Exam 2 Practice Questions

True or False: The concentration of Na+ outside the cell is higher than it is inside. True False

(Na+) is indeed higher outside the cell compared to inside. This concentration gradient is maintained by the action of the sodium-potassium pump, which actively transports sodium ions out of the cell and potassium ions into the cell, against their respective concentration gradients. This pump is crucial for various cellular processes, including maintaining cell volume, generating electrical signals, and facilitating the transport of other molecules across the cell membrane.

The protein:lipid ratio in a typical membrane (e.g. red blood cells) is approximately: 1:1 2:1 1:10 1:2

1.1

Glycolysis nets _____ molecule(s) of ATP per molecule of glucose. 1 2 3 4

2

Cholesterol generally makes up what percentage of the lipid mass of the plasma membrane? 5% 25% 0% 10%

25

Protein makes up what percentage of the mass of the plasma membrane in a typical cell (e.g. red blood cells)? 50% 25% 10% 5%

50

Phosphatases vs Phosphorylases

A "phosphatase" takes a phosphate OFF of a substrate, hydrolyzing it to yield phosphoric acid. A "phosphorylase" puts a phosphate ONTO a substrate, in a special way.

If you had a patient in which the lung epithelium was leaking fluids from the bloodstream into the lumen of the lung, which of the following is the most likely cause? A mutation in a cell adhesion molecule A mutation in actin High levels of cholesterol A mutation in an extracellular matrix protein

A mutation in a cell adhesion molecule

If it were injected directly into liver cells, cAMP would have the effect of: Activating Protein Kinase A and, therefore, glycogen breakdown None of the above; nothing would happen in the absence of the "first messenger" Activating G-alpha. Catalyzing the hydrolysis of GTP.

Activating Protein Kinase A and, therefore, glycogen breakdown

rotons (H+) are moved up their concentration gradients into the lysosome in order to activate lysosomal enzymes. This is an example of: Active transport Ion channels Simple diffusion Facilitated diffusion

Active Transport

Which of the following is true for both GPCR signaling and steroid hormone signaling? An extracellular signal is transduced to an intracellular response. They may have widespread effects because they may be secreted into the bloodstream. Both of the above They involve enzyme cascades

An extracellular signal is transduced to an intracellular response. They may have widespread effects because they may be secreted into the bloodstream.

catabolism vs anabolism

Anabolic reactions use energy to build complex molecules from simpler organic compounds (e.g., proteins from amino acids, carbohydrates from sugars, fats from fatty acids and glycerol); catabolic reactions break complex molecules down into simpler ones, releasing chemical energy.

Which adaptation specific to becoming multicellular compensates for the destabilizing effect of increased size? (Think carefully about answer choices!) Extracellular matrix Tight junctions Cytoskeleton Both ECM and tight junctions All of the above

Both ECM and tight junctions

Which of the following is a reactant of the first reaction of glycolysis? Glucose ADP ATP O2 Both glucose and ATP

Both glucose and ATP

Which of the following is/are likely to elicit a slow, but long-lasting or even permanent cellular response? An odorant that binds to a G protein-coupled receptor A growth factor that binds to a receptor tyrosine kinase A steroid hormone Both growth factor signaling and steroid hormone signaling

Both growth factor signaling and steroid hormone signaling

Converting CO2 into glucose _______ and the pathways that do so are, therefore, ________. requires energy; anabolic releases energy; anabolic requires energy; catabolic releases energy; catabolic

Converting CO2 into glucose _______ and the pathways that do so are, therefore, ________. requires energy; anabolic releases energy; anabolic requires energy; catabolic releases energy; catabolic

In prokaryotes, where does glycolysis occur? Mitochondria Rough ER Plasma membrane Cytoplasm

Cytoplasm

You are most likely to find Ca++ channels in the membranes of what organelle? Smooth ER Lysosome Secretory vesicle Nucleus Golgi Complex

ER Smooth-To regulate calcium levels within the ER and facilitate calcium release into the cytoplasm when needed, Ca++ channels are present in the membrane of the smooth ER. These channels allow for the controlled movement of calcium ions across the ER membrane.

Which organelle stores Ca++ except when it is need in the cytoplasm?

ER bc Calcium ions are actively transported into the lumen of the Smooth ER by specific pumps and channels, such as calcium ATPases and calcium channels. Once inside the Smooth ER, calcium ions can be stored at high concentrations until they are needed for cellular processes such as signaling, muscle contraction, or enzyme activation.

