Chapter 6 - Mastering Biology

You are part of a research team working on developing a stem cell treatment for amyotrophic lateral sclerosis. What type of cells are you trying to repair?

Nerve

Where is a bacterial cell's DNA found?

Nucleoid region (Bacteria lack a nucleus; their DNA is found in the nucleoid region.)

Which cell would be best for studying lysosomes?

phagocytic white blood cell

The primary role of _____ is to bind animal cells together.

desmosomes (anchoring junctions)

The cilia and flagella of eukaryotic cells are composed of _____.

microtubules

Which structure-function pair is mismatched?

Microtubule; muscle contraction

What is the ratio of the volume of typical eukaryotic:prokaryotic cells?

1000:1 (The diameter of a typical eukaryotic cell is approximately ten times the diameter of a typical prokaryote.)

Which of these are hollow rods that shape and support the cell?

Microtubules (Microtubules are rods that also play a role in organelle movement.)

Which of the following correctly matches an organelle with its function?

central vacuole ... storage

What cell junction forms a barrier to the passage of materials?

tight junctions (Tight junctions form a barrier that prevents fluids from moving between cells.)

Which structure is not part of the endomembrane system?

Chloroplast

True or False: Your cheek cells contain the same DNA as your brain cells.

True

Which of these structures stores, modifies, and packages products?

A (The Golgi apparatus modifies, stores, and packages products of the ER.)

______ is/are identical in structure to centrioles.

Basal bodies (Basal bodies and centrioles have identical structures.)

Which of the following treatments with stem cells is currently most likely to be effective?

Bone marrow transplant.

Choose the letter that indicates the organelle that contains most of a cell's DNA.

C

The structure that regulates the passage of material into and out of this bacterial cell is indicated by the letter _____.

C (The plasma membrane is selectively permeable.)

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?

Cell Wall (The cell wall is a rigid supporting structure.)

The _____ is composed of DNA and protein

Chromatin (Chromatin is composed of DNA and protein.)

Which of these provides the cell with structural support?

D (Microfilaments are a component of the cytoskeleton.)

The DNA-containing region of this bacterial cell is indicated by the letter _____.

D (The nucleoid region contains DNA.)

Which molecules do not normally cross the nuclear membrane?

DNA

A cell has formed a food vacuole as it ingested a food particle. Which of the following events is associated with the breakdown of that food particle

Digestion of the food particle occurs in a vesicle enclosed by a membrane that separates the digestion from the cytoplasm. (Digestion occurs within a vesicle. If the digestive enzymes were in the cytosol, they might degrade essential components of the cell.)

Which of these is the double membrane that encloses the nucleus?

E

What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?

ER → Golgi → vesicles that fuse with plasma membrane

True or false? Large proteins containing a nuclear localization signal (NLS) bind to the nuclear pore and enter the nucleus without any expenditure of energy.

False (Cytoplasmic proteins called importins bind to large proteins containing an NLS and mediate their transport across the nuclear membrane through an active transport (energy-requiring) process.)

_________ are surface appendages that allow a bacterium to stick to a surface.

Fimbriae

_____ aid in the coordination of the activities of adjacent animal cells.

Gap junctions (allow for the passage of material between cells, thus facilitating communication between these cells.)

Cyanide binds to at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within the _______

Mitochondria

Which of these organelles carries out cellular respiration?

Mitochondrion (Mitochondria convert the chemical energy of organic molecules to chemical energy in the form of ATP.)

Which of the following functions is NOT associated with the cytoskeleton in eukaryotic cells?

Movement of RNA molecules from the nucleus to the cytoplasm (RNA molecules exit the nucleus via nuclear pores.)

Nucleoplasmin is a nuclear protein. This protein was divided into two segments and linked to the same large cytoplasmic protein, generating two fusion proteins. After injecting these fusion proteins into a cell, one of the proteins was found in the nucleus and the other in the cytoplasm. Which of the following conclusions can be drawn from these results?

Only one of the two fusion proteins possesses a nuclear localization signal. (The nuclear localization signal is only present in the fusion protein that enters the nucleus.)

A small protein (molecular weight = 25,000 daltons) is injected into a cell and observed in the nucleus a short time later. What type of transport has taken place?

Passive Transport (A 25,000-dalton protein is small enough to diffuse through nuclear pores without any expenditure of energy.)

What organelle produces H2O2 as a by-product?

Peroxisome (Peroxisomes produce hydrogen peroxide as a by-product of their metabolic processes.)

In a bacterium, where are proteins synthesized?

Ribosomes (Ribosomes are involved in the manufacture of polypeptides (proteins).)

The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.

Plasma membrane (The plasma membrane is selectively permeable.)

Which statement correctly describes an endomembrane function?

Products of the ER are usually modified during their transit from the cis to the trans region of the Golgi apparatus. (The cis and trans regions of the Golgi apparatus act as receiving and shipping departments. As molecules move from the cis to the trans face of the Golgi apparatus, they are usually modified.)

What is the function of a bacterium's capsule?

Protection (A bacterium's capsule has a protective role.)

_____ are the sites of protein synthesis.

Ribosomes

What statement about the nuclear envelope is false?

The nuclear envelope is continuous with the Golgi apparatus

Identify the correct statement about differences between rough and smooth endoplasmic reticulum (ER).

The outer surface of smooth ER lacks ribosomes, whereas the outer surface of rough ER has ribosomes.

In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules?

To make the proteins easy to see (Fluorescent tags make the location of the proteins easy to visualize.)

Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____.

Transferring of information from DNA to messenger RNA (Transcription is the first of the two main steps of protein synthesis.)

Your uncle has a stem cell treatment in which he has skin cells injected into his lungs. A benign tumor of skin cells resulted. What is this called?

a teratoma

Which of the following choices correctly matches a tool and its proper application?

cell fractionation to study the function of specific organelles

What are some proteins that are synthesized by bound ribosomes?

insulin, lysosomal enzyme, ER protein

The _____ is a selective barrier, regulating the passage of material into and out of the cell.

plasma membrane (The plasma membrane regulates the passage of material into and out of the cell.)

Which of these organelles manufactures proteins bound for secretion out of the cell?

rough endoplasmic reticulum (The ribosomes associated with the rough ER synthesize secretory proteins bound for the exterior of the cell. Further processing and packaging occurs in the Golgi apparatus.)

Where is calcium stored?

smooth endoplasmic reticulum (In addition to storing calcium, the smooth ER also plays a role in detoxification and lipid synthesis.)

Which organelle plays a role in intracellular digestion?

Lysosome (The prefix "lyso-" means decomposition.)

Ribosomal subunits are manufactured by the _____.

Nucleolus (Ribosomes are manufactured by the nucleolus.)

Which one of the following statements about the endomembrane system is correct?

Proteins that will be secreted from the cell are likely to be found in closed spaces bounded by membranes of the endomembrane system.

True or False: All cells in the human body can be traced back to an embryonic stem cell.

True