Test 3 Biology 103
protein pumps
Use ATP to transport Solutes
DAG is the second messenger.
G protein-linked receptor
In the accompanying figure, what is the form of cellular junction?
Gap Junctions
Plasmodesmata of plant cells are functionally equivalent to the ____ of animal cells.
Gap junctions
Proteins that are synthesized by ribosomes may be further modified within which organelle?
Golgi complex.
A receptor on the cell surface usually has several domains. What is the function of the external domain?
It is the docking site for a signaling molecule.
Typically, the gate of an ion channel remains closed until a(n) ____ binds to the receptor.
Ligand
Which one of these are the most convenient unit for measuring cells?
Micrometer
Use the figure to answer the corresponding question(s). What enzyme in the ER lumen catalyzes the efficient folding of proteins into proper conformations?
Molecular chaperones
What type of chemical compound diffuses across synapses?
Neurotransmitters
What is the passive movement of water along a concentration gradient?
Osmosis
What method does a human white blood cell employ to engulf a bacterial cell?
Phagocytosis
A cell is surrounded by which distinctive surface membrane?
Plasma membrane
What is a characteristic found in both prokaryotic and eukaryotic cells?
Plasma membrane
The process by which the plasma membrane separates from the cell wall is called ______.
Plasmolysis
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.
What is the purpose of the cristae of the inner membrane of mitochondria?
To increase surface area
LDL cholesterol is taken into the cell by receptor-mediated endocytosis.
True
Mutations to ABC transporter genes contribute to cystic fibrosis.
True
Scaffold proteins organize groups of intracellular signaling kinases into signaling complexes.
True
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
Plants lack organ systems for disposing of toxic metabolic waste products. Their cells' vacuoles are similar to which animal cell organelle?
lysosomes
DNA transcribes its information into what type of molecule?
mRNA
Use the figure to answer the corresponding question(s). The cellular structure indicated by the arrow in the accompanying figure is responsible for:
protein synthesis
Why is it advantageous for cells to be small?
A small cell has a small volume relative to surface area, which allows efficient transport through the plasma membrane.
Integrins
Anchor cell to extracellular matrix
Which list describes the correct sequence of events involved in cell signaling?
Signal transmission, reception, signal transduction, response
Which is a major group of enzyme-linked receptors?
Tyrosine kinases
Where are calcium ions stored before a signaling pathway releases them into the cytosol?
Endoplasmic reticulum
Phosphate comes from ATP.
Enzyme-linked receptor
Protein kinase sites are active.
Enzyme-linked receptor
Biological membranes are one-dimensional fluids.
False
Cotransport systems directly provide energy for active transport of solutes.
False
Enzymes called proteases in the ER lumen catalyze folding of proteins into proper conformations.
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.
False
Groups of eight connexin molecules cluster to form a cylinder that spans the plasma membrane.
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
In the sodium-potassium pump, sodium ion release causes the carrier protein to return to its original shape and releases two K+ ions into the cell.
False
What is the difference between a first messenger and a second messenger? Give an example of each.
First messenger is the ligand,second messenger is any small, non-protein components of a signal pathway.
membrane-bound enzymes
Catalyze reactions which take place within or along the membrane surface
A glycoprotein destined for secretion from the cell would move through the Golgi complex in which sequence?
Cis face to medial region to trans face
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.
Which is an example of a second messenger?
Cyclic AMP
Which statement about lipid bilayers is false?
they are inflexible
What is the primary function of mitochondria?
transformation of energy
The sodium-potassium pump is a carrier protein that maintains a(n) ____ gradient across the plasma membrane.
Electrochemical
The outer membrane of the nuclear envelope is continuous with the membrane of the ____ and is usually covered with attached ribosomes.
Endoplasmic reticulum
Which cellular mechanism ejects products, such as hormones, by the fusion of a vesicle with the plasma membrane?
Exocytosis
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
GDP is replaced with GTP.
G protein-linked receptor
Which local regulator is stored in cells of the immune system and released during an allergic reaction?
Histamine
What does the nucleolus, within the nucleus, synthesize?
Ribosomal RNA
The smooth ER is the primary site for the synthesis of phospholipids and cholesterol needed to make ____.
Ribosomes
What type of molecule can rapidly cross a plasma membrane?
Small, hydrophobic molecules
Choanoflagellates are important in the study of cell communication evolution because choanoflagellates have
Protein kinases similar to those in animals.
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.
Most intracellular receptors are what type of protein
Transcription factors
Almost every vertebrate cell has a primary cilium, a single cilium on the cell surface that serves as a cellular antenna.
True
Barbiturates and benzodiazepine drugs bind to GABA receptors to open chloride channels, inhibit neural impulse, and induce tranquility.
True
The many short appendages that a cell has are called cilia.
True
Peripheral proteins are linked to either surface of the plasma membrane by
bonding to integral proteins through noncovalent interactions.
The following are different types of neurotransmitters EXCEPT
cyclic adenosine.
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
Which of the following organelles plays an important role in apoptosis, or programmed cell death?
mitochondria
Which of the following serves as a framework for the orderly distribution of chromosomes during cell division?
mitotic spindle
The process of receiving an incoming signal is known as _______.
reception
What is the process in which one activated receptor can give rise to thousands of final products?
Signal amplification
What does an ABC transporter use to move larger ions and molecules across the cell membrane?
ATP
channels
Allows selective transport of ions or molecules
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
What happens during the cotransport of glucose and sodium ions?
Both D and E
What type of microscopy uses a laser to excite fluorophores in a thin "slice" through a cell?
Confocal microscopy
What activates protein kinase C?
DAG
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 with hydrolytic enzymes for later export from the cell
Sodium ions enter the cell.
Ion channel-linked receptor
A patient who has had a severe hemorrhage accidentally receives a large transfusion of distilled water directly into a major blood vessel. What effect will this have on the patient?
It will have serious, perhaps fatal consequences because the red blood cells could swell and burst.
What can happen when GABA binds to its receptor?
Neural signaling is inhibited.
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.
How are integral proteins unique in cell membranes?
They are firmly bound to the membrane.
signal transduction receptors
Transmit information into cell
In animal cells, the main microtubule organizing center (or centrosome) is important in cell division
True
Microfilaments are linked with one another and with other proteins by linker proteins.
True
The gas ethylene is a plant hormone that regulates a variety of processes, including seed germination and ripening of fruit.
True
Intermediate filaments are most closely associated with which of the following?
keratins
A molecule that binds specifically to a receptor is called a ______________.
ligand