Chapter 9 & 11 Bio Exam 2 review
Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that can still transfer electrons from NADH to oxygen and synthesize ATP. After the disruption, when electron transfer and ATP synthesis still occur, what must be present?
all of the electron transport proteins and ATP synthase
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that can still transfer electrons from NADH to oxygen and synthesize ATP. Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in _________.
all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
A cell has enough available ATP to meet its needs for about 3 seconds. What is likely to happen when an athlete exhausts his or her ATP supply?
catabolic processes are activated that generate more ATP
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the ______.
creation of a proton-motive force
The activation of a receptor tyrosine kinases is characterized by
dimerization and phophorylation
Fatty acids usually have an even number of carbons in their structures. They are catabolized by a process called beta-oxidation. The end products of the metabolic pathway are acetyl groups of acetyl coA molecules. These acetyl groups ____________.
directly enter the citric acid cycle
New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Why do athletes need to monitor lactate levels?
during anaerobic respiration, lactate levels increase when muscle cells need more energy, however muscle cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.
Sutherland discovered that the signaling molecule epinephrine ________.
elevates cytosolic concentrations of cyclic AMP
Calcium ions that act as second messengers are stored in _______.
endoplasmic reticula
the chemiosmotic hypothesis is an important concept in understanding of cellular metabolism in general because it explains _______.
how ATP is synthesized by a proton motive force
GTPase activity is important in the regulation of signal transduction because it
hydrolyzes GTP to GDP, thus shutting down the pathway
Scaffolding proteins are _______.
large molecules in which several really proteins attach to facilitate cascade effects
During anaerobic respiration, H2O is formed. Where does the oxygen for the formation of water come from?
molecular oxygen (O2)
If you were to add one of the 8 citric acid cycle intermediates to the medium of yeast growing in the lab, what do you think would happen to the rates of ATP and carbon dioxide production?
the rates of ATP production and carbon dioxide production would both increase.
Which of the following is true of steroid receptors?
the receptor may be inside the nucleus of a target cell
Protein phosphorylation is not commonly involved with:
-activation of G protein coupled receptors
Substrate-level phosphorylation accounts for approx what percentage of ATP formed by the reactions of glycolysis?
100%
If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approx how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?
14
Starting with one molecule of glucose, the energy-containing products of glycolysis are:
2 NADH, 2 pyruvate, and 2 ATP
If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals in generated by the reactions of the citric acid cycle?
2/3
Starting with citrate, which combination would result from three acetyl coA molecules entering the citric acid cycle?
3 ATP, 6 CO2, 9 NADH, and 3 FADH2
Approx how many molecules of ATP are produced from the complete oxidation of one molecule of glucose in aerobic cellular respiration?
30-32
For each mole of glucose oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle?
4
In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of what?
ATP, CO2, ad ethanol (ethyl alcohol)
Which of the following is true during a typical cAMP-type signal transduction event?
Andenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation of proteins occurs.
Which of the listed statements describes the results of the following reaction? C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
C6H12O6 is oxidized and O2 is reduced
You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave his body?
CO2 and H2O
At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogen and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?
Estrogen binds to specific receptors inside many kinds of cells, each with different responses.
During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
FADH2
Which of the following is a correct association?
GTPase activity and hydrolysis of GTP to GDP
The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol and the free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?
Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
Which of the following statements about NAD+ is true? -NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. -NAD+ has more chemical energy than NADH. -NAD+ can donate electrons for use in oxidative phosphorylation. -In the absence of NAD+ glycolysis can still function.
NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point of the process, however, is in the form of ________.
NADH
Which electron carrier(s) function in the citric acid cycle?
NADH and FADH2
A drug designed to inhibit the response of cells to testosterone would most likely result in ________
a decrease in transcriptional activity of certain genes
If an adult person has a faulty version of the human analog to ced-4 of the nematode, which of the following is the most likely to result?
a form of cancer in which there is insufficient apoptosis
Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction?
a lipid-soluble signal
The oxygen consumed during cellular respiration is involved directly in which process or event?
accepting electrons at the end of the electron transport chain
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. What is formed by the removal of a carbon (as CO2) from a molecule of pyruvate?
acetyl coA
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. The three steps listed result in the formation of:
acetyl coA, NADH, and CO2.
