) the S phase of interphase in both somatic and reproductive cells c) the G1 phase of interphase in reproductive cells only d) prophase of both mitosis and meiosis e) the cytokinesis portion of the cell's life cycle

b) the S phase of interphase in both somatic and reproductive cells

The decline of MPF activity at the end of mitosis is due to a) decreased synthesis of Cdk. b) the degradation of cyclin. c) synthesis of DNA. d) the destruction of the protein kinase Cdk. e) the accumulation of cyclin.

b) the degradation of cyclin.

How many maternal chromosomes are present in a somatic human cell not engaged in cell division? a) 92 b) 46 c) 23 d) 184 e) None of the listed responses is correct.

c) 23

If a somatic human cell is just about to divide, it has _____ chromatids. a) There is insufficient information to answer the question. b) 46 c) 92 d) 23 e) 0

c) 92

A human cell containing 22 autosomes and a Y chromosome is a) a zygote. b) an egg. c) a sperm. d) a somatic cell of a male. e) a somatic cell of a female.

c) a sperm.

One difference between cancer cells and normal cells is that cancer cells a) are unable to synthesize DNA. b) are always in the M phase of the cell cycle. c) continue to divide even when they are tightly packed together. d) cannot function properly because they are affected by density-dependent inhibition. e) are arrested at the S phase of the cell cycle.

c) continue to divide even when they are tightly packed together.

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of micro-tubules, its effectiveness must be related to a) myosin denaturation and inhibition of cleavage furrow formation. b) inhibition of DNA synthesis. c) disruption of mitotic spindle formation. d) inhibition of regulatory protein phosphorylation. e) suppression of cyclin production.

c) disruption of mitotic spindle formation.

You would be unlikely to see which of the following human cells dividing? a) intestinal lining cell b) skin cell c) nerve cell d) cell from an embryo e) cancer cell

c) nerve cell

Following cytokinesis in an animal cell, how many centrioles does each new daughter cell possess? a) four b) zero c) two d) one e) eight

c) two

Down syndrome is characterized by cells having three copies of chromosome 21. As a cell in an individual with Down syndrome prepares to enter mitosis, how many chromatids would be present? a) 98 b) 46 c) 92 d) 94 e) 23

d) 94

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be a) x. b) 0.5x. c) 4x. d) 2x. e) 0.25x.

d) 2x.

How many genes are present in the human genome? a) 23 b) 46 c) hundreds d) tens of thousands e) a virtually infinite number

d) tens of thousands

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) a bacterial cell dividing. b) a plant cell in metaphase. c) an animal cell in the S phase of the cell cycle. d) a plant cell in the process of cytokinesis. e) an animal cell in the process of cytokinesis.

d) a plant cell in the process of cytokinesis.

A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in the cells doubled _____. a) during the M phase of the cell cycle b) between anaphase and telophase c) between the G2 phase and prophase d) between the G1 and G2 phases e) between prophase and anaphase

d) between the G1 and G2 phases

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in a) cells lacking nuclei. b) destruction of chromosomes. c) cell cycles lacking an S phase. d) cells with more than one nucleus. e) cells that are unusually small.

d) cells with more than one nucleus.

In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle? a) anaphase b) prophase c) the G1 phase d) cytokinesis e) metaphase

d) cytokinesis

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

d) dispersed in the nucleus as long strands of chromatin

Which of the following is involved in the binary fission of bacteria? a) formation of a cell plate b) formation of a spindle apparatus c) disintegration of the nuclear membrane d) distribution of a copy of the single parental chromosome to each daughter cell e) prophase, prometaphase, metaphase, anaphase, and telophase

d) distribution of a copy of the single parental chromosome to each daughter cell

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 contained 200 units of DNA. What would be the amount of DNA at G1 of the cell cycle in one of the grasshopper daughter cells? a) 200 units b) between 50 and 100 units c) 400 units d) 50 units e) 100 units

e) 100 units

If a cell contains 60 chromatids at the start of mitosis, how many chromosomes will be found in each daughter cell at the completion of the cell cycle? a) 15 b) 120 c) 60 d) 45 e) 30

e) 30

Which event or events occur during anaphase? a) identical chromatids move to opposite poles b) a spindle made of microtubules is present c) the centrioles are at opposite poles d) the centromeres divide e) All of the listed responses are correct.

e) All of the listed responses are correct.

