BYS 300 Final
spectrin
Red blood cells have been very useful in the study of membranes and the protein components that provide structural support. Which of the following proteins is the principal fibrous protein in the cortex of the red blood cell?
Synthesis of proteins ___________
Ribosomes
True
Ribosomes are cytoplasmic structures that, during protein synthesis, become linked by an mRNA molecule to form polyribosomes.
True
Ribosomes are cytoplasmic structures that, during protein synthesis, become linked by an mRNA molecule to form polyribosomes.
False. The outer nuclear membrane is continuous with the ER in all proteins made by ribosomes bound there end up in the ER lumen
Ribosomes bound to the outer nuclear membrane make proteins that are translocated co-translationally into the membrane.
True
Secretory vesicles bud off the trans face of the Golgi.
True
The final electron acceptor in the mitochondrial electron transport chain is oxygen.
Chloroplast
The final electron acceptor is NADP+
Answer: True
The final electron acceptor is oxygen.
False. Acetylcholine is short-lived and exerts its affects locally. Indeed, the consequences of prolonging its lifetime can be disastrous. Compounds that inhibit the enzyme acetylcholinesterase Which normally breaks down acetylcholine a nerve muscle synapse, are extremely toxic: for example, the nerve gas sarin, used in chemical warfare is in acetylcholinesterase inhibitor.
After acetylcholine is secreted from cells, it is long-lived, because it has to reach target cells all over the body.
True
After an electron has been removed by light, the positively charged chlorophyll in the reaction center of the first photosystem (photosystem II) has a greater affinity for electrons than O2 has
How do Wee 1 and Cdc25 regulate the activity of the mitotic CDK?
As soon as the M cyclin-CDK complex is formed, it is phosphorylated at two adjacent sites by the inhibitory protein Wee1. This modification results in an inactive M cyclin-CDK complex. The phosphates are then removed from the activating phosphatase Cdc25, which dephosphorylates the M cyclin-CDK complex, resulting in its active form.
True
Glycolipids move between different membrane-enclosed compartments during their synthesis but remain restricted to one side of the lipid bilayer
True
Glycolysis can occur in the absence of oxygen
Fermentation will occur, rather than proceeding to the TCA cycle. This process occurs to regenerate NAD+.
Glycolysis is considered an anaerobic process where oxygen is not used in the pathway. However, oxygen is necessary for glycolysis to occur. Explain what will happen during this condition (when oxygen is not present). Why?
False (glycolysis will still occur)
Glycolysis will not occur in the absence of oxygen.
False
Green plants have only chlorophyll as the photosynthetic pigment in their leaves.
Where does mitochondrial electron transport chain occur?
Inner Mitochondrial Membrane
Which enzyme can join two ends of DNA together?
ligase
Name the process in which larger molecules are broken down into smaller molecules
catabolism
How many ATP and NADPH are used in the calvin cycle?
9ATP and 6NADPH
False
A cell can live on its own without any messages from its surroundings.
For a reaction A + B→C + D which is at equilibrium, which of the following is true? A. ∆G = 0 B. Keq = 1 C. ∆G > 0 D. ∆G < 0
A. ∆G = 0
What are the similarities and differences between the reactions that lead to the activation of G proteins and the reactions that lead to the activation of Ras?
Activation in both cases depends on proteins that catalyze GDP-GTP exchange on the G protein or Ras protein. Whereas activated GPCRs perform this function directly for G proteins, enzyme-linked receptors assemble multiple signaling proteins into a signaling complex when the receptors are activated by phosphorylation; one of these is an adaptor protein that recruits a guanine nucleotide exchange factor that fulfills this function for Ras.
False
All eukaryotic cells take 24 hours to complete the cell cycle.
True
All transport vesicles in the cell must have a v-SNARE protein in their membrane.
False
An action potential can move in both directions
True
Because it requires the removal of four electrons to release one O2 molecule from two H2O molecules, the water-splitting enzyme in photosystem II has to keep the reaction intermediates tightly bound so as to prevent partly reduced, and therefore hazardous, superoxide radicals from escaping.
True
Chloroplast's electron transport chain has one pump only
True
Both the concentration gradient and the membrane potential affect the passive transport of charged solutes
Which of these proteins is not found in the nucleosome core? A. H3 B. H2A C. H1 D. H4
C. H1
Which of the following organelles has three membranes? A. lysosome B. nucleus C. chloroplasts D. mitochondria
C. chloroplasts
In eukaryotes translation occurs in the _________ and transcription occurs in the ________. A. nucleus, cytosol B. nucleus, nucleus C. cytosol, nucleus D. nucleolus, cytosol
C. cytosol, nucleus
Energetically favorable reactions A. are not possible B. have a Keq < 1 C. have a negative ∆G D. create order in the universe
C. have a negative ∆G
Which type of eukaryotic RNA is synthesized by RNA Polymerase I? A. tRNA B. hnRNA C. rRNA D. micro RNA
C. rRNA
Lactate
During anaerobic metabolism in muscle cells pyruvate is converted to
True
During glycolysis there is a net production of 2 ATP
True
During glycolysis, there is a net production of 2 ATPs.
False (unsaturation will decrease)
During high temperatures, unsaturation increases.
Both mitochondria and chloroplasts
Electron transfer leads to establishment of a proton gradient
What organelle is directly attached to the nucleus?
Endoplasmic reticulum
Site of addition of lipids and carbohydrates to proteins being secreted ________________
Golgi Apparatus
1. A: Extrinsic apoptosis stimulated by cell-surface receptor 2. A: Intrinsic apoptosis stimulated by p53 3. A: Necrosis
Read and indicate if the following statements undergo necrosis, extrinsic apoptosis, or intrinsic apoptosis. Describe what initiates both extrinsic and intrinsic apoptotic pathways. 1. A viral-infected cell recognized by phagocytic cells. 2. The DNA of a skin cell is damaged by UV light. 3. The buildup of reactive oxygen intermediates within a somatic cell leading to cell lysis.
