Six types of enzymes | Chemical Processes | MCAT | Khan Academy

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6 Dec 201307:03
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TLDRThe video script provides an insightful overview of enzymes, highlighting their role in catalyzing various biochemical reactions and making them proceed more rapidly by reducing activation energy. It explains the systematic naming of enzymes, which often reflects their function, using DNA polymerase and hexokinase as examples. The script categorizes enzymes into six main types based on the reactions they catalyze: transferases, which move functional groups; ligases, which join molecules; oxidoreductases, involved in electron transfer; isomerases, converting one isomer to another; hydrolases, which use water to break bonds; and lyases, which catalyze bond dissociation without water or oxidation. Each category is exemplified with a specific enzyme and its role in biological processes, such as peptidyl transferase in protein translation, DNA ligase in DNA replication, lactate dehydrogenase in lactic acid fermentation, phosphoglucose isomerase in glycolysis, and argininosuccinate lyase in the urea cycle. The summary underscores the specificity and diversity of enzymatic functions in cellular metabolism.

Takeaways
  • 🚀 Enzymes are biological catalysts that speed up biochemical reactions by lowering the activation energy required for the reaction to occur.
  • 🔍 Enzyme names often reflect their function; for instance, DNA polymerase is involved in making polymers of DNA during replication.
  • 🔬 The suffix 'ase' is commonly found at the end of enzyme names, indicating their catalytic role.
  • 🔄 Transferases are a class of enzymes that catalyze the transfer of a functional group from one molecule to another, such as during protein translation.
  • 🧬 Ligases join two molecules together to form a complex, exemplified by DNA ligase which joins DNA strands during replication.
  • ⚡ Oxidoreductases facilitate electron transfer between molecules, with oxidases removing electrons and reductases donating electrons.
  • 🔁 Isomerases convert a molecule into one of its isomers, like phosphoglucose isomerase converting glucose-6-phosphate to fructose-6-phosphate.
  • ⛓ Hydrolases cleave molecules using water, such as serine hydrolases breaking peptide bonds in proteins.
  • ⚒ Lyases catalyze the dissociation of molecules into two without using water or oxidation, like argininosuccinate lyase in the urea cycle.
  • 🔬 Enzymes can be categorized into six main groups based on the type of reactions they catalyze: transferases, ligases, oxidoreductases, isomerases, hydrolases, and lyases.
  • 📚 Understanding enzyme names and their classifications helps in remembering their functions and the specific biochemical reactions they catalyze.
Q & A

  • How do enzymes speed up biochemical reactions?

    -Enzymes speed up biochemical reactions by lowering their activation energy, making it easier for the reaction to proceed.

  • What is the general naming convention for enzymes?

    -Enzymes are generally named based on the reactions they catalyze, often with the suffix 'ase' at the end of their names.

  • What is the role of DNA polymerase in DNA replication?

    -DNA polymerase acts on DNA to make polymers of DNA, playing a crucial role in DNA replication.

  • How does the naming of hexokinase reflect its function?

    -Hexokinase adds phosphate groups to six-carbon sugars like glucose, with 'hexo' referring to the number 6 and 'kinase' indicating the addition of phosphate groups.

  • What is the basic reaction catalyzed by transferases?

    -Transferases catalyze reactions where a functional group X is moved from molecule B to molecule A.

  • Can you provide an example of a reaction catalyzed by peptidyl transferase?

    -Peptidyl transferase catalyzes the transfer of amino acids from tRNA molecules to the growing polypeptide chain during protein translation.

  • What is the primary function of ligases?

    -Ligases catalyze reactions where two molecules, A and B, combine to form a complex or a single molecule, AB.

  • How does DNA ligase contribute to DNA replication?

    -DNA ligase catalyzes the joining of two DNA strands together during DNA replication.

  • What are oxidoreductases and what types of reactions do they catalyze?

    -Oxidoreductases catalyze reactions involving the transfer of electrons between molecules, either from molecule B to A or from molecule A to B.

