Chapter 4 Learning Curve
A mutation in a single gene in fruit flies results in a flightless phenotype. Which protein does this gene likely code for?
Actin
Which word could be used to describe the cytoplasm of a prokaryote?
Active
The process of photosynthesis is complex and relies on a cell's ability to establish chemical gradients during the conversion of light energy to chemical energy. Membranes provide a means for establishing such gradients by allowing a chemical substance to increase in concentration on one side of the membrane and not on the other. Some prokaryotes are photosynthetic, which suggests that even though they do not have specific organelle structures devoted to this process, they do have the basic membrane structure needed. What would enable a photosynthetic prokaryote to form chemical gradients?
An internal membrane system with embedded proteins
Though both plant and animal cells are classified as eukaryotic, they do have some differences. Of the following, which denotes a correct pairing of an animal and a plant cell structure with one or more overlapping functions?
Animal lysosome: plant vacuole
Which structure facilitates coordination of the ion movement that allows electrical signals to travel from one cardiac muscle cell to another?
Gap junctions
A moss cell is placed in culture with an unknown chemical substance. The cell appears able to "divide," because it is observed to grow and replicate its internal organelles and nuclei, but it does not form primary cell walls. It appears that the substance has affected the synthesis of the polysaccharides that compose the cell wall. Which organelle has possibly been targeted by the unknown chemical?
Golgi apparatus
Which of the following structures is (are) involved with anchoring cell structures within a cell?
Intermediate filaments
You discover what seems to be a new organelle that is smaller than a mitochondrion, but you need to do further testing to best determine its cellular function. What would be your best plan of action?
Isolate the organelle using cell fractionation and follow with further biochemical analysis
A pediatrician examines an infant with extremely fragile skin that blisters and flakes off easily with minor rubbing. The pediatrician orders genetic tests, which confirm that the infant has a mutation in a cytoskeletal protein important in maintaining connections between skin cells. Which protein is involved?
Keratin
Muscle cells need large amounts of calcium and ATP for contraction. Based on these requirements, you would expect that muscle cells would have an increased amount of what type of organelles (per unit volume)?
Mitochondria and smooth endoplasmic reticulum
Which statement correctly states how cell size affects the ability of the cell to take in and use nutrients from its environment?
The smaller the cell, the larger its surface area-to-volume ratio, which increases the rate of transport of nutrients into all parts of the cell
Which of the following statements about lysosomes is true?
They are the sites where autophagy occurs
What is the surface area-to-volume ratio of a cube-shaped cell with sides of 12 μm in length?
.5:1
Some cells require a certain kind of junction to ensure proper function. If tight junctions were replaced by desmosomes in cells lining the bladder, what might be the result?
Bladder cells content would move into the extracellular matrix
How are microfilaments and microtubules similar?
Both undergo dynamic shifts between assembly and disassembly.
Which statement represents one of the three central principles of cell theory?
New cells arise from existing cells
Which is the correct order of the series of structures that a macromolecule would encounter after being engulfed by a protist or animal cell and used as an energy source?
Phagosome, secondary lysosome, cytoplasm, mitochondria
Which type of cell structure is found in plants but not in animals?
Plastids
Which statement correctly compares prokaryotic cells and eukaryotic cells?
Prokaryotic cells tend to be smaller than eukaryotic cells, and examples of both cell types exist as single cells and as clusters
Which function is not carried out by the cell membrane?
Protein production
Which structure is not involved in the breakdown of macromolecules in most animal cells?
Ribosome
Which feature is shared by all prokaryotes?
Ribosomes
What key feature distinguishes eukaryotes from prokaryotes?
Separation of cell functions into different compartments
Suppose you could travel through a prokaryotic cell from the outside to the inside. Assuming that this cell contains a cell membrane, a cell wall, a capsule, and an outer membrane, in what order would you encounter each of the various layers?
Slimy polysaccharide layer, polysaccharide-rich phospholipid membrane, peptidoglycan layer, phospholipid bilayer
A mutant mouse cell line is examined. Under normal conditions this cell type excretes the hormone estrogen, but it is found that this particular line does not. Where should a researcher look to determine if the cells' defect is in hormone excretion or in hormone synthesis?
Smooth endoplasmic reticulum
Which of the following is a function of a plant cell vacuole?
Storage of toxic by-products and wastes; Support of the plant by assisting with turgor pressure; Containment of animal-attracting pigments that aid in pollination; Hydrolysis of seed proteins into food for the plant embryo
What is one role for extracellular structures, such as the plant cell wall or the animal extracellular matrix?
Support
You examine an unknown organism using transmission electron microscopy and discover that it has a double-layer outer membrane and ribosomes. You also find that it has inner membranes, but it is difficult to tell whether they are contiguous with the cell membrane. The presence of _______ on the organism would allow you to classify this as a prokaryote.
a capsule
One difference between plant and animal cells is that
animal cells lack a large central vacuole
A _______ can be seen with a light microscope.
bacterium
Biologists use blenders as tools for preparing biological systems for study. If a particular system is subjected to blender action and the contents poured into a test tube, as shown, what would be present in the test tube?
cellular contents free in solution, following cell membrane disruption
Movement of materials among plant cells is made possible by
channels called plasmodesmata
Ribosomes are
composed of protein and nucleic acid components
All of the following are specialized cell junctions except
connexins
An organism made up of many small cells as opposed to one large cell has all of the following advantages except
decreased diffusion between nucleoplasm and the cytoplasm
Lysosomes are important to many eukaryotic animal cells because they contain
digestive enzymes
If you wanted to stop the movement of a ciliated protist in culture, you could incubate it in a substance that inhibits
dynein
While examining the cell membrane of a bacterium using transmission electron microscopy, you discover the presence of a complex motor protein assembly. You do not find any evidence of a proper flagellum. You can conclude that the bacterium most likely has lost its ability to make
flagellin
A new protein with a molecular weight of 25,000 kilodaltons is discovered and found to reside in the cell nucleus. For this to happen, the protein must
have entered the nucleus through a nuclear pore
A transmembrane protein that plays a role in cell adhesion and cell structure is
integrin
A secondary lysosome
is a primary lysosome that has fused with a phagosome
Hair and some intermediate filaments are composed of
keratin
A structure is considered extracellular if it
lies outside the cell membrane
The membranes of the endoplasmic reticulum are continuous with the membranes of the
nuclear envelope
A prokaryotic cell does not typically have a _______ or _______.
nucleus; membrane-bound organelles
A benefit of electron microscopy is that it allows
observation of internal compartments and organelles.
Chloroplasts are a kind of
plastid
Components of the cytoskeleton can be linked to all of the following functions of eukaryotic cells except
protein synthesis
A function of the nucleolus is to
provide a space for ribosome assembly
Ribosomes are not found in or associated with
the Golgi apparatus
What does the nucleoid region of a prokaryotic cell contain?
the hereditary material that directs cell functions
Microtubules are made of
tubulin, and they are essential in chromosome movement during mitosis