Key Concepts in Chemistry and Biology

Independent variable

Factor changed by the experimenter

Dependent variable

Factor measured in response to changes

Controlled variables

Conditions kept constant during the experiment

Testable hypothesis

Falsifiable explanation for a phenomenon

Negative control

Group not receiving treatment for comparison

Protons

Positively charged particles in the nucleus

Neutrons

Neutral particles in the nucleus of an atom

Electrons

Negatively charged particles orbiting the nucleus

Net charge

Total of positive and negative charges

Atomic mass

Mass of an atom, primarily from protons and neutrons

Isotope

Element variant with different neutron count

Electron shells

regions around nucleus containing electrons

Valence electrons

Electrons in the outermost electron shell

Inert atom

Atom with a full valence shell, unreactive

Chemical bond

Attraction between atoms forming molecules

Molecule

Two or more bonded atoms, same or different

Ionic bond

Bond formed by electron transfer between atoms

Cation

Positively charged ion, electron donor

Anion

Negatively charged ion, electron acceptor

Salt

Compound formed from cation-anion interactions

Sodium chloride

Common salt formed by sodium and chlorine

Sodium Ions

Regulate blood volume and pressure.

Ionic Bonds

Form and maintain protein shapes.

Covalent Bonds

Atoms share pairs of electrons.

Electronegativity

Atom's ability to attract electrons.

Nonpolar Covalent Bond

Equal sharing of electrons between atoms.

Polar Covalent Bond

Unequal sharing of electrons creates partial charges.

Hydrogen Bond

Attraction between hydrogen and electronegative atoms.

Electrons in Outer Shell

the number of bonds an atom forms.

Covalent Bonding Elements

Involves carbon, oxygen, nitrogen, hydrogen.

Glucose and Fructose

Sugars held together by covalent bonds.

Partial Positive Charge

Developed by less electronegative atom in polar bond.

Partial Negative Charge

Developed by more electronegative atom in polar bond.

Ionic Bonding

Atoms transfer electrons, carrying full charges.

Hydrogen Bonding in Water

Water's polar bonds lead to hydrogen bonds.

Covalent Bond Example

Hydrogen atoms share electrons equally.

Chlorine's Electronegativity

Stronger attraction for shared electrons than hydrogen.

Net Movement in Nonpolar Molecules

Polar bonds cancel each other out.

Hydrogen Bond

Attraction between hydrogen and electronegative atom.

Covalent Bonding

Essential for living organisms' molecular structure.

Polar Bonds

Bonds with partial positive and negative charges.

Cohesion

Attraction between like molecules, e.g., water.

Surface Tension

Resistance of water surface due to hydrogen bonds.

Capillarity

Movement of water against gravity through cohesion and adhesion.

High Specific Heat

Heat required to change 1g's temperature by 1°C.

Hydrophilic

Molecules that interact favorably with water.

Hydrophobic

Molecules that do not interact with water.

Hydrophilic Interaction

Polar regions of solutes form hydrogen bonds with water.

Proton (H+)

Hydrogen atom without its electron, highly reactive.

Hydroxide Ion (OH-)

Water molecule retains hydrogen's electron, reactive ion.

Acid

Substance that increases H+ concentration in solution.

Base

Substance that decreases H+ concentration or increases OH-.

Ocean Acidification

Decrease in ocean pH due to CO2 absorption.

Carbonic Acid (H2CO3)

Formed when CO2 dissolves in seawater.

Bicarbonate (HCO3-)

Produced from H+ combining with carbonate ions.

Functional Groups

Groups that determine chemical reactivity of molecules.

Macromolecules

Large organic molecules, often with 1000+ atoms.

Carbohydrates

Sugars and starches, energy sources for organisms.

Biomolecules

Organic molecules essential for life, containing CHON.

Covalent Bond

Bond linking functional groups to carbon skeleton.

Hydrophilic vs Hydrophobic

Carbs are generally hydrophilic, interacting with water.

Polymerization

Process of linking monomers to form polymers.

Glycosidic bond

Covalent bond linking sugar molecules.

Disaccharides

Two monosaccharides linked by glycosidic bond.

Polysaccharides

Long chains of monosaccharide units.

Ionic bonds

Electrostatic attraction between charged ions.

Covalent bonds

Bonds formed by shared electron pairs.

Hydrogen bonds

Weak bonds between polar molecules.

Hydrophobic bonds

Interactions between nonpolar molecules in water.

Cellulose

Structural polysaccharide in plant cell walls.

Chitin

Structural polysaccharide in arthropods and fungi.

Starches

Polysaccharides serving as glucose storage in plants.

Glycogen

Carbohydrate storage molecule in animals.

Fat

Glycerol linked to three fatty acids.

Phospholipids

Molecules with hydrophilic heads and hydrophobic tails.

Amphipathic

Molecules with both hydrophilic and hydrophobic regions.

Sterols

Subgroup of steroids, important for membrane structure.

Cholesterol

Essential for animal cell membrane stability.

Lipoproteins

Molecules that transport cholesterol in bloodstream.

Cholesterol

Hydrophobic substance, not soluble in blood.

Amphipathic molecules

Contain both hydrophilic and hydrophobic regions.

Globular proteins

Water-soluble proteins with compact shapes.

Fibrous proteins

Structural proteins, long and narrow.

Membrane proteins

Proteins that function as receptors and channels.

Carbohydrates

Organic compounds, including glucose and polysaccharides.

Amino acids

Monomers that make up proteins, 20 types.

Peptide bonds

Covalent bonds linking amino acids in proteins.

Dehydration reaction

Process forming peptide bonds by removing water.

Polypeptides

Chains of amino acids linked by peptide bonds.

Hydrolysis reaction

Process breaking down polypeptides into amino acids.

Primary structure

Sequence of amino acids in a protein.

Secondary structure

Local folding patterns like alpha helices and beta sheets.

Tertiary structure

Overall 3D shape of a polypeptide.

Quaternary structure

Assembly of multiple polypeptides into a functional protein.

Denaturation

Unfolding of proteins, inhibiting their function.

Nucleic acids

Biomolecules that store and transmit genetic information.

Gene

Unit of inheritance located on chromosomes.

Nucleotides

Monomers of nucleic acids, consisting of three parts.

DNA backbone

Structure formed by phosphate and sugar groups.

Chromatin

Complex of DNA and histones in the nucleus.