False
In prokaryotes the TCA cycle occurs in the mitochondria
False
In prokaryotes, the electron transport chain involves the mitochondrial membrane.
False (ethanol)
In yeast cells, lactate is produced during anaerobic conditions
Adaptin
The protein that determines which cargo proteins will be transported in a specific vesicle is
Answer: True
The proton-motive force consists of membrane potential and pH.
T or F: ∆G is different from ∆G˚
True
Plus, minus, plus
Tubulin add to the ______ end of microtubules and fall off of the _______ end of the microtubules. However, actin filaments add to and dissociate from the _______ end.
False
Twelve ATP molecules are produced from one acetyl-CoA during the TCA cycle
True
Tyrosine phosphorylation serves to build binding sites for other proteins to bind to RTKs.
True
Ubiquinone and cyctochrome c are both diffusable electron carriers
Answer: False (Ubiquinone or Cytochrome Q is an electron carrier not a protein)
Ubiquinone is a protein embedded in the membrane.
Mitochondria
Water is produced as a result of electron transfer.
In the endoplasmic reticulum
Where does most new membrane synthesis take place in a eukaryotic cell?
from sunlight
Where does the energy for photosynthesis come from?
True
Most enzyme-linked receptors have turned out to be tyrosine kinases.
Answer: True
NADH produces more ATP than FADH2.
False (NADH has more energy)
NADH yields less energy than FADH2
What process can form larger molecules from smaller molecules?
anabolism
Which of the following modifications are not known to occur to histone proteins? A. acetylation B. methylation C. phosphorylation D. sulfonylation
D. sulfonylation
T or F: The ∆G of a spontaneous reaction is always >0.
False
False
Fermentation only occurs during anaerobic conditions to regenerate FADH2
False (Lateral movement is spontaneous)
Flip-Flop movement of phospholipids is spontaneous
False. Two cars bending,
GTP is hydrolyzed by tubulin to cause the bending of flagella.
What organelle has 3 membranes?
chloroplast
Name the organelle that metabolizes reactive oxygen species:
peroxisomes
Surrounds the cytoplasm ____________ __________
plasma membrane
False (low pH)
High proton concentration means high pH
Where does light-independent stage occur in the cell?
Stroma
Seven Characteristics of Life
1. Highly organized 2. Maintain Homeostasis 3. Ability to reproduce 4. Growth and development 5. Metabolize energy 6. Respond to stimuli 7. Adapt to their environment
Alpha helix and beta sheet are types of __________ structures of _________. A. secondary, proteins B. tertiary, proteins C. secondary, nucleic acids D. primary, proteins
A. secondary, proteins
Answer: 20 ATP 6 NADH * 2.5 ATP = 15 ATP 2 FADH2 * 1.5 ATP = 3 ATP 2 ATP Total: 15 ATP + 3 ATP + 2 ATP = 20 ATP
2 NADH and 2 ATP are produced during Glycolysis and 2 NADH are produced from pyruvate oxidation to acetyl-CoA. However, the citric acid cycle produces 6 NADH, 2FADH2, and 2ATP. How many ATP are produced? (Hint: NADH = 2.5 ATP and FADH2 = 1.5 ATP)
Amphipathic
A molecule that has both a hydrophilic portion and a hydrophobic portion is said to be
Diagram and describe the process by which proteins are transported from the cytosol into the nucleus.
A protein containing a nuclear localization signal is recognized by a cytosolic import receptor. The import receptor and the signal sequence on the protein bind. The import receptor associates with the cytosolic fibrils and the protein and receptor move into the nucleus through a nuclear pore. Once in the nucleus, the protein and the signal sequence dissociate from the import receptor by the binding of Ran-GTP to the import receptor. The protein and the signal sequence stay in the nucleus while the import receptor and Ran-GTP exit the nucleus and enter the cytosol. Once in the cytosol, the Ran-GTP is hydrolyzed to become Ran-GDP which will then dissociate from the import receptor. The import receptor is now ready to recognize more proteins destined for the nucleus.
Diagram and describe the process by which proteins are transported from the cytosol into the nucleus. (Part 2)
A protein containing a nuclear localization signal is recognized by a cytosolic import receptor. The import receptor and the signal sequence on the protein bind. The import receptor associates with the cytosolic fibrils and the protein and receptor move into the nucleus through a nuclear pore. Once in the nucleus, the protein and the signal sequence dissociate from the import receptor by the binding of Ran-GTP to the import receptor. The protein and the signal sequence stay in the nucleus while the import receptor and Ran-GTP exit the nucleus and enter the cytosol. Once in the cytosol, the Ran-GTP is hydrolyzed to become Ran-GDP which will then dissociate from the import receptor. The import receptor is now ready to recognize more proteins destined for the nucleus.
Topoisomerase
A researcher testing plant products as potential new therapeutics notes that molecule X induces cultured human cells to arrest within the S phase of the cell cycle. Which of the following is the most likely target of molecule X?
a membrane protein
A start-stop sequence is found in a protein that will be
False
A symport would function as an antiport if its orientation in the membrane were reversed (i.e., if the portion of the molecule normally exposed to the cytosol faced the outside of the cell instead)
By definition, prokaryotic cells do not possess __________. A. nucleus B. ribosomes C. DNA D. RNA
A. nucelus
The structure consisting of histone proteins with DNA wrapped around them is a A. nucleosome B. nucleolus C. nucleus D. nuclear membrane
A. nucleosome
Non-coding sequences at the ends of eukaryotic chromosomes are called A. telomeres B. exons C. introns D. origins of replication
A. telomeres
True
Actin filaments can add new monomers to either the plus end or the minus end.
True
Actin protein monomers associate with each other non-covalently to form actin filaments.