  • What is the role of lactate dehydrogenase in lactic acid fermentation?

    -Lactate dehydrogenase catalyzes the oxidation-reduction reaction during lactic acid fermentation, transferring electrons between NADH and pyruvate or between lactic acid and NAD.

  • How do isomerases differ from other enzyme categories in their function?

    -Isomerases are involved in converting a molecule, like molecule A, into one of its isomers without the addition or removal of electrons or the use of water.

  • What is the key feature of hydrolase enzymes?

    -Hydrolases use water to cleave a molecule into two other molecules, breaking bonds through a hydrolysis reaction.

  • What is unique about the reactions catalyzed by lyases?

    -Lyases catalyze the dissociation of a molecule into two other molecules without using water or oxidation, often generating a double bond or a ring structure in the process.

Outlines
00:00
🧬 Enzymes and Their Role in Biochemical Reactions

This paragraph introduces the topic of enzymes and their function in catalyzing biochemical reactions. Enzymes are shown to increase the speed of these reactions by reducing the activation energy, as illustrated by a reaction coordinate diagram. The naming convention for enzymes is discussed, highlighting how it often reflects the type of reaction the enzyme catalyzes, with examples such as DNA polymerase and hexokinase. The paragraph also explains the 'ase' suffix commonly found in enzyme names and categorizes enzymes into six groups based on the reactions they catalyze: transferases, ligases, oxidoreductases, isomerases, hydrolases, and lyases. Each category is briefly introduced with examples of the types of reactions they perform.

05:01
🔄 Classification of Enzymes and Their Specific Reactions

The second paragraph delves into the specifics of each enzyme category. Transferases are described as enzymes that move functional groups between molecules, with peptidyl transferase being a key example in protein translation. Ligases are shown to join two molecules together, exemplified by DNA ligase in DNA replication. Oxidoreductases are unique for involving electron transfer, with oxidases and reductases highlighted, and lactate dehydrogenase given as an example in lactic acid fermentation. Isomerases are characterized by their ability to convert a molecule into an isomer, with phosphoglucose isomerase mentioned for its role in glycolysis. Hydrolases are introduced as enzymes that use water to break molecular bonds, with serine hydrolases or proteases noted for their role in peptide bond hydrolysis. Lastly, lyases are discussed for their ability to break bonds without water or oxidation, using the example of argininosuccinate lyase in the urea cycle. The paragraph concludes by emphasizing the importance of recognizing the unique mechanisms of each enzyme class.

