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