PCB3134 EXAM 1 REVIEW
The atoms O, C, N, S, and P can be easily found in biological molecules. The order of the electronegativities of these atoms is ________.
P < C < S < N < O
Which of the following statements is NOT true for phase-contrast microscope?
Scaning across the specimen at a single depth, thus illuminating only a thin plane.
Which of the following is a similarity between prokaryotes and eukaryotes?
Similar mechanism for synthesizing and inserting membrane proteins
Which of the following is NOT a property of virus?
Some viruses can reproduce in the extracellular evironment.
Which reaction below might be a good coupled reaction for the reaction A + B <—> C + D (delta G = +8.3 kcal/mole)?
C + F <—> G + H (ΔG = -8.7 kcal/mole)
Understand the experiments conducted by Ernest Overton and E. Gorter/F. Grendel in studying the composition of the plasma membrane.
-During the 1890s, Ernest Overton (University of Zurich) ---Root hairs into hundreds of different solutions containing a diverse array of solutes ---Dissolving power of outer cell boundary matched that of fatty oil. -In 1925, E. Gorter and F. Grendel (Dutch scientists) ---The ratio of the surface area of water covered by the lipid extracted from red blood cells to the surface area of the red blood cells from which the lipid was extracted varied between 1.8 to 1 and 2.2 to 1 ---The plasma membrane is a lipid bilayer.
What is electronegativity? What determines an atom's electronegativity? Read Figure 2.1 (page 33) and compare the eletronegativities of H, C, N, O, P, and S (slide 3 in the notes).
-Electronegativity: F > O > Cl > N > S > C > H > P > Si 3.98 3.44 3.16 3.04 2.58 2.55 2.20 2.19 1.90 -Two factors determining electronegativity: 1. The number of positive charges in its nucleus; 2. The distance of the outer electrons from the nucleus.
Competitive and noncompetitive inhibitors of enzymes and their effect on enzyme kinetics.
-Enzyme inhibitors are molecules that are able to bind to an enzyme and decrease its activity. 1. Cells use inhibitors to regulate the activity of many enzymes. 2. Researchers use inhibitors to study the properties of enzymes. 3. Enzyme inhibitors can be used as drugs, antibiotics, or pesticides. -Irreversible inhibitors: bind very tightly to an enzyme, often by forming a covalent bond to one of its amino acid residues. -Reversible inhibitors: bind only loosely to an enzyme, and thus are readily displaced. -Competitive inhibitors: compete with a substrate for access to the active site of an enzyme. -Noncompetitive inhibitors: act at a site other than the enzyme's active site.
What are enzymes and ribozymes? Cofactors and coenzymes. Properties of enzymes.
-Enzymes are proteins. Many are conjugated proteins with nonprotein components - cofactors may be inorganic (metals) or organic (coenzymes). ---Properties: Are required only in small amounts Are not altered irreversibly during course of reaction Have no effect on reaction thermodynamics Are highly specific for their Substrates Produce only appropriate metabolic products Can be regulated to meet the needs of a cell
Anaerobic and aerobic catabolism. Glycolysis and fermentation. Why fermentation is needed.
-Fermentation - Regeneration of NAD+ ---Yeast cells under anaerobic conditions ---Skeletal muscle cells undergoing strenuous contraction
What are the first and second laws of thermodynamics? Spontaneous event.
-First law: This principle asserts that in a closed system energy is conserved. Energy can neither be created or destroyed. However, it can be converted from one form to another form. ---System: a certain space or a certain amount of matter under study ---Surroundings: the reminder of the universe ----Internal energy (E): the energy of a system -Second Law: Events in the universe tend to proceed "downhill" from a state of higher energy to a state of lower energy. ---Spontaneous events leads to increase in randomness or disorder ---Spontaneous events: can occur without the input of external energy -Entropy: the randomness or disorder of the universe,a system or its surroundings.
Compare glycolysis and gluconeogenesis and how they are regulated.
-Glycolysis and gluconeogenesis are the catabolic and anabolic pathways of glucose metabolism. ---Synthesis of fructose 1,6-bisphosphate is coupled to hydrolysis of ATP. ---Breakdown of fructose 1,6-bisphosphate is via hydrolysis by fructose 1,6-bisphosphatase in gluconeogenesis.
Glycoproteins and glycolipids. The projection direction of membrane carbohydrates.
