Ch 1: Science Flashcards
What is science
- Work with evidence, not proof
- Propose explanations based on what we observe
Hypothesis
A statement that might be true
Fact
Hypothesis confirmed to extremely High degree
Theory
A comprehensive explanation of some aspect of nature that is supposed by a vast body of evidence
Element
- defined by the number of protons
- cannot be broken down into other substances
Molecule
Two or more atoms held together by chemical bonding
Compound
Molecules with 2 or more elements
Emergent properties
Properties of a compound that are not just the combination of each elements’ properties
Life is an emergent property of a particular arrangement of certain molecules
Polar molecule
Molecule with uneven distribution of charges
Hydrogen bond
Weak attraction between polar molecules
Crystal
3D lattice of atoms
Homogenous mixture or solution
Each component cannot be distinguished with a light microscope
Enzyme
- catalyst
- makes a chemical reaction take place more easily
Diffusion
Net movement of a substance from an area of high concentration to an area of low concentration
Osmosis
Diffusion of water across a semi-permeable membrane
Acid
- substance that increased concentration of H+ ions in water
- Acidity: Concentration of H+ ions
Base
- Substance that increases the concentration of hydroxide (OH-) ions in water
Acidity of water
H2O = H+ + OH-
pH
Below 7 : acid
7 : neutral
More than 7: base
Polymer
Large molecule composed of many repeated subunits
4 classes of biologically important macromolecules (large molecules)
Lipids
Carbohydrates
Nucleic acids
Proteins
Lipids
Non-polar
High in chemical energy
Ex: fat, oil, wax, phospholipid bilayers
Carbohydrates
Polar
High in chemical energy
- Monosaccharides: each molecule has a single sugar unit (glucose, fructose)
- Disaccharides: each molecule has two sugar units (sucrose, lactose)
- Polysaccharides: many sugar units (starch, cellulose, glycogen)
Proteins
- Enzymes, hormones, structural proteins
- Folded chain of amino acids (unfolded = polypeptide)
- some parts polar some parts non-polar
- Primary structure: the sequence of amino acids
- Secondary structure: repeated coils or folds of the primary structure
- Tertiary structure: irregular folding of the primary and secondary structures
- Quaternary structure (not always present): two or more tertiary structures integrated into a functional unit
Nucleic acids
DNA, RNA
Polymers of nucleotides
Living matter elements
96% C, O, N, H
4% Ca, P, K, S, Na…
