cells, cell membranes, & signal transduction (6,7,&11)

put the steps of the process of signal transduction in the order they occur: 1. a conformational change in the signal-receptor complex activates an enzyme. 2. protein kinases are activated. 3. a signal molecule binds to a receptor. 4. target proteins are phosphorylated. 5. second messenger molecules are released.

3, 1, 5, 2, 4

the nuclear lamina is an array of filaments on the inner side of the nuclear membrane. if a method were found that could cause the lamina to fall into disarray, what would you most likely expect to be the immediate consequence?

a change in the shape of the nucleus

if an adult person has a faulty version of the human analog to ced-4 of the nematode, which of the following is most likely to result?

a form of cancer in which there is insufficient apoptosis

not all intercellular signals require transduction. what signal would be processed without transduction?

a lipid - soluble signal

what is most likely true of a protein that cotransports glucose & sodium ions into the intestinal cells of an animal?

a substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.

protein phosphorylation is commonly involved with all of the following EXCEPT _____.

activation of g protein coupled receptors

in the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function

aggregation of bacteria that can cause cavities

what statements correctly describes the normal tonicity conditions for typical plant & animal cells? the animal cell is in _____

an isotonic solution, & the plant cell is in a hypotonic solution

what is NOT true? both chloroplast & mitochondria ______

are part of the end-membrane system

use this description to answer the following questions: a major group of g protein-coupled receptors contains seven transmembrane α helices. the amino end of the protein lies at the exterior of the plasma membrane. loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. the loop on the cytosol side between helices 5 & 6 is usually substantially longer than the others. where would you expect to find the carboxyl end?

at the cytosol surface

caffeine is an inhibitor of phosphodiesterase. therefore, the cells of a person who has recently consumed coffee would have increased levels of _____

camp

according to the fluid mosaic model of cell membranes, phospholipids ______

can move laterally along the plane of the membrane

the sodium potassium pump is called an electrogenic pump because it _______

contributes to the membrane potential

in some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. the gradients of the other ions are most likely accounted for by _____.

cotransport protiens

what is true during a typical camp-type signal transduction event?

denylyl cyclase is activated after the hormone binds to the cell & before phosphorylation of proteins occurs.

cells that are infected, damaged, or have reached the end of their functional life span often undergo "programmed cell death." this controlled cell suicide is called apoptosis. the appropriate description of this event on a cell's life cycle is :

during apoptosis, cellular agents chop up the dna & fragment the organelles & other cytoplasmic components of a cell

sutherland discovered that the signaling molecule epinephrine _____

elevates cytosolic concentrations of cyclic amp

the evolution of eukaryotic cells most likely involved ______

endosymbiosis of an aerobic bacterium in a larger host cell—the endosymbiont evolved into mitochondria

at puberty, an adolescent female body changes in both structure & function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. how can one hormone, such as estrogen, mediate so many effects?

estrogen binds to specific receptors inside many kinds of cells, each with different responses.

which of the following is a major difference between prokaryotic cells & eukaryotic cells?

eukaryotic cells have more intracellular organelles than prokaryotes.

which pair contains the 9 + 2 arrangement of microtubules, consisting of nine doublets of microtubules surrounding a pair of single microtubules?

flagella & motile cilia

ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through _____.

gap junctions

plasmodesmata in plant cells are most similar in function to what structure in animal cells?

gap junctions

which observation suggested to sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

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

where are proteins produced other than on ribosomes free in the cytosol or ribosomes attached to the ER?

in mitochondria

what is true of osmosis?

in osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

in a plant cell, dna may be found where

in the nucleus, mitochondria, & chloroplasts

the membrane of winter wheat are able to remain fluid when it is extremely cold by _______

increasing the percentage of unsaturated phospholipids in the membrane

scientists have found that extracellular matrix components may induce specific gene expression in embryonic tissues such as the liver and testes. for this to happen there must be direct communication between the extracellular matrix & the developing cells. which kind of transmembrane protein would most likely be involved in this kind of induction?

integrins

the extracellular matrix is thought to participate in the regulation of animal cell behavior by communicating information from the outside to the inside of the cell via which of the following?

integrins

what is a characteristic of a steroid hormone action

internal receptor binding

celery stalks that are immersed in fresh water for several hours become stiff. similar stalks left in a 0.15 M salt solution become limp. from this we can deduce that the fresh water_____.

is hypotonic & the salt solution is hypertonic to the cells of the celery stalks

a g protein receptor with gtp bound to it

is in its active state

if an animal cell suddenly lost the ability to produce gtp, what might happen to its signaling system?

it would not be able to activate & inactivate the g protein on the cytoplasmic side of the plasma membrane.

