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Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

a) They are species specific
b) They always lead to the same cellular response
c) They amplify the original signal manyfold
d) They counter the harmful effects of phosphates
e) The number of molecules used is small and fixed

c) They amplify the original signal manyfold

Binding of a signaling molecule to which type of receptor leads directly to a change in the distributin of ions on opposite sides of the membrane?

a) Receptor tyrosine kinase
b) G protein-coupled receptor
c) Phosphorylated receptor tyrosine kinase dimer
d) Ligand-gated ion channel
e) Intracellular receptor

d) ligand-gated ion channel

The activation of receptor tyrosine kinases is characterized by

a) Dimerization and phosphorylation
b) IP3 binding
c) A phosphorylation cascade
d) GTP hydrolysis
e) Channel protein shape change

a) dimerization and phosphorylation

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine effect on liver cells?

a) Enzymatic activity was proportional to the amount of calcium added to a cell-free extract
b) Receptor studies indicated that epinephrine was a ligand
c) Glycogen breakdown was observed only when epinephrine was administered to intact cells
d) Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined
e) Epinephrine was known to have different effects on different types of cells

c) glycogen breakdown was observed only when epinephrine was administered to intact cells

Protein phosphorylation is commonly involved with all of the following except

a) Regulation of transcription by extracellular signaling molecules
b) Enzyme activation
c) Activation of G protein-coupled receptors
d) Activation of receptor tyrosine kinases
e) Activation of protein kinase molecules

c) activation of G protein-coupled receptors

Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because

a) Only target cells retain the appropriate DNA segments
b) Intracellular receptors are present only in target cells
c) Most cells lack the Y chromosome required
d) Only target cells possess the cytosolic enzymes that transduce the testosterone
e) Only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor

b) intracellular receptors are present only in target cells

Consider this pathway: epinephrine --> G protein-coupled receptor --> G protein --> adenylyl cyclase --> cAMP. Identify the second messenger.

a) cAMP
b) G protein
c) GTP
d) Adenylyl cyclase
e) G protein-coupled receptor

a) cAMP

Apoptosis involves all but the following:

a) Fragmentation of the DNA
b) Cell-signaling pathways
c) Activation of cellular enzymes
d) Lysis of the cell
e) Digestion of cellular contents by scavenger cells

d) lysis of the cell

Through a microscope, you can see a cell plate beginning to devleop across the middle of a cell and nuclei re-forming on either side of the cell plate. This cell is most likely

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

b) a plant cell in the process of cytokinesis

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to _____________________

a) Disruption of mitotic spindle formation
b) Inhibition of regulatory protein phosphorylation
c) Suppression of cyclin production
d) Myosin denaturation and inhibition of cleavage furrow formation
e) Inhibition of DNA synthesis

a) disruption of mitotic spindle formation

One difference between cancer cells and normal cells is that cancer cells ____________________________

a) Are unable to synthesize DNA
b) Are arrested at the S 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 always in the M phase of the cell cycle

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

The decline of MPF activity at the end of mitosis is due to _____________

a) The destruction of the protein kinase Cdk
b) Decreased synthesis of cyclin
c) The degradation of cyclin
d) Synthesis of DNA
e) An increase in the cell's volume-to-genome ratior

c) the degradation of cyclin

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?

a) Spindle formation
b) Spindle attachment to kinetochores
c) DNA synthesis
d) Cell elongation during anaphase
e) Cleavage furrow formation

e) Cleavage-furrow formation

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in _________

a) Cells with more than one nucleus
b) Cells that are usually small
c) Cells lacking nuclei
d) Destruction of chromosomes
e) Cell cycles lacking an S phase

a) cells with more than one nucleus

Which of the following does not occur during mitosis?

a) Condensation of the chromosomes
b) Replication of the DNA
c) Separation of sister chromatids
d) Spindle formation
e) Separation of the spindle poles

b) replication of the DNA

A human cell containing 22 autosomes and a Y chromosome is ______

a) A sperm
b) An egg
c) A zygote
d) A somatic cell of a male
e) A somatic cell of a female

a) a sperm

Which life cycle stage is found in plants but not animals?

a) Gamete
b) Zygote
c) Multicellular diploid
d) Multicellular haploid
e) Unicellular diploid

d) multicellular haploid

Homologous chromosomes move toward opposite poles of a dividing cell during _____

a) Mitosis
b) Meiosis I
c) Meiosis II
d) Fertilization
e) Binary Fission

b) meiosis I

Meiosis II is similar to mitosis in that _______

a) Sister chromatids separate during anaphase
b) DNA replicates before the division
c) The daughter cells are diploid
d) Homologous chromosomes synapse
e) The chromosomes number is reduced

a) sister chromatids separate during anaphase

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 a metaphase of meiosis I would be ______

a) 0.25x
b) 0.5x
c) x
d) 2x
e) 4x

d) 2x

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) 0.25x
b) 0.5x
c) x
d) 2x
e) 4x

c) x

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=8)

a) 2
b) 4
c) 8
d) 16
e) 32

d) 16

Molecules can pass between adjacent cells through openings between cytoplasms at _____________

a) Cell junctions
b) Cell-cell recognition
c) Paracrine signaling

a) cell junctions

Receptors in the plasma membrane ____________________________________

a) Transmit info from outside the cell into the cell
b) Transmit info from inside the cell out of the cell
c) Receive information through brain generated waves
d) Receive nutrients from extra-cellular fluid

a) transmit info from outside the cell into the cell

The centromere is a region in which __________________

a) Chromatids remain attached to one another until anaphase
b) Metaphase chromosomes become aligned at the metaphase plate
c) Chromosomes are grouped duing telophase
d) The nucleus is located prior to mitosis
e) New spindle microtubules form at either end

a) chromatids remain attached to one another until anaphase

Which term describes centrioles beginning to move apart in animal cells?

a) Telophase
b) Anaphase
c) Prometaphase
d) Metaphase
e) Prophase

e) Prophase

Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants _______________________________________

a) The spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils
b) Sister chromatids are identical, but they differ from one another in animals
c) A cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage
d) Chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase
e) Spindle poles contain centrioles, whereas spindle poles in animals do not

c) a cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage

Chromosomes first become visible during which phase of mitosis?

a) Prometaphase
b) Telophase
c) Prophase
d) Metaphase
e) Anaphase

c) prophase

What is a genome?

a) The complete complement of an organism's genes
b) A specific set of polypeptides within each cell
c) A specialized polymer of four different kinds of monomers
d) A specific segment of DNA that is found within a prokaryotic chromosome
e) An ordered display of chromosomes arranged from largest to smallest

a) The complete complement of an organism's genes

A gene's location along a chromosome is known as whichof the following?

a) Allele
b) Sequence
c) Locus
d) Variant
e) Trait

c) Locus

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) G2
c) Prophase
d) Metaphase
e) Anaphase

a) G1

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