BIO CH4-6 SG
How do gap junctions differ from desmosomes? A gap junction can control the passage of materials between cells. A gap junction requires the use of ATP to open and close its channels. A gap junction provides communication between cells. A gap junction is a much larger space between cells. A gap junction bridges the space between cells.
A gap junction provides communication between cells
Suppose that acetylcholine binds its receptor on the surface of a muscle cell. What happens next? Tyrosine kinase is activated. Tyrosine is phosphorylated. G protein is activated. A sodium gate opens. A neurotransmitter crosses the synapse.
A sodium gate opens.
What can happen when GABA binds to its receptor? New signals are transmitted. Sodium ions enter the cell. Enzyme-linked receptors are activated. Muscle contraction is stimulated. Neural signaling is inhibited.
Neural signaling is inhibited.
Which molecule is least likely to cross a cellular membrane by simple diffusion? Oxygen Potassium ion Water Nitrogen Carbon dioxide
Potassium ion
What process halts the net movement of water from a hypotonic solution into a plant's cells and often provides the structural support to many plants? Dynamic equilibrium Plasmolysis Osmotic pressure Facilitated diffusion Turgor pressure
Turgor pressure
Which is a major group of enzyme-linked receptors? G proteins Ion channels Adenylyl cyclases Tyrosine kinases Phospholipases
Tyrosine kinases
Adenylyl cyclase catalyzes the reaction in which a protein is phosphorylated. GTP is converted to GDP. ATP is converted to cAMP.t! calcium ions bind calmodulin. PIP2 is split.
ATP is converted to cAMP.
The cis face of the Golgi complex is most directly involved in which process? Catalyzing the efficient folding of proteins Synthesizing proteins Accepting vesicles from the ER Transporting molecules out of the Golgi Packaging molecules in vesicles
Accepting vesicles from the ER
During signal transduction of a G protein, the first messenger binds to the receptor, and the G protein is activated. What happens next? Formation of cAMP Cellular response Phosphorylation of the G protein Activation of adenylyl cyclase Activation of protein kinase
Activation of adenylyl cyclase
What type of cellular junction cements cells together that use cadherins as a belt around each cell? Tight junctions Plasmodesmata Desmosomes Adhering junctions Gap junctions
Adhering junctions
In the IP3 pathway, what is the function of IP3? Activates protein kinase C Phosphorylates a protein You Answered Activates adenylyl cyclase Activates phospholipase C Binds calcium channels in the ER
Binds calcium channels in the ER
What happens when Ras proteins become stuck in their "on" state? There is an increase in protein synthesis. Cellular responses are slowed down. Additional ions are catalyzed. Ligand-gated channels close off the membrane. There is unregulated cell division.
Correct Answer There is unregulated cell division.
Which is an example of a second messenger? An ion channel Protein kinase A Cyclic AMP GABA Insulin
Cyclic AMP
Name the part of the cell outside the nucleus. Flagella Ribosomes Nucleoplasm Cytoplasm Nuclear pores
Cytoplasm
What activates protein kinase C? IP3 Calcium ions cAMP DAG PIP2
DAG
Where are hormones produced in animals? Exocrine glands Endocrine glands Neuron cells Blood cells Skin cells
Endocrine glands
Where are calcium ions stored before a signaling pathway releases them into the cytosol? Endoplasmic reticulum Ribosome Plasma membrane Nucleus Lysosome
Endoplasmic reticulum
Biological membranes are one-dimensional fluids. True False
False
Cotransport systems directly provide energy for active transport of solutes. True False
False
G protein-linked receptors are transmembrane proteins with a binding site for a signaling molecule outside the cell and a neuron component inside the cell. True False
False
In cell membranes, cholesterol and glycoproteins are exposed to the extracellular surface for cell recognition and adhesion to other cells. True False
False
When food is abundant, the cellular slime mold Dictyostelium secretes cAMP into the environment to signal the formation of a multicellular slug-shaped colony. True False
False
In the phospholipase C signal transduction pathway, which pair of second messengers is produced? Phospholipase C and protein kinase A PIP2 and IP3 cAMP and IP3 IP3 and DAG Phospholipase C and G protein