the advantage of light microscopy over electron microscopy is that ______

light microscopy allows one to view dynamic processes in living cells

apoptosis does not involve what

lysis of the cell

a bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in _____.

lysosomes

asbestos is a material that was once used extensively in construction. one risk from working in a building that contains asbestos is the development of asbestosis caused by the inhalation of asbestos fibers. cells will phagocytize asbestos, but are not able to degrade it. as a result, asbestos fibers accumulate in _____

lysosomes

the voltage across a membrane is called the ______

membrane potential

an unlabeled signaling diagram for steroid hormones: Fig. 11.8 p. 213, Campbell 8e. a steroid hormone, like estrogen, passes through the plasma membrane & binds to an intracellular protein as shown in the diagram below. this activates a signal-transduction pathway which results in an increased production of a specific protein. which of the following statements would explain what would occur as a result of the signal pathway represented by the diagram?

messsenger rna (m-rna) levels would increase in order to be translated into the protein required by the cell.

suppose a young boy is always tired and fatigued, suffering from a metabolic disease. what organelle is most likely involved in this disease?

mitochondria

the smallest cell structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope is a _____

mitochondrion

which organelle is the primary site of atp synthesis in eukaryotic cells

mitochondrion

in receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. where do they end up after endocytosis?

on the inside surface of the vesicle

what most accurately describes selective permeability?

only certain molecules can cross a membrane

what is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells?

paracrine signaling

what is NOT embedded in the hydrophobic portion of the lipid bilayer at all?

peripheral proteins

you have a planar bilayer with equal amounts of saturated and unsaturated phospholipids. after testing the permeability of this membrane to glucose, you increase the proportion of unsaturated phospholipids in the bilayer. what will happen to the membrane's permeability to glucose?

permeability to glucose will increase

an organism with a cell wall would most likely be unable to take in materials through _________

phagocytosis

the difference between pinocytosis & receptor mediated endocytosis is that ______

pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.

in what ways do plant hormones differ from hormones in animals

plant hormones most often travel in air as a gas

a cell with a predominance of free ribosomes is most likely ______

primarily producing proteins in the cytosol

the liver is involved in detoxification of many poisons and drugs. which structure is primarily involved in this process &, therefore, abundant in liver cells?

smooth er

what technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division?

standard light microscopy

the receptors for steroid hormones are located inside the cell instead of on the membrane surface like most other signal receptors. this is not a problem for steroids because _____.

steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane

if a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound _____.

that increases phosphodiesterate activity

what will happen to a red blood cell (rbc), which has an internal ion concentration of about 0.9 percent, if it is placed into a beaker of pure water?

the cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the rbc.

what describes the events of apoptosis?

the cell's dna & organelles become fragmented, the cell shrinks & forms blebs, & the cell's parts are packaged in vesicles that are digested by specialized cells.

viagra causes dilation of blood vessels and increased blood flow to the penis, facilitating erection. viagra acts by inhibiting _____.

the hydrolysis of cgmp to gmp

hv wilson worked with sponges to gain some insight into exactly what was responsible for holding adjacent cells together. he exposed two species of differently pigmented sponges to a chemical that disrupted the cell-cell interaction (cell junctions), & the cells of the sponges dissociated. wilson then mixed the cells of the two species & removed the chemical that caused the cells to dissociate. wilson found that the sponges reassembled into two separate species. the cells from one species did not interact or form associations with the cells of the other species. how do you explain the results of wilson's experiments?

the molecules responsible for cell-cell adhesion (cell junctions) differed between the two species of sponge

in a bacterium, we will find dna in _____

the nucleoid

a patient was involved a serious accident & lost a large quantity of blood. in an attempt to replenish body fluids, distilled water—equal to the volume of blood lost—is added to the blood directly via one of his veins. what will be the most probable result of this transfusion?

the patient's red blood cells will swell & possibly burst because the blood has become hypotonic compared to the cells.

what does it mean to say that a signal is transduced?

the physical form of the signal changes from one form to another

a newspaper ad for a local toy store indicates that an inexpensive toy microscope available for a small child is able to magnify specimens nearly as much as the more costly microscope available in your college lab. what is the primary reason for the price difference?

the toy microscope magnifies a good deal, but has low resolution & therefore poor quality images.

the cell walls of bacteria, fungi, & plant cells & the extracellular matrix of animal cells are all external to the plasma membrane. what is a characteristic common to all of these extracellular structures?

they are constructed of polymers that are synthesized in the cytoplasm & then transported out of the cell.

cells require what to form cilia or flagella?

tubulin

what organelle often takes up much of the volume of a plant cell?

vacuole