Endocrine

Endocrine signaling is a type of cell communication in which specialized cells release hormones into the bloodstream. These hormones are then carried throughout the body, where they travel to target cells or tissues that possess specific receptors for the hormone

facilitated diffusion

Facilitated diffusion refers to the process of passive transport where molecules move across the cell membrane through specific transmembrane proteins called transporters or channels. In this case, calcium ions (Ca++) are moving down their concentration gradient through a specific Ca++ channel. This process does not require energy input and relies solely on the concentration gradient of Ca++.

GPCR

G protein-coupled receptors; a broad category of receptors that are associated with regulatory complexs called G proteins because they bind to GTP and GDP

Which of the following is an enzyme? epinephrine G-alpha ATP All of the above None of the above

G-alpha

Which of the following is an advantage of multicellularity? Easier to absorb nutrients Greater mobility Increased stability Shorter generation times

Greater Mobility:The advantage of greater mobility in multicellular organisms allows for better exploration of environments, escaping from predators, and seeking out resources. However, the specialization of cells for specific functions also contributes to the stability of multicellular organisms, ensuring that different tasks necessary for survival are efficiently carried out by specialized cells or tissues.

Which of the following is least likely to diffuse through a cell's plasma membrane? H+ O2 glycerol H2O

H+-Hydrogen ions (H+) are least likely to diffuse through a cell's plasma membrane compared to the other options listed. The plasma membrane is primarily composed of a lipid bilayer, which is selectively permeable to non-polar molecules. Charged particles like H+ ions have difficulty crossing the lipid bilayer directly due to their charge and the hydrophobic nature of the membrane interior.

What is the second messenger in the receptor tyrosine kinase signaling pathway? The receptor The small GTPase ras The enzyme MAPK that gets transported into the nucleus to activate gene transcription None of the above

Hide question 15 feedback RTK signaling doesn't involve production of any new molecules, only activation of proteins including enzymes.

Which of the following never uses simple diffusion to pass through the cell membrane? Large hydrophobic molecules. Ions Small hydrophobic molecules Small polar uncharged molecules

IOns

Ca++ flowing down its concentration gradient through a Ca++ channel is an example of:

In this case, calcium ions (Ca++) are moving down their concentration gradient through a specific Ca++ channel. This process does not require energy input and relies solely on the concentration gradient of Ca++.

Even though the blood glucose concentration may drop below the intracellular glucose concentration - for example, during a long fast - brain cells can still absorb glucose from the bloodstream. Under these circumstances, how does glucose get into the cells? Simple diffusion Indirect active transport Facilitated diffusion Direct active transport

Indirect active transport

Archeological evidence suggests that Neanderthals may have been aware of the medicinal properties of plants over 60,000 years ago. Imagine you are a modern-day ethnobotanist and have identified a compound from fossilized tree pollen that binds to the alpha subunit of the most common G-proteins. To test how the compound affects the activity of Gα, you treat liver cells with the compound and then epinephrine. You observe that the cells fail to produce glucose. Which of the following could be how the compound acts? It could inhibit the GTPase activity of Gα. It could increase the affinity of Gα for GTP. It could cause Gα to bind more tightly to adenylate cyclase. None of the above

Instead, based on the observed outcome, it's more likely that the compound interferes with the normal signaling pathway mediated by epinephrine and G-proteins, possibly by directly inhibiting the downstream effectors of Gα or by interfering with the interaction between Gα and its downstream targets. Therefore, the specific mechanism of action of the compound would need further investigation beyond the options provided.

do chart of free energy

It is true that increasing entropy tends to make a reaction more energetically favorable - however, if there is a large increase in enthalpy at the same time, this could outweigh the effects of increased entropy, i.e. if the magnitude of an unfavorable enthalpy change is greater than the magnitude of favorable TΔS: ΔG = ΔH - TΔS

Whooping cough, also known as pertussis, is caused by the bacterium Bordetella pertussis. Some of its effects result from production of Pertussis toxin, which prevents Gα from binding to G-protein coupled receptors, and thereby "locking" Gα in the GDP-bound state. If you treated liver cells with Pertussis toxin, how would it affect liver cell responses to epinephrine? It would decrease proliferation. It would decrease secretion of digestive enzymes. It would decrease glucose production. It would increase glucose production. It would increase proliferation.

