Biochemistry Vocabulary - 4U Biology

Activation Energy

Minimum energy required to start a chemical reaction

Activator

Molecule that binds to an enzyme (often at the allosteric site) to increase its activity

Active Form

Functional shape of a protein or enzyme capable of performing its role

Active Site

Region of an enzyme where the substrate binds

Active Transport

Movement of substances against their concentration gradient using ATP

Adenine

Purine nitrogenous base found in DNA and RNA that pairs with thymine (DNA) or uracil (RNA)

Adhesion

Attraction between molecules of different substances

Aldehyde

Organic functional group with a carbonyl at the end of a carbon chain

Allosteric Activator

Molecule that binds to an allosteric site and enhances enzyme activity

Allosteric Inhibitor

Molecule that binds to an allosteric site and decreases enzyme activity

Allosteric Regulation

Control of enzyme activity through binding at a site other than the active site

Allosteric Site

Site on an enzyme separate from the active site where regulators bind

Amino

Functional group (-NH₂) found in amino acids

Amino Acid

Monomer of proteins containing amino group, carboxyl group, hydrogen, and R group

Amphipathic

Molecule with both hydrophilic and hydrophobic regions

Anabolic

Metabolic reactions that build larger molecules from smaller ones requiring energy

Analytical

Relating to breaking down complex information into components for understanding

Antiport

Transport protein moving two substances in opposite directions across a membrane

Aquaporin

Channel protein that facilitates water movement across membranes

ATP

Adenosine triphosphate, main energy currency of the cell

Base Pair

Two complementary nitrogenous bases held together by hydrogen bonds

Bond Energy

Energy required to break a chemical bond

Carbohydrate

Macromolecule composed of sugars used for energy and structure

Carbonyl

Functional group (C=O) found in aldehydes and ketones

Catabolic Reactions

Metabolic reactions that break down molecules and release energy

Catalyst

Substance that speeds up a reaction without being consumed

Cholesterol

Steroid lipid that regulates membrane fluidity

Coenzyme

Organic helper molecule assisting enzyme function (e.g., NAD⁺)

Cofactor

Non-protein component required for enzyme activity (e.g., metal ion)

Cohesion

Attraction between molecules of the same substance

Competitive Inhibition

Inhibitor competes with substrate for the active site

Concentration

Amount of solute in a given volume

Concentration Gradient

Difference in concentration across space or membrane

Condensation

Chemical process forming a larger molecule with release of water

Condensation Reaction

Reaction joining two molecules while removing water

Coupled Transport

Active transport using energy from movement of one substance to move another

Covalent Bond

Bond formed by sharing electrons between atoms

Cytosine

Pyrimidine base that pairs with guanine

Dehydration Synthesis

Reaction joining monomers by removing water

Denature

Loss of protein shape and function due to environmental change

Deoxyribose

Pentose sugar found in DNA lacking one oxygen

Dialysis

Diffusion of solutes across a selectively permeable membrane

Diffusion

Movement of molecules from high to low concentration

Dipole

Molecule with partial positive and negative charges

Disaccharide

Two monosaccharides joined by glycosidic linkage

Disulfide Bridge

Covalent bond between sulfur atoms of two cysteine residues stabilizing protein structure

DNA

Double-stranded nucleic acid carrying genetic information

Dynamic

Characterized by constant change or movement

Electronegativity

Ability of an atom to attract electrons

Endergonic

Reaction requiring energy input

Endocytosis

Process of bringing materials into cell via vesicle formation

Energy

Capacity to do work or cause change

Enzyme

Biological catalyst that lowers activation energy

Enzyme-Substrate Complex

Temporary complex formed when enzyme binds substrate

Equilibrium

State where forward and reverse reactions occur at equal rates

Ester Bond

Covalent bond formed between glycerol and fatty acid

Eukaryote

Organism with membrane-bound nucleus and organelles

Exergonic

Reaction that releases energy

Exocytosis

Process of releasing materials from cell via vesicle fusion

Facilitated Diffusion

Passive transport using membrane proteins

Feedback Inhibition

End product inhibits an earlier enzyme in pathway

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed

Fluid Mosaic Model

Model describing membrane as fluid bilayer with embedded proteins

Functional Group

Specific group of atoms determining molecule properties

Glycerol

Three-carbon alcohol forming backbone of triglycerides

Glycolipid

Lipid with attached carbohydrate for recognition

Glycoprotein

Protein with attached carbohydrate chain

Glycosidic Linkage

Covalent bond between monosaccharides

Guanine

Purine base that pairs with cytosine

Heat Capacity

Ability of a substance to absorb heat without large temperature change

Hydrogen Bonds

Weak attractions between partial positive hydrogen and electronegative atom

Hydrolysis

Reaction breaking bonds by adding water

Hydrophilic

Water-attracting polar substance

Hydrophobic

Water-repelling nonpolar substance

Hydroxyl

Functional group (-OH)

Hypertonic

Solution with higher solute concentration causing water to leave cell

Hypotonic

Solution with lower solute concentration causing water to enter cell

Inactive Form

Nonfunctional shape of a protein or enzyme

Induced Fit Model

Model where enzyme changes shape to fit substrate

Inhibitor

Molecule that decreases enzyme activity

Integral Protein

Protein embedded within membrane

Ionic Bond

Attraction between oppositely charged ions

Isomer

Molecules with same formula but different structures

Isotonic

Solution with equal solute concentration inside and outside cell

Isotope

Atom of same element with different number of neutrons

Ketone

Carbonyl-containing functional group within carbon chain

Kinetic

Related to motion or movement

Lipid

Hydrophobic macromolecule used for energy and membranes

Lock and Key

Model describing enzyme specificity with rigid active site

Membrane

Phospholipid bilayer surrounding cells or organelles

Metabolism

Sum of all chemical reactions in a cell

Monomer

Small repeating subunit of polymer

Monosaccharide

Single sugar molecule

Na+/K+ Pump

ATP-driven antiporter moving sodium out and potassium into cell

Negative

Having excess electrons or negative charge

Nitrogenous Base

Nitrogen-containing base in nucleotides

Non-competitive Inhibition

Inhibitor binds allosteric site reducing enzyme activity

Non-Polar

Lacking partial charges and hydrophobic

Nucleic Acid

Polymer of nucleotides storing genetic information

Nucleotide

Monomer of nucleic acids composed of phosphate, sugar, and base