question

receptor molecule

answer

b

question

A signal transduction pathway is initiated when a _____ binds to a receptor.

answer

signal molecule

question

which is a signal molecule

answer

a

question

A signal molecule is also known as a(n) _____.

answer

ligand

question

Part complete Which of these is the second of the three stages of cell signaling?

answer

transduction

question

Which of these extracellular signal molecules could diffuse through a plasma membrane and bind to an intracellular receptor?

answer

estrogen

question

A(n) _____ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off.

answer

steriod

question

Thyroid hormones bind to _____ receptors.

answer

intracellular

question

Part complete What role does a transcription factor play in a signal transduction pathway?

answer

By binding to DNA it triggers the transcription of a specific gene.

question

A signal transduction pathway is initiated when a _____ binds to a receptor.

answer

signal molecule

question

Which of these acts as a second messenger?

answer

cyclic AMP

question

Calcium ions that act as second messengers are stored in _____.

answer

endoplasmic reticula

question

_____ catalyzes the production of _____, which then opens an ion channel that releases _____ into the cell's cytoplasm.

answer

Phospholipase C ... IP3 .... Ca2+

question

a protein kinase activating many other protein kinases is an example of _____.

answer

amplification

question

The cleavage of glycogen by glycogen phosphorylase releases _____.

answer

glucose-1-phosphate

question

Epinephrine acts as a signal molecule that attaches to _____ proteins

answer

G-protein-linked receptor

question

Which of these is activated by calcium ions?

answer

calmodulin

question

Which of these is NOT correct?

answer

Cyclic AMP binds to calmodulin.

question

A toxin that inhibits the production of GTP would interfere with the function of a signal transduction pathway that is initiated by the binding of a signal molecule to _____ receptors.

answer

G-protein-linked

question

During _____ both the contents of the nucleus and the cytoplasm are divided.

answer

the mitotic phase

question

during _____ the cell grows and replicates both its organelles and its chromosomes.

answer

interphase

question

Nucleoli are present during ____

answer

interphase

question

Cytokinesis often, but not always, accompanies _____.

answer

telophase

question

Chromosomes become visible during _____.

answer

prophase

question

Centromeres divide and sister chromatids become full-fledged chromosomes during _____.

answer

anaphase

question

Spindle fibers attach to kinetochores during _____.

answer

prometaphase

question

During prophase a homologous pair of chromosomes consists of _____.

answer

two chromosomes and four chromatids

question

Which of these is NOT a carcinogen?

answer

all of the above are carcinogens

question

_____ is a carcinogen that promotes colon cancer.

answer

fat

question

prophase

answer

Cohesins join sister chromatids of duplicated chromosome. Tubulins assemble into spindle microtubules

question

prometaphase

answer

Microtubules attach to kinetochores.

question

metphase

answer

Kinetochores are motionless in relation to poles of cell.

question

anaphase

answer

Cohesins break down. Kinetochores move toward poles of cell.

question

telophase

answer

Spindle microtubules disassemble.

question

During prophase, the microtubules of the mitotic spindle

answer

lengthen

question

during anaphase, the nonkinetochore microtubules ________ and move past each other, and the kinetochore microtubules _________.

answer

lengthen, shorten

question

during telophase the nonkinetochore microtubles

answer

disassemble

question

DNA replication produces two identical DNA molecules, called ________________, which separate during mitosis.

answer

sister chromatid(s)

question

After chromosomes condense, the ____________ is the region where the identical DNA molecules are most tightly attached to each other.

answer

centromere(s)

question

During mitosis, microtubules attach to chromosomes at the ___________

answer

kinetochore(s).

question

in dividing cells, most of the cell's growth occurs during ____________

answer

interphase

question

The ___________ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.

answer

mitotic spindle(s)

question

during interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called

answer

chromatin

question

in most eukaryotes, division of the nucleus is followed by _____________ when the rest of the cell divides.

answer

cytokinesis,

question

The___________ are the organizing centers for microtubules involved in separating chromosomes during mitosis.

answer

centrosome(s)

question

are sister chromatids present in all or part of this phase

answer

G1: no S: yes G2: yes beginning of Mitosis: Yes end of mitosis: no

question

is the DNA condense in all or part of this phase

answer

G1: no S: no G2: no Beg. of M: yes End of M: yes

question

does the cell contain twice as much DNA in this phase as it did in the G1 phase

answer

G1: no S: yes G2: yes Beg of M: yes End of M: yes

question

bacteria mitosis only

answer

Chromosome separation begins at the origin of replication on DNA.

question

Eukaryotes Only mitosis

answer

Before separation, duplicated chromosomes condense.Nuclear envelope fragments, permitting chromosome separation.Two copies of the duplicated chromosome are attached at their centromeres before separating.

question

both Bacteria and Eukaryotes Mitosis

answer

Replicated chromosomes separate by attaching to some other structural feature of the cell.Chromosomes replicate before cell division.

question

Which of the following statements are true of cytokinesis in plant cells? Select the two that apply.

answer

Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate. The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells.

question

cells divide by constriction of a ring of protein

answer

Bacteria: T Animals: T Plants: T

question

The presence of a cell wall prevents the cell from dividing by constriction

answer

Bacteria: false Animals: false Plants: true

question

tubulin or tubulin-like molecules function in binary fission (in bacteria) or cytokinesis (in animals and plants)

answer

Bacteria: true Animals: false Plants: true

question

Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II?

answer

DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.

question

Human gametes are produced by _____.

answer

meiosis

question

Normal human gametes carry _____ chromosomes.

answer

23

question

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

answer

16

question

Meiosis I produces _____ cells, each of which is _____.

answer

two ... haploid

question

Meiosis II typically produces _____ cells, each of which is _____.

answer

four ... haploid

question

During _____ sister chromatids separate.

answer

anaphase II

question

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

answer

telophase I

question

Synapsis occurs during _____

answer

prophase I

question

Homologous chromosomes migrate to opposite poles during _____.

answer

anaphase 1

question

During _____ chromosomes align single file along the equator of a haploid cell.

answer

metaphase II

question

At the end of _____ and cytokinesis there are four haploid cells.

answer

telophase II

question

During _____ a spindle forms in a haploid cell.

answer

prophase II

question

Which processes lead to most genetic variation in sexually reproducing organisms

answer

independent assortment of chromosomes in meiosis crossing over random fertilization

question

If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.

answer

There would be less genetic variation among gametes.

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