Chapter 2: Biochemistry Flashcards
Isotopes
Atoms of one element where the number of neutrons vary.
Half-life
The rate of decay for some isotopes.
Radioisotopes
Radioactive isotopes that can be used to diagnose and treat certain diseases of the thyroid gland. A good example is I-131.
Tracer
Used to trace the path of a certain molecule, such as radioactive carbon.
Bond
Formed when two atomic nuclei attract the same electrons. Making bonds releases energy, but breaking bonds requires energy.
Ionic Bonds
Bonds that result from the transfer of electrons.
Covalent Bonds
Bonds that result from atoms sharing electrons, which creates molecules.
Hydrophilic
“Water-loving.” Refers to substances that are polar and can dissolve like (polar) substances.
Hydrophobic
“Water-hating.” Refers to substances that are non polar and can only dissolve equally non polar substances.
Since the plasma membrance is a phospholipid bilayer, only non polar substances can easily pass through. Large polar molecules must use special hydrophilic channels.
Properties of Water
- Water can make hydrogen bonds between other water molecules.
- Water is highly polar.
- Water has high specific heat, which means they resist changes in temperature and warm the nearby land.
- Water has a high heat of vaporization.
- Water is the universal solvent.
- Water has strong cohesion, such as capillary action and surface tension.
- Only substance where the solid is less dense than the liquid form.
pH
Measure of the acidity and alkalinity of a solution. Calculate it using -log(H+ moles/L).
pH of water, blood, and acid rain
Water: 7
Blood: 7.4
Acid rain: 1.5-5.4
Buffers
Substances that resist changes in pH. Works by absorbing H+ ions or donating H+ ions when necessary.q
Isomers
Organic compounds with the same molecular formula but different structures.
Structural Isomers
Differing in the atom arrangement.
Cis-Trans Isomers
Differing in the double bond arrangement.
Enantiomers
Mirror images (L and D sides). For example, the L-dopa is effective against Parkinson’s, but D-dopa is useless.
Macromolecules
Carbohydrates, lipids, nucleic acids, proteins
Carbohydrates
Made from C, H, O. The ratio between H atoms and O atoms is always 2:1. Carbohydrates are often used for quick energy. There are three classes of carbohydrates: monosaccharides, disaccharides, and polysaccharides.
Monosaccharides
Glucose, galactose, fructose.
Disaccharides
Two monosaccharides glued together with the release of a water through dehydration or condensation.
glucose + glucose -> maltose + H2O
glucose + galactose -> lactose + H2O
glucose + fructose -> sucrose +H2O
Hydrolysis
The breakdown of a compound by adding water.
Polysaccharides
Macromolecules. They are polymers of carbohydrates and formed by many monosaccharides joined together through dehydration reactions.
Plants have cellulose (plant walls) and starch for storage, whereas animals have chitin (exoskeleton and cell walls) and “animal starch.”
Lipids
Hydrophobic substances that include fats, oils, steroids, and waxes. Composed of 1 glycerol and 3 fatty acids.
Fatty acid
A hydrocarbon chain with a carboxyl group at the end. They can be either saturated or unsaturated.
Saturated Fatty Acid
- Solid at room temperature (example: butter).
- Only contains single bonds.
Unsaturated Fatty Acid
- Liquid at room temperature (example: oil).
- Contains at least one double bond.
Steroids
Composed of four lipid rings. Examples include cholesterol, testosterone, estradiol.
Lipid Functions
- Energy storage.
- Upkeeping the structure of the cell membrane.
- Hormones.
Phospholipids
Made of a hydrophobic tail and a hydrophilic head. When these make contact with the water, they self-form into a bilayer, with the heads facing the water and the tails towards the insides.
Proteins
Functions:
- Growth and repair.
- Cell-cell signaling.
- Enzymatic activity.
- Homeostasis.
- Movement.
Proteins are composed of amino acids joined together by peptide bonds, and have an amino group, carboxyl group, and an R group.
Protein Structure
Primary, secondary, tertiary, quaternary.
Primary: single linear sequence of amino acids.
Secondary: the linear sequence begins to fold and coil due to hydrogen bonds, and can form either an alpha helix or beta pleated sheet.
Tertiary: the 3D shape of a protein that is created by the folding in of the secondary structure.
Quaternary: proteins that consist of more than one polypeptide chain.
Denaturation
Unfavorable conditions for a protein can cause a protein to lose the strong intermolecular forces and its characteristic shape.
Chaperonins
Proteins that assist in the folding of proteins.
Prions
Misfolded proteins that can cause brain diseases.
Nucleic acids
The two types of nucleic acid are RNA and DNA, which encode hereditary information.
Made up of nucleotides, which consist of a nitrogenous base, 5 carbon sugar, and phosphate group.
Laws of Thermodynamics
- Energy cannot be created or destroyed, only converted.
2. With more energy conversions, the universe become more disordered.
Metabolism
Sum of all the chemical reactions that take place in the cells. Some reactions involve breaking down molecules (catabolism) and building molecules (anabolism).
Characteristics of Enzymes
Enzymes are “globular proteins” and have a 3D (tertiary) shape. They are also substrate specific, and follow the induced-fit model, meaning the enzymes chances its shape slightly to fit the substrate.
Competitive Inhibition
When some similar looking compounds look similar and “compete” for the same active site on the enzyme. This reduces the amount of product made from the enzymes, as well as limiting the substrates binding to the enzyme.
Noncompetitive Inhibitors
Bind to a site distinct and separate from the enzyme’s active site.
