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