Which of the following is false regarding sister chromatids? a) Sister chromatids are separated during mitosis. b) Sister chromatids are created when DNA is replicated. c) Sister chromatids form in the S-phase stage of the cell cycle. d) Sister chromatids are attached to one another at the centromere. e) Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.

e) Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.

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

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

When a cell in S phase is fused with a cell in G1, _____. a) the chromosomes of the original G1 nucleus condense in preparation for mitosis b) the original G1 cell will divide immediately c) the replication of DNA occurring in the original S nucleus is terminated d) the two nuclei fuse and further division is arrested e) DNA synthesis begins immediately in the original G1 nucleus

e) DNA synthesis begins immediately in the original G1 nucleus

A cell entering the cell cycle with 32 chromosomes will produce two daughter cells, each with _____. a) 16 chromosomes b) 64 pairs of chromosomes c) 32 pairs of chromosomes d) 64 chromosomes e) None of the listed responses is correct.

e) None of the listed responses is correct.

The person credited with first recognizing (in the 1860s) that living cells cannot arise spontaneously, but arise only from previously existing cells, is _____. a) Louis Pasteur b) Anton van Leeuwenhoek c) Robert Hooke d) Watson e) Rudolf Virchow

e) Rudolf Virchow

The complex of DNA and protein that makes up a eukaryotic chromosome is properly called _____. a) a centrosome b) a centromere c) a chromatid d) a chromoplast e) chromatin

e) chromatin

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B? a) cell elongation during anaphase b) spindle formation c) DNA synthesis d) spindle attachment to kinetochores e) cleavage furrow formation and cytokinesis

e) cleavage furrow formation and cytokinesis

Which of the following does NOT occur during mitosis? a) alignment of chromosomes along the cell's equator b) condensation of chromatin c) the movement of chromosomes to opposite poles d) separation of chromatids e) replication of chromosomes

e) replication of chromosomes

The centromere is a region in which _____. a) the new cell plate forms in telophase b) the chromosomes are connected to the cell plate in metaphase c) chromosomes become aligned during metaphase d) microtubules are fastened to the centrioles during anaphase e) sister chromatids are attached to one another in prophase

e) sister chromatids are attached to one another in prophase

Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope? a) interphase b) anaphase c) metaphase d) S phase e) telophase

e) telophase

One event occurring during prophase is _____. a) cytokinesis b) division of the centromere c) the alignment of chromosomes in a single plane d) the synthesis of a new nuclear envelope e) the beginning of the formation of a spindle apparatus

e) the beginning of the formation of a spindle apparatus

During binary fission in a bacterium _____. a) the two DNA molecules divide in half, forming four DNA fragments b) the two DNA molecules float free in the cell and are guided to daughter cells by a spindle-like apparatus c) the two DNA molecules break up into plasmids d) the two DNA molecules attach to the centrioles e) the origins of replication move apart

e) the origins of replication move apart

origin of replication

site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.

chromatin

the complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.

telophase

the fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun

cleavage furrow

the firs sign of cleavage in an animal cell; a shallow groove around the cell in the cell surface near the old metaphase plate.

G1 phase

the first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.

prophase

the first stage of mitosis, in which the chromatin condenses into discrete chromosomes visible with a light microscope, the mitotic spindle begins to form, and the nucleolus disappears but the nucleus remains intact.

anaphase

the fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell.

genome

the genetic material of an organism or virus; the complete complement of an organism's or virus's genes along with its noncoding nucleic acid sequences.

mitotic (M) phase

the phase of the cell cycle that includes mitosis and cytokinesis

density-dependent inhibition

the phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another

anchorage dependence

the requirement that a cell must be attached to a substratum in order to initiate cell division.

prometaphase

the second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes.

metastasis

the spread of cancer cells to locations distant from their original site.

S phase

the synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated

sister chromatids

two copies of a duplicated chromosome attached to each other by proteins at the centromere and, sometimes, along the arms. While joined, two sister chromatids make up one chromosome. Chromatids are eventually separated during mitosis or meiosis II.