What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?
The _______ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell
In eukaryotic flagella, the fibers that slide past one another due to the activity if dynein proteins are _______.
Many cell organelles, most notably the nucleus, are anchored by _______, which are assembled from a diverse class of proteins.
The extension of pseudopodia in amoeba is due to the regulated assembly and destruction of _______.
The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are the _______.
Which of these organelles carries out cellular respiration?
smooth endoplasmic reticulum
Which of these manufactures cellular membranes by adding membrane proteins and phospholipids to its own membrane?
rough endoplasmic reticulum
rough endoplasmic reticulum
The _______ is a selective barrier, regulating the passage of material into and out of the cell.
Which of these are hollow rods that shape and support the cell?
The protein sorting pathway involves the following organelles/compartments in order
RER, transport vesicle, Golgi, final destination
Which of the following is not true of secreted proteins?
-They are transported between organelles in membrane-bound vesicles.
-They enter the ER lumen during translation.
-They are synthesized using ribosomes.
-They contain a signal that directs them into the lysosome.
They contain a signal that directs them into the lysosome.
Molecular zip codes direct molecules to particular destinations in the cell. How are these signals read?
They bind to receptor proteins.
Which of the following statements would best describe a cell that has an extensive area of smooth endoplasmic reticulum?
-It synthesizes large quantities of lipids.
-It actively exports protein molecules.
-It plays a role in storage.
-It is able to both import and export protein molecules.
It synthesizes large quantities of lipids.
Why are lysosomes considered part of the endomembrane system?
because they are formed from products synthesized by the endoplasmic reticulum and processed by the Golgi
Categorize each function to either smooth ER, rough ER, golgi apparatus, or lysosomes.
-Calcium ion storage
-Protein modification and sorting
Smooth ER- calcium ion storage, lipid synthesis, poison detoxification
Rough ER- protein synthesis
Golgi apparatus- Cisternal maturation, protein modification and sorting
Lysosomes- macromolecule digestion, autophagy
All proteins are synthesized by ribosomes in the cell. Some ribosomes float freely in the cytosol, while others are bound to the surface of the endoplasmic reticulum. Most proteins made by free ribosomes function in the cytosol. Proteins made by bound ribosomes either function within the endomembrane system or pass through it and are secreted from the cell.
Which of the following proteins are synthesized by bound ribosomes?
Identify the path a secretory protein follows from synthesis to secretion.
protein synthesis -> endoplasmic reticulum -> cis Golgi cisternae -> medial Golgi cisternae -> trans Golgi cisternae -> plasma membrane -> extracellular space
Pancreatic cells, which secrete a large amount of digestive enzymes, are labeled with radioactive leucine and then chased for several hours with nonradioactive leucine. Photographic emulsions are prepared at different times during the chase. Where would the black spots appear on an emulsion prepared 3 hours after the pulse?
Exterior of the cell
What path does a protein in the secretory pathway take, starting from its site of synthesis?
Rough ER, Golgi apparatus, secretory vesicles, plasma membrane
During a pulse-chase experiment, photographic emulsions were prepared at different times during the chase, and radioactive spots were detected at the following times and locations: 5 minutes: rough ER; 10 minutes: Golgi apparatus; 40 minutes: endosomes; 70 minutes: lysosomes; 140 minutes: lysosomes. Which of the following conclusions can be drawn from these results?
-The proteins were secreted.
-The final destination of the proteins was the lysosome.
-The proteins traveled from lysosomes to endosomes.
-The proteins did not travel through the Golgi apparatus.
The final destination of the proteins was the lysosome
What scientific hypotheses can be tested by a pulse-chase experiment?
Movement of molecules through a cell over time
True or false? Proteins produced during the "chase" phase of a pulse-chase experiment are labeled with radioactive material
Which statement most accurately describes what happens to proteins that lack an ER signal sequence?
They are released into the cytosol.
Scientists have found that polypeptides that are normally synthesized in the endoplasmic reticulum are about 20 amino acids longer when they are synthesized by ribosomes not attached to the endoplasmic reticulum. What is/are possible explanations for the greater length of these polypeptides?
The 20 amino acids serve as a signal sequence that directs the forming polypeptide to the endoplasmic reticulum, where they are cleaved off during processing.
Which of the following statements would be true about lysosomes that lack mannose-6-phosphate receptors?
-They have unstable membranes.
-They stick to transport vesicles and impede the transfer of enzymes.
-They receive "modified" enzymes, so are unable to break down carbohydrates.
-They do not receive enzyme shipments from the Golgi apparatus.
They do not receive enzyme shipments from the Golgi apparatus.