The primary role of oxygen in cellular respiration is to
act as an acceptor for electrons and hydrogen, forming water
Protein kinase is an enzyme that _______.
activates or inactivates other proteins by adding a phosphate group to them
In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function?
aggregation of bacteria that can cause cavities
Even though plant cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in ________.
all cells all the time
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of:
allosteric regulation
Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they _________.
amplify the original signal many times
What kind of metabolic poison would most directly interfere with glycolysis?
an agent that closely mimics the structure of glucose but is not metabolized
The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of _______.
an endergonic reaction coupled to an exergonic reaction
Canine phosphofructokinase deficiency (PFK) afflicts springer spaniels, affecting an estimated 10% of the breed. Given its critical role in glycolysis, one implication of the genetic defect resulting in PFK deficiency in dogs is ______.
an intolerance for exercise
A major group of G-protein-coupled contains 7 transmembrane helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others. Where would you expect to find the carboxyl end?
at the cytosol surface
A major group of G-protein-coupled contains 7 transmembrane helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others. The coupled G protein most likely interacts with this receptor where?
at the loop between the H5 and H6
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that can still transfer electrons from NADH to oxygen and synthesize ATP. These inside out vesicles will __________.
become acidic inside the vesicles when NADH is added
Testosterone functions inside a cell by __________.
binding with a receptor protein that enters the nucleus and activates specific genes
In yeast signal transduction, a yeast cell releases a mating factor which _________.
binds to receptors on the membranes of other types of yeast cells
In respiration, beta oxidation involves the
breakdown of fatty acids
Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of:
cAMP
What is false about quorum sensing?
cell-cell communication in eukaryotes
Most of the CO2 from the catabolism of glucose is released during:
citric acid cycle
If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a ___________.
compound that increase phosphodiesterase activity.
If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a ___________.
compound to block G protein activity in liver cells
Transcription factors ________.
control gene expression
Cells that are infected, damaged, or have reached the end of their functional life span often undergo "programmed cell death." This controlled cell suicide is called apoptosis. Select the appropriate description of this event on a cell's life cycle.
during apoptosis, cellular agents chop up the DNA and fragment the organelles and other cytoplasmic components of a cell.
In chemiosmosis, what is the most direct source of energy that is used to convert ADP + i to ATP?
energy released from movement of protons through ATP synthase, down their electrochemical gradient
Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy?
glucose
During aerobic respiration, electrons travel downhill in which sequence?
glucose to NADH to electron transport chain to oxygen
Which observations suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?
glycogen breakdown was observed only when epinepherine was administered to intact cells
Which of the following occurs whether or not oxygen is present?
glycolysis
Which of the following occurs in the cytosol of a eukaryotic cell?
glycolysis and fermentation
In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following, if found in cells or organisms as they age, would provide evidence that this is related to cell signaling?
growth factor ligands do not bind as efficiently to receptors
Carbohydrates and fats are considered high-energy foods because they ______.
have a lot of electrons associated with hydrogen
Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. For the target organ to respond to a particular hormone, it must ___________.
have receptors that recognize and bind to the hormone molecule
A young dog has never had much energy. He is brought to a vet for help and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can only use fatty acids and amino acids for respiration, and his cells produce more lactate than normal. What is the best explanation of the dog's condition?
his mitochondria lacks the transport protein that moves pyruvate across the outer mitochondrial membrane.
Particular receptor tyrosine kinases (RTKs) that promote excessive cell division are found at high levels on various cancer cells. A protein, herceptin, has been found to bind to an RTK known as HER2. HER2 is sometimes excessive in cancer cells. This info can now be utilized in breast cancer treatment if which of the following is true?
if the patients cancer cells have excessive levels of HER2
Where does substrate level phosphorylation occur?
in both glycolysis and the citric acid cycle
In signal transduction, phosphatases, ________.
inactivate protein kinases and turn off the signal transduction
Which of the following is the best explanation for the inability of a specific animal cell to reduce the Ca2+ concentration in its cytosol compared with the extracellular fluid?
insufficient ATP levels in the cytosol
Scientists have found that extracellular matrix components may induce specific gene expression in embryonic tissues such as the liver and testes. For this to happen there must be direct communication between the extracellular matric and the developing cells. Which kind of transmembrane protein would most likely be involved in this kind of induction?
integrins
What is a characteristic of a steroid hormone action?
internal receptor binding
Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because
intracellular receptors are present only in target cells
An organism is discovered that thrives in both the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organisms environment, even though the organism does not gain much weight. This organism _______.
is a facultative anaerobe.
The electron transport chain ______.
is a series of redox reactions
A G protein receptor with GTP bound to it _________.
is in its active state
In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?
it increases the surface for oxidative phosphorylation
The toxin vibrio cholerae cause profuse diarrhea, why?
it modifies a G protein involved in regulating salt and water secretion
In the nematode C. elegans, ced-9 prevents apoptosis in a normal cell in which of the following ways?
it prevents the caspase activity of ced-3 and ced-4
If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?
it would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane
Binding of a signaling molecule to which type of receptor leads directly to a change in distribution of ions on opposite sides of the membrane?
ligand-gated ion channel
Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?
ligand-gated ion channel
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction ________________.
loses electrons and loses potential energy
Glycolysis is active when cellular energy levels are _______; the regulatory enzyme, phosphofructokinase, is ___________ by ATP.
low;inhibited
Apoptosis involves all but which of the following?
lysis of the cell
What does apoptosis involve?
lysis of the cell
Why is apoptosis potentially threatening to the healthy "neighbors" of a dying cell?
lysosomal enzymes exiting the dying cell would damage the surrounding cell
Where are the proteins of the electron transport train located?
mitochondrial inner membrane
Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?
mitochondrial intermembrane space
If pyruvate oxidation is blocked what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle?
oxaloacetate will accumulate and citric acid will decrease.
Carbon dioxide is released during which of the following stages of cellular respiration?
oxidation of pyruvate to acetyl coA and the citric acid cycle.
One function of both alcohol fermentation and lactic acid fermentation is to ________.
oxidize NADH to NAD+
When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes __________.
oxidized
Which is a type of local signaling that affects neighbor cells?
paracrine
Adenylyl cyclase has the opposite effect of which of the following?
phosphodiesterase
An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?
phospholipase C
In which way do plant hormones differ from hormones in animals?
plant hormones most often travel in air as a gas
What is true of signal molecules?
protein kinase A activation is one possible result of signal molecules binding to G protein-coupled receptors
Which of the following would most likely be an immediate result of a growth factor binding to its receptor
protein kinase activity
What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+
pyruvate
Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins?
receptor tyrosine kinase activity
One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this?
receptor tyrosine kinases
When a molecule of NAD + gains a hydrogen atom (not a proton) the molecule becomes _________.
reduced
When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is __________.
reduced, and energy is released
In general, a signal transmitted via phosphorylation of a series of proteins ______.
results in a conformational change to each protein
Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction?
serine and threonine
When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?
signal molecule
Which of the following poses the best evidence that cell-signaling pathways evolved early in the history of life?
signal transduction molecules identified in distantly related organisms are similar.
The receptors for steroid hormones are located inside the cell instead of on the membrane like most other signal receptors. This is not a problem for steroids because ________.
steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane
Which of the following describes the events of apoptosis?
the cell's DNA become and organelles become fragmented, the cell shrinks and forms blebs, and the cell's parts are packaged in vesicles that are digested by specialized cells
What event takes place in the electron transport chain?
the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle.
Viagra cause dilation of blood vessels and increased blood flow to the penis, facilitating erection. Viagra act by inhibiting what?
the hydrolysis of cGMP to GMP
Why has C. elegans proven to be a useful model for understanding apoptosis?
the nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development.
What does It mean to say that a signal is transduced?
the physical form of the signal changes from one form to another
In glycolysis, for each molecule of glucose oxidized to pyruvate _______.
two molecules of ATP are used and 4 molecules of ATP are produced.