False
All of the energy produced is in the form of heat
Na+
All of the following can diffuse through the cell membrane except
Cl-
All of the following can diffuse through the cell membrane except:
False
All proteins in the membrane can freely diffuse
True. Otherwise they could not dock at the correct target membrane or recruit a fusion complex to a docking site.
All transport vesicles in the cell must have a v-SNARE protein in their membrane.
False
Although cholesterol is a hydrophobic molecule, it has a hydrophillic head group like all other membrane lipids.
A ligand gated channel
An ion channel that is opened by binding of a signal molecule to it is called
Ligand-gated channel
An ion channel that opens and closes based on the binding of a hormone to it is called a
False
Decreasing the percentage of unsaturated fatty acids in a biological membrane will increase its fluidity.
The transmembrane proton gradient is used to drive ATP synthesis
Define chemiosomotic coupling.
During translation, each animo-acyl tRNA binds in which site on the ribosome? A. P B. A C. E D. stop codon
B. A
Which of the following types of bonds is a covalent bond between cysteine amino acids? A. hydrogen bonds B. disulfide bonds C. ionic bonds D. hydrophobic forces
B. disulfide bonds
The 3' to 5' exonuclease activity of DNA Polymerase III is used to A. fill gaps B. proofread DNA synthesis C. remove primers D. synthesize the DNA
B. proofread DNA synthesis
In prokaryotes the role of the sigma factor is A. recognize the start codon for translation B. recognize the promoter for transcription C. help DNA polymerase bind to the origin of replication D. be a termination factor for translation
B. recognize the promoter for transcription
Answer: False (NADH donates electrons to complex I)
Both NADH and FADH2 donate electrons to complex I (NADH Dehydrogenase)
False (transporters are not gated)
Both channels and transporters are selective and gated.
True
Both chlorophyll and heme contain an extensive system of double bonds that allows them to absorb visible light
False
Both chloroplasts and mitochondria have three membranes
True. Nucleotide free Beta-gamma complexes can activate ion channels, GTP-bound alpha subunits can activate enzymes. The GDP-bound form of trimeric G proteins is the inactive state.
Both the GTP-bound alpha subunits and nucleotide-free beta gamma complexes--but not GDP-bound, fully assembled G proteins--can activate other molecules downstream of GPCRs.
True
Both the GTP-bound α subunits and nucleotide-free ẞɣ complexes—but not GDP-bound, fully assembled G proteins—can activate other molecules downstream of GPCRs.
Answer: True
During the presence of uncoupling agents, the energy stored in proton is released as heat.
Which of the following types of microscopy employs a light microscope and requires that samples be fixed and stained in order to reveal cellular details?
Bright field
False
Calmodulin regulates the intracellular Ca 2+ concentration.
False. Calmodulin senses but does not regulate intracellular Ca2+ levels
Calmodulin regulates the intracellular Ca2+ concentration.
True
Carbon dioxide is produced during the Krebs' cycle
True
Cells expend energy in the form of ATP hydrolysis so as to maintain ion concentrations that differ from those found outside the cell.
H+ symporter
Cells make use of H+ electrochemical gradients in many ways. Which of the following proton transporters is used to regulate pH in animal cells?
True
Certain H+ pumps are fueled by light energy
False
Channels have specific binding pockets for the solute molecules they allow to pass
What makes a good model organism?
Cheap, easy to grow, and easy to genetically manipulate
True
Complex 2 of the electron transport chain accepts the electrons from FADH2
Answer: False (Complex II is the only complex that is not a pump)
Complex II or Succinate Dehydrogenase is a proton pump.
False (2 is not a proton pump)
Complexes I, II, III are proton pumps
Answer: False (Complexes I, III, and IV are transmembrane proteins, while Complex II is a peripheral protein)
Complexes II, III, and I are transmembrane proteins.
ATP; GTP
Cyclic AMP is derived from _________________, while cyclic GMP is derived from ________________.
How does cyclic AMP become AMP?
Cyclic AMP is formed from ATP by using the enzyme adenylyl cyclase to remove two phosphate groups from ATP and join the remaining phosphate to the sugar part of the AMP molecule. Once cyclic AMP is formed, it can be degraded by the enzyme cyclic AMP phosphodiesterase which adds water to the compound, breaking the bond between the phosphate and the sugar, thereby creating AMP.
False
Cyclic phosphodiesterase converts cyclic AMP back to ATP.
Muscle contraction Amoeboid movements of phagocytic cells Formation of the cleavage furrow following telophase of mitosis
Cytochalasin D inhibits the formation of microfilaments. Which of the following biological activities will be hindered?
Answer: False (Cytochrome c receives electrons from complex III and donates the electrons to complex IV. Complex IV will donate electrons to oxygen)
Cytochrome c is a soluble protein that receives electrons from complex II and donates electrons directly to oxygen.
False
Cytochrome c is embedded in the membrane.
True
Cytochromes have heme with Fe to accept and donate electrons
Answer: 10 ATP Products of TCA cycle: 1 FADH2, 1 GTP, 3 NADH 3 NADH * 2.5 ATP = 7.5 ATP 1 FADH2 = 1.5 ATP 1 GTP = 1 ATP Total = 7.5 ATP + 1.5 ATP + 1 ATP = 10 ATP
How many ATP are produced from one acetyl-CoA?
Name the sequence known as the Central Dogma
DNA transcribes to RNA translates to Proteins
True
Hydrogen bonds that form between lipid head groups and water molecules are continually broken and re-formed
Contact dependent
Delta binding to the Notch receptor is a type of __________ signaling.
Microtubules: Figure in book Intermediate filaments: Figure in book Actin filaments: Figure in book
Describe the formation mechanism of microtubules, intermediate filaments, and actin filaments.
True
Different signals originating from the plasma membrane can be integrated by cross-talk between different signaling pathways inside the cell.
True
During the light-dependent reactions of photosynthesis the pH in the thylakoid lumen decreases
True
During the presence of uncoupling agents, oxygen consumption occurs but ATP production is inhibited
Answer: True
During the presence of uncoupling agents, oxygen consumption occurs but ATP production is inhibited.