It would decrease glucose production.

Dr. Hutson really likes coffee. Despite that, this is not a question about caffeine. How does a compound that inhibits the GTPase activity of Gα affect liver cell responses to epinephrine? It would increase glucose production. It would decrease glucose production. It would increase proliferation. It would decrease proliferation.

It would increase glucose production.Liver cells only produce glucose in response to epi - the GTPase activity counteracts this effect. So you have to figure out what would happen if you inhibit the GTPase.

G-alpha is not only an activator of Adenylate cyclase, but it is a GTPase. How does mutation in G-alpha that decreases its GTPase activity affect liver cell responses to epinephrine? It would decrease protein kinase A activity. It would increase proliferation. It would increase glycogen phosphorylase activity. It would increase secretion of epinephrine.

It would increase glycogen phosphorylase activity.

G-alpha is not only an activator of Adenylate cyclase, but it is a GTPase. How does mutation in G-alpha that decreases its GTPase activity affect liver cell responses to epinephrine? It would increase glycogen phosphorylase activity. It would increase secretion of epinephrine. It would increase proliferation. It would decrease protein kinase A activity.

It would increase glycogen phosphorylase activity. Anything upstream - i.e. preceding - the activity won't be affected, and epinephrine is upstream of G-alpha.

Which of the following enzymes catalyzes phosphorylation of proteins using a phosphate group from ATP? Phosphatases Phosphorylases Kinases Cyclases

Kinease

For solutes that cannot diffuse through the membrane, water moves across the membrane from a region of ______ to a region of ______ solute concentration. High to low Low to high

Low to high

Which of the following is NOT true of cell membranes? Membranes are fluid, which allows proteins to move laterally in the membrane like "icebergs floating in a lipid sea." Proteins and lipids are oriented asymmetrically in the membrane. Membranes consist of rigid patches of lipids arranged together in a mosaic like the tectonic plates. Membranes are amphipathic: regions of both lipids and proteins are in the membrane interior with hydrophilic regions on the outside.

Membranes consist of rigid patches of lipids arranged together in a mosaic like the tectonic plates.

Which of the following is a disadvantage of being a multicellular organism specifically as opposed to unicellular? (read and think carefully!) Increased mobility More difficult to absorb nutrients Loss of peptidoglycan reduces stability All of the above

More difficult to absorb nutrients-In unicellular organisms, such as bacteria or protists, the entire cell surface is available for nutrient absorption. They can directly take in nutrients from their environment through processes like diffusion, osmosis, or active transport. This direct exposure to the environment allows them to efficiently absorb nutrients.

NADH and FADH2 differ in that: Only NADH results in pumping of H+ it the intermembrane space. NAD+ has a higher reduction potential. Only NADH involves transfer of electrons from Complex I to Ubiquinone/CoQ. Only NADH transfers electrons through Complex II.

Only NADH involves transfer of electrons from Complex I to Ubiquinone/CoQ.

Which of the following should be able to diffuse most easily through a cell's plasma membrane? H2O H+ glucose O2

Oxygen (O2) is a small, non-polar molecule, which allows it to readily diffuse through the lipid bilayer of the cell membrane. The lipid bilayer is permeable to non-polar molecules like oxygen due to its hydrophobic interior. Oxygen molecules can passively diffuse across the membrane from areas of higher concentration to areas of lower concentration, driven by the concentration gradient.

If you wanted to decrease liver cell responses to epinephrine, which of the following classes of enzymes would you want to increase in activity? Adenylate cyclase Phosphorylases Kinases Protein phosphatase (catalyzes dephosphorylation)

Protein phosphatase (catalyzes dephosphorylation) If you wanted to decrease liver cell responses to epinephrine, which typically triggers the "fight or flight" response, you would want to reduce the activity of pathways involved in amplifying the signal initiated by epinephrine. Epinephrine typically activates adenylate cyclase, which increases cAMP levels, leading to activation of protein kinase A (PKA) and subsequent phosphorylation of target proteins to carry out the cellular response.

Which of the following is/are NET products of glycolysis? ADP NAD+ Pyruvate All of the above

Pyruvate

What uses simple diffusion?

Small molecules (like respiratory gasses) and nonpolar hydrophobic substances

Where in the cell would you expect to see a Ca++ ATPase? Smooth ER Nucleus Golgi complex Lysosome

Smooth er Which organelle stores large amounts of Ca++?