-Glycoproteins ----Oligosaccharides: Branched, < 15 sugars, High variability ----Two major types of linkages: N-glycosidic linkage, O-glycosidic linkage -Glycolipids: Cerebroside, Ganglioside
Coenzymes NAD(H) and NADP(H).
1. Enzymes playing a reductive role in anabolic pathways use NADPH as their coenzyme, whereas enzymes acting as dehydrogenase in catabolic pathways recognize NAD+. 2. NAD+ + ATP > NADP+ + ADP 3. NADH + NADP+ > NAD+ + NADPH 4. A cell's reservoir of NADH and NADPH represents its reducing power, which is an important measure of the cell's usable energy content.
How do cell achieve negative G?
1. Maintaining reactant/product ratio above that defined by K'eq 2. Coupling endergonic and exergonic reactions -In cells, glutamic acid is converted to glutamine in two sequential reactions, both of which are exergonic: Glutamic acid + ATP + NH3glutamine + ADP +Pi G°' = -3.9kcal/mol
In a pulse-chase experiment, radioactive chemicals are added into the growth medium ________.
during the pulse period
There are four groups of macromolecules in the cell. Which of the following is NOT a macromolecule?
fatty acid
The carbohydrates of the glycolipids of the red blood cell plasma membrane determine whether a person's blood type is A, B, AB, or O. A person with type B blood has an enzyme adding ________ to the oligosaccharide chain terminus.
galactose
Different membranes contain different types of lipids. The lipid composition of E. coli membranes is very different from that of human cells. E. coli membranes do NOT contain ________.
glycolipids
In a light microscope, the light passes through several lenses and the specimen. Which of the following is the correct order of these lenses and the specimen?
light source to condenser lens to specimen to objective lens to ocular lens
Fluorochromes absorb invisible, UV light and subsequently release a portion of the energy as visible light of ________ wavelengths. This phenomenon is called ________.
longer, fluorescence
In order to extract integral membrane proteins and keep their activity, you need to add ________ in the extraction buffer.
nonionic detergent
The effect of a competitive inhibitor on the kinetics of an enzyme is that the Vmax will ________ and the Km will ________.
not change, increase
In some cases, the infecting virus inserts its DNA into the host genome. The integrated viral DNA is called ________.
provirus
What level of structure in proteins is held together by intermolecular R group interactions?
quaternary structure
Beamsplitting (dichroic) mirror reflects light ________ than a certain wavelength and pass light ________ than that wavelength.
shorter, longer
For transmission electron microscopy, samples are ________ and ________, whereas for scanning electron microscopy, samples are ________ and ________.
sliced, stained with solutions of heavy metals; critical-point dried, coated with metal
In confocal scanning light microscopy, the finely focused laser beam rapidly scans across the specimen at a single depth, thus illuminating only a thin plane. Light emitted from the specimen is brought to focus at a site within the microscope that contains a pinhole aperture. Thus ________ and ________ are confocal.
the pinhole aperture, the illuminated plane in the specimen
An objective lens that is designed for use in water usually provides a better resolution than an objective lens that is designed for use in air, because ________.
the refractive index of water is bigger than that of air
Unlike light, which has a constant wavelength, the wavelength of a beam of electrons is determined by the accelerating voltage (V) applied in the microscope. The wavelength of the electrons equals to ________.
the square root of 150/V
Which of the following amino acids is a polar uncharged amino acid?
threonine
Under anaerobic conditions, the end product of glycolysis, pyruvate, is further processed through fermentation. The purpose of fermentation is ________.
to regerenate NAD+ from NADH
There are 20 amino acids in nature. Which of the following is NOT a nonpolar amino acid?
tyrosine
When a virus exists outside of living cells, it is called ________.
virion
As shown in the following figure, the building blocks of cellulose are________, and are linked together by ________.
β-D-Glucose, β (1→4) glycosidic bond
The building blocks of chitin are ________, and they are linked together by ________.
β-D-N-acetylglucosamine, β (1→4) glycosidic bond
Phosphate transfer potential.
-ATP formation is only moderately endergonic compared with other phosphate transfer in cells. -Phosphate Transfer potential : energy difference between the molecules higher on the scale and the ones lower on the scale. -The lower the affinity for the Pi group, the better the donor.
Understand equilibrium and steady state?
-As reactions reach equilibrium, the free energy available to do work decreases toward a minimum and the entropy increases toward a maximum. -The living cells, unlike nonliving, closed systems, such as the environment within a test tube, are open systems. Many cellular reactions exist in a state. -In a steady state, the concentrations of reactants and products remain relatively constant, even though the individual are not necessarily at equilibrium.