GTP
Dynamic instability in microtubules is driven by the hydrolysis of
Mutations that inhibit the activity of p53
Each of the following events is likely to trigger cell apoptosis, except:
False
In eukaryotes, all membrane-enclosed organelles are surrounded by one lipid bilayer
True
Electrons are donated to the molecule with the highest reduction potential.
A chemical reaction is defined as spontaneous if there is a net loss of free energy during the reaction process. However, spontaneous reactions do not always occur rapidly. Favorable biological reaction required ___________ to selectively speed up reactions and meet the demands of the cell.
Enzymes
False
Equal solutes concentration on both sides of the membrane generates a positive potential. (Hint: V = 62/z * log(Cout/Cin)
We see light that bounces off of objects (reflected light). Chlorophyll is best at trapping and absorbing the red - orange wavelengths of light and the blue, indigo, and violet wavelengths of light. It is not good at absorbing the green wavelengths. The green light is reflected, so it is the part we see. Therefore, chlorophyll looks green to us.
Explain why chlorophyll appears green to us in terms of what happens to different wavelengths of light that strike a chlorophyll molecule.
False
FAD+ reduction to FADH2 occurs during pyruvate oxidation
T or F: All amino acids are hydrophobic.
False
T or F: All amino acids have more than one codon.
False
T or F: DNA Polymerase adds nucleotides in the 5' to 3' direction on one strand and in the 3' to 5' direction on the other.
False
T or F: Histones have large numbers of negatively charged amino acids.
False
T or F: Ribosomes must wait for transcription to finish before it can start translating an mRNA molecule
False
T or F: TEM and SEM illuminate the specimen using a beam of light.
False
True
Fifteen ATP molecules are produced from 6 NADH
Answer: False (intermembrane space)
High proton concentration is established in the matrix.
False (intermembrane space and thylakoid space)
High proton concentration is established in the mitochondrial matrix and chloroplast's stroma.
It is stored as starch.
How can cells store the sugar that is produced in photosynthesis?
As soon as the M cyclin-CDK complex is formed, it is phosphorylated at two adjacent sites by the inhibitory protein Wee1. This modification results in an inactive M cyclin- CDK complex. The phosphates are then removed from the activating phosphatase Cdc25, which dephosphorylates the M cyclin-CDK complex, resulting in its active form.
How do Wee 1 and Cdc25 regulate the activity of the mitotic cdk?
Use Figures in book. You will not have to describe this in detail on your exam, but you may have a question that asks about a specific segment of this mechanism.
How do muscles contract? Describe this mechanism in detail.
Cyclic AMP is formed from ATP by using the enzyme adenylyl cyclase to remove two phosphate groups from ATP and join the remaining phosphate to the sugar part of the AMP molecule. Once cyclic AMP is formed, it can be degraded by the enzyme cyclic AMP phosphodiesterase which adds water to the compound, breaking the bond between the phosphate and the sugar, thereby creating AMP.
How does cyclic AMP become AMP?
As wavelength increases, amount of energy decreases. Thus, violet light (which has a shorter wavelength) has more energy that red light (which has a longer wavelength).
How does the amount of energy in light change as the wavelength increases?
It is the reverse of the overall reaction for cellular respiration.
How does this compare to the overall reaction for cellular respiration?
False
Hydrophobic portions of molecules interact well with water molecules
True
IP 3 is produced directly by cleavage of an inositol phospholipid without incorporation of an additional phosphate group.
True. The inositol phospholipid that is cleaved to produce IP3 contains three phosphate groups, one of which links the sugar to the diacylglycerol live bed. IP3 is generated by a simple hydrolysis reaction
IP3 is produced directly by cleavage of an inositol phospholipid without incorporation of an additional phsophate group.
True. Lysosomal proteins are selected in the trans Golgi network and packaged into transport vesicles that deliver them to the late endosomes. If not selected, they would enter by default into transport vesicles that move constitutively to the cell surface.
If the delivery of prospective lysosomal proteins from the trans Golgi network to the late endosomes were blocked, lysosomal proteins would be secreted by the constitutive secretion pathways shown in Figure 15-30.
K+; Na+ and Cl-
In a typical mammalian cell, _______ is (are) higher on the inside, and _________ is (are) higher on the outside.
Na+ and Cl-; K+
In a typical mammalian cell, _________ is (are) higher on the outside, and __________ is (are) higher on the on the inside
False
In animal cells DNA is copied during the G 1 phase of the cell cycle.
True
In cells, the reaction takes place in more than one step
NADH
In the Citric Acid Cycle, 3 of which of the following are produced?
True
Kinase is responsible for phosphorylation
True
In the electron transport chain, electrons are transferred from NADH with a low reduction potential to oxygen with a high reduction potential.
in the chloroplasts
In what organelle of a plant cell does photosynthesis take place?
Removal of heart muscle cells damaged by oxygen depletion following cardiac infarction
In which of the following situations would cells die by necrosis, not apoptosis?
The light reactions take place in the thylakoids. The Calvin cycle takes place in the stroma.
In which part of the chloroplast does each stage occur?
True
Increasing the percentage of unsaturated fatty acids in a biological membrane will increase its fluidity.
Plectin
Intermediate filaments provide a great deal of strength to cells in epithelial sheets due to being crosslinked by the protein
What are the specific roles of kinesin and dynein in the cell and what provides energy for them?
Kinesin and dynein are motor proteins that move cargo (vesicles and organelles) to specific places in the cell. For example, kinesin moves towards the positive end of a microtubules while dynein moves toward the negative end of a microtubule. For kinesin and dynein to move, ATP hydrolysis must occur on their globular heads. How this movement occurs: ATP hydrolysis causes a globular head to release from the microtubule and move the head forward. This continual ATP hydrolysis is responsible for the movement, release, and binding of the globular head to the microtubule
True. A continual outward movement of ER is required; in the absence of microtubules, the ER collapses toward the center of the sale.
