Which of the following statements about the formation of polypeptides from amino acids is true?
A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.
Which statement correctly characterizes bound ribosomes?
Bound ribosomes generally synthesize membrane proteins and secretory proteins.
Cells of the pancreas will incorporate radioactively labeled amino acids into proteins. This "tagging" of newly synthesized proteins enables a researcher to track their location. In this case, we are tracking an enzyme secreted by pancreatic cells. What is its most likely pathway?
ER -> Golgi -> vesicles that fuse with the plasma membrane
Cyanide binds with at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide would be found within the
A primary objective of cell fractionation is to
separate the major organelles so that their particular functions can be determined.
In the fractionation of homogenized cells using centrifugation, the primary factor that determines whether a specific cellular component ends up in the supernatant or the pellet is
the size and weight of the component.
Which of the following correctly lists the order in which cellular components will be found in the pellet when homogenized cells are treated with increasingly rapid spins in a centrifuge?
nucleus, mitochondria, ribosomes
If a modern electron microscope (TEM) can resolve biological images to the nanometer level, as opposed to the best light microscope, this is due to which of the following?
Electron beams have much shorter wavelengths than visible light.
A biologist is studying kidney tubules in small mammals. She wants specifically to examine the juxtaposition of different types of cells in these structures. The cells in question can be distinguished by external shape, size, and 3-dimensional characteristics. Which would be the optimum method for her study?
scanning electron microscopy
What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?
The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.
The volume enclosed by the plasma membrane of plant cells is often much larger than the corresponding volume in animal cells. The most reasonable explanation for this observation is that
plant cells contain a large vacuole that reduces the volume of the cytoplasm.
In eukaryotic cells the first step in protein synthesis is the _____.
transferring of information from DNA to messenger RNA
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
Under which of the following conditions would you expect to find a cell with a predominance of free ribosomes?
a cell that is producing cytoplasmic enzymes
Which type of organelle is primarily involved in the synthesis of oils, phospholipids, and steroids?
smooth endoplasmic reticulum
Which structure is the site of the synthesis of proteins that may be exported from the cell?
In animal cells, hydrolytic enzymes are packaged to prevent general destruction of cellular components. Which of the following organelles functions in this compartmentalization?
Which of the following is a compartment that often takes up much of the volume of a plant cell?
Which of the following contains enzymes that transfer hydrogen from various substrates to oxygen?
A biologist ground up some plant leaf cells and then centrifuged the mixture to fractionate the organelles. Organelles in one of the heavier fractions could produce ATP in the light, while organelles in the lighter fraction could produce ATP in the dark. The heavier and lighter fractions are most likely to contain, respectively,
chloroplasts and mitochondria.
Cells can be described as having a cytoskeleton of internal structures that contribute to the shape, organization, and movement of the cell. Which of the following are part of the cytoskeleton?
_____ aid in the coordination of the activities of adjacent animal cells.
Gap (communicating) junctions
All of the following serve an important role in determining or maintaining the structure of plant cells. Which of the following are distinct from the others in their composition?
plant cell walls
Which of the following relationships between cell structures and their respective functions is correct?
cell wall: support, protection
When a potassium ion (K+) moves from the soil into the vacuole of a cell on the surface of a root, it must pass through several cellular structures. Which of the following correctly describes the order in which these structures will be encountered by the ion?
primary cell wall -> plasma membrane -> cytoplasm
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?
Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?
Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through