The three domains of life and how they are defined.
-Bacteria: include Gram positive, Gram negative, and cyanobacteria. -Archaea: include halophiles, thermophiles, methanogens and acidophiles -Eucarya: include plants, animals, fungi, and protists
Four types of macromolecules: carbohydrate (this group is more complicated), lipid, protein and nucleic acid, including their building blocks, bonds, and structure as well as nomenclature.
-Carbohydrates ----Storage of chemical energy ----Durable building materials for biological constructions ----Covalently attached to lipids and proteins to form glycolipids and glycoproteins -----Monosaccharides: triose, tetrose, pentose, hexose, heptoses, etc. -----Oligosaccharides: small sugar chains covalently attached to lipids and proteins to form glycolipids and glycoproteins -----Polysaccharides: glycogen, starch, cellulose, etc. ---Sucrose: alpha -D-Glucose, fructose; alpha (12) linkage ---Lactose: beta-D-Glucose, beta-D-galatose; beta(14) linkage -Lipids --A diverse group of nonpolar biological molecules, which can dissolve in organic solvents but not water. ---Fats: triacylglycerol ---Steroids: cholesterol, steroid hormones ---Phospholipids -Steroids ---Cholesterol: Smaller and less amphipathic. Headgroup: -OH group Tail: 4 hydrocarbon rings, flat and rigid -Proteins --Proteins are molecular tools and machines, which carry out virtually all of a cell's activities. Proteins exhibit a high degree of specificity, which allows proteins to interact selectively with other molecules. ----Enzymes ----Structural cables ----Hormones, growth factors, gene activators -----Membrane receptors and transporters -----Contractile filaments and molecular motors ----Many others: antibodies, toxins, etc. -Classification of Amino Acids --The highly variable side chain (R group) among the 20 amino acids gives proteins their diverse structure and activities. -Nucleic Acid ----Nucleic acids are long linear polymers of nucleotides. They function primarily in the storage and transmission of genetic information, but they may also have structural or catalytic roles. --DNA: deoxyribonucleic acid, genetic materials ---RNA: ribonucleic acid: message RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA) ---RNA functions in transmission of genetic information from DNA to protein, but it may also carry genetic information such as in viruses.
Definition of all the chemical bonds.
-Covalent bonds -Biological molecules are made of atoms, mainly C, H, N, O, S, and P, that are linked together. The links are covalent bonds. -The covalent bonds are formed through shared electrons between atoms. The valence depends on the electron orbits of specific atoms. -Single bond: such as in H2O, H:O:H ------Atoms joined by a single bond are able to rotate relative to one another. -Double bond: such as in O2, O::O ------Double bonds can function as energy capturing centers. -Triple bond: such as in N2, N::N -Quadruple bond: not known -Noncovalent bonds: 1. Ionic bonds 2. Hydrogen bonds 3. Hydrophobic interactions 4. van der Waals forces
Understand metabolic regulation: covalent modification, allosteric modulation: inhibition and activation.
-Covalent modification - an enzyme's activity may be regulated by covalent modification of the enzyme -Allosteric modulation - enzymes whose activity is regulated by the binding of regulator molecules (allosteric effectors) to a site on the enzyme away from the active site ---Allosteric inhibition (feedback inhibition)- the product of a metabolic pathway acts as an allosteric inhibitor of an enzyme early in the pathway ---Allosteric activation - a mechanism by which a metabolite activates an enzyme either in its own pathway or a related pathway
Differences and similarities between animal cells and plant cells.
-Differences: genetic content (gene pools), size, shape, organelles, cellular functions -Similarities: Common genetic language, chemical components, metabolic pathways, dynamic and kinetic principles, and well conserved structures and functions among similar macromolecular complexes. -Plant cells have cell wall, chloroplasts (plastids), and large central vacuoles, whereas animal cells do not have cell wall and chloroplasts and have small vacuoles. -Both have plasma membranes and may be surrounded by a rigid cell wall. Plant cells are much more complex, with many organelles.
Integral proteins, peripheral proteins, and lipid-anchored protein. How are they associated with membrane? Their functions.
