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Questions and Answers
Questions and Answers
What is the role of NAD+ primarily associated with?
What is the role of NAD+ primarily associated with?
- Synthesis of carbohydrates
- Biosynthesis of lipids
- Catabolic reactions (correct)
- Anabolic reactions
How is FAD reduced to FADH2?
How is FAD reduced to FADH2?
- By donating an electron and a proton
- By taking up a proton and two electrons (correct)
- By accepting two protons only
- By undergoing hydrolysis
Which vitamin is a precursor for Thiamine Pyrophosphate (TPP)?
Which vitamin is a precursor for Thiamine Pyrophosphate (TPP)?
- Vitamin C
- Vitamin B1 (correct)
- Vitamin B2
- Vitamin B6
What type of reactions is Coenzyme A (CoA) primarily involved in?
What type of reactions is Coenzyme A (CoA) primarily involved in?
What is a key characteristic of FAD and FMN as prosthetic groups?
What is a key characteristic of FAD and FMN as prosthetic groups?
What is the primary function of NADPH in biological systems?
What is the primary function of NADPH in biological systems?
Which type of reaction is primarily catalyzed by enzymes utilizing Pyridoxal Phosphate (PLP)?
Which type of reaction is primarily catalyzed by enzymes utilizing Pyridoxal Phosphate (PLP)?
Which enzyme class is associated with the transfer of functional groups to water?
Which enzyme class is associated with the transfer of functional groups to water?
What is the general function of cofactors in enzymatic reactions?
What is the general function of cofactors in enzymatic reactions?
Which of the following classes of enzymes involves the addition of groups to double bonds?
Which of the following classes of enzymes involves the addition of groups to double bonds?
What is the best description of the reaction catalyzed by hexokinase?
What is the best description of the reaction catalyzed by hexokinase?
Which statement about enzymes is true?
Which statement about enzymes is true?
What is the role of absolute requirement for added metal ions in metal-activated enzymes?
What is the role of absolute requirement for added metal ions in metal-activated enzymes?
What type of reaction does the enzyme class transferases primarily catalyze?
What type of reaction does the enzyme class transferases primarily catalyze?
Which enzyme class includes enzymes that catalyze the formation of C-C, C-S, C-O, and C-N bonds?
Which enzyme class includes enzymes that catalyze the formation of C-C, C-S, C-O, and C-N bonds?
Which metal ions are most commonly found in metalloenzymes?
Which metal ions are most commonly found in metalloenzymes?
What is a characteristic feature of cosubstrates compared to prosthetic groups?
What is a characteristic feature of cosubstrates compared to prosthetic groups?
Why do animals, including humans, require external sources of coenzymes?
Why do animals, including humans, require external sources of coenzymes?
What is the purpose of the recommended dietary allowance (RDA) for vitamins?
What is the purpose of the recommended dietary allowance (RDA) for vitamins?
Which of the following is NOT a recognized cause of nutritional-deficiency diseases?
Which of the following is NOT a recognized cause of nutritional-deficiency diseases?
Which vitamin can be synthesized endogenously from 7-dehydrocholesterol?
Which vitamin can be synthesized endogenously from 7-dehydrocholesterol?
What units are used to measure vitamin concentration in the diet?
What units are used to measure vitamin concentration in the diet?
During which of the following conditions might a nutritional-deficiency disease occur?
During which of the following conditions might a nutritional-deficiency disease occur?
Which type of organisms are the ultimate sources of vitamins for mammals?
Which type of organisms are the ultimate sources of vitamins for mammals?
What can be considered a provitamin?
What can be considered a provitamin?
Which vitamin deficiency is primarily associated with neural tube defects in developing embryos?
Which vitamin deficiency is primarily associated with neural tube defects in developing embryos?
What is the primary cofactor form of Vitamin B9 in the body?
What is the primary cofactor form of Vitamin B9 in the body?
Which of the following sources is NOT recommended for acquiring Vitamin B12?