Kinesin moves ER membranes along microtubules so tgat the network of ER tubules becomes wretched throughout the cell.
Plus end; minus end
Kinesins move toward the __________ of a microtubule, while dyneins move toward the __________ of a microtubule.
True. Both extensions are associated with transmembrane proteins that protrude from the plasma membrane and enable the cell to form new anchor points on the substratum.
Lamellipodia and filopodia are "feelers" that a cell extends to find anchor points on the substratum that it will then crawl over
True
Lipids in a lipid bilayer do not flip-flop readily from one lipid monolayer to the other
True
Lipids in a lipid bilayer rapidly exchange positions with one another in their own monolayer
True
Lipids in a lipid bilayer spin rapidly around their long axis
Contains degradative enzymes to digest proteins ______________
Lysosome
False. Lysosomes also digest internal organelles by autophagy
Lysosomes digest only substances that have been taken up by cells by endocytosis.
False
Many steps in the oxidation of sugar molecules involve reaction with oxygen gas
True
Many, but not all, electron-transfer reactions involve metal ions
True
Margarine contains more saturated lipids than the vegetable oil form which it is made
True
Margarine contains more saturated lipids than the vegetable oil from which it is made
Answer: False (Matrix has high pH because of low proton concentration, while intermembrane space has low pH because of high proton concentration)
Measuring the pH of both matrix and intermembrane space indicated that the matrix has low pH and intermembrane space has high pH.
False
Membrane lipids frequently flip-flop between one monolayer and the other
False
Membrane phospholipids often flip-flop across the membrane
Detergent
Membrane proteins, unlike cytosolic proteins, are more difficult to purify. Which of the following substances is most commonly used to help purify a membrane protein?
False
Metabolic reactions that help synthesize all cellular components is catabolism
Oxidative metabolism for ATP production ____________________
Mitochondria
...
Mitochondrial ETC
Where does pyruvate oxidation occur in the cell?
Mitochondrial Matrix
False
Most of the dry weight of a tree comes from the minerals that are taken up by the roots
False. Mitochondria do not participate in vesicular transport, and therefore N-linked glycoproteins Which are exclusively assembled in the ER, cannot be transported to mitochondria
N-linked sugar chains are found on glycoproteins that face the cell-surface, as well as glycoproteins that face the lumen of the ER, trans Golgi network, and mitochondria
False (NAD+ is oxidized form)
NAD+ is the reduced form of NADH
Answer: False (NADH produces 2.5 ATP and FADH2 produces 1.5 ATP)
NADH produces 1.5 ATP, while FADH2 produces 2.5 ATP.
False
NADPH is found in plants only.
False (NADH is catabolic, NADPH is anabolic)
NADPH is used in catabolic reactions, while NADH is used in anabolic reactions.
Guanylyl cyclase
Nitric oxide is a vasodilator, which functions in activating __________________.
False
None of the produced energy is in the form of heat
Mitochondria
One source of electrons is NADH
True
Oxygen is known as the final electron acceptor in the electron transport chain
Chloroplast
Oxygen is produced as a result of electron transfer
False
Paracrine signaling molecules travel in the blood stream to their target organs.
True
Protein kinase A can stimulate both downstream enzymes and transcription regulators.
True
Phospholipids have different polar head groups attached to them.
True
Phosphorylation of glycogen phosphorylase activates it.
Light Dependent and Light Independent
Photosynthesis consists of two stages including:
True
Photosynthesis is the light-driven transfer of an electron from chlorophyll to a second molecule that normally has a much lower affinity for electrons
False (they do not pump protons)
Photosystems I and II are proton pumps
Plants use Carbon dioxide, which we expell, and produce oxygen, which we take in.
Plants are important for our survival. Explain.
False
Plants have chloroplasts and therefore can live without mitochondria
False (photosystem 2)
Plastoquinone transfers electrons from photosystem I to a proton pump called cytochrome b-f6 complex.
Compare and contrast protein transport into the ER and into the nucleus. List at least two major differences in the mechanisms and speculate why the ER mechanism might not work for nuclear import and vice versa.
Proteins are imported into the nucleus after they have been synthesized, folded, and, if appropriate, assembled into complexes. In contrast, unfolded polypeptide chains are translocated into the ER as they are being made by the ribosomes. Ribosomes are assembled in the nucleus yet function in the cytosol, and the enzyme complexes that catalyze RNA transcription and splicing are assembled in the cytosol yet function in the nucleus. Thus, both ribosomes and these enzyme complexes need to be transported through the nuclear pores intact. Nuclear pores are gates, which are always open to small molecules; in contrast, translocation channels in the ER membrane are normally closed, and open only after the ribosome has attached to the membrane and the translocating polypeptide chain has sealed the channel from the cytosol. It is important that the ER membrane remain impermeable to small molecules during the translocation process, as the ER is a major store for calcium in the cell, and calcium release into the cytosol must be tightly controlled. Nuclear localization signals are not cleaved off after protein import into the nucleus; in contrast, ER signal peptides are usually cleaved off. Nuclear localization signals are needed to repeatedly re-import nuclear proteins after they have been released into the cytosol during mitosis, when the nuclear envelope breaks down.
Ribosomes
Proteins are synthesized by
True
Proteins are transported into the nucleus in their completely folded conformation.
Both mitochondria and chloroplasts
Proton flow through a transmembrane protein results in the phosphorylation of ADP
Answer: True
Proton pumping through the inner membrane produces an electrochemical gradient, which is responsible for ATP production.
False (carry out active transport)
Pumps carry out passive transport.
True
Pyruvate is the final product of glycolysis.
Growth and development
RTKs are examples of enzyme-coupled receptors. Therefore, RTKs can regulate _______.
0 mV
What would be the resting potential across an artificial membrane if all charged molecules on both sides were equally permeable?
