Lipids, Membranes, Steroids, and Proteins - Vocabulary

Vocabulary flashcards covering lipids, membranes, steroids, and proteins from the notes.

Lipids

A diverse group of macromolecules including triglycerides, phospholipids, and steroids; the body's major energy store

Triglycerides

Fats formed by glycerol and three fatty acids; a major energy reserve with saturated, unsaturated, and trans forms.

Saturated fats

Fats with no double bonds in fatty acids; typically solid at room temperature.

Unsaturated fats

Fats with one or more double bonds in fatty acids; typically liquid at room temperature.

Trans fats

A type of unsaturated fat with trans double bonds, often produced and associated with health concerns.

Phospholipids

Lipids containing a phosphate group; have a hydrophilic polar head and a hydrophobic nonpolar tail.

Phospholipid bilayer

Two-layer arrangement of phospholipids that forms the basis of cell membranes; hydrophilic heads face water, hydrophobic tails face inward.

Hydrophilic

Water-loving; polar; tends to interact with water.

Hydrophobic

Water-fearing; nonpolar; tends to avoid water.

Membrane

The phospholipid bilayer that acts as a selective barrier and site of regulated transport.

Selective permeability

Property of membranes allowing some substances to cross while restricting others.

Steroids

Lipids with fused carbon rings; include sex hormones and regulators of growth, development, and immune responses.

Cholesterol

A common lipid important as a precursor to other steroids and as a membrane component influencing fluidity.

Testosterone

Primary male sex hormone; a steroid.

Estrogen

Primary female sex hormone; a steroid.

Proteins

Macromolecules built from amino acids