Unit 1 Vocab

Polar molecule

A neutral, or uncharged molecule that has an asymmetric internal distribution of charge, leading to partially positive and partially negative regions.

Cohesion

The attraction of molecules for other molecules of the same kind. This attraction is due to intermolecular forces, most notably hydrogen bonds in the case of water. Cohesion is responsible for properties like surface tension.

Adhesion

The attraction of molecules for other molecules of a different kind. Helps facilitate capillary action.

Density

The mass per unit volume of a substance

Specific heat capacity

The amount of heat needed to raise the temperature of 1 g of a substance by 10C

Heat of vaporization

The amount of energy needed to change 1 g of a liquid substance to a gas at constant temperature

Dehydration synthesis

Dehydration synthesis covalently bonds monomers together, building polymers

Hydrolysis

Breaks down covalent bonds between monomers, which breaks down polymers

Linear carbohydrates

Usually used for structure, tightly packed monomers lead to the polymer being strong and more difficult to break down.

Branched carbohydrates

These are ideal for energy storage. The branched structure makes it easier to break down, as the individual monomers are more accessible to get broken off.

Lipid function

To store energy, support cell function, signal molecules, and provide insulation.

Saturated fatty acids

These only contain a single bond between carbon atoms.

Unsaturated fatty acids

These contain one or more double bonds between carbon atoms. Can cause kinks in the molecule.

Triglycerides

These fats are primarily used for long-term energy storage and supporting cell function. The components of a triglyceride are: one glycerol molecule and three fatty acids.

Protein function

Protein is the most functionally diverse macromolecule. It has various cell functions that include transport, storage, and regulation. Proteins help make up hormones and enzymes.

Peptide bond

A covalent bond that connects amino acid monomers. It is located between the carboxyl group of one amino acid and the amine group of the next.

N terminus

End of polypeptide chain with a free amino group

C Terminus

End of a polypeptide chain with free carboxyl group

Primary protein structure

The unique, linear sequence of amino acids in a polypeptide chain.

Secondary protein structure

Local folding of the polypeptide chain into helices (alpha-helix) or sheets (beta-pleated sheet) due to hydrogen bonding between backbone atoms.

Tertiary protein structure

The overall three-dimensional shape of a single polypeptide chain, resulting from interactions between amino acid side chains (R-groups).

Quaternary protein structure

The arrangement of multiple polypeptide chains (subunits) in a multisubunit protein.

Secondary protein structure

Local folding of the polypeptide chain into helices (alpha-helix) or sheets (beta-pleated sheet) due to hydrogen bonding between backbone atoms.

Tertiary protein structure

The overall three-dimensional shape of a single polypeptide chain, resulting from interactions between amino acid side chains (R-groups).

Quaternary protein structure

The arrangement of multiple polypeptide chains (subunits) in a multisubunit protein.

Polar

Molecules with an unequal distribution of electrons; this polarity arises from differences in electronegativity between bonded atoms.

Covalent bond

A strong chemical bond formed when two atoms share one or more pairs of electrons to achieve a stable electron configuration; the sharing of electrons allows atoms to stick together, forming stable molecules, and can be either polar (unequal sharing) or nonpolar (equal sharing).

Electronegative

An atom that has a strong attraction for electrons within a chemical bond, often pulling them closer to itself and resulting in a partial negative charge on the atom.

Hydrogen bond

A weak electrostatic attraction between a positively charged hydrogen atom (covalently bonded to a highly electronegative atom like oxygen or nitrogen) and another electronegative atom with a lone pair of electrons in a different or same molecule.

Capillary action

The process by which a liquid, such as water, moves upward through a narrow space (like the xylem in a plant) due to the combined forces of cohesion (water molecules sticking to each other), adhesion (water molecules sticking to the tube's walls), and surface tension.

Surface tension

The cohesive property of a liquid, typically water, where the molecules at the surface are pulled inward, creating a 'skin-like' effect that allows it to resist external forces, like a water strider walking on water; this tension arises from the stronger intermolecular forces among surface molecules compared to those on the interior, which lack an upward pull from the surrounding air.

Solvency

The ability of a substance (like water) to dissolve other substances, forming a solution.