True
Reduction potential is the measure of electron affinities.
Which of the following types of microscopy requires the specimen be placed in a vacuum?
Scanning Electron or Transmission Electron
Which of the following types of microscopy requires coating the sample with a thin layer of a heavy metal to produce three-dimensional images of the surface of the sample?
Scanning electron
What structural feature of proteins directs them to the correct cellular compartment?
Signal sequence: a continuous stretch of an amino acid sequence on a protein, typically 15-60 amino acids long, that specifies the destination of the protein. If a protein does not have a signal sequence, then the protein will remain in the cytosol.
False
Steroid hormones bind to receptors on the cell surface only.
False (antiport)
Sodium-potassium pump is an example of a symport pump
True
Some cells that grow in the absence of O2 produce CO2
True
Some membrane proteins are enzymes
True
Some organisms carry out the reverse reaction
Microtubule function
Taxol and Vinblastine are anticancer drugs that interfere with chromosome separation in dividing cells. These drugs then most likely affect
True
The Calvin Cycle uses 9 ATP directly in the synthesis of the one 3C sugar phosphate
MAP kinase kinase kinase activates MAP kinase kinase by phosphorylation (Converting ATP to ADP and P). Once MAP kinase kinase is activated, it activates MAP kinase by the same mechanism. MAP kinase then phosphorylates various effector proteins, sending the signal downstream to either change protein activity or change gene expression.
The activation of Ras further transmits a signal by activating MAP kinase kinase kinase. Which enzyme does MAP kinase kinase kinase activate, how does it activate this enzyme, and it turn, what does this enzyme do?
True
The alpha subunit of a G protein stimulates downstream enzymes, while the beta-gamma complex of a G protein stimulates ion channels.
False. The single sequences that direct proteins to the ER contain a core of eight or more hydrophobic amino acids. The sequence shown here contains many hydrophilic amino acid side chains, including the charged amino acids His, Arg, Asp, , and, The uncharged hydrophilic amino acids
The amino acid sequence Leu-His-Arg-Leu-Asp-Ala-Gln-Ser-Lys-Leu-Ser-Ser is a signal sequence that directs proteins to the ER.
False
The amount of cyclin-dependent kinases goes up and down through the various phases of the cell cycle.
True
The antenna complex has many chlorophyll molecules that are responsible for capturing light energy and converting light energy to chemical energy.
Plectin
The budding of coated vesicles from eukaryotic plasma membrane fragments was observed in a mixture of clathrin, dynamin, adaptin, plectin, and GTP. Which of these could be eliminated without affecting the vesicle budding process?
On the extracellular face
The carbohydrate portion of glycolipids is found in membranes
Actin
The cell cortex just under the plasma membrane is made of
True
The electrochemical gradient determines the direction of solute flow.
True
The electrochemical proton gradient consists of two components: a pH difference and an electrical potential
Answer: True
The electron transport chain in animal cells has three pumps.
False
The electron-transport chain generates an electrical potential across the membrane because it moves electrons from the intermembrane space into the matrix
pyruvate
The end product of glycolysis
Pyruvate
The end product of glycolysis is
True
The energy is produced by a process that involves the oxidation of carbon atoms
False
The energy of ATP synthesis comes from proton pumping
True
The energy of pumping protons comes from electron transfer
Answer: True
The energy released by electron transportation is reserved in proton pumping.
True
The extracellular signal molecule acetylcholine has different effects on different cell types in an animal and often binds to different cell-surface receptor molecules on different cell types.
True. Acetylcholine, for example, slows the beating heart muscle cells by binding to a GPCR, and stimulates the contraction of skeletal muscle cells by binding to a different acetylcholine receptor, which is an ion channel coupled receptor
The extracellular signal molecule acetylcholine has different effects on different cell types in an animal amd often binds to different cell-surface receptor molecules on different cell types.
By phosphorylating glucose, glucose will then be trapped inside the cell, forcing it to undergo glycolysis rather than being expelled throughout the body for other needs. This phosphorylation also aids in the production of ATP and facilitates enzyme binding and specificity.
What is the goal of glucose phosphorylation?
Kinase
The general name for an enzyme that transfers phosphate groups from ATP to a protein is:
Pyruvate Dehydrogenase Complex
What is the name of the complex responsible for pyruvate oxidation?
True
The inactivation of sodium channels is responsible for action potential propagation in one direction.
False (becomes positive)
The inside of the cell becomes negative during an action potential.
True
The low cytosolic Ca2+ concentration sensitizes the cell to an influx of Ca2+, ensuring a rapid response to environment stimuli.
False
The membrane potential of an axon temporarily becomes more negative when an action potential excites it.
Phospholipids
The most abundant type of molecule that makes up the cell membrane is
facilitated diffusion
The movement of a molecule across a membrane, down its concentration gradient, through a transport protein is called
False (spontaneous)
The movement of electrons from low to high reduction potentials is a nonspontaneous process.
Answer: True
The movement of electrons is coupled to the pumping of protons.
True
The movement of ions toward their concentration gradient has a positive delta G
True
The number and location of mitochondria within a cell can change, depending on both the cell type and the amount of energy required.
Rubisco
What is the name of the enzyme that catalyzes the first step of the light-independent stage?
False
The only non-protein portion of the electron transport chain is cytochrome c
Both mitochondria and chloroplasts
The organelle contains cytochromes and iron-sulfur proteins in its electron transport chain
Both mitochondria and chloroplasts
The organelle requires a system of intact membranes to generate ATP
Answer: 122 ATP 1 acetyl-CoA = 10 ATP (from previous question) 9 acetyl-CoA = 90 ATP 8 NADH * 2.5 ATP = 20 ATP 8 FADH2 * 1.5 ATP = 12 ATP Total: 90 ATP + 20 ATP + 12 ATP = 122 ATP
The oxidation of 18-carbon fatty acid yields 9 acetyl-CoA, 8 NADH, and 8 FADH2. How many ATP are produced from the 18-carbon fatty acid? (Hint: Acetyl-CoA goes through the citric acid cycle)
False
The plasma membrane is highly impenetrable to all charged molecules
True
The plasma membrane of many animal cells contains open K+ channels, yet the K+ concentration in the cytosol is much higher than outside the cell
False
The plus ends of microtubules grow faster because they have a larger GTP cap.
