Chemistry of Life - AP Biology

100 vocabulary-style flashcards covering the key terms and concepts from the notes on chemistry of life, properties of water, biomolecules, enzymes, and nucleic acids.

Polarity

Water's polarity creates partial charges that enable hydrogen bonding and solvent properties.

Covalent bond

A bond formed by sharing electrons; in water, the O–H covalent bonds are covalent bonds.

Polar covalent bond

A covalent bond in which electrons are not shared equally, producing partial charges.

Hydrogen bond

A weak attraction between a partially positive hydrogen and a negatively charged atom, crucial for water's properties and biomolecules.

Cohesion

Water molecules are attracted to each other, helping surface tension and column rise in plants.

Adhesion

Water molecules are attracted to unlike surfaces, aiding movement along surfaces.

Capillary action

Movement of water up narrow tubes due to adhesion to walls and cohesion between molecules.

Surface tension

The cohesive forces at the surface of a liquid that create a ‘skin’-like layer.

Hydrophilic

Water-loving; polar or charged substances that dissolve in water.

Hydrophobic

Water-fearing; nonpolar substances that do not readily dissolve in water.

Solvent

A substance (often water) that dissolves solutes, forming a solution.

Dehydration synthesis

A reaction that builds larger molecules by removing water; monomers join to form polymers.

Hydrolysis

A reaction that breaks polymers into monomers by adding water.

Monomer

A small molecule that can join with others to form a polymer.

Polymer

A large molecule built from many monomer subunits.

Carbohydrates

Biological macromolecules made of C, H, O in about a 1:2:1 ratio; used for energy and structure.

Monosaccharide

A simple sugar; the monomer of carbohydrates.

Disaccharide

Two monosaccharides linked together.

Polysaccharide

Many monosaccharides linked together; complex carbohydrate.

Glycosidic bond

Covalent bond that links sugar units in carbohydrates.

Glucose

A common monosaccharide used for energy in cells.

Fructose

A monosaccharide; a structural isomer of glucose.

Galactose

A monosaccharide isomer of glucose found in lactose.

Lipids

Nonpolar biomolecules that store energy and form cell membranes; insoluble in water.

Fatty acid

Long hydrocarbon chain with a terminal carboxyl group; part of fats and lipids.

Glycerol

A backbone molecule that attaches to fatty acids to form fats and lipids.

Saturated fatty acid

Fatty acid with no double bonds; typically solid at room temperature.

Unsaturated fatty acid

Fatty acid with one or more double bonds; typically liquid at room temperature.

Triglyceride

A lipid with three fatty acids attached to glycerol; a major fat storage form.

Phospholipid

A lipid with two fatty acids and a phosphate head; key component of cell membranes.

Wax

A lipid with long fatty acid tails bonded to long-chain alcohols; water-resistant.

Steroid

Lipids with four fused carbon rings and no fatty acid tails.

Cholesterol

A steroid essential for membrane structure and precursor to other steroids.

Estrogen

A steroid hormone involved in female reproductive development.

Testosterone

A steroid hormone involved in male reproductive development.

Vitamin D

A steroid-related molecule important for bone health and calcium metabolism.

Proteins

Diverse biomolecules that perform most cellular functions; built from amino acids.

Amino acid

A molecule with an amino group, a carboxyl group, and a variable R group.

R group

The side chain of an amino acid; determines its properties.

Polypeptide

A chain of amino acids linked by peptide bonds.

Peptide bond

A covalent bond between the amino group of one amino acid and the carboxyl group of another.

Primary structure

The unique amino acid sequence of a protein.

Secondary structure

Protein folding patterns like alpha helices and beta sheets held by hydrogen bonds.

Alpha helix

A common coiled secondary structure stabilized by hydrogen bonds.

Beta sheet

A secondary structure formed by linking strands by hydrogen bonds.

Tertiary structure

Three-dimensional folding driven by R-group interactions (hydrogen bonds, hydrophobic interactions, disulfide bridges, ionic bonds).

Disulfide bridge

A covalent bond between sulfur-containing side chains stabilizing a protein's shape.

Quaternary structure

Association of two or more polypeptide subunits into a functional protein.

Hemoglobin

A quaternary protein made of four polypeptides; carries oxygen in blood.