IP3 and DAG
In the phospholipase C signal transduction pathway, which pair of second messengers is produced? Phospholipase C and protein kinase A PIP2 and IP3 cAMP and IP3 IP3 and DAG Phospholipase C and G protein
IP3 and DAG
What type of protein can transduce a signal in two directions? Integrins Phosphorylated proteins G proteins Scaffold proteins Ras proteins
Integrins
Why can cholesterol act as a "fluidity buffer" in cell membranes? It is slightly hydrophobic because of the presence of one hydroxyl group. It is slightly amphipathic because of the presence of one carboxyl group. It is slightly hydrophobic because of the presence of one carboxyl group. It is slightly hydrophilic because of the presence of one hydrocarbon group. It is slightly amphipathic because of the presence of one hydroxyl group
It is slightly amphipathic because of the presence of one hydroxyl group
Which proteins are located on the inner or outer surface of the plasma membrane, usually bound to exposed regions of integral proteins by noncovalent interactions? Peripheral membrane proteins Integral membrane proteins Transmembrane proteins Plasma membrane proteins Biological membrane proteins
Peripheral membrane proteins
What method does a human white blood cell employ to engulf a bacterial cell? Exocytosis Pinocytosis Phagocytosis Osmosis Facilitated diffusion
Phagocytosis
If a bacterial toxin destroys ribosomes, what cellular activity will be affected first? Active transport Energy storage DNA synthesis Protein synthesis Movement
Protein synthesis
Which is a part of a signal transduction pathway that enables vision in dim light in vertebrates? Rhodopsin Brassinosteroids Histamine Acetylcholine Phosphorylation
Rhodopsin
What is the process in which one activated receptor can give rise to thousands of final products? Signal transcription Signal transmission Signal termination Signal amplification Signal transduction
Signal amplification
What type of molecule can rapidly cross a plasma membrane? Large, polar molecules Small, hydrophilic molecules Large, hydrophilic molecules Small, hydrophobic molecules Small, polar molecules
Small, hydrophobic molecules
What type of cells must receive, relay, and respond to the information signaled? GABA Integrins Neurotransmitters Local regulators Target cells
Target cells
In cells that are constantly involved in secretion, an equivalent amount of membrane must be returned to the interior of the cell for each vesicle that fuses with the plasma membrane; if this does not occur, then what would happen? The cell surface will keep expanding. The surface area would remain constant. The ratio of cell surface would decrease, compared to cell volume. The cell surface would shrivel. The number of membrane receptor proteins would decrease.
The cell surface will keep expanding.
Under which of the following situations would receptor downregulation most likely occur? The number of G proteins is too high. You Answered The number of receptors in the plasma membrane is too low. The concentration of a hormone is too high. The cell is unable to manufacture cyclic AMP. The concentration of a neurotransmitter is too low.
The concentration of a hormone is too high.
In the cAMP signal transduction pathway, a protein kinase is activated. What happens next? cAMP is converted to ATP. Adenylyl cyclase is activated. GDP is replaced by GTP. G protein is activated. The protein kinase activates a cellular response.
The protein kinase activates a cellular response.
Although glucose molecules constantly diffuse into a red blood cell along their concentration gradient, equilibrium is never reached and a steep concentration gradient is continually maintained. What causes this? The very fast turnover rate of glucose metabolism The continuous excretion of glucose from other parts of the cell The active transport of glucose The rapid addition of a phosphate to the glucose molecules The ability of the cell to engulf glucose by pinocytosis
The rapid addition of a phosphate to the glucose molecules
Which statement about lipid bilayers is false? They are self-sealing. They resist forming free ends. They can fuse with other bilayers. They spontaneously form closed vesicles. They are inflexible.
They are inflexible.