True
The principle site of intracellular degradation is the lysosome.
Clathrin
The protein responsible for forming the spherical structure of endocytic vesicles from the plasma membrane is
Caspases
The proteins that ultimately result in apoptosis of cells are
False
The reaction supplies the cell with essential water
False
The role of chlorophyll in photosynthesis is equivalent to that of heme in mitochondrial electron transport
True
The source of electrons for photosynthetic electron transport is H2O
False (water)
The source of electrons in chloroplast's electron transport chain is NADPH
False (also FADH2)
The source of electrons in the mitochondrial electron transport chain is NADH only
Answer: True
The sources of electrons are NADH and FADH2.
True
The sugar layer that surrounds all cells makes cells more slippery
False (located on extracellular side)
The sugars of glycoproteins are located in the intracellular side
Explain how electron transport in both mitochondria and chloroplast help ATP synthesis?
The transport of electron is coupled to the pumping of protons, which provides ATP synthase the energy it needs to produce ATP
True
The transverse tubules in muscle cells are an extension of the plasma membrane, with which they are continuous; similarly, the sarcoplasmic reticulum is an extension of the endoplasmic reticulum.
True
The ẞɣ subunits of trimeric G proteins can activate phospholipase C.
Microfilaments - myosin Microtubules - kinesin and dynein Intermediate filaments have no motor proteins because they lack polarity, which is present in both microfilaments and microtubules. Instead, the ends of intermediate filaments are chemically modified.
There are different motor proteins that move on microfilaments and microtubules. Name the motor proteins that move on both microfilaments and microtubules. Explain why intermediate filaments lack motor proteins.
a) Association with the appropriate cyclin b) Presence of an activating phosphorylation c) Removal of an inhibitory phosphorylation
What is the necessary condition or set of conditions for full activity of the M-phase CDK? (Note: There are multiple answers.)
6 CO2 + 6 H2O 🡪 glucose (C6H12O6) + 6 O2
What is the overall reaction for photosynthesis?
Produce activated carriers (NADH and FADH2)
What is the purpose of the citric acid cycle?
Produce activated carriers (ATP and NADPH)
What is the purpose of the light-dependent stage?
T or F: The highest resolution of microscopy is obtained using the electron microscope.
True
T or F: The nucleolus is where many of the genes for rRNA are located.
True
T or F: Transmembrane proteins generally have alpha-helix regions that span the lipid bilayer.
True
True
Two NADH are produced during pyruvate oxidation
To generate NAD+ from NADH so glycolysis can continue under anaerobic conditions, glycolysis is the only way to produce ATP
What is the purpose of the production of ethanol by yeast under anaerobic condition?
True
Three ATP molecules are produced from 2 FADH2.
Which type of microscopy has the ability to resolve cellular components as small as 2 nm?
Transmission electron
True
Transport vesicles deliver proteins and lipids to the cell surface.
False
Transporters allow solutes to cross a membrane at much faster rates than do channels
False
Transporters are similar to channels, except that they are larger, allowing folded proteins as well as smaller organic molecules to pass through them.
False (Channels have higher rate than transporters)
Transporters have a higher rate of transport that channels do.
T or F: A cell's genome is its complete set of DNA
True
T or F: Antibodies are Y-shaped
True
T or F: Confocal microscopy is a type of fluorescent microscopy.
True
T or F: Eukaryotic cells are in general bigger than prokaryotic cells.
True
T or F: Kinase can add a phosphate group to molecules
True
T or F: Methylation is one modification of histone proteins that can change gene expression.
True
T or F: New cells only arise from and division of existing cells.
True
T or F: Plant cells have a cell wall that animals lack.
True
Answer: False (Ubiquinone accepts electrons from complex I)
Ubiquinone accepts electrons from both complex I and complex II.
Answer: True
Ubiquinone is hydrophobic.
True
Ubiquinone is the only non-protein component in the electron transport chain.
False (donates them to complex 3)
Ubiquinone receives electrons from both NADH and FADH2 and donates the electrons to complex II
True
Unsaturation maintains membrane fluidity
oxygen gas (O2)
What photosynthesis waste product is formed in the light reactions?
chlorophyll a, chlorophyll b, and carotenoids
What plant pigments are involved in photosynthesis?
1) Contact-dependent and Autocrine 2) Neuronal 3) Paracrine 4) Endocrine
What are the five types of signaling mechanisms? Describe or diagram each signaling mechanism. Rank the signaling mechanisms from 1 to 4, where 1 is the signaling mechanism that travels the shortest distance and 4 is the signaling mechanism that travels the largest distance.
2NADH + 2H+ + 2pyruvate + 2ATP
What are the products of glycolysis?
2 pyrvate→2 acetyl-CoA + 2CO2 + 2NADH + 2H+
What are the products of pyruvate oxidation?
Per 1: 3NADH + 3H+ + 2CO2 + 1FADH2 + 1GTP Per 2: 6NADH + 6H+ + 4CO2 + 2FADH2 + 2GTP
What are the products of the citirc acid cycle (per one acetyl-CoA + per two acetyl-CoA)?
Amino acids, Steroids, and Proteins
What are the three different classes of hormones? Give examples of each along with their origin and action.
light reactions and Calvin cycle
What are the two stages of photosynthesis?
Replacement of GDP with GTP
What event would activate a G protein?
Pyruvate is then shuttled to the mitocondrial matrix where it is converted to acetyl-CoA
What happens after the production of pyruvate under aerobic conditions.
