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Questions and Answers
What is the basic unit structure of nucleic acids?
Which of the following nitrogenous bases has a single ring structure?
What is the charge of the sugar-phosphate backbone in a polynucleotide chain?
What is the characteristic of a free radical?
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What is the result of incomplete oxygen reduction?
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What is a characteristic of H2O2?
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What is the term used to describe tissue damage caused by oxygen radicals?
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What is the primary function of antioxidants in the body?
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What type of antioxidant is Vitamin E?
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Which antioxidant is 20 times stronger than Vitamin C and 50 times stronger than Vitamin E?
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What is the ability of antioxidants like Vitamin C to reactivate themselves?
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Which antioxidant is able to cross the blood-brain barrier?
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Study Notes
Nucleotides
- Nucleotides are the basic structural units of nucleic acids
- Composed of three components: nitrogenous base, pentose sugar, and phosphate
- Nitrogenous bases are of two types: purines (double-ring structure: Adenine and Guanine) and pyrimidines (single-ring structure: Cytosine, Thymine, or Uracil)
Polymerization of Nucleotides
- Forms a polynucleotide chain with a negative sugar-phosphate backbone
- Free 5' phosphate on one end (5' end) and free 3' hydroxyl on the other end (3' end)
- Nitrogenous bases are attached to the backbone and are free to pair with nitrogenous bases of other polynucleotide chains
Free Radicals
- A molecule or atom with an unpaired electron in its outermost orbital
- Highly reactive and has an extremely short half-life of microseconds
- Reacts randomly with any molecule to achieve stability by either accepting or donating an electron
ROS and Oxidative Damage
- Incomplete reduction of oxygen produces ROS (superoxide, hydroxyl, perhydroxyl) and H2O2 (a highly reactive ROS)
- Tissue damage caused by oxygen radicals is called oxidative damage
Antioxidants
- Substances that protect against cellular injury by ROS or other oxidants by scavenging them
- Can be supplemented from outside (in vitro antioxidants)
- Examples:
- Enzymes: glutathione peroxidase, catalase, superoxide dismutase (SOD)
- Non-enzymes: transferrin, ferritin, ceruloplasmin, albumin, glutathione, uric acid, bilirubin, ubiquinone, vitamins E and C, beta carotene, selenium
Vitamin E
- Fat-soluble antioxidant absorbed in the small intestine
- Primary defender against effects of free radicals in the body
- Stored in liver and fat cells, protecting components of the cell and their membrane from destruction
Vitamin C
- Water-soluble antioxidant that gives up electrons easily
- Helps reactivate other antioxidants like vitamins E and C, glutathione, urate, and beta carotene
- Protects oxygen and iron from oxidation, and arteries from oxidative damage
- Works in aqueous environments, breaking chain reactions and scavenging reactive oxygen and nitrogen species
Flavonoids
- 20 times stronger antioxidant than vitamin C and 50 times stronger than vitamin E
- Water-soluble and able to attach to cells and their proteins for up to 72 hours, protecting them from oxidation and free radical damage
- Able to cross the blood-brain barrier
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Description
This quiz covers the basics of nucleotides, the building blocks of nucleic acids, including their composition, nitrogenous bases, and polymerization.