Which of the following sources is NOT recommended for acquiring Vitamin B12?
What process facilitates the absorption of lipid vitamins in the intestine?
What process facilitates the absorption of lipid vitamins in the intestine?
What deficiency leads to pernicious anemia?
What deficiency leads to pernicious anemia?
Which function is NOT associated with Vitamin C?
Which function is NOT associated with Vitamin C?
What is the Recommended Daily Allowance (RDA) for Vitamin B9?
What is the Recommended Daily Allowance (RDA) for Vitamin B9?
What binds Vitamin B12 in the ileum for cellular uptake?
What binds Vitamin B12 in the ileum for cellular uptake?
Which type of anemia results from Vitamin B9 deficiency?
Which type of anemia results from Vitamin B9 deficiency?
What role does Vitamin C play in the body?
What role does Vitamin C play in the body?
What is one of the advanced symptoms associated with the Wernicke-Korsakoff syndrome?
What is one of the advanced symptoms associated with the Wernicke-Korsakoff syndrome?
Which vitamin's deficiency is characterized by Pellagra, known for its three 'D's?
Which vitamin's deficiency is characterized by Pellagra, known for its three 'D's?
Which dietary source is rich in Riboflavin (Vitamin B2)?
Which dietary source is rich in Riboflavin (Vitamin B2)?
What is the recommended daily allowance of Vitamin B6 (Pyridoxine)?
What is the recommended daily allowance of Vitamin B6 (Pyridoxine)?
Which cofactor is associated with Vitamin B5 (Pantothenic acid)?
Which cofactor is associated with Vitamin B5 (Pantothenic acid)?
What are the symptoms of riboflavin deficiency in the context of hypothyroidism?
What are the symptoms of riboflavin deficiency in the context of hypothyroidism?
What is a significant effect of alcohol on the body's vitamin metabolism?
What is a significant effect of alcohol on the body's vitamin metabolism?
Which of the following is a dietary source of Vitamin B7 (Biotin)?
Which of the following is a dietary source of Vitamin B7 (Biotin)?
What is the primary role of TPP in the body?
What is the primary role of TPP in the body?
Which condition is indicated by the 'necklace' lesions on the skin?
Which condition is indicated by the 'necklace' lesions on the skin?
Questions and Answers
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Flashcards
Flashcards
Transferases
Transferases
A group of enzymes that catalyze the transfer of functional groups from one molecule to another.
Active Site
Active Site
The specific site on an enzyme where the substrate binds and the reaction occurs.
Substrate
Substrate
A molecule that binds to the enzyme's active site and is acted upon by the enzyme.
Enzymes and Activation Energy
Enzymes and Activation Energy
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Apoenzyme
Apoenzyme
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Cofactor
Cofactor
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Holoenzyme
Holoenzyme
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Essential Ions
Essential Ions
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Metalloenzymes
Metalloenzymes
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Cosubstrates
Cosubstrates
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Prosthetic Group
Prosthetic Group
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Avitaminosis
Avitaminosis
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Recommended Dietary Allowance (RDA)
Recommended Dietary Allowance (RDA)
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Provitamin
Provitamin
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Endogenous Vitamin Synthesis
Endogenous Vitamin Synthesis
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Vitamins
Vitamins
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Iron
Iron
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Zinc
Zinc
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What are NAD+ and NADP+?
What are NAD+ and NADP+?
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What is the primary role of NADH?
What is the primary role of NADH?
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What is the primary role of NADPH?
What is the primary role of NADPH?
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What are FAD and FMN?
What are FAD and FMN?
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What is Coenzyme A (CoA) and its role?
What is Coenzyme A (CoA) and its role?
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What is Thiamine Pyrophosphate (TPP) and its role?
What is Thiamine Pyrophosphate (TPP) and its role?
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What is Pyridoxal Phosphate (PLP) and its role?
What is Pyridoxal Phosphate (PLP) and its role?
