The enzymes required for hepatic glycogenolysis include
A、Phosphorylase
B、Debranching enzyme
C、Branching enzyme
D、Glucose kinase
E、Glucose-6-phosphatase
A、Phosphorylase
B、Debranching enzyme
C、Branching enzyme
D、Glucose kinase
E、Glucose-6-phosphatase
听力原文: Let's begin today by discussing enzymes. Enzymes are what make many of the body's biochemical reactions possible. Actually biochemical reactions can take place without them, but at much lower rates. In fact an enzyme may cause a reaction to proceed billions of times faster than it would otherwise. Before I go on to the biochemical specifics of how this works, let me provide a figurative example. I think it will help illustrate the power of enzymes more clearly. Now, suppose you got a bag and you put a bunch of locks in it, just small padlocks. Then you put in all the keys that go with the locks. And you closed the bag and shook it hard. No matter how long you shook, chances are very small that any key would get inserted in any of the locks. But if you took them all out of the bag and this time used your hands to insert the keys in the locks, you could combine them much quicker.
Enzymes act like your hands, quickly allowing chemical reactions that would otherwise take much longer. Now, there are 2 reasons that enzymes are so effective at enabling biochemical reactions. Firs enzymes greatly reduce the amount of energy required to start the reactions, and with less energy needed the reactions can proceed a lot faster than they, could without the enzyme. The second mason is that on a small amount of an enzyme is needed to enable the biochemical reaction. That's because the chemical structure of the enzyme itself does not become altered as if enables the reaction. So a single enzyme can be used to start the same biochemical reaction over and over again.
(43)
A.The impact of enzymes on chemical reactions.
B.The way the body produces enzymes.
C.The structure of enzymes.
D.Types of chemical products created with enzymes.
二、FILL IN: (20 points, 1point for each) 1. Any piece of DNA which replicates as a single unit is called a (). 2. Almost all RNA start sites consist of a () residue. G is more common at the transcription start site than A. 3. RNA Pol III synthesizes the precurssors of () rRNA, tRNA and other () and cytosolic RNAs. Like RNA Pol II, it is located in the (). 4. The tRNA () adds the sequence 5’-CCA-3’ to the 3’-end to generate the mature 3’-end of the tRNA in tRNATyr processing of eukaryotes. 5. The replicase in prokaryotes is (), while in eukaryotes is (). 6. The major force involved in maintaining the secondary structure of protein is () bond. 7. In NER,an endonuclease () cleaves the DNA a precise number of bases on either side of the lesion. In E.coli, the gap is filled by () and the final phosphodiester bond made by (). 8. Enzymes exist which regulate the level of supercoiling of DNA molecules, these termed (). 9. The () factor is not required for transcription elongation and is released from the transcription complex after initiation. The remaining enzyme, which translocates along the DNA, is known as the () enzyme. 10. The assembled ribosome has two tRNA-binding sites. These are called the A- and P-sites, for () and () sites. 11. Alternative splicing includes the following items: alternative selection of (), alternative selection of poly(A), retention of an () and () skipping.
A、regulation by membrane receptors
B、regulating the contents of intracellular enzymes
C、covalent modification of enzymes
D、allosteric regulation of enzymes
A、Inducible enzymes
B、Repressible enzymes
C、Corepressors
D、Activator
A、The key enzymes are glycogen synthase and glycogen phosphorylase.
B、The key enzymes have phosphorylated forms and dephosphorylated forms.
C、Activity of key enzymes are regulated by hormones.
D、The phosphorylated glycogen phosphorylase is inactive.
A、Enzymatic reactions need mild conditions
B、Enzymes are highly specific
C、Enzyme activity can be regulated
D、Enzymes can catalyze all chemical reactions
A、regulate intracellular enzyme contents
B、regulation by membrane receptors
C、covalent modification of enzymes
D、regulation by intracellular receptors
E、allosteric regulation of enzymes
A.Vectors
B.Enzymes
C.Foreign DNA
D.GMO
A、Plasmid
B、Pilus
C、Capsule
D、Plasma Membrane
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