Biology week 1
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50 terms
Terms | Definitions |
|---|---|
 Hierarchial | A system of ranking and organizing things or people, where each element of the system (except for the top element) is subordinate to a single other element. |
| Covalent bond | A type of strong chemical bond in which two atoms share one of more pairs of valence electrons. |
| Hydrogen bond | A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule. |
| Polar molecules | Molecules with opposit charges on opposite sides (example = water). |
| Hydrophobic | Having an aversion to water; tending to coalesce and form droplets in water (example = motor oil). |
| Ion | An atom that has gained or lost electrons, thus acquiring a charge. |
| Hydrogen ion | A single proton with a charge of 1+. The dissociation of a water molecule leads to the generation of a hydroxide ion and a hydrogen ion. |
| pH | A measure of hydrogen ion concentration equal to -log[H+] and ranging in value from 0 to 14. |
| Polymer | A long molecule consisting of many similar or identical monomers linked together. |
| Macromolecule | A giant molecule formed by the joining of smaller molecules, usually by a condensation reaction (examples = polysaccharides, proteins, nucleic acids). |
| Hydrolysis | A chemical process that lyses, or splits, molecules by the addition of water. |
| Dehydration synthesis | A chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule. |
| Protein | A three-dimensional biological polymer constructed from a set of 20 different monomers called amino acids. |
| Polypeptide | A polymer (chain) of many amino acids linked together by peptide bonds. |
| Peptide | The makeup of a polypeptide, also made from amino acids. |
| Amino acid | An organic molecule possessing both carboxyl and amino groups. Amino acids serve as the monomers of proteins. |
| Polysaccharide | A polymer of up to over 1000 monosaccharides, formed by dehydration reactions. |
| Monosaccharide | The simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides. Also known as simple sugars, the molecular formulas of monosaccharides are generally some multiple of CH20. |
| Sugar | Either a monosaccharide, disaccharide, or polysaccharide. |
| Nucleic acid | A polymer (polynucleotide) consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities. The types are DNA and RNA. |
| Nucleotide | The building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous bas and a phosphate group. |
| Phosphate group | A functional group important in energy transfer (ATP and ADP). |
| Phospholipid bilayer | Molecules that are constituents of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail. |
| Primary structure | The level of protein structure referring to the specific sequence of amino acids. |
| Secondary structure | The localized, repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bond formation between peptide linkages. |
| Tertiary structure | Irregular contortions of a protein molecule due to interactions of side chains involved in hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges. |
| Quaternary structure | The paticular shape of a complex, aggregate protein, defined by the characteristc three-dimensional arrangement of its constituent subunits, each a polypeptide. |
| Denaturation | In proteins, a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. Denaturation occurs under extreme conditions in pH, salt, concentration, and temperature. |
| Renaturation | Opposite of denaturation. |
| Amphipathic | A molecule that has both a hydrophilic region and a hydrophobic region. |
| Micelle | An electrically charged particle formed by an aggregate of molecules and occuring in certain colloidal electrolyte solutions. |
| Biological membrane | A membrane surrounding the cell. It does differ between plant membrae and animal membrane. |
| Semi-permeable membrane | Membrane that allows vertain particles to flow freely through the membrane without any energy required. |
| Diffusion | The tendenc of molecules of any substance to spread out evenly into the available space. |
| Osmosis | The diffusion of water across a selectively permeable membrane. |
| Turgid | Very firm; health state for most plant cells. |
| Flaccid | Limp due to isotonic environment, thus having no water enter and stay in. |
| Plasmolyzed cell | A cell involved in plasmolysis, which is when the cell is immersed in a hypertonic environment, and the cell will lose water to its surroundings and shrink. The plasma membrane pulls away from the cell wall, also. |
| Hypertonic | The cell wall will lose water to its environment, shrivel, and probably die. |
| Hypotonic | Water will enter the cell faster than it can leave, and the cell wall will burst (lyse) like an overfilled balloon. |
| Passive transport | The diffusion of a substance across a biological membrane. |
| Facilitated transport | The spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients. It moves from high to low concentration. |
| Active transport | The movement of a substance across a biological membrane against its concentration or electrochemical gradient with the help of energy input and specific transport proteins. It moves from low to high concentration. |
| Cotransport | The coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient. |
| Ion pump | Transports one ion into the membrane and takes another ion out. The protein changes its shape so the ion can fit in it for transport. |
| Sodium-potassium pump | A type of ion pump that transfers K+ ions into the cell and Na+ ions out of the cell. |
| Hydrogen ion pump | A hydrogen ion is forced out of the cell by ATP through a protein and comes back into the cell with a sucrose molecule. The hydrogen ion helps the sucrose enter the cell and keeps the cell alive. |
| Exocytosis | The cellular secretion of macromolecules by the fusion of vesicles with the plasma membrane. |
| Endocytosis | The cellular uptake of macromolecules and particular substances by localized regions of the plasma membrane that surround the substance and pinch off to form an intracellular vesicle. |
| Vesicle | A sac made of membrane inside of cells. |
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