Heat capacity

The amount of heat energy required to raise the temperature of a given amount of biological matter, such as water in a cell or an organism's body, by 10C. Organisms and biological substances like water have high heat capacities, allowing them to resist rapid temperature changes and maintain stable internal temperatures, which is crucial for metabolic processes and survival.

Monomer

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

Polymer

A large molecule made of many repeating monomers bonded together.

Carbohydrate

Organic molecule made of carbon, hydrogen, and oxygen; includes sugars and starches, used mainly for energy.

Monosaccharide

Simple sugar; basic building block of carbohydrates (e.g., glucose).

Disaccharide

Sugar made of two monosaccharides joined together (e.g., sucrose).

Polysaccharide

Complex carbohydrates made of many monosaccharides (e.g., starch, cellulose).

Lipid

Hydrophobic organic compound used for long-term energy storage and insulation (includes fats, oils, waxes).

Fatty acid

Long hydrocarbon chain with a carboxyl group; component of lipids.

Glycerol

A three-carbon alcohol that combines with fatty acids to form lipids.

Unsaturated fatty acid

Fatty acid with one or more double bonds; usually liquid at room temp (e.g., oils).

Saturated fatty acid

Fatty acid with no double bonds; usually solid at room temp (e.g., butter).

Phospholipid

Lipid with a phosphate group; key component of cell membranes.

Phospholipid bilayer

Double layer of phospholipids that forms the cell membrane.

Steroid

Lipid molecule with four fused carbon rings (e.g., cholesterol, hormones).

Hormone

Chemical messenger that regulates body processes (can be proteins or steroids).

Cholesterol

Steroid found in cell membranes; precursor to other steroids like hormones.

Nucleic Acid

Macromolecule made of nucleotides; includes DNA and RNA.

Nucleotide

Building block of nucleic acids, consisting of a sugar, phosphate group, and nitrogenous base.

Polynucleotide

Long chain of nucleotides bonded together.

DNA (Deoxyribonucleic acid)

Genetic material that stores information; double-stranded.

RNA (Ribonucleic acid)

Nucleic acid that helps in protein synthesis; usually single-stranded.

Deoxyribose

The sugar in DNA nucleotides.

Ribose

The sugar in RNA nucleotides.

Nitrogenous base

A nitrogen-containing molecule in nucleotides; includes A, T, G, C, U.

Sugar-phosphate backbone

The repeating chain of sugar and phosphate in DNA/RNA.

Phosphodiester bond

Covalent bond that links nucleotides in DNA or RNA.

5′ (five prime)

End of a nucleotide strand with a free phosphate group on the 5′ carbon of sugar.

3′ (three prime)

End of a nucleotide strand with a free hydroxyl group on the 3′ carbon of sugar.

Adenosine

Nucleoside made of adenine + ribose; part of ATP and RNA.

Thymine

DNA nitrogenous base that pairs with adenine.

Cytosine

Nitrogenous base found in DNA and RNA; pairs with guanine.

Guanine

Nitrogenous base found in DNA and RNA; pairs with cytosine.

Uracil

RNA-only base; replaces thymine and pairs with adenine.

Double helix

Twisted ladder shape of the DNA molecule.

Antiparallel

Refers to the opposite orientation of the two strands in DNA (5′ to 3′ and 3′ to 5′).

Protein

Macromolecule made of amino acids; used for structure, enzymes, transport, etc.

Amino acid

Monomer of proteins; contains an amino group, carboxyl group, and R group.

Polypeptide

Long chain of amino acids linked by peptide bonds.

Enzyme

Protein that acts as a biological catalyst to speed up chemical reactions.

Amino group

Functional group (-NH₂) found in amino acids.

Carboxyl group

Functional group (-COOH) found in amino acids.

Variable group (R group/side chain)

Part of an amino acid that determines its identity and properties.

Alpha helix

A spiral shape formed by coiling of a polypeptide chain (secondary structure).

Beta pleated sheet

Sheet-like structure formed by folding of polypeptide chains (secondary structure).

Denature

Loss of a protein’s shape and function due to heat, pH, or chemicals.

Disulfide bridge

Strong covalent bond between sulfur atoms in two cysteine amino acids; helps stabilize protein structure