Which of the following is not a property of membranes? They inhibit the passage of materials. They serve as surfaces for chemical reactions. They adhere to and communicate with other cells. They divide the cell into compartments. They transmit signals between the environment and the interior of the cell
They inhibit the passage of materials.
Almost every vertebrate cell has a primary cilium, a single cilium on the cell surface that serves as a cellular antenna. True False
True
In animal cells, the main microtubule organizing center (or centrosome) is important in cell division. True False
True
The gas ethylene is a plant hormone that regulates a variety of processes, including seed germination and ripening of fruit. True False
True
The peripheral membrane proteins can be easily removed without disrupting the bilayer structure of the membrane. True False
True
While testing an experimental drip on a vertebrate cell, you notice that the cell cortex becomes more fluid and the cell loses its ability to move. Despite this, you determine that cell strength is maintained. Based on these observations, you correctly conclude that the drug most directly affects: β-tubulin actin filaments α-tubulin myosin intermediate filaments
actin filaments
eripheral proteins are linked to either surface of the plasma membrane by associating with fatty acids through hydrophobic interactions. covalent disulfide bonds. bonding to integral proteins through noncovalent interactions associating with glycoproteins on the inner membrane surface. embedding in only one side of the membrane.
bonding to integral proteins through noncovalent interactions.
The smooth ER is the primary site for the synthesis of phospholipids and cholesterol needed to make ____. cell membranes ATP DNA hormones ribosomes
cell membranes
In many cells, including almost all animal cells, the centrosome contains two structures called _________. flagella primary cilium mitotic spindle centrosome centrioles
centrioles
Which cellular structure is correctly matched to the role it plays within the cell? chloroplast−storage of enzymes plastids−structural support of the cell centrosome−cell division lysosome−powerhouse of the cell Golgi complex−production of energy
centrosome−cell division
Once ligand molecules bind to receptors in coated pits of a plasma membrane, the next step of receptor-mediated endocytosis would be coated vesicle forms by endocytosis. contents of secondary lysosome are digested and released into the cytosol. ligands separate from receptors, which are recycled. endosome fuses with primary lysosome, forming secondary lysosome.
coated vesicle forms by endocytosis.
During an infection, white blood cells travel to the infected site and phagocytize the pathogens. After phagocytosis, primary lysosomes fuse with the phagocytic vesicle to form a larger vesicle called a secondary lysosome. The purpose for this process is to: degrade the pathogens into components, which the cell recycles or uses as an energy source isolate the pathogens in an additional membrane to render them harmless coat the pathogens in lipids to tag it for neutralization degrade the pathogens with hydrolytic enzymes for later export from the cell export the intact secondary lysosome containing the pathogens from the cell
degrade the pathogens with hydrolytic enzymes for later export from the cell
Scaffold proteins ensure that signals are relayed ____. simultaneously efficiently slowly methodically inaccurately
efficiently
The outer membrane of the nuclear envelope is continuous with the membrane of the ____ and is usually covered with attached ribosomes. cell wall plasma membrane endoplasmic reticulum chromatin nucleolus
endoplasmic reticulum
Insulin stimulates cells to take in glucose by facilitated diffusion, so the down regulation of insulin receptors increases the ability of cells to take in glucose. __________________ True False
false
Peroxisomes are found in large numbers in cells that synthesize, store, and degrade lipids, and one of their functions is to break down protein molecules. True False
false
A basal body anchors what part of a cell? flagellum centriole lysosome thylakoid ribosome
flagellum
Which of the following is necessary for a cell to maintain its function and growth? food sugar sunlight blood milk
food
What protects a cell and may help keep other cells at a distance?glycocalyx cell wall microfilaments extracellular matrix
glycocalyx
Fluid that has a higher osmotic pressure than a cell is called ___________. hypertonic turgor pressure isotonic plasmolysis hypotonic
hypertonic
Intermediate filaments are most closely associated with which of the following? keratins actin microvilli pseudopodia myosin
keratins
A molecule that binds specifically to a receptor is called a ______________. endosome ligand clathrin low-density lipoprotein macrophage
