a state of biological balance

Temperature, moisture level, acidity must remain within tolerance range of an organism. Maintained by systems that monitor internal conditions and make routine and necessary adjustments

a group of similarly constructed organisms that successfully interbreed

the largest classification category

3 domains: bacteria, archaea, and eukarya

microscopic unicellular prokaryotes, which lack the membrane-bounded nucleus found in the eukaryotes of domain Eukarya

well known for living in aquatic environments that lack oxygen or are too salty, too hot, or too acidic for most other organisms

may be representative of first cells that evolved

like archaea, they are microscopic unicellular prokaryotes, which lack the membrane-bounded nucleus found in the eukaryotes of domain Eukarya

variously adapted to living almost anywhere: water, soil, and atmosphere, as well as on our skin and in our mouths and large intestines

some cause diseases, others give valuable services

bacteria and archaea are microscopic unicellular prokaryotes

structurally simple but metabolically complex

one of the categories used to classify organisms; the category above phylum

protista (protists), plantae (plants), fungi, animalia (animals)

class of organic compounds that includes monosaccharides, disaccharides, and polysaccharides

food example: bread, pasta

polymer: polysaccharide

monomer: monosaccharide

class of organic compounds that tends o be soluble only in nonpolar solvents such as alcohol; includes fats and oils

food example: meat with fat

polymer: fat

monomer: glycerol and fatty acids

molecule consisting of one or more polypeptides

food example: meat

polymer: polypeptide

monomer: amino acid

polymer of nucleotides; both DNA and RNA are nucleic acids

food example: fish, eggs, milk

polymer: DNA, RNA

monomer: nucleotide

six-carbon sugar that organisms degrade as a source of energy during cellular respiration

the major source of cellular fuel for all living things

broken down to release energy

animals store glucose as glycogen

liver cells contain granules where glycogen is stored until needed

the release of the hormone insulin from the pancreas promotes the storage of glucose as glycogen

plants store glucose as starch

exists in 2 forms: unbranched and branched

both forms of starch serve as glucose reservoirs in plants

plants and animals can hydrolyze starch and therefore can tap into these reservoirs for energy

some types of polysaccharides are structural polysaccharides, such as cellulose in plants

the cellulose monomer is simply glucose

cellulose is the most abundant carbohydrate and most abundant organic molecule on Earth-plants produce over 100 billion tons of cellulose each year

wood and cotton are cellulose plant products

a lipid used for insulation and long-term energy storage

contain 2 types of subunit molecules: glycerol and fatty acids

solid at room temperature and contain saturated fatty acids

fat stores more energy than glycogen

plants use oil instead of fat for long-term energy storage

2 types of subunit molecules: glycerol and fatty acids

liquids in the refrigerator are of plant origin and contain unsaturated fatty acids

no double bonds between the carbon atoms

fats contain saturated fatty acids

have double bonds in the carbon chain wherever the number of hydrogens is less than 2 per carbon atom

oils contain unsaturated fatty acids

like fats, they contain glycerol and 3 groups bonded to glycerol

only 2 of these groups are fatty acids

they are lipids that have entirely different structure from that of fat

a steroid molecule has a skeleton of 4 fused carbon rings

primary: sequence of amino acids

secondary: alpha helix and pleated sheet

tertiary: globular shape

quaternary: more than one polypeptide