Unit 2: Macromolecules - Lipids and Proteins

Vocabulary practice flashcards covering macromolecules, focusing on the structures, types, synthesis, and functions of lipids and proteins.

Macromolecule

A large molecule critically important to all living things; the prefix "macro" means large.

Monomer

A single repeating unit or single molecule of a macromolecule that acts as a building block ("mono" = one, "mer" = unit).

Polymer

A large molecule composed of repeating units ("poly" = many, "mer" = unit).

Dehydration Synthesis

A chemical reaction in which monomers bond together to form a polymer, releasing a molecule of water ($H_2O$).

Hydrolysis

A chemical reaction in which a polymer is broken apart into its monomers by the addition of water ($H_2O$).

Lipids

A category of macromolecules composed of carbon, hydrogen, and oxygen that have no true monomers or polymers and function to store energy, provide insulation, protect against water loss, and form cell membranes.

Fatty Acid

A molecule consisting of a long chain or tail of carbon and hydrogen atoms attached to a carboxyl group.

Saturated Fatty Acid

A fatty acid with no double bonds, characterized by long straight tails, and typically solid at room temperature.

Unsaturated Fatty Acid

A fatty acid containing one or more double bonds, exhibiting a kinked or crooked shape, capable of adding more hydrogen atoms, and usually existing as a liquid oil.

Triglyceride

A lipid formed by 1 glycerol molecule bonded to 3 fatty acids; functions to store long-term energy and provide insulation without dissolving in water.

Ester Bond

The specific chemical bond that links a glycerol molecule to each fatty acid tail in a triglyceride.

Phospholipid

A lipid composed of a phosphate head (phosphate and glycerol) and two fatty acid tails that serves as the fundamental building block of cell membranes.

Phospholipid Bilayer

A double layer of phospholipids forming the cell membrane, consisting of hydrophilic heads facing outward and hydrophobic tails facing inward to control what enters and leaves the cell.

Wax

A type of lipid that helps prevent water loss, such as the protective coating found on the leaves of plants.

Steroid

A class of lipids characterized by four connected carbon rings, including certain hormones like testosterone and estrogen.

Cholesterol

A steroid lipid embedded in animal cell membranes that helps maintain membrane fluidity.

LDL Cholesterol

Low-density lipoprotein, commonly known as "bad" cholesterol, which can lead to fatty buildup in arteries.

HDL Cholesterol

High-density lipoprotein, commonly known as "good" cholesterol, which helps transport cholesterol back to the liver.

Protein

A macromolecule composed of carbon, hydrogen, oxygen, and nitrogen ($\text{C, H, O, N}$) made from one or more chains of amino acids.

Amino Acid

The monomer of proteins, consisting of a central carbon bonded to an amino group, a carboxyl group, a hydrogen atom, and a unique variable R-group (side chain).

Essential Amino Acids

The $9$ out of $20$ amino acids that cannot be synthesized by the human body and must be obtained through food.

Peptide Bond

The covalent bond formed between two amino acids when a water molecule is removed during dehydration synthesis.

Dipeptide

A molecule consisting of two amino acids joined together by a single peptide bond.

Polypeptide

A chain of many amino acids linked together by multiple peptide bonds.

Digestive Enzymes

Proteins that speed up the chemical breakdown of food molecules, such as lactase breaking down lactose.

Contractile Proteins

Proteins that facilitate movement by contracting, such as actin (thin filaments) and myosin (thick filaments) in muscle fibers.

Transport Proteins

Proteins that carry substances across cell membranes or through the bloodstream, such as membrane channels, pumps, or hemoglobin carrying oxygen.

Defense Proteins

Proteins, such as antibodies, that recognize and help neutralize foreign pathogens to protect the body.

Hormones (Protein)

Proteins that act as chemical messengers circulating in the body to signal target cells or organs, such as insulin.

Structural Proteins

Proteins that construct and maintain physical structures in the body, such as keratin in hair and collagen in connective tissue.

Storage Proteins

Proteins responsible for holding and preserving amino acids or nutrients for later use by the body.