Exam 2

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ΔG Indicated the change in the standard free energy as a reactant is converted to product. Given what you know about these values, which reaction below is the most favorable?
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ΔG Indicated the change in the standard free energy as a reactant is converted to product. Given what you know about these values, which reaction below is the most favorable?
Glucose --> CO2 + H2O ΔG = -686 kcal/mole
Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds?
Water
Proteins bind selectively to small-molecule targets called ligands. The selection of one ligand out of a mixture of possible ligands depends on the number of weak, noncovalent interactions in the protein's ligand-binding site. Where is the binding site typically located in the protein structure?
Inside the cavity on the protein surface
At first glance, it may seem that living systems are able to defy the second law of thermodynamics. However, on closer examination it becomes clear that although cells create organization from raw materials in the environment, they also contribute to disorder in the environment by releasing _____________.
Heat
Studies conducted with a lysozyme mutant that contains an Asp --> Asn change at position 52 and a Glu --> Gln change at position 35 exhibited almost a complete loss in enzymatic activity. What is the most likely explanation for the decrease in enzyme activity in the mutant?
Absence of negative charges in the active site
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 reactions require ---------- to selectively speed up reactions and meet the demands of the cell
Enzymes
Substances that release protons when they dissolve in water are acids.m Which of the following household substance is acidic?
Coffee
Which of the following is NOT a feature commonly observed in B sheets?
Coiled-coil patterns
Which subatomic particles contribute to the atomic number for any given element?
Protons
In a DNA double helix
The two DNA strands run antiparallel
The overall relationship that links bond forming reactions to membrane transport processes in the mitochondria is calledChemiosmotic couplingSpecific regions of eukaryotic chromosomes contain sequence elements that are absolutely required for the proper transmission of genetic information from a mother cell to each daughter cell. Which of the following is NOT known to be one of these required elements in eukaryotes?Protein-coding regionsWhen elemental sodium is added to water, the sodium atoms ionize spontaneously. Uncharged Na becomes Na+. This means that the Na atoms have beenOxidizedThe inactivation of one X chromosome is established by the directed spreading of heterochromatin. The silent state of this chromosome is ------ in the subsequent cell divisions.MaintainedWhich DNA base pair is represented in Figure 5-7?G-CWhich of the following statements is TRUE?The pH in the mitochondrial matrix is higher than the pH in the intermembrane space.The second law of thermodynamic states that the disorder in any system is always increasing. In simple terms, you can think about dropping NaCl crystals into a glass of water. The solvation and diffusion of ions is favored because there is an increase inEntropyA difference between electron transport in mitochondria and chloroplasts is thatIt results in the generation of NADPH in chloroplast but not in mitochondria--------- Play an important role in organizing lipid molecules with long hydrocarbon tails into biological membranes.Hydrophobic forcesOsmosis describes the movement of water across a biological membrane and down its concentration gradient. In chemiosmosis, useful energy is harnessed by the cell from the movement of ------- across the inner mitochondrial membrane into the matrix ---------- a concentration gradient.Protons, downComplete the sentence with the best option provided below. The primary structure pf a protein is theAmino acid sequenceProkaryotic cells do not possesA nucleusProtein folding can be studied using a solution of purified protein and a a denaturant (urea), a solvent that interferes with noncovalent interactions. Which of the following is observed after the denaturant is removed from the protein solution?The polypeptide returns to its original conformationThe equilibrium constant (K) for the reaction Y --> X can be expressed with respect to the concentration of the reactant and product molecules. Which of the expressions below shows the correct relationship between K, [Y], and [X]?K = [X]/[Y]Chemical reactions carried out by living systems depend on the ability of some organisms to capture and use atoms from nonliving sources in the environment. The specific subset of these reactions that break down nutrients in food can be described asCatabolicIn the 1940s, proteins were thought to be the more likely molecules to house genetic information. What was the primary reason that DNA was not originally believed to be the genetic material?DNA was found to contain only four different chemical building blocksWhich of the following statements about mitochondria divisions is TRUE?Mitochondrial division is mechanistically similar to prokaryotic cell divisionWhich of the following chemical groups is NOT used to construct a DNA molecule?Six-carbon sugarAn ionic bond between two atoms is formed as a result of thetransfer of electrons from one atom to