Chapter 7

Gold particles below a certain size limit that are injected into the cytoplasm can later be observed in the nucleus. This suggests which of the following?

Molecules below a certain size can diffuse nonselectively through the nuclear pore complex.

The mixing of purified microtubules with transport vesicles and ATP does not result in movement of the vesicles. Why?

Kinesin is missing

A certain eukaryotic cell type specializes in synthesizing lipids. Which organelle would be found in greater abundance in this cell type than in other cell types that do not synthesize lipids?

Smooth endoplasmic reticulum

Thylakoids, DNA, and ribosomes are all components found in ______________.

chloroplasts

Keratin is __________.

an intermediate filament

In the diagram of a prokaryotic cell, which structure is best represented by the letter "E"? Overview of a Prokaryotic Cell. Prokaryotic cells are identified by a negative trait—the absence of a membrane-bound nucleus. Although there is wide variation in the size and shape of bacterial and archaeal cells, they all contain a plasma membrane, a chromosome, and protein-synthesizing ribosomes.

plasma membrane

What is the function of fimbriae in prokaryotic cells?

Attachment

Cytokinesis involves which of the following cytoskeletal filaments?

Actin and myosin

Which of the following statements describes a fundamental difference between plant cells and animal cells?

Animal cells do not have chloroplasts.

In the diagram of a prokaryotic cell, which structure(s) is/are best represented by the letter "D"? Overview of a Prokaryotic Cell. Prokaryotic cells are identified by a negative trait—the absence of a membrane-bound nucleus. Although there is wide variation in the size and shape of bacterial and archaeal cells, they all contain a plasma membrane, a chromosome, and protein-synthesizing ribosomes.

Cell wall

In the diagram of a prokaryotic cell, which structure is best represented by the letter "F"? Overview of a Prokaryotic Cell. Prokaryotic cells are identified by a negative trait—the absence of a membrane-bound nucleus. Although there is wide variation in the size and shape of bacterial and archaeal cells, they all contain a plasma membrane, a chromosome, and protein-synthesizing ribosomes.

Chromosome

All cells contain which three structures?

Chromosomes, ribosomes, and a plasma membrane

In the diagram of a prokaryotic cell, which structure(s) is/are best represented by the letter "C"? Overview of a Prokaryotic Cell. Prokaryotic cells are identified by a negative trait—the absence of a membrane-bound nucleus. Although there is wide variation in the size and shape of bacterial and archaeal cells, they all contain a plasma membrane, a chromosome, and protein-synthesizing ribosomes.

Cytoplasm

Consider the experimental design used by George Palade and colleagues to track protein movement. During which phase would the concentration of radiolabeled proteins be highest?

During the "pulse" phase

If it could be stretched out, the circular chromosome of prokaryotic cells would be 500 times longer than the cell itself. What molecules assist in the supercoiling of the DNA so that it can fit in the cell?

Enzymes

In prokaryotic cells, where are the photosynthetic pigments located?

In folds of the plasma membrane

Where are glycoproteins and glycolipids processed for export?

In the cisternae of the Golgi bodies

What type of cell is shown in this diagram? Overview of a Eukaryotic Cell. This is an animal cell that illustrates the cellular structures in the "typical" eukaryote.

Eukaryotic

Which of the following statements best describes the fundamental difference between prokaryotic and eukaryotic cells?

Eukaryotic cells have a nucleus, whereas prokaryotic cells do not have a nucleus.

In the diagram of a prokaryotic cell, which structure is best represented by the letter "G"? Close-up View of a Prokaryotic Cell. This painting is David Goodsell's representation of a cross section through part of a bacterial cell. It is based on electron micrographs of bacterial cells and is drawn to scale. Note that the cell is packed with proteins, DNA, ribosomes, and other molecular machinery.

Flagellum

Where is DNA located in eukaryotes?

In the nucleus

A large carbohydrate is tagged with a fluorescent marker and placed in the extracellular environment surrounding a eukaryotic cell. The cell ingests the carbohydrate via endocytosis. Which of the following cellular structures is most likely to be the first one fluorescently labeled?

Lysosomes

Tay-Sachs disease is a human genetic abnormality that results in cells becoming packed with very large undigested lipids. Which cellular organelle is malfunctioning in this condition?

Lysosomes

Which of the following molecules will move from the inside to the outside of the nucleus via the nuclear pores?

Messenger RNA (mRNA)

What is the function of the flagella?

Movement

Which of the following organelles have a double membrane?

Nucleus, mitochondria, and chloroplasts

The organelles of plants and animals can differ. Which of the following statements correctly identifies plant and animal organelles?

Only animal cells have lysosomes, and only plant cells have vacuoles.

Which of the following accurately represents how intermediate filaments differ from actin filaments and microtubules?

Only intermediate filaments play a purely structural role.

For eukaryotic cells, which answer correctly pairs the organelle with its correct function?