-Integral proteins are the proteins that are tightly bound to the membranes. Some of them are attached to lipids in the bilayer. Others are transmembrane proteins. They pass entirely through the lipid bilayer and thus have domains that protrude from both the extracellular and cytoplasmic sides of the membrane. -----Freeze fracture: The exposed faces are called ectoplasmic face (E) and protoplasmic face (P) 1. Ionic (charged) detergent sodium dodecyl sulfate (SDS) 2. Nonionic (uncharged) detergent Triton X-100 ----Freeze fracture allows an investigation of the microheterogeneity of the membrane -Peripheral proteins on the cytoplasmic side function as a membrane "skeleton", enzymes, specialized coats, or factors transmitting signals. -Peripheral proteins on the extracellular side are typically part of the extracellular matrix. -Lipid-anchored proteins ---GPI-anchored proteins is bound on the external surface of the PM by glycosylphosphatidylinositol linkage ---On the cytoplasmic side, proteins are anchored to the membrane by one or more long hydrocarbon chains embedded in the inner leaflet of the lipid bilayer.
What are the properties of carbon that allowed it to construct the backbone of biological molecules? Compare with silicon.
-Linear -Cyclic -Branched -Hydrocarbon: Ethane
What is a lipid bilayer? What are the three layers of a membrane observed under an electron microscope? What are the functions of membrane?
-Lipid bilayer: The total thickness of the membrane is only about 6 nm (nanometers -10 -9 m) yet this thin molecular "sheet" is essential for the function and survival of cells and the membrane-bound organelles within the cells. -Membrane Functions 1. Compartmentalization 2. Scaffold for biochemical activities 3. Providing a selectively permeable barrier 4. Transporting solutes 5. Responding to external signals 6. Intercellular interactions 7. Energy transduction
Four categories of the organic molecules commonly found in living cells based on their role in metabolism.
-Macromolecules: huge, highly organized molecules that form the structure and carry out the activities of the cells, including proteins, nucleic acids polysaccharides, and lipids. -The building blocks of macromolecules: low-molecular- weight precursors of the macromolecules. -Metabolic intermediates (metabolites): compounds formed along a metabolic pathway having no function per se. -Molecules of miscellaneous function: vitamins, certain steroid and amino acid hormones, ATP, cAMP, urea, etc.
Understand the enzyme kinetics. What are maximal velocity (Vmax) and Michaelis constant (Km)? For a specific enzyme, how can Km be changed?
-Maximal velocity (Vmax): the initial velocity when the enzyme approaches a state of saturation -Michaelis constant (KM): the substrate concentration when the reaction velocity is one-half of Vmax. The KM is independent of substrate and enzyme concentration. The KM for most enzymes ranges between 10-1 and 10-7, with a typical value about 10-4 M.
Chemical compositions of membranes: membrane lipids, membrane carbohydrates, and membrane proteins.
-Membrane Lipids: Membranes contain a wide diversity of lipids, all of which are amphipathic, that is, they contain both hydrophilic and hydrophobic regions. The three main types of membrane lipids are: ---Phosphoglycerides ---Sphingolipids --- Cholesterol -Membrane Carbohydrates ---All of the carbohydrate of membranes faces away from the cytosol. ----Glycoproteins ----Glycolipids: Cerebroside, Ganglioside
What is the membrane "sidedness" and how to determine it?
-Membranes may contain hundreds of different proteins. Each membrane protein has a defined orientation relative to the cytoplasm, so that the properties of one surface of a membrane are very different from those of the other surface. This asymmetry is called membrane "sidedness". -In PM, those parts of membrane proteins that interact with other cells or with extracellular ligands project outward into the extracellular space, whereas parts that interact with cytoplasmic molecules project into the cytosol. -Determination of Membrane Sidedness ---The membrane sidedness can be determined using nonpenetrating agents that either label or modify the proteins. ---Nonionic detergents or osmotic shock can make cells permeable to trypsin.
What are metabolism and metabolic pathway? Catabolic and anabolic pathways.
-Metabolism is the collection of biochemical reactions that occur in a cell, which include a tremendous diversity of molecular conversions. Most of these reactions can be grouped into metabolic pathways containing a sequence of chemical reactions in which each reaction is catalyzed by a specific enzyme, and the product of one reaction is the substrate for the next. ---Catabolic pathways: disassembly of complex molecules to form simpler products ----- provide raw materials for synthesis -----provide energy for cell activities in the forms of high-energy phosphates (ATP) and high-energy electrons (NADPH) ---Anabolic pathways: synthesis of more complex compounds from simpler starting materials
Virus and its properties.
