Endocytosis moves materials _____ a cell via _____.
Definition
into ... membranous vesicles
Term
A white blood cell engulfing a bacterium is an example of _____.
Definition
Term
You know that this process is _____ because _____.
Definition
pinocytosis ... the cell is engulfing extracellular fluid
Term
Which organelle plays a role in intracellular digestion?
Definition
lysosome
Term
Which molecules do not normally cross the nuclear membrane?
Definition
DNA
Term
Which of the following statements about the nuclear envelope is false?
Definition
Term
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.
Definition
False
Term
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?
Definition
Passive transport
Term
In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules?
Definition
To make the proteins easy to see
Term
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?
Definition
Only one of the two fusion proteins possesses a nuclear localization signal.
Term
Definition
All of the listed responses correctly describe polarity characteristics of the Golgi function.
Term
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle must be involved in this condition?
Definition
the lysosome
Term
Which of the following macromolecules leaves the nucleus of a eukaryotic cell through pores in the nuclear membrane?
Definition
mRNA
Term
What is the function of the nuclear pore complex found in eukaryotes?
Definition
It regulates the movement of proteins and RNAs into and out of the nucleus.
Term
Definition
Term
Eukaryotic cells manufacture cytoskeletal proteins, which help to maintain cell shapes and functions. What would you predict about these proteins?
Definition
Term
Definition
components of the cytoskeleton
Term
Definition
microtubules and motor proteins
Term
ANSWER:
Definition
Cilia and flagella arise from centrioles.
Term
Which of the following statements about the cytoskeleton is true?
Definition
Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.
Term
Cells require which of the following to form cilia or flagella?
Definition
Tublin
Term
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?
Definition
adding radiolabeled actin subunits to a mixture of actin filaments in which conditions are favorable for polymerization
Term
Amoebae move by crawling over a surface (cell crawling), which involves _
Definition
setting up microtubule extensions that vesicles can follow in the movement of cytoplasm
Term
Researchers tried to explain how vesicular transport occurs in cells by attempting to assemble the transport components. They set up microtubular tracks along which vesicles could be transported, and they added vesicles and ATP (because they knew the transport process requires energy). Yet, when they put everything together, there was no movement or transport of vesicles. What were they missing?
Definition
motor proteins
Term
Cilia and flagella bend because of _____.
Definition
a motor protein called dynein
Term
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?
Definition
Term
What path does a protein in the secretory pathway take, starting from its site of synthesis?
Definition
Term
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?
Definition
The final destination of the proteins was the lysosome
Term
What scientific hypotheses can be tested by a pulse-chase experiment?
Definition
Movement of molecules through a cell over time
Term
True or false? Proteins produced during the "chase" phase of a pulse–chase experiment are labeled with radioactive material.
Definition
False
Term
What is the first step in a pulse-chase experiment?
Definition
Term
Which of the following results provided evidence of a discrete nuclear localization signal somewhere on the nucleoplasmin protein?
Definition
After cleavage of the nucleoplasmin protein, only the tail segments appeared in the nucleus.
Term
The part of the endomembrane system that is studded with ribosomes for protein synthesis is the _____.
Definition
rough ER
Term
Definition
The protein is translated on free ribosomes and then passes through the pore complex to enter the nucleus.
Term
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?
Definition
Term
The cilia and flagella of eukaryotic cells are composed of _____.
Definition
microtubules
Term
Which of these cell junctions form a barrier to the passage of materials?
Definition
tight junctions
Term
The primary role of _____ is to bind animal cells together.
Definition
desmosomes
Term
Definition
Term
Which of these extracellular signal molecules could diffuse through a plasma membrane and bind to an intracellular receptor?
Definition
estrogen
Term
A(n) _____ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off.
Definition
steroid
Term
Thyroid hormones bind to _____ receptors.
Definition
intracellular
Term
What role does a transcription factor play in a signal transduction pathway?
Definition
By binding to DNA it triggers the transcription of a specific gene.
Term
In this animation, which of the following, when activated by a signal transduction pathway, moved from the cytoplasm to the nucleus of a cell?
Definition
transcription factor
Term
A signal transduction pathway is initiated when a _____ binds to a receptor.
Definition
signal molecule
Term
Which of these acts as a second messenger?
Definition
cyclic AMP
Term
Definition
ER
Term
Definition
Phospholipase C ... IP3 .... Ca2+
Term
A protein kinase activating many other protein kinases is an example of _____.
Definition
amplification
Term
What do the cell walls of plants and the extracellular matrix of animal cells have in common?
Definition
They have functional connections with the cytoskeleton inside the cell.
Term
Definition
Term
Signals from the extracellular matrix to the cytoskeleton may be transmitted by
Definition
intergrins
Term
Summarize the experimental evidence in sponges showing that animal cells adhere to each other selectively. Explain the molecular basis of selective adhesion.