Peroxisome; redox center

Hydrogen peroxide is produced during several chemical reactions within the cell. However, hydrogen peroxide is poisonous to the cell. Which organelle contains the enzyme catalase, which is needed to quickly detoxify hydrogen peroxide?

Peroxisomes

In the diagram of a prokaryotic cell, which structure(s) is/are best represented by the letter "B"? Overview of a Prokaryotic Cell. Prokaryotic cells are identified by a negative trait—the absence of a membrane-bound nucleus. Although there is wide variation in the size and shape of bacterial and archaeal cells, they all contain a plasma membrane, a chromosome, and protein-synthesizing ribosomes.

Plasmids

What is the function of the plasmid in a prokaryotic cell?

Plasmids contain genetic material.

If a cell has a very high density of smooth endoplasmic reticulum, it is likely to be involved in which of the following activities?

Production of lipids

There are hundreds, if not thousands, of proteins that are specifically localized to the cell nucleus. What is likely to be true about transport of these proteins into the nucleus?

Proteins specifically localized to the nucleus must have the same or a similar nuclear localization signal that directs them to the nucleus.

In the diagram of a prokaryotic cell, which structure(s) is/are best represented by the letter "A"? Overview of a Prokaryotic Cell. Prokaryotic cells are identified by a negative trait—the absence of a membrane-bound nucleus. Although there is wide variation in the size and shape of bacterial and archaeal cells, they all contain a plasma membrane, a chromosome, and protein-synthesizing ribosomes.

Ribosomes

Researchers supplied a short pulse of radioactively labeled leucine, followed by a long chase of unlabeled leucine, to cells that secrete digestive enzymes. The bulk of the radioactive label was initially found in the rough endoplasmic reticulum (rough ER), then in the Golgi apparatus, then in secretory vesicles, and finally outside the cell. These results support which of the following hypotheses?

Secreted proteins are synthesized in the rough ER and travel through the Golgi apparatus to be packaged into secretory vesicles that fuse with the plasma membrane.

In plant and fungal cells, why are toxins like nicotine, cocaine, and caffeine stored in vacuoles?

Storing the toxins in vacuoles separates them from the rest of cell, where they could do harm.

What is the ER signal sequence?

The ER signal sequence is a sequence of amino acids that moves proteins into the lumen of the endoplasmic reticulum.

What is the axoneme?

The arrangement of nine microtubule pairs surrounding two centrally located microtubules in most eukaryotic cilia and flagella

Why is the actin filament a polar molecule?

The asymmetrical arrangement of the actin results in a polar molecule.

Which of the following is an advantage of compartmentalization seen in eukaryotic cells?

The cell can separate chemical reactions

Suppose that a transmembrane protein destined for the plasma membrane was labeled with a fluorescent dye on the part of the protein exposed on the outer face of the endoplasmic reticulum membrane. If the protein were to be distributed among cellular compartments, where would the dye likely be located?

The dye will first move to the inside of the cell's rough ER, then to the Golgi apparatus, and finally to the secretory vesicles of the cell or secreted from the cell.

In the eukaryotic cell, where are proteins folded?

The lumen of the rough endoplasmic reticulum

What are the three structures that make up the nucleus?

The nuclear envelope, the nucleolus, and the chromosomes

If a mutation occurs such that the intermediate filaments cannot be formed, which of the following would be observed?

The nucleus would not be anchored.

Prokaryotes and eukaryotes both have flagella; however, the structure of the flagella differs between these two groups. Which of the following correctly describes the differences between the flagella of prokaryotes and eukaryotes?

The protein the makes up bacterial flagella is called flagellin, whereas eukaryotic flagella are composed of tubulin dimers.

Which of the following will cause protein synthesis to stop?

The signal recognition particle

Suppose that the plasma membrane around a eukaryotic flagellum is opened to reveal the axoneme inside. The dynein arms between the peripheral microtubule doublets are removed by chemical treatment, and ATP is added. Which of these would be the most expected observation?

There will be no movement because the ability to use ATP is lost.

What do myosin, dynein, and kinesin have in common?

They all hydrolyze ATP to provide energy for movement.

Why are ribosomes not considered to be organelles?

They lack a membrane.

A researcher discovers a new type of animal cell and views it under an electron microscope. This view reveals many peroxisomes—more than in other cell types. Which of the following is a reasonable assumption?

This cell type is specialized for oxidizing molecules.

Dynein walking in the axoneme is characterized by __________.

a bending of the cilia and flagellum

A protein lacking a signal sequence directing it to a particular location in a cell will likely reside __________.

in the cytoplasm

Differential centrifugation is a technique that allows researchers to __________.

isolate cell components from each other

Which of the following is true of the nucleus?

it is surrounded by a double membrane

The endoplasmic reticulum is an extensive network of membranes. It has two distinctive regions, rough endoplasmic reticulum and smooth endoplasmic reticulum, that differ in both structure and function. The rough endoplasmic reticulum synthesizes proteins, but the smooth endoplasmic reticulum cannot because ______.

there are no ribosomes attached to its surface