-Microscopic particles that can infect the cells of biological organisms. -Viral structure: Genetic material and protein capsid. Some with a lipid envelope. -Common virus properties - not considered living since need host to reproduce, metabolize, etc. 1. All are obligatory intracellular parasites 2. Outside of living cell, it exists as particle or virion, essentially a macromolecular package 3. Genetic material is surrounded by protein capsule (capsid) usually made up of a specific number of subunits 4. Viruses have surface proteins that bind to particular host cell surface component (specificity) 5. Most viruses have relatively narrow host range -Lytic infection: the infecting virus kill the host cell. -Lysogenic infection: the infecting virus does not kill the host cell.
Glycolysis and its free-energy profile. What steps are irreversible and why.
-Of the reactions of glycolysis, all but three are near equilibrium (ΔG ~ 0) under cellular conditions. -The driving forces of glycolysis are three reactions that involve hexokinase, phosphofructokinase, and pyruvate kinase.
What is a functional group? Read Table 2.2.
-Particular groups of atoms that often behave as a unit and give biological molecules their physical properties, chemical reactivity, and solubility in aqueous solution. -Methyl, hydroxyl. Arboxyl, amino, phosphate, arboxyl, sulfhydryl
Basic properties of cells.
1. Cells are highly complex and organized 2. Cells possess a genetic program and the means to use it 3. Cells are capable of producing more of themselves 4. Cells acquire and utilize energy 5. Cells carry out a variety of chemical reactions 6. Cells engage in mechanical activities 7. Cells are able to respond to stimuli 8. Cells are capable of self-regulation 9. Cells evolve
Basic structure of phosphoglycerides, sphingolipids, and cholesterol (such as composition & charge). Lipid composition in different membranes (Table 4.1).
-Phosphoglycerides ---Most abundant in membranes -Sphingolipids are a less abundant class of membrane lipids. They are derivatives of sphingosine, an amino alcohol that contains a long hydrocarbon chain. Sphingolipids consist of sphingosine linked to a fatty acid (R group). ----Sphingomyelin is the only phospholipid without a glycerol backbone. ----Glycolipid ---------Cerebroside ---------Ganglioside -Cholesterol is found in certain membranes. In certain animal cells it may constitute up to 50% of the lipid molecules in the PM. However, cholesterol is absent from the PM of most plant and all bacterial cells. The placement of the cholesterol molecules in the lipid bilayer interferes with the tight packing of the phospholipids, which tends to increase the fluidity of the bilayer.
Differences and similarities between prokaryotic cells and eukaryotic cells.
-Prokaryotic cells: ---Archaea (archaebacteria) ---Bacteria (eubacteria) -Eukaryotic cells: ---Protists, fungi, plants, and animals -Complexity: Prokaryotes are relatively simple; eukaryotes are more complex in structure and function. -Cytoplasm: Eukaryotes have membrane-bound organelles and complex cytoskeletal proteins. Both have ribosomes but they differ in size. -Cellular reproduction: Eukaryotes divide by mitosis; prokaryotes divide by simple fission. -Locomotion: Eukaryotes use both cytoplasmic movement, and cilia and flagella; prokaryotes have flagella, but they differ in both form and mechanism. -Genetic material: Packaging: Prokaryotes have a nucleoid region whereas eukaryotes have a membrane-bound nucleus. Amount: Eukaryotes have much more genetic material than prokaryotes. Form: Eukaryotes have many chromosomes made of both DNA and protein whereas prokaryotes have a single, circular DNA. -Eukaryotic cells have nuclei, but prokaryotic ones don't: Compartmentalization by nuclear envelope, plasma and cytoplasmic membranes
12. How to isolate different membrane proteins? What is the difference between SDS and Triton X-100 when used for membrane protein extraction?
-Solubilization of Integral Proteins 1. Ionic (charged) detergent sodium dodecyl sulfate (SDS) 2. Nonionic (uncharged) detergent Triton X-100
Activation energy(EA) How does enzymes affect the activation energy?
-The amount of energy required for the reactants to achieve an activated state in which the atomic rearrangements necessary for the reaction can occur. -When the reactants are at the crest of the energy hump (transition state), the reactants form a fleeting, activated complex in which bonds are being formed and broken. -Enzymes Decrease the Magnitude of the EA Barrier ---Different mechanisms used by enzymes and heat to increase the rate of reactions
How is the blood type (A, B, AB, or O) determined?