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What is Wernicke-Korsakoff Syndrome?
What is Wernicke-Korsakoff Syndrome?
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What is Thiamine (B1) essential for?
What is Thiamine (B1) essential for?
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What are the active coenzymes of Riboflavin (B2)?
What are the active coenzymes of Riboflavin (B2)?
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What are the symptoms of Riboflavin (B2) deficiency?
What are the symptoms of Riboflavin (B2) deficiency?
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What are the active coenzymes of Niacin (B3)?
What are the active coenzymes of Niacin (B3)?
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What is Pellagra, and what causes it?
What is Pellagra, and what causes it?
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What is Pantothenic acid (B5) converted into, and what is its function?
What is Pantothenic acid (B5) converted into, and what is its function?
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What is Pyridoxine (B6) essential for?
What is Pyridoxine (B6) essential for?
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What is Biotin (B7) involved in?
What is Biotin (B7) involved in?
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What are the symptoms of Biotin (B7) deficiency?
What are the symptoms of Biotin (B7) deficiency?
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What is the function of folate (vitamin B9)?
What is the function of folate (vitamin B9)?
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What is a major consequence of folate deficiency during pregnancy?
What is a major consequence of folate deficiency during pregnancy?
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What is the function of 5'-deoxyadenosylcobalamin (cobalamin)?
What is the function of 5'-deoxyadenosylcobalamin (cobalamin)?
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What is intrinsic factor (IF) and what is its role in vitamin B12 absorption?
What is intrinsic factor (IF) and what is its role in vitamin B12 absorption?
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What is megaloblastic anemia and what causes it?
What is megaloblastic anemia and what causes it?
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What is the main function of vitamin C (ascorbic acid)?
What is the main function of vitamin C (ascorbic acid)?
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What causes scurvy and what are its symptoms?
What causes scurvy and what are its symptoms?
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Where can you find vitamin C in your diet?
Where can you find vitamin C in your diet?
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What are the structural characteristics of lipid-soluble vitamins (A, D, E, and K)?
What are the structural characteristics of lipid-soluble vitamins (A, D, E, and K)?
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How are lipid-soluble vitamins absorbed in the digestive system?
How are lipid-soluble vitamins absorbed in the digestive system?
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Flashcards
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Study Notes
Study Notes
Vitamins and Cofactors
- Vitamins are essential compounds that animals often obtain from plants or microorganisms
- Mammals and carnivorous animals might obtain vitamins from eating meat
- Some vitamins are provitamins, meaning they need to be activated in the body
- Some vitamins can be synthesized endogenously
- Recommended daily allowances (RDAs) for vitamins are determined by international health organizations and vary based on age and gender
Enzymes
- Organisms need enzymes to efficiently and selectively catalyze chemical reactions.
- Enzymes are central to all biochemical processes
- Enzymes are highly specific for their substrates
- Enzymes accelerate chemical reactions significantly
- Enzymes typically function at mild temperature and pH in aqueous solutions
- All enzymes are proteins, except for a small group of catalytic RNA molecules (ribozymes)
- Their catalytic activity relies on their native protein conformation
- Molecular weights of enzymes range from 12,000 to more than one million Daltons
- Some enzymes only require amino acid residues for activity, while others need additional cofactors
Cofactors
- Cofactors are inorganic ions (e.g., Fe²⁺, Mg²⁺, Mn²⁺, Zn²⁺), or complex organic/metalloorganic molecules (coenzymes)
- Coenzymes act as transient carriers of functional groups
- A tightly bound coenzyme or metal ion is called a prosthetic group
- The complete, active enzyme with its cofactors is called a holoenzyme
- The protein part of the enzyme without the cofactor is called an apoenzyme or apoprotein
Enzyme Classification
- Enzymes are categorized based on the reactions they catalyze
- Many enzymes are named by adding "-ase" to the substrate name or a descriptor of their activity
- Examples include: Urease (hydrolysis of urea); DNA polymerase (polymerization of nucleotides to form DNA); Pepsin (digestion); Lysozyme (lyse bacterial walls)
- Enzymes may have different names or there may be different enzymes with the same name.