the otherTable 2-14 indicates the number and arrangement of electrons in the first four atomic electrons shells for selected elements. On the basis of the information in the chart and what you know about atomic structure, which elements will form ions with a net charge of +1 in solution?Sodium; PotassiumWhich statement is NOT true about the events/conclusions from studies during the mid-1800s surrounding the discovery of cells?Scientists came to the conclusion that new cells can form spontaneously from the remnants of ruptured cells.Fully folded proteins typically have polar side chains on their surfaces, where electrostatic attractions and hydrogen bonds can form between the polar group on the amino acid and the polar molecules in the solvent. In contrast, some proteins have a polar side chain in their hydrophobic interior. Which of the following would NOT occur to help accommodate an internal, polar side chain?A hydrogen bond forms between a polar side chain and an aromatic side chain.Proteins are important architectural and catalytic components within the cell, helping to determine its chemistry, its shape and tis ability to respond to changes in the environment. Remarkably, all of the different proteins in a cell are made from the same 20 -------------, by linking them in different sequences. The cell can make protein molecules with different conformations and surface chemistries, and therefore different functions.Amino acidsThe Ras protein is a GTPase that functions in many growth factor -signaling pathways. In its active form, with GTP bound, it transmits a downstream signal that leads to cell proliferation in its inactive form, with GDP bound, the signal is not transmitted. Mutations in the gene for Ras are found in many cancers. Of the choices below, which alteration of Ras activity is most likely to contribute to the uncontrolled growth of cancer cells?A change the decreases the rate of hydrolysis of GTP by RasWhich of the following statements describes the phosphorylation event that occurs during the process known as "Oxidative phosphorylation"A phosphate group is added to ADPTwo or three alpha helices can sometimes wrap around each other to form coiled coils. The stable wrapping of one helix around another is typically driven by ___________ interactions.HydrophobicThe biosynthetic pathway for the two amino acids E and H is shown schematically in Figure 4-33. You are able to show that E inhibits enzyme V, and H inhibits enzyme X. Which biosynthetic product is most likely the inhibitor of enzyme T?CActivated carriers are small molecules that can diffuse rapidly and be used to drive biosynthetic reactions in the cell. Their energy is stored in a readily transferable form such as high-energy electrons or chemical groups. Which of the molecules below donates a chemical group rather than electrons?ATPMitochondria contain their own genome, are able to duplicate, and actually divide on a different time line from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they areEndosymbiosisSome proteins have alpha helices, some have B sheets, and still others have a combination of both. What makes it possible for proteins to have these common structural elements?Hydrogen bonds along the protein backboneStage 2 of photosynthesis, sometimes referred to as the dark reactions, involves the reduction of CO2 to produce organic compounds such as sucrose. What cofactor is the electron donor for carbon fixation?NADPHCells require one particular monosaccharide as a starting material to synthesize nucleotide building blocks. Which of the monosaccharides below fills this important role?RIBOSEThe chromosomes we typically see in images are isolated from mitotic cells. These mitotic chromosomes, are in the most highly condensed form. Interphase cells contain chromosomes that are less densely packed andOccupy discrete territories in the nucleusIn the electron transport chain in chloroplasts, ---------- -energy electrons are taken from --------Low, H2OAlthough the chromatin structure of interphase and mitotic chromosomes is very compact, DNA-binding proteins and protein complexes must be able to gain access to the DNA molecule. Chromatin-remodeling complexes provide this access by __________________.Using the energy of ATP hydrolysis to move nucleosomesThe process of generating monoclonal antibodies is labor-intensive and expensive. An alternative is to use polyclonal antibodies. Aa subpopulation of purified polyclonal antibodies that recognize a particular antigen can be isolated by chromatography. Which type of chromatography is used for this purpose?AffinityDouble covalent bonds are both shorter and stronger than single covalent bonds, but they also limit the geometry of the molecule because theyLimit the rotation of the bonded atomsPhotosynthesis is a process that takes place in chloroplasts and uses light energy to generate high-energy electrons, which are passed along an electron-transport chain. Where are the proteins of the electron-transport chain located in chloroplast?Thylakoid membraneThe potential energy stored in high energy bonds is commonly harnessed when the bonds when the bonds are split by the addition of -------- in a process called --------Water, hydrolysisNADH contains a high-energy bond that, when cleaved, donates a pair of electrons to the electron-transport chain. What are the immediate products of this bond cleavage?NAD+ + H+