Module 3
integrins
Anchor cell to extracellular matrix
Since sodium-potassium pumps transport sodium ions out of a cell and potassium ions into a cell, what type of carrier proteins are they?
Antiporters
membrane-bound enzymes
Catalyze reactions which take place within or along the membrane surface
Which technique is used to separate different part of cells so that they can be studied by both physical and chemical methods?
Cell fractionation
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. __________________
False
Kinesin transports organelles toward the minus end of a microtubule.
False
Which statement about the accompanying figures is true?
Figure B has a smaller surface area to volume ratio than Figure A.
The main signaling cascade for cell division and differentiation is the ____ cascade.
MAP kinase
What type of chemical compound diffuses across synapses?
Neurotransmitters
What is the passive movement of water along a concentration gradient?
Osmosis
Which statement about plasma membranes is false?
Plasma membranes prevent communication with other cells.
What is found between adjacent plant cells that allows signal molecules to pass quickly from one cell to another?
Plasmodesmata
If a bacterial toxin destroys ribosomes, what cellular activity will be affected first?
Protein synthesis
Which list describes the correct sequence of events involved in cell signaling?
Signal transmission, reception, signal transduction, response
You light a scented candle in the guest bathroom. Within a few minutes, you can smell the candle's scent throughout the hallway. What process is occurring?
Simple diffusion
Cells that secrete large amounts of glycoprotein have many Golgi stacks.
True
LDL cholesterol is taken into the cell by receptor-mediated endocytosis.
True
Microfilaments are linked with one another and with other proteins by linker proteins.
True
The force necessary to cause microtubules of cilia and flagella to slide alongside one another is provided through the action of ____ proteins, which derive the energy to perform their work directly from ____ molecules.
dynein; ATP
If the concentration of solutes in a cell is less than the concentration of solutes in the surrounding fluid, then the extracellular fluid is said to be
hypertonic
Which of the following pairs is correctly matched?
integrins−receptors
What is the microtubule arrangement of a flagellum or cilium?
9 + 2 arrangement
What is typically the result of receptor upregulation?
A hormone's signal is amplified.
Cotransport systems directly provide energy for active transport of solutes.
False
Plasmolysis occurs in plant cells when the soil or water contains low concentrations of salts or fertilizers.
False
The smooth ER is the primary site for the synthesis of proteins and cholesterol needed to make membranes.
False
The hydrolysis of GTP to GDP deactivates the ____.
G protein
Suppose that acetylcholine binds its receptor on the surface of a muscle cell. What happens next?
G protein is activated.
Which statement about G protein is false?
One subunit binds ATP.
What have studies of glucose transport in liposomes revealed?
The binding of glucose triggers a conformational change in the carrier protein.
Under which of the following situations would receptor downregulation most likely occur?
The concentration of a hormone is too high.
What are the colors of an electron micrograph?
black and white
What type of microscopy uses a laser to excite fluorophores in a thin "slice" through a cell?
confocal microscopy
The following are different types of neurotransmitters EXCEPT
cyclic adenosine.
The sodium-potassium pump is a carrier protein that maintains a(n) ____ gradient across the plasma membrane.
electrochemical
Plasmodesmata of plant cells are functionally equivalent to the ____ of animal cells.
gap junctions
What protects a cell and may help keep other cells at a distance?
glycocalyx
DNA transcribes its information into what type of molecule?
mRNA
Sodium-potassium pumps help to maintain a separation of charges across the plasma membrane, which is called the _________________.
membrane potential
Choanoflagellates are important in the study of cell communication evolution because choanoflagellates have
protein kinases similar to those in animals.
The process of receiving an incoming signal is known as _______.
reception
If the cells are physically close to one another, a signaling molecule on one cell may combine with a _________ on another cell.
receptor
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.
False
When a signaling molecule binds to a G protein-linked receptor, the ligand-receptor complex associates with GDP protein and causes GDP to be replaced by GTP. __________________
False
You conduct an experiment in which you inactivate Ras proteins in fibroblast cells. Which of the following is the most immediate consequence of this procedure?
The fibroblasts no longer synthesize DNA in response to growth factors.
The outer membrane of the nuclear envelope is continuous with the membrane of the ____ and is usually covered with attached ribosomes.
endoplasmic reticulum
A basal body anchors what part of a cell?
flagellum
Scaffold proteins organize groups of intracellular signaling kinases into signaling complexes.
True
The gas ethylene is a plant hormone that regulates a variety of processes, including seed germination and ripening of fruit.