ligand
Plants lack organ systems for disposing of toxic metabolic waste products. Their cells' vacuoles are similar to which animal cell organelle? mitochondria chloroplasts endoplasmic reticulum lysosomes nucleolus
lysosomes
What is found between the primary walls of adjacent cells which cause them to tightly adhere to one another? secondary cell wall intermediate filaments middle lamella cytosol collagen
middle lamella
Which two organelles are responsible for converting energy into forms that can be used by cells? ribosomes and chloroplasts lysosomes and chloroplasts mitochondria and lysosomes mitochondria and peroxisomes mitochondria and chloroplasts
mitochondria and chloroplasts
A cell is surrounded by which distinctive surface membrane? peripheral membrane integral membrane biological membrane trans membrane plasma membrane
plasma membrane
What is a characteristic found in both prokaryotic and eukaryotic cells? nucleoplasm plasma membrane nucleus mitochondria chloroplast
plasma membrane
Choanoflagellates are important in the study of cell communication evolution because choanoflagellates have G proteins different from those in prokaryotes. signal transduction pathways unlike those in other bacteria. protein kinases similar to those in animals. signal transduction pathways that interfere with the cells they infect. signaling molecules similar to those of other protists.
protein kinases similar to those in animals.
If the cells are physically close to one another, a signaling molecule on one cell may combine with a _________ on another cell. membrane peripheral membrane protein ligand vacuole receptor
receptor
What does the nucleolus, within the nucleus, synthesize? genes DNA hormones messenger RNA ribosomal RNA
ribosomal RNA
The accompanying image is the product of which type of microscope? (black and white cells thing) confocal fluorescence microscope scanning electron microscope Nomarski differential interference microscope transmission electron microscope phase-contrast light microscope
scanning electron microscope
Transmit information into cell
signal transduction receptors
Evidence that all living cells have a common origin is best illustrated by: the cell theory which states that the cell is the basic unit of life the basic similarities in cell structure and chemistry the fact that cells are the building blocks of the most complex plants the idea that cells are the smallest units that can carry out all life activities the fact that all new cells come from previously existing cells
the basic similarities in cell structure and chemistry
The term "fluid mosaic model" refers to the solubility of water in the membrane. the movement of surface proteins through the membrane. the method of substance transport across the membrane. the movement of lipids and integral proteins within the lipid bilayer. the diffusion of lipid-soluble substances across the lipid bilayer.
the movement of lipids and integral proteins within the lipid bilayer.
Carrier proteins are also called ______. transporters aquaporins passive transport pores active transport
transporters
The hydrolysis of GTP to GDP deactivates the ____. cAMP Ras protein G protein protein kinase pathway ligand-gated channel
G protein
What does an ABC transporter use to move larger ions and molecules across the cell membrane? Tunnels ATP Porins Signals Water
ATP
Which technique is used to separate different part of cells so that they can be studied by both physical and chemical methods? Chemical separation techniques Object separation techniques Cell fractionation Physical separation techniques Biochemical techniques
Cell fractionation
A receptor on the cell surface usually has several domains. What is the function of the external domain? It transmits the signal to the inside of the cell. It is the docking site for a signaling molecule. It holds the receptor within the membrane. It functions as an enzyme. It attaches the receptor to the DNA.
It is the docking site for a signaling molecule.
Mutations to ABC transporter genes contribute to cystic fibrosis. True False
True
Which statement about Ras proteins is false? They are activated by tyrosine kinase receptors. They are active when bound to GTP. They include MAP kinases. They are G proteins. They are inactivated when phosphorylated
They are inactivated when phosphorylated
LDL cholesterol is taken into the cell by receptor-mediated endocytosis. True False
True
What are the colors of an electron micrograph? black and white white and orange white and red black and red
black and white
Plasmodesmata of plant cells are functionally equivalent to the ____ of animal cells. tight junctions vesicles anchoring junctions gap junctions cell surface receptors
gap junctions
Anchor cell to extracellular matrix
integrins