Chapter 6

Bacterial cells are prokaryotic. Unlike a typical eukaryotic cell they __________.

have no membrane-bounded organelles in their cytoplasm

A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________.

in the rough endoplasmic reticulum

The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized __________.

in the rough endoplasmic reticulum and in the Golgi apparatus

The endosymbiont theory explains the origins of __________.

mitochondria and chloroplasts

Microfilaments function in cell motility including __________.

muscle contraction, amoeboid movement, and cytoplasmic streaming in plants

The endoplasmic reticulum is part of the endomembrane system, which also includes the __________.

nuclear envelope, the Golgi apparatus, lysosomes, and vesicles

Observing a fluorescent micrograph cell with intermediate filaments would help you identify the cell as a __________.

human skin cell

The function of the rough endoplasmic reticulum (RER) is __________.

to synthesize proteins that are secreted as glycoproteins

What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane?

Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores.

The extracellular matrix of the animal cell has all of the following molecular components except __________.

a middle lamella

Cell motility, which includes changes both in cell location and in the movement of cell parts, requires interactions of the cytoskeleton __________.

with motor proteins

A substance moving from outside the cell into the cytoplasm must pass through __________.

the plasma membrane

Which statement about the cytoskeleton is true?

Components of the cytoskeleton often mediate the movement of organelles within the cytoplasm. The cytoskeleton, which plays a major role in organizing the structures and activities of the cell, is composed of microtubules, microfilaments, and intermediate filaments. Several types of cell motility (movement) involve the cytoskeleton. The term cell motility encompasses both changes in cell location and more limited movements of parts of the cell.

Which of the following is false in respect to cells' chromosomes? Chromosomes only exist when cells are actively synthesizing proteins. Chromosomes are present throughout a cell's reproductive cycle. Chromosomes only appear as a cell is about to divide. All cells possess one or more chromosomes.

Chromosomes only appear as a cell is about to divide.

In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells?

Eukaryotic cells are compartmentalized, which allows for specialization. A major difference between prokaryotic and eukaryotic cells is the location of their DNA. In a eukaryotic cell, most of the DNA is in an organelle called the nucleus, which is bounded by a double membrane. In a prokaryotic cell, the DNA is concentrated in a region that is not membrane-enclosed, called the nucleoid. In addition, within the cytoplasm of a eukaryotic cell, suspended in cytosol, are a variety of organelles of specialized form and function. These membrane-bounded structures are absent in prokaryotic cells. Thus, the presence or absence of a true nucleus is just one aspect of the disparity in structural complexity between the two types of cells.

the cytoplasm encompasses

Intermediate filaments are specialized for bearing tension (like microfilaments) and are a diverse class of cytoskeletal elements. Microtubules shape the cell, guide organelle movement, and separate chromosomes in dividing cells. Cilia and flagella are motile appendages containing microtubules. Microfilaments are thin rods functioning in muscle contraction, amoeboid movement, cytoplasmic streaming, and microvillus support.

Cilia and flagella move due to the interaction of the cytoskeleton with which of the following?

Motor proteins

__________ are membrane-bound metabolic compartments that specialize in the production of hydrogen peroxide (H2O2) and its conversion to water.

Peroxisomes

Which of the following groups is primarily involved in synthesizing molecules needed by the cell?

Ribosomes, rough endoplasmic reticulum, and smooth endoplasmic reticulum

Your intestine is lined with individual cells. No fluids leak between these cells from the gut into your body. Why?

The intestinal cells are bound together by tight junctions.

The organelle that is a plant cell's compartment for the storage of inorganic ions such as potassium and chloride is the __________.

central vacuole

Animal cells have unique organelles called __________ that are composed of structures called __________.

centrosomes; centrioles In animal cells, microtubules grow out from a centrosome, a region that is often located near the nucleus. These microtubules function as compression-resisting girders of the cytoskeleton. Within the centrosome is a pair of centrioles, each composed of nine sets of triplet microtubules arranged in a ring. Although centrosomes with centrioles may help organize microtubule assembly in animal cells, many other eukaryotic cells lack centrosomes with centrioles and instead organize microtubules by other means.

Basal bodies are most closely associated with which of the following cell components?

cilia

The network of fibers that organizes structures and activities in a cell __________.

cytoskeleton

Evidence that supports the prokaryotic origins of mitochondria and chloroplasts are all of the following except __________.

that mitochondria and chloroplasts have multiple copies of linear DNA molecules associated with their inner membranes

The region of a bacterial cell that contains the genetic material is called the __________.

nucleoid

Cells are small because __________.

of the geometric relationships between surface and volume

Dye injected into a plant cell might be able to enter an adjacent cell through __________.

plasmodesmata

Cell junctions in plant cells are called __________, and communicating junctions in animal cells are called __________.

plasmodesmata; gap junctions

Which of the following is present in a prokaryotic cell?

ribosomes

You would expect a cell with an extensive Golgi apparatus to __________.

secrete a lot of protein