Globin

The protein subunits that make up hemoglobin.

Heme

Iron-containing non-protein component in hemoglobin.

Denaturation

Loss of a protein's three-dimensional shape and function.

Enzymes

Biological catalysts that speed reactions by lowering activation energy.

Substrate

The reactant that an enzyme acts upon.

Active site

The region of the enzyme where the substrate binds.

Induced fit

Enzyme slightly changes shape to accommodate the substrate.

Enzyme-substrate complex

Temporary complex formed when an enzyme binds its substrate.

Catalase

An enzyme that decomposes hydrogen peroxide into water and oxygen.

Temperature effect on enzyme activity

Enzyme activity increases to an optimum temperature and then declines or denatures with further heating.

pH effect on enzyme activity

Enzyme activity varies with pH; deviations reduce activity or denature proteins.

Activators

Substances that stabilize the active form of an enzyme; include coenzymes and cofactors.

Cofactor

Inorganic nonprotein helper for enzymes (e.g., minerals).</

Coenzyme

Organic nonprotein helper for enzymes (e.g., vitamin-derived molecules).

Nucleic acids

DNA and RNA; polymers of nucleotides that store and transmit genetic information.

Nucleotide

A nucleotide includes a phosphate group, a five-carbon sugar, and a nitrogen base.

Phosphate group

A negatively charged group essential to the backbone of nucleic acids.

Deoxyribose

The five-carbon sugar in DNA.

Ribose

The five-carbon sugar in RNA.

Adenine

Purine base that pairs with thymine in DNA and with uracil in RNA.

Thymine

Pyrimidine base that pairs with adenine in DNA.

Cytosine

Pyrimidine base that pairs with guanine in DNA and RNA.

Guanine

Purine base that pairs with cytosine in DNA and RNA.

Uracil

Pyrimidine base that replaces thymine in RNA.

DNA

Deoxyribonucleic acid; double-stranded polymer of nucleotides with deoxyribose.

RNA

Ribonucleic acid; usually single-stranded polymer of nucleotides with ribose.

Base pairing rules (DNA)

A pairs with T (2 hydrogen bonds); G pairs with C (3 hydrogen bonds).

Antiparallel

DNA strands run in opposite directions (5' to 3' and 3' to 5').

Hydrogen bonds in DNA

Weak bonds between bases: A–T (2) and G–C (3) that stabilize the double helix.

Phosphodiester bond

Strong covalent bonds that link nucleotides together in the backbone.

5' to 3' directionality

One end of a nucleotide chain has a 5' phosphate group and the other a 3' hydroxyl.

3' to 5' directionality

Opposite orientation of the DNA strand relative to 5' to 3'.

Nonpolar

Hydrophobic; molecules that do not mix well with water.

Polar

Hydrophilic; molecules that dissolve in water.

Acidic amino acids

Amino acids with negatively charged R groups at physiological pH.

Basic amino acids

Amino acids with positively charged R groups at physiological pH.

Glycogen

Polysaccharide storage form of glucose in animals.

Cellulose

Polysaccharide that provides structural support in plant cell walls.

Chitin

Polysaccharide that forms the exoskeletons of arthropods and fungal cell walls.

Glycosidic linkage

Bond formed between sugar molecules during dehydration synthesis.

Monomer vs. polymer

Monomer is a repeating subunit; polymer is a chain built from monomers.

Macromolecule

A large biomolecule formed by polymerization (carbohydrates, lipids, proteins, nucleic acids).

Solubility of sugars

Many carbohydrates (like glucose) are soluble in water due to hydrophilic groups.

Hydration shell

Layer of water molecules surrounding each dissolved ion or molecule.

Lipids are insoluble in water

Nonpolar nature makes lipids repel water.

Cholesterol in membranes

Steroid that helps maintain membrane structure and fluidity.

Phospholipid bilayer

Two layers of phospholipids forming the cell membrane's structure.

Saturated fats vs. oils

Saturated fats are solid at room temperature; unsaturated fats are liquids.

Hydrophobic interactions

Nonpolar R groups cluster away from water affecting protein folding.

Hydrogen bonds in proteins

Bonds that help stabilize secondary and tertiary protein structures.

Feedback inhibition

A product inhibits an earlier step to regulate a pathway.