Assuming O2 is available, in which of the following structures would you expect to see the highest pH? The intermembrane space of the mitochondria The mitochondrial matrix The cytoplasm

The mitochondrial matrix

Which of the following is true of steroid hormones but not a signaling molecule such as a ligand for G-protein coupled receptors? An extracellular signal is transduced to an intracellular response. Their cellular effects are strong due to signal amplification. Their receptors regulate gene transcription. They may have widespread effects because they may be secreted into the bloodstream.

Their receptors regulate gene transcription. teroid hormones, unlike signaling molecules such as ligands for G-protein coupled receptors, exert their effects by binding to intracellular receptors, which then regulate gene transcription. This process leads to the synthesis of specific proteins that mediate the hormonal response. On the other hand, ligands for G-protein coupled receptors typically initiate signaling cascades through second messengers without directly influencing gene transcription

Which of the following is true of both GPCR signaling and steroid hormone signaling? They both involve intracellular receptors. They may result from endocrine signals. Both effects are rapid and reversible. They both involve enzyme cascades.

They may result from endocrine signals.

Cell adhesion molecules are important components of: Tight junctions Extracellular matrix plant cell walls bacterial cell walls

Tight Junctions-Cell adhesion molecules are crucial components of tight junctions, as they help to anchor cells together and maintain the integrity of the junctions. These molecules facilitate the adhesion of adjacent cells in the epithelial layer, contributing to the sealing function of tight junction

True or False: The concentration of Ca++ inside the cell is higher than it is outside. True False

True

autocrine signaling

Type of cell communication in which a cell secretes signaling molecules (such as hormones or growth factors) that bind to receptors on its own cell surface or nearby cells of the same type. In other words, the signaling molecule acts on the same cell that produced it or on neighboring cells of the same type.

direct active transport

accumulation of solute or ions on one side of the membrane is directly coupled to an exergonic reaction (i.e., hydrolysis of ATP) which leads to transport across the membrane

Consuming very large amounts of certain foods/drinks can affect the digestive system in profound ways. Which of the following would LEAST likely cause some sort of osmotic shock to your stomach and intestinal cells if you consumed a very large amount of it in a short period of time? Water Table salt (NaCl) Amino acid supplements for body-building Sugar Butter

butter

In prokaryotes, where does the Krebs Cycle occur? Cytoplasm Rough ER Mitochondria Plasma membrane

cyto

Glycolysis: Takes place in mitochondria. Does not produce ATP. Is anabolic. Does not require O2. Produces CO2

does not require O2

Phosphofructokinase (PFK-1) may be the most tightly regulated enzymes in cells. Based on all of the principles we have learned in this class, which of the following would be most likely to be an allosteric activator of PFK-1? CO2 ATP Acetyl-CoA glucose

glucose

Which of the following pathways DOES NOT require O2? Glycolysis Pyruvate oxidation in the PDH The Krebs Cycle Electron transport system All of the above None of the above

glycosis

Factors that increase membrane fluidity have the effect of _______ membrane permeability: Increasing Decreasing There is no relationship

increasing

For solutes that cannot diffuse through the membrane, water moves across the membrane from a region of ______ to a region of ______ solute concentration. Low to high High to low

low to high

indirect active transport

membrane transport involving the cotransport of two solutes in which the movement of one solute down its gradient drives the movement of the other solute up its gradient

simple diffusion

movement of a solute from an area of high concentration to an area of low concentration

If you blocked fermentation in an anaerobic cell, would it survive? Yes No

no

The energy for ADP phosphorylation by Synthase (F1) comes directly from: The decrease in pH resulting from H+ flux Rotation ATP hydrolysis by F0 The H2O produced at the end of the electron transport system

rotation

endocrine

the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream tissue that makes and releases hormones that travel in the bloodstream and control the actions of other cells or organs. Some examples of endocrine tissues are the pituitary, thyroid, and adrenal glands.

comes from glycolysis. True False

true

Juxcrine

type of cell communication in which the signaling molecule remains attached to the cell surface of the signaling cell and interacts with receptors on the surface of an adjacent target cell. In juxtacrine signaling, direct contact between the two cells is required for the transmission of signals, as opposed to the diffusion of signaling molecules through the extracellular space