Mindmap
Keywords
💡Enzymes
Enzymes are biological catalysts that speed up biochemical reactions by lowering their activation energy. They are central to the video's theme as it discusses their role in various types of reactions. For example, DNA polymerase is an enzyme that facilitates DNA replication by synthesizing polymers of DNA.
💡Activation Energy
Activation energy is the minimum energy required to initiate a chemical reaction. In the context of the video, enzymes are shown to speed up reactions by reducing this energy, making biochemical processes more efficient. The concept is illustrated with a reaction coordinate diagram.
💡DNA Polymerase
DNA polymerase is an enzyme involved in DNA replication. It is named for its function, which is to synthesize DNA polymers. The video uses DNA polymerase as an example to demonstrate how enzyme names often reflect their reactions, emphasizing the enzyme's role in the replication of DNA.
💡Hexokinase
Hexokinase is an enzyme that catalyzes the first step of glycolysis, where it adds a phosphate group to glucose, forming glucose-6-phosphate. The name 'hexokinase' is derived from 'hexo', referring to the six-carbon sugar, and 'kinase', indicating the enzyme adds phosphate groups, highlighting the specificity of enzyme names to their reactions.
💡Transferase
Transferases are a class of enzymes that catalyze the transfer of a specific functional group from one molecule (B) to another (A). The video mentions peptidyl transferase as an example, which is involved in protein translation, transferring amino acids from tRNA to the growing polypeptide chain.
💡Ligase
Ligases are enzymes that join two molecules (A and B) to form a complex or a single molecule (AB). DNA ligase is used as an example in the video, which is crucial during DNA replication for joining two DNA strands together, emphasizing the role of ligases in forming molecular bonds.
💡Oxidoreductase
Oxidoreductases are enzymes that catalyze oxidation-reduction (redox) reactions, transferring electrons from one molecule to another. The video explains that these enzymes can catalyze both the forward and reverse reactions, and uses lactate dehydrogenase as an example, which is involved in lactic acid fermentation.
💡Dehydrogenase
Dehydrogenases are a type of oxidoreductase enzyme that specifically remove a hydride ion (which consists of hydrogen and two electrons) from a molecule. The video mentions lactate dehydrogenase, which removes a hydride from lactic acid, illustrating the role of dehydrogenases in electron transfer reactions.
💡Isomerase
Isomerases are enzymes that catalyze the conversion of a molecule (A) into one of its isomers. The video uses phosphoglucose isomerase as an example, which converts glucose-6-phosphate into fructose-6-phosphate, an important step in glycolysis, demonstrating the role of isomerases in molecular rearrangement.
💡Hydrolase
Hydrolases are enzymes that use water to cleave a molecule (A) into two molecules (B and C). The video provides the example of serine hydrolases or serine proteases, which are involved in the hydrolysis of peptide bonds, showing how hydrolases facilitate the breakdown of larger molecules into smaller ones.
💡Lyase
Lyases are enzymes that catalyze the dissociation of a molecule into two smaller molecules without using water or oxidation. Argininosuccinate lyase is given as an example, which breaks down argininosuccinate into arginine and succinate during the urea cycle, highlighting the unique mechanism of lyases in bond cleavage.
Highlights

Enzymes make biochemical reactions go faster by lowering their activation energy.

Enzymes are generally named for their reactions, which helps in remembering what an enzyme does.

DNA polymerase is an enzyme involved in DNA replication that acts on DNA to make polymers.

The suffix 'ase' is commonly found at the end of most enzyme names.

Hexokinase is an enzyme that catalyzes the first step of glycolysis, adding phosphates to six-carbon sugars like glucose.

Enzymes can be divided into six different categories based on the types of reactions they catalyze.

Transferases catalyze reactions where a functional group is moved from one molecule to another.

Peptidyl transferase is an enzyme that catalyzes the transfer of amino acids from tRNA to the growing polypeptide chain during protein translation.

Ligases catalyze reactions where two molecules combine to form a complex.

DNA ligase is an enzyme that joins two separated DNA polymers together during DNA replication.

Oxidoreductases catalyze reactions involving the transfer of electrons between molecules.

Lactate dehydrogenase is an enzyme that catalyzes oxidation reduction reactions during lactic acid fermentation.

Isomerase enzymes catalyze reactions where a molecule is converted to one of its isomers.

Phosphoglucose isomerase catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate in glycolysis.

Hydrolases use water to cleave a molecule into two other molecules.

Serine hydrolases/proteases catalyze the hydrolysis of peptide bonds using a serine residue as the key catalytic amino acid.

Lyases catalyze the dissociation of a molecule into two without using water or oxidation.

Argininosuccinate lyase catalyzes the cleavage of argininosuccinate into arginine and succinate during the urea cycle.

Lyases need to generate a double bond or a ring structure to work since they don't use water or oxidation to break a bond.

Transcripts

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Related Tags
Enzyme FunctionsBiochemical ReactionsDNA PolymeraseHexokinaseProtein TranslationPeptidyl TransferaseDNA LigationOxidation ReductionLactate DehydrogenasePhosphoglucose IsomeraseSerine HydrolasesArgininosuccinate LyaseMolecular BondingBiological CatalystsEnzyme ClassificationBiochemistry EducationCellular ProcessesMolecular BiologyLife SciencesBiological Mechanisms