- Enzymes are grouped into classes. An international classification system exists.
Essential lons
- More than 25% of known enzymes require metal ions for full activity
- Some enzymes have an absolute requirement for specific metal ions while others are stimulated by added metal ions
- Examples of essential ions for enzyme activity include Mg2+ and Ca2+ for many metabolic reactions and K+ for some enzymes
Metalloenzymes
- Metalloenzymes contain firmly bound metal ions at active sites
- Common metal ions include iron (Fe) and zinc (Zn), with less common use of copper (Cu) and cobalt (Co)
- Examples include carbonic anhydrase (erythrocytes) that catalyzes CO₂ + H₂O → H⁺ + HCO₃⁻
Inorganic elements
- Many inorganic elements serve as cofactors for enzymes.
- Several examples include Cu²⁺, Fe²⁺/Fe³⁺, K⁺, Mg²⁺, Mn²⁺, Mo, Ni²⁺, Se, and Zn²⁺, each with specific enzyme functions
Coenzymes
- Cosubstrates: temporarily bind and dissociate from the enzyme during the reaction.
- Prosthetic groups: tightly bind to the enzyme and remain associated throughout the reaction.
- Animals require a source of coenzymes or precursors to survive because they cannot synthesize all of them.
- Prokaryotes, protists, fungi and plants are capable of synthesizing coenzymes from simple precursors. But animals (including humans) cannot.
Structure and Function of Vitamins
- Vertebrates typically rely on other organisms for vitamin supply.
- Most vitamin sources are plants or microorganisms even though carnivorous animals can obtain them from meat.
- Some vitamins are provitamins, which need to be activated in the body. .
- Some vitamins can be synthesized endogenously by the body. This is true for vitamin D from 7-dehydrocholesterol and vitamin K from intestinal flora
RDA for Vitamins
- RDAs or DRIs are defined as the amount of a vitamin needed to protect the body against illness
- They differ based on a person's age and gender.
- Units for vitamin concentrations are mcg (μg) and International Unit (IU)
Nutritional deficiency Diseases (Avitaminoses)
- A deficiency of a vitamin or absence of vitamins in an animal's diet can result in nutritional or vitamin deficiency diseases
- Some examples of vitamin-deficiency diseases include scurvy (vitamin C deficiency); pellagra (niacin deficiency); growth retardation (riboflavin deficiency); dermatitis (pantothenate deficiency), beri beri (thiamine deficiency)
Vitamin Classification
- Water-soluble vitamins are excreted in urine, do not cause hypervitaminosis, and are often heat sensitive (except B12).
- Fat-soluble vitamins are absorbed with fats, are stored in the body (and an overdose can cause toxicity), and are not as sensitive to heat.
Specific Vitamins
- Detailed information about individual vitamins (B1, B2, B3, B5, B6, biotin, B9, B12, vitamin C, A, D, E, K) including their sources, functions, cofactors, and deficiencies are presented in the provided text.
How Enzymes Work
- Active site: The location where the enzyme-catalyzed reaction occurs
- Substrate: The molecule acted upon in the active site
- Enzymes reduce the activation energy of a reaction (but do not change the overall free energy change or the equilibrium concentrations).
Cofactor Requirements
- Cofactors are often essential for converting inactive apoenzymes to active holoenzymes.
Nucleotide-sugar coenzymes
- Provide detailed examples of nucleotide-sugar coenzymes, such as UDP-glucose, and their involvement in biosynthetic reactions, particularly glycogen synthesis.
Other coenzymes
- Detailed information is presented in the provided text about various coenzymes like NAD+, NADP+, FAD, FMN, CoA, lipoamide, Ubiquinone (Coenzyme Q). This information includes sources, functions, and the reactions they are involved in
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