Table of contents

1. Introduction to Biochemistry4h 34m
2. Water3h 23m
3. Amino Acids8h 10m
4. Protein Structure10h 4m
5. Protein Techniques14h 5m
6. Enzymes and Enzyme Kinetics13h 38m
7. Enzyme Inhibition and Regulation 8h 42m
8. Protein Function 9h 41m
9. Carbohydrates7h 49m
10. Lipids5h 49m
11. Biological Membranes and Transport 6h 37m
12. Biosignaling9h 45m
Review 1: Nucleic Acids, Lipids, & Membranes2h 47m
Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway3h 12m
Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism2h 26m
Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation1h 48m

6. Enzymes and Enzyme Kinetics

Enzymes

Biochemistry

6. Enzymes and Enzyme Kinetics

Enzymes

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Multiple Choice

Which two classes of enzymes are required for the two-step conversion of cytosine to 5-hydroxymethylcytosine (5hmC) in DNA?

Ligases and helicases

Kinases and phosphatases

DNA methyltransferases and TET dioxygenases

Proteases and isomerases

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Verified step by step guidance

Step 1: Understand the context of the problem. The question is asking about the enzymatic conversion of cytosine to 5-hydroxymethylcytosine (5hmC) in DNA, which involves two distinct steps catalyzed by specific classes of enzymes.

Step 2: Recall the first step in the conversion process. Cytosine is initially methylated to form 5-methylcytosine (5mC). This reaction is catalyzed by DNA methyltransferases, which transfer a methyl group to the cytosine base in DNA.

Step 3: Consider the second step in the conversion process. The 5-methylcytosine (5mC) is then oxidized to form 5-hydroxymethylcytosine (5hmC). This reaction is catalyzed by TET dioxygenases, which use molecular oxygen and cofactors like Fe(II) and α-ketoglutarate to perform the oxidation.

Step 4: Review the roles of the other enzyme classes mentioned in the options. Ligases and helicases are involved in DNA repair and replication, kinases and phosphatases regulate phosphorylation, and proteases and isomerases are involved in protein processing and structural rearrangements. None of these are relevant to the conversion of cytosine to 5hmC.

Step 5: Conclude that the correct answer is DNA methyltransferases and TET dioxygenases, as these are the two enzyme classes directly involved in the two-step conversion of cytosine to 5-hydroxymethylcytosine in DNA.