Human Biology Ch. 1-2
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59 terms
Terms | Definitions |
|---|---|
 Homeostasis | state of chemical and physical stability inside the body that must be maintained in order for individual cells, and the whole body to stay alive |
| Evolution | change in the body plan and functioning of organisms through the generations |
| Levels of Organization | 1. atom 2. molecule 3. cell 4. tissue 5. organ 6. organ system 7. multi-cellular organism 8. population 9. community 10. ecosystem 11. biosphere |
| Biosphere | all parts of Earth's waters, crust, and atmosphere in which organisms live |
| Eukarya | domain for kingdoms including animals, plants, fungi, protists, and other multi-cellular organisms |
| Cell | an organized unit that can live and reproduce by itself, using energy, the required raw materials, and instructions from DNA |
| Steps of the Scientific Method | 1. observation 2. question 3. hypothesis 4. prediction 5. experiment 6. repeat test or develop new ones 7. Analyze and report |
| Controlled Experiment | an experiment that would only test a single prediction of a hypothesis at a time |
| Variable | a factor that can change with time or in different circumstances |
| Pathogen | an infectious, disease-causing agent, such as a virus or bacterium |
| Molecule | a unit of matter in which chemical bonding holds together two or more atoms of the same or different elements |
| Chemical Bond | a union between the electron structures of two or more atoms |
| Tracer | a substance with a radioisotope attached to it so that its pathway or destination in a cell, organism, ecosystem, or some other system can be tracked, as by scintillation counters that detect its emissions |
| Radioisotope | an unstable atom that spontaneously decays to a new, stable atom that is not radioactive |
| Atom | the smallest unit of matter that is unique to a particular element |
| Isotope | for a given element, an atom with the same number of protons as the other atoms but with a different number of neutrons |
| Compounds | a substance in which the relative proportions of two or more elements never vary |
| Mixture | atoms of two or more elements intermingled in proportions that can and usually do vary |
| Ion | an atom or a compound that has gained or lost on or more electrons and hence has acquire an overall negative or positive charge |
| Ionic Bond | an association between ions of opposite charge |
| Hydrogen Bond | a weak attraction between an electronegative atom and a hydrogen atom that is already taking part in a polar covalent bond |
| Covalent Bond | a sharing of one or more electrons between atoms or groups of atoms; when electrons are shared equally, the bond is nonpolar; when electrons are shared unequally, the bond is polar (e.g. water is polar) |
| Hydrophilic Substance | a polar substance that is attracted to the polar water molecule and so dissolves easily in water (e.g. sugars) |
| Hydrophobic Substance | a nonpolar substance that is repelled by the polar water molecule and so does no readily dissolve in water (e.g. oil) |
| Solvent | fluid in which one or more substances is dissolved |
| Solute | any substance dissolved in a solution |
| Oxidation-Reduction Reaction | an electron transfer from one atom or molecule to another; often hydrogen is transferred along with the electron(s) |
| Free Radical | any highly reactive molecule or molecule fragment having an unpaired electron; unstable; steals electrons from other molecules |
| Antioxidant | a chemical that can give up an electron to a free radical before the free radical damages DNA or some other cell constituent |
| Acids | a substance that releases hydrogen ions in water or other solutes |
| Bases | a substance that accepts H+ in water |
| Salts | compound that releases ions other than H+ and OH- in solution |
| Buffer System | a weak acid and the base that forms when it dissolves in water; work as a pair to counter slight shifts in pH |
| Organic Compound | a compound having a carbon backbone, often with carbon atoms arranged as a chain or ring structure, and at least one hydrogen atom |
| Functional Group | an atom or group of atoms that are covalently bonded to the carbon backbone of an organic compound and that influences its behavior |
| Enzymes | one of a class of proteins that greatly speed up (catalyze) reactions between specific substances |
| Condensation Reaction | chemical step in which two molecules and water often forms as a by-product |
| Polymer | a molecule composed of three to millions of small subunits that may or may not be identical |
| Hydrolysis | enzyme-driven reaction in which covalent bonds break, splitting a molecule into two or more parts and H+ and OH- (derived from a water molecule) become attached to the exposed bonding sites |
| Carbohydrates | a simple sugar or large molecules composed of sugar units; used as structural materials, energy stores, and transportable forms of energy in all cells; consist of carbon, hydrogen, and oxygen atoms in a ration of 1:2:1 |
| Lipid | a greasy or oily compound of mostly carbon and hydrogen that shows little tendency to dissolve in water, but that dissolves in nonpolar solvents (such as ether); used by cells as energy stores and structural materials |
| Fat | a lipid with a glycerol head and one, two, or three fatty acid tails |
| Fatty Acid | a long, flexible hydrocarbon chain with a --COOH group at one end |
| Triglycerides | a lipid having three fatty acid tails attached to a glycerol backbone; body's most abundant lipids and richest energy source; neutral fat |
| Phospholipid | a type of lipid that is the main structural component of cell membranes; has a hydrophobic tail (of two fatty acids) and a hydrophilic head that incorporates glycerol and a phosphate group |
| Sterol | a type of lipid with a rigid backbone of four fused carbon rings; occur in cell membranes (mainly cholesterol in human tissues) |
| Protein | a large, organic compound composed of one or more chains of amino acids held together by peptide bonds; have unique sequences of amino acids in polypeptide chains |
| Amino Acid | a small organic molecule having a hydrogen atom, an amino group, an acid group, and an R group covalently bonded to a central carbon atom |
| Polypeptide Chain | three or more amino acids joined by peptide bonds |
| Lipoproteins | Molecule that forms when proteins circulating in blood combine with cholesterol, triglycerides, and phospholipids absorbed from the small intestine |
| Glycoproteins | a protein having oligosaccharides covalently bonded to it |
| Nucleotide | a small organic compound having a five-carbon sugar, nitrogen-containing base, and phosphate group; structural unites of adenosine phosphates , nucleotide coenzymes, and nucleic acids |
| ATP | adenosine triphosphate; a nucleotide composed of adenine, ribose, and three phosphate groups; main energy carrier in cells, and directly or indirectly delivers energy to or picks up energy from nearly all metabolic pathways |
| Coenzymes | a type of nucleotide that transfers hydrogen atoms and electrons from one reaction site to another; NAD+ is an example |
| Nucleic Acids | a long, single- or double- stranded chain of four different nucleotides joined at their phosphate groups; differ in which nucleotide base follows the next in the sequence (ex. DNA and RNA) |
| DNA | for all cells (and many viruses), the molecule of inheritance; a category of nucleic acids, usually consisting of two nucleotide strands twisted together helically and held together by hydrogen bonds; encodes instructions for assembling proteins & new individuals |
| RNAs | a category of single-stranded nucleic acids that function in processes by which genetic instructions are used to build proteins |
| Saturated Fats | tails only have single bonds between carbon atoms and hydrogen atoms attached to all other bonding sites |
| Unsaturated Fats | have one or more double bonds between certain carbon atoms |
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