True
The many short appendages that a cell has are called cilia.
True
The peripheral membrane proteins can be easily removed without disrupting the bilayer structure of the membrane.
True
Which is a major group of enzyme-linked receptors?
Tyrosine kinases
protein pumps
Use ATP to transport solutes
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:
actin filaments
The cis face of the Golgi complex is most directly involved in which process?
Accepting vesicles from the ER
Which molecule is a first messenger but not a second messenger?
Acetylcholine
Which neurotransmitter opens ligand-gated sodium channels?
Acetylcholine
channels
Allow selective transport of ions or molecules
What facilitates the rapid transport of water through the plasma membrane?
Aquaporins
In the IP3 pathway, what is the function of IP3?
Bind calcium channels in the ER
What happens during the cotransport of glucose and sodium ions?
Both D and E
How are hormones produced by endocrine glands typically transported to target cells?
By the blood
What activates protein kinase C?
DAG
Where are calcium ions stored before a signaling pathway releases them into the cytosol?
Endoplasmic reticulum
Which cellular mechanism ejects products, such as hormones, by the fusion of a vesicle with the plasma membrane?
Exocytosis
Groups of eight connexin molecules cluster to form a cylinder that spans the plasma membrane.
False
In cell membranes, cholesterol and glycoproteins are exposed to the extracellular surface for cell recognition and adhesion to other cells.
False
In scanning electron microscopy, an electron beam passes through a very thin slice of a specimen and then falls onto a photographic plate or a fluorescent screen.
False
What type of protein can transduce a signal in two directions?
Integrins
Why can cholesterol act as a "fluidity buffer" in cell membranes?
It is slightly amphipathic because of the presence of one hydroxyl group.
What can happen when GABA binds to its receptor?
Neural signaling is inhibited.
What transmits information electrically and chemically?
Neurons
A local regulator is a signaling molecule that diffuses through the interstitial fluid, the fluid surrounding the cells, and acts on nearby cells. What is this process?
Paracrine regulation
What method does a human white blood cell employ to engulf a bacterial cell?
Phagocytosis
Mammalian red blood cells contain which type of membrane?
Plasma membrane
What is the process in which one activated receptor can give rise to thousands of final products?
Signal amplification
What type of cells must receive, relay, and respond to the information signaled?
Target cells
Mutations to ABC transporter genes contribute to cystic fibrosis.
True
A person has a genetic disease that prevents the phospholipids in the plasma membrane of the white blood cells from freely fusing with the other membranes within the cell. How would this disease affect phagocytosis?
The phagocytic vacuole would not fuse with the lysosome.
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 rapid addition of a phosphate to the glucose molecules
What happens when Ras proteins become stuck in their "on" state?
There is unregulated cell division.
Refer to the accompanying figure. Which best describes the red blood cells in Fig. B?
These red blood cells have shrunk in response to a hypertonic external solution.
In the accompanying figure, what is the role of the structures between the membranes?
They allow the transport of small molecules and ions between adjacent cells.
What is the purpose of the cristae of the inner membrane of mitochondria?
To increase surface area
signal transduction receptors
Transmit information into cell
What is calmodulin?
calcium binding protein
Which cellular structure is correctly matched to the role it plays within the cell?
centrosome−cell division
DNA is associated with certain proteins, forming a complex called:
chromatin
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.
During enzyme-linked reception, signal molecules bind to two tyrosine kinase receptors. The receptor proteins move closer together in the plasma membrane and pair, forming a(n) ____.
dimer
Which strategy is the most effective for larger cells to have an effective surface area to volume ratio?
having thin, finger-like projections
When the net movement of water in and out a cell is zero, that solution is said to be
isotonic
A molecule that binds specifically to a receptor is called a ______________.
ligand
Which of the following is a key component of the cytoskeleton?
microtubules
What is found between the primary walls of adjacent cells which cause them to tightly adhere to one another?
middle lamella
What enzyme in the ER lumen catalyzes the efficient folding of proteins into proper conformations?
molecular chaperones
Specialized structures within a living cell are known as ___________.
organelles
The outer part of a G protein-linked receptor binds to a(n) ____, and its inner part binds to a(n) ____.
signaling molecule; G protein
Evidence that all living cells have a common origin is best illustrated by:
the basic similarities in cell structure and chemistry
The role of ATP in the sodium-potassium pump is
to transfer Na+ to the outside of a cell.
What is the primary function of mitochondria?
transformation of energy
Carrier proteins are also called ______.
transporters