The compartmentalization of areas within eukaryotic cells: _______
allows them to perform several biochemical functions simultaneously
Cellular organelles: _______
typically work in coordination with other organelles to accomplish and overall cellular activity.
Which statement is not true regarding illness associated with malfunctioning cellular organelles? The illness _______
-may be lethal
-is typically simple to diagnose
-can result in a diverse set of symptoms
-may impact multiple body systems
is typically simple to diagnose
Using concepts from Chapter 3, which statement best explains why proteins-and not RNA, DNA, carbohydrates, or lipids-are the molecules responsible for "reading" the array of molecular zip codes in cells?
-Because protein enzymes can have a diversity of active site structures, they can "read" different zip codes by specifically degrading them.
-Because proteins can store energy, they provide the energy to transport other proteins with zip codes to their correct destinations.
-Because proteins store and process information, they can "read" different zip codes via base pairing.
-Because proteins can have diverse structures and chemical properties, different proteins can "read" different zip codes by interacting specifically with them.
Because proteins can have diverse structures and chemical properties, different proteins can "read" different zip codes by interacting specifically with them.
Which statement best explains how pulse-chase experiments allowed researchers to study cells as dynamic enterprises—specifically looking at how molecules move inside cells?
-By pulsing cells with light at regular intervals, researchers were able to take "snapshot" images of molecules moving inside cells.
-By marking a specific population of molecules by providing label continuously, researchers were able to follow their fate over time.
-By marking a specific population of molecules with a pulse of label, researchers were able to follow their fate over time.
-By marking a specific population of molecules with a chase of label, researchers were able to follow their fate over time
By marking a specific population of molecules with a pulse of label, researchers were able to follow their fate over time.
The preparation of liver mitochondrial enzymes begins by placing liver and a buffered solution in a blender. What is the purpose of the blender?
to prepare a cell homogenate; to break open the liver cells and to release the organelles
Sort the phrases into either exocytosis, endocytosis, or both.
-requires cellular energy
-forms vesicles from inward folding of the plasma membrane
-requires fusion of vesicles with the plasma membrane
-transported substances never physically cross the plasma membrane
-increases the surface area of the plasma membrane
-secretes large molecules out of the cell
-decreases the surface area of the plasma membrane
exocytosis- increases the surface area of the plasma membrane, requires fusion of vesicles with the plasma membrane, secretes large molecules out of the cell
endocytosis- decreases the surface area of the plasma membrane, forms vesicles from inward folding of the plasma membrane
both- requires cellular energy, transported substances never physically cross the plasma membrane
High speed transport of vesicles over long distances in a cell requires _______.
-a head that attaches to the visicle
-a connector molecule or stalk between the head and the motor protein that walks on the microtubule.
-a motor protein such as dynin or kinesin
-microtubules along which to transport the vesicles.
-all of the above.
all of the above
The structureal support fibers found under the nuclear membrane which maintains the shape and integrity of the nuclear membrane and provides attachement points for the ends of chromosomes is made of _________ filaments and is called the Nuclear _________.
A globular protein that forms the microfilaments and is responsible for cell movement such as cell crawling is ________.
The region surrounding the centrioles that acts as the cell's microtubule-organizing center is called the _______.
A cytoskeleton fiber consisting of alpha and beta tubulin subunits arranged side by side to form a hollow tube is called a _______.
The cytoskeleton elements that dissasemble, then reorganizes and grows from the opposite poles of a dividing cell and is responsible for the separtion of chromosomes during cell division is the _____________.
The protein fiber called the thick filament found in vertebrate skeletal muscles that pull actin filaments to produce muscle contraction is made of the protein __________.
Which statement most accurately describes what will happen to endomembrane system products if experimental cells are treated with drugs that inhibit formation of microtubules?
-They will still enter the ER and transport to their destinations will be unimpaired.
-They will still enter the ER but they will be transported to incorrect destinations.
-They will still enter the ER but transport to their destinations will be impaired.
-They will fail to enter the ER and transport to their destinations will be impaired.
They will still enter the ER but transport to their destinations will be impaired.
What three distinct elements make up the cytoskeleton in eukaryotic cells?
actin filaments, intermediate filaments, and microtubules
Actin filaments have polarity. This means that the two ends can be identified due to structural differences. The plus end is the end to which subunits are added more rapidly, or the end of polymerization. Which of the following would enable you to identify the plus end of actin filaments?
-Determine the ionic charge of the ends of the actin filaments.
-Add radiolabeled actin subunits to a mixture of actin filaments in which conditions are favorable for polymerization.
-Add radiolabeled actin subunits to a mixture of actin filaments in which conditions favor depolymerization.
Add radiolabeled actin subunits to a mixture of actin filaments in which conditions are favorable for polymerization.