In the Calvin cycle, carbon dioxide molecules (CO2) are combined with each other and with the electrons and H's from NADPH to form glucose (C6H12O6).
What happens to carbon dioxide molecules in the Calvin cycle reactions?
Water molecules (H2O) are split to give electrons, H+ ions, and oxygen gas (O2) .
What happens to water molecules in the light reactions?
Protein kinase B; cell growth and survival
What is another name for Akt and what is Akt responsible for?
Substrate-level phosphorylation is the process of producing ATP by removing a phosphate from a substarate molecule and adding it to ADP. Oxidative phosphorylation is the production of ATP from oxidized NADH and FADH2. Photophosphorylation is the phosphorylation of ADP to form ATP using the energy derived from sunlight.
What is the difference between substrate-level phosphorylation, oxidative phosphorylation, and photophosphorylation (light-depenedent stage of photosynthesis)?
3×ribulose 1,5-bisphosphate + 3×CO2→6×3-phosphoglycerate
What is the first step of the light-independent stage?
ATP and NADPH
What two products of the light reactions are used up in the Calvin cycle?
A small monomeric GTPase switch protein
What type of protein is Ras?
False
When a cell enters G 0 it is permanently removed from the cell cycle.
False
When activated by binding of a signal molecule to a GPCR, the associated G-protein exchanges the bound GTP for GDP.
Synaptic
When glutamate functions as a neurotransmitter the kind of signaling it does is
Mitochondrial Matrix
Where does citric acid cycle occur in the cell?
Cytosol
Where does glycolysis occur in the cell?
Thylakoid Membrane
Where does light-dependent stage occur in the cell?
Intermediate filament protein
Which class of cytoskeletal proteins regulates the disassembly of the nuclear envelope during mitosis?
Chlorophyll looks green to us because most of the green wavelengths are reflected rather than being absorbed. For this reason, green light is not an effective color of light to power photosynthesis. Chlorophyll a and b together absorb light most effectively in the blue to violet range and the orange to red range. Since violet wavelengths have the most energy in the visible light range (due to their shorter wavelengths) they can provide the maximum energy for photosynthesis
Which colors of light are most effective for photosynthesis? Explain why.
cytochrome c oxidase
Which components of the electron-transport chain is required to combine the pair of electrons with molecular oxygen?
Enzyme-coupled receptor
Which coupled receptor does insulin use?
anaerobically growing yeast
Which of the following cells rely exclusively on glycolysis to supply then with ATP?
Mitochondria
Which of the following cellular organelles is involved in the initiation of the intrinsic pathway of apoptosis?
A. The cell's DNA is damaged. B. The cell is lacking nutrients
Which of the following conditions could prevent a skin cell from passing the G1 checkpoint? (Note: There are multiple answers.)
Opening of Ca2+ channels in the ER
Which of the following is a result of increased IP3 in the cell?
IP3
Which of the following is a secondary messenger derived from a membrane phospholipid?
Triglycerides
Which of the following is not a component of cell membranes?
Cholesterol
Which of the following membrane lipids does not contain a fatty acid tail?
Intermediate filaments and mitosis
Which of the following pairs is incorrect?
Ran
Which of the following proteins is NOT part of the synthesis of proteins that are intended for the ER lumen?
Diacylglycerol
Which of the following second messengers remain bound to the plasma membrane
For molecules that have a strong tendency to pass along their electrons, the standard redox potential is negative.
Which of the following statements about "redox potential" is true?
All the proteins in a membrane are anchored to the cell cortex so that they can't move
Which of the following statements about membranes is NOT true:
It results, in part, from the concentration gradients for Na+ and K+
Which of the following statements about the resting membrane potential is TRUE?
Synaptic response changes in magnitude depending on frequency of stimulation.
Which of the following statements best reflects the nature of the synaptic plasticity?
Estrogen
Which of the following would have an intracellular receptor?
Adaptin
Which of these proteins is NOT a GTPase?
A. Water-soluble hormones bind to cell-surface receptors, while water-insoluble hormones bind to either cytosolic or nuclear receptors. B. Water-soluble hormones are associated with secondary messengers, while water- insoluble hormones are associated with gene expression.
Which statement is true regarding both water-soluble and water-insoluble hormones?
True. Actin is needed to make the contractile ring that causes the physical cleavage between the two daughter cells, whereas the mitotic spindle that partitions the chromosomes is composed of microtubules.
Without actin, cells can form a functional mitotic spindle and pull their chromosomes apart but cannot divide
1. Cyclic AMP concentration will decrease because the alpha subunit is inactivated; therefore, adenylyl cyclase is inactivated. 2. Cyclic AMP concentration will decrease because alpha subunit is unable to dissociate from Beta-gamma complex; therefore, adenylyl cyclase is inactivated. 3. Cyclic AMP concentration will increase because alpha subunit remains active during GTP binding; therefore, adenylyl cyclase remains active.
You are studying the effects of various mutations in a β-adrenergic receptor (G-protein coupled receptor). The intracellular concentration of cyclic AMP increases when epinephrine is bound to the β-adrenergic receptor. How will the mutations listed below affect cyclic AMP concentration? Explain your answers. 1. A mutation in the alpha subunit of a G protein that inhibits nucleotide exchange: 2. A mutation in the beta subunit of a G protein that increases its affinity to the alpha subunit in its GTP bound state: 3. A mutation in the alpha subunit of a G protein that prevents GTP hydrolysis:
uptake of calcium
cyclic GMP cause vasodilation of blood vessels by ____________.
Enzymes ________ the activation energy for a specific reaction.
decrease
Feedback inhibition involves down-regulating enzyme activity by the accumulation of a product ________ in the pathway.
earlier
Name the organelle that degrades cell components and other molecules brought to into the cell:
lysosome
The reduction of a molecule can sometimes result in the acquisition of a proton, a reaction referred to as ______________.
protonation or hydrogenation