Definition
selective adhesion results from the presence of specific types of cell adhesion proteins in the plasma membrane, including cadherins. Each type of protein can bind only to proteins of the same type.
Term
What is a major difference between the extracellular matrix (ECM) of a plant cell and the ECM of an animal cell?
Definition
Plant ECM is primarily carbohydrate in nature, whereas animal ECM is mainly proteins.
Term
All of the following proteins may be found in the extracellular matrix of animal cells EXCEPT _____.
Definition
actin
Term
Definition
gap junctions
Term
For a tissue or an organ to function as a unit, ________.
Definition
Term
In plant cells, the middle lamella _____.
Definition
allows adjacent cells to adhere to one another
Term
Definition
in the epithelium of an animal's stomach
Term
A gap junction is a channel that connects adjacent cells. Which one of the following cannot pass through a gap junction?
Definition
ribosomes
Term
Plasmodesmata are cellcell junctions that are found between ________.
Definition
adjacent plant cells
Term
Definition
target cell
Term
The receptors for steroid hormones are located inside the cell instead of on the membrane surface like most other signal receptors. This is not a problem for steroids because _____.
Definition
steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane
Term
Definition
Term
Definition
Term
Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction?
Definition
Term
What does it mean to say that a signal is transduced?
Definition
The physical form of the signal changes from one form to another.
Term
A G-protein receptor with GTP bound to it _____.
Definition
is in its active state
Term
A signal transduction pathway is initiated when a _____ binds to a receptor.
Definition
signal molecule
Term
A signal molecule is also known as a(n) _____.
Definition
ligand
Term
Which of these is the second of the three stages of cell signaling?
Definition
transduction
Term
f these is a logical signal transduction pathway?
Definition
A G-protein-linked receptor activates G protein, which activates phospholipase C, which cleaves a membrane lipid to form IP3, which binds to a calcium channel on the ER, which opens to release calcium ions into the cytoplasm, which bind to an intracellular enzyme that carries out a response.
Term
Definition
glucose-1-phosphate
Term
Epinephrine acts as a signal molecule that attaches to _____ proteins.
Definition
Term
Which of these is activated by calcium ions?
Definition
Term
Definition
Cyclic AMP binds to calmodulin.
Term
Definition
Cyclic AMP binds to calmodulin.
Term
A toxin that inhibits the production of GTP would interfere with the function of a signal transduction pathway that is initiated by the binding of a signal molecule to _____ receptors
Definition
G-Protein-linked
Term
The cancer-causing forms of the Ras protein are involved in which of the following processes?
Definition
Term
Which of the following statements about quorum sensing is FALSE? Quorum sensing ________.
Definition
is cellcell communication in eukaryotes
Term
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?
Definition
Term
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?
Definition
100%
Term
In glycolysis, for each molecule of glucose oxidized to pyruvate _____.
Definition
two molecules of ATP are used and four molecules of ATP are produced.
Term
Why is glycolysis described as having an investment phase and a payoff phase?
Definition
Term
How many NADH are produced by glycolysis?
Definition
2
Term
In glycolysis, ATP molecules are produced by _____.
Definition
Term
Which of these is NOT a product of glycolysis?
Definition
FADH2
Term
In glycolysis, what starts the process of glucose oxidation?
Definition
ATP
Term
In glycolysis there is a net gain of _____ ATP.
Definition
2
Term
During cellular respiration, acetyl CoA accumulates in which location?
Definition
mitochondrial matrix
Term
Which of these enters the citric acid cycle?
Definition
acetyl CoA
Term
In the citric acid cycle, ATP molecules are produced by _____.
Definition
substrate-level phosphorylation
Term
Which of these is NOT a product of the citric acid cycle?
Definition
acetyl CoA
Term
Which electron carrier(s) function in the citric acid cycle?
Definition
NADH and FADH2
Term
C6H12O6 (glucose) + 6 O2 → 6 CO2 + 6 H2O Where is most of the water in this reaction produced?
Definition
in the electron transport chain
Term
When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?
Definition
The pH of the matrix increases.
Term
In mitochondrial electron transport, what is the direct role of O2?
Definition
Term
How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)
Definition
Both electron transport and ATP synthesis would stop.
Term
NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule.
Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2?
Definition
Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.
Term
The oxygen consumed during cellular respiration is involved directly in which process or event?
Definition
accepting electrons at the end of the electron transport chain
Term
Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?
Definition
mitochondrial intermembrane space
Term
In mitochondria, exergonic redox reactions _____.
Definition
provide the energy that establishes the proton gradient
Term
Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in ________.
Definition
all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
Term
Definition
lactate and NAD+
Term
In fermentation _____ is reduced and _____ is oxidized.
Definition
pyruvate ... NADH
Term
Which metabolic pathway is common to both cellular respiration and fermentation?