-The carbohydrates of the glycolipids of the red blood cell PM determine whether a person's blood type is A, B, AB, or O. ---A person with type A blood has an enzyme adding an N-acetylgalatosamine (GalNAc) to the end of the chain. ---A person with type B blood has an enzyme adding galactose (Gal) to the chain terminus. ---A person with AB blood type has both enzymes. ---A person with O type blood lacks both enzymes.
Oxidative phosphorylation vs. substrate-level phosphorylation.
-The energy released during electron transport is utilized to form ATP by oxidative phosphorylation. -Substrate-level phosphorylation is the direct formation of ATP by transfer of a phosphate group from substrates to ADP.
Virion, provirus, and viroid.
-The integrated viral DNA is called a provirus. 1. Upon a stimulus, become lytic. 2. Produce new viral progeny without lysing the host cell. 3. The host cell becomes malignant. -Infectious agent was small circular RNA totally lacking a protein coat (called it a viroid) 1. 240 to 600 nucleotides (10% size of smaller viruses) 2. Do not codes for proteins
What are energy, bioenergetics and thermodynamics?
-The study of various types of energy transformations that occur in living organisms. -----A living cell must acquire and expend energy to synthesize macromolecules from raw materials, to produce and excrete waste products, to transmit genetic information from DNA to protein, to move vesicles, to transport ions across cell membranes. -Energy is the capacity to do work. --Potential Energy: PE = mgh --Kinetic Energy: KE = (1/2)mv2
Free energy. Exergonic and endergonic reactions.
-The thermodynamics laws indicate that the energy of the universe is constant, but the entropy continues to increase toward a maximum. -When G< 0, the reaction is exergonic, which is thermodynamically favored. When G > 0, the reaction is endergonic, which is thermodynamically unfavorable. H = G +TS
Transmembrane domain and how to identify the transmembrane segment in a protein?
-Transmembrane domains is generally predicted from the AA sequence. They typically consist of a string of about 20 predominantly nonpolar AAs that adopt an alpha helical structure. -In glycophorin, the transmembrane domain contains 20 Aas (74 to 93), all but three of which have hydrophobic side chains.
First step of glycolysis and the net equation.
-net: Glucose+2ADP+2Pi+2NAD2pyruvate+2ATP+2NADH+2H++2H2O
What is pH? How to calculate pH value? What is a buffer?
-pH is used to express the acidity of a solution. -In water solution, [H+][OH-] = 10-14 at 25 °C. -For acids, which releasing H+ into the solution, [H+] increase ,H+ + OH- forms H2O, [OH-] derease, pH < 7. -For bases, which accepting H+ from the solution, [H+]decrease , H2O dissociates to H+ + OH-, [OH-] increase , pH > 7.
Definition of a cell. Three tenets of cell theory.
1. A cell is the simplest form of life that is capable of living and reproducing in a non-living environment. 2. 2. All cells are surrounded by a plasma membrane. -Three tenets 1. The cell is the structural unit of life for all organisms. 2. All organisms are composed of one or more cells. 3. Cells can arise only by division from a preexisting cell.
The fluid-mosaic model of membrane and its current modification (addition).
1. The bilayer of a membrane is present in a fluid state, and individual lipid molecules can move laterally within the plane of the membrane. 2. The membrane proteins occur as a mosaic of discontinuous particle that penetrate the lipid sheet. 3. The membranes are dynamic structures in which the component are mobile and capable of coming together to engage in various types of transient or semipermanent interactions. 1. Most membrane proteins and a small portion of phospholipids contain short sugar chains, making them glycoproteins and glycolipids. 2. The portions of the polypeptides that extend through the lipid bilayer typically occur as alpha helices composed of hydrophobic AA 3. The two leaflets of the bilayer contain different types of lipids. 4. The outer leaflet contains microdomain "rafts" consisting of clusters of specific lipid species.
Properties of water.
1. Water is a highly asymmetric molecule. 2. The two covalent bonds in water are highly polarized. 3. All three atoms in water are adept at forming hydrogen bonds. A. Solvent dissolving many types of substances B. Determining the structure of biological molecules and their interactions C. Medium in which materials are transported E. Reactant or product in many cellular reactions F. Protecting cells from excessive heat, cold, or damaging radiation
Cardiolipin is a unique lipid that contains ________, ________ and ________ with ________ charge(s).
3 glycerol groups, 2 phosphate groups, 4 fatty-acyl groups, 2 negative
The resolution of a naked eye is about 0.1 mm, which is about ________ times bigger than that of a light microscope.
500
If the concentration of OH- in a MOPS buffer is 10-8 at 25 °C, what is the pH of the MOPS buffer?
6
The irreversible steps in glycolysis are catalyzed by different enzymes from those in gluconeogenesis. Phosphofructokinase catalyzes fructose 6-phosphate phosphorylation in glycolysis, whereas fructose bisphosphatase catalyzes the reverse reaction. Which of the following statements about these enzymes is NOT true?
A high ATP/AMP ratio activates phosphofructokinase.
There are four groups of macromolecules inside the cell. Which of the following is NOT a macromolecule?
ATP
According to the Cell Theory, which of the following statements is true?
All organisms are composed of at least one cell.
In organic reactions, oxidation and reduction refer to the polarization of shared electrons. Which of the following organic molecules is at the most reduced state?
CH2=CH-CH2-CH2-OH
Which of the following are not considered to belong to the Archaea?
Eubacteria
Oxidation and reduction.
In chemical reaction: Fe0 + Cu2+ Fe2+ + Cu0 -Two electrons are transferred from metallic iron (Fe0) to cupric copper ion (Cu2+). -In this reaction: Fe0, a reducing agent, is oxidized to ferrous state (Fe2+); Cu2+, an oxidizing agent, is reduced to metallic copper (Cu0).
In a light microscope, the lens that concentrates light from the illumination source to the specimen is called
condenser lens
The atoms O, C, N and H can be easily found in biological molecules. The electronegativity order of these atoms is
H < C < N < O
There are two different secondary structures for polypeptides: alpha-helix and beta-pleated sheet. The beta-pleated sheet is characterized by orientation of ______ the molecular axis.
H bonds perpendicular to
It is well known that integral membrane proteins are difficult to study due to multiple problems with this group of proteins. Which of the following is NOT considered a problem for studying integral membrane proteins?
Integral membrane proteins are large proteins.
Which of the following statements about glycoproteins is NOT correct?
Oligosaccharides are attached to a serine residue in N-glycosidic linkage.
How the permeability of the membrane is preserved when proteins are inserted into the lipid bilayer.
Membranes prevent the unrestricted exchange of molecules from one side to the other, while promote the movement of select molecules into and out of the enclosed cellular compartment.
Which of the following is NOT true for cells?
Most reactions in cells reach equilibrium.
Numerical Aperture (N.A.) determines the quality of an objective lens. Which of the following combinations would provide the best resolution?
N.A. = 0.68 and blue light
Which of the following statements is NOT true according to the current model of plasma membrane?
The two leaflets of the lipid bilayer contain same types of lipids.
Based on the three tenets of Cell Theory, which of the following statements is NOT true?
Virus can reproduce itself in a living environment, so it can be considered a living organism.
The chemical reactions that break down complex molecules to form simpler products in a cell is called ________.
catabolic pathways
The simplest form of life is ________.
a cell
The building blocks of a nucleotide are ___________.
a pentose sugar, a phosphate group and a nitrogenous base
Phospholipids contain at least one phosphate group. Which of the following lipids is a phospholipid?
a sphingomyelin
Buffers are used by organisms to protect cells from pH fluctuation. Which of the following can form a good buffer.
a weak acid and its conjugate base or a weak base and its conjugate acid
Prekaryotic and eukaryotic cells share which of the following features? a. plasma membrane of similar structure b. proteasomes of similar structure c. cytoplasmic organelles of similar structure d. ribosomes of similar structure e. nuclei of similar structure
a+b+d
Which of the following structures can be found in plants but not in animal cells? a. cell wall b. ribosome c. big central vacuole d. lysosome e. chloroplast
a+c+e
Which of the following organelles or structures can be found in both plant and animal cells? a. plasma membrane b. endoplasmic reticulum c. large central vacuole d. nucleus e. ribosome
a, b, d, and e
Transmembrane domains are generally predicted from the amino acid (AA) sequence. They typically consist of a string of ________ predominantly ________ AAs that adopt an ________ structure.
about 20, nonpolar, alpha helical
The chemical reactions that synthesize more complex compounds from simpler starting materials in a cell is called ________.
anabolic pathways
Why do electron microscopes provide much greater resolving power than light microscopes?
because the wavelength of an electron beam is much shorter than that of visible light.
