Which of the following is true of all allosteric enzymes? They have more than one active site on each subunit. They consist of proteins only. They have a nonprotein portion. Binding at one site affects the protein function at a second site. Which of the following explains why glycosides do not undergo mutarotation? There are no longer any stereocenters. There is no longer an anomeric carbon. The ring structure does not open to become the open-chain structure. None of the above is correct.

When the enzyme hexokinase binds to glucose and ATP it undergoes a conformational change. All of the following are true about this enzyme-substrate binding EXCEPT: The active site changes shape so that it binds more tightly to the substrates   The substrates are optimally positioned for the reaction to occur   The substrates become contorted or strained, which increases their reactivity   The activation energy of the reaction increases

Which of the following about the glycosylation of proteins in the ER is false?    Dolichol phosphate serves as a lipid carrier. Oligosaccaryltransferase add the oligosaccharide to the protein.  The oligosaccharide ‘tree’ is made up of glucose and mannose.   Asn-X-Ser/Thr serves as the glycosylation site on the protein.  Carbohydrates are added to the lipid carrier by glycosyltransferases.

Many enzymes are switched "on" by attachment of a phosphate group at a specific serine somewhere on the protein (phosphorylation). The basic reaction is: E + ATP2 Ep + ADP Po SERINE PHOSPHO SERINC (Note the "squiggles" before the backone amide and carbonyl indicate the polypeptide chain continues on either side of the serine). For phosphorylation to have this effect, there has to be some equilibrium between inactive and active forms conformations of the enzyme: [Eactive] [Einactive] Einactive 2 Eactive; K* The same basic equilibrium must exist for the phosphorylated protein: [Ep,active] [Ep,inactive] EP,inactive 2 Ep,active; Kp = (a) If phosphorylation increases the measured activity of the enzyme, is K* or K larger? Why? (b) Does the phosphorylation site need to be near the site where the enzyme binds its substrate (e.g. the reactant whose chemistry it catalyzes)? Why or why not?

OOC H H fumarase Fumarate S-malate What class of enzyme most likely catalyzes the reaction shown in the figure? choose the one best answer) Oxidoreductase COO H₂O HR IIII... Hs OOC OH COO IIIH

If you are using cellular respiration to get energy from proteins rather than carbohydrates, which of the following is true? there are completely different reactions for protein breakdown as compared to carbohydrates so a different set of pathways is used the amino acids must be broken down into individual C-H or C-C bonds and then those bonds will join with others to create a sugar that enters into the glycolysis pathway O the amino acids are joined with a covalent bond to a sugar and then the hybrid molecule will enter the cellular respiration pathways the amino group is removed and then the rest of the molecule is converted into molecules such as pyruvate or oxaloacetate that can then enter cellular respiration pathways O the amino acids must first be converted into glucose and then they can go through the cellular respiration pathways

An organic cofactor (usually derived from a vitamin or a nucleotide), which is tightly attached to the enzyme (like FAD when used by the Krebs cycle enzyme succinate dehydrogenase), is always called: the metalloenzyme the metal-activated enzyme the holoenzyme the prosthetic group the cosubstrate

Which is the most versatile (related to bonding) glycogen metabolism (catabolism or anabolism) enzyme?  What bond(s) does this enzyme make and/or break? Enzyme:    Make:   Break:

Why is ATP an important molecule in metabolism? It provides energy coupling between exergonic and endergonic reactions. Its hydrolysis provides an input of free energy for exergonic reaction Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. It is one of the four building blocks for DNA synthesis.

Lactose is a disaccharide made of a glucose and a galactose bonded together. Lactose is found in milk yet does not taste sweet because our taste receptors do not sense lactose. Our taste receptors do sense galactose and glucose. How can a mug of warm milk taste sweet, without adding sugar? [Select the best answer.] The activation energy required for the hydrolysis of lactose into glucose and galactose is supplied by heating the milk. The milk proteins are denatured by the heat. The reaction is endergonic so the heat is the energy required for the reaction to occur. The lactose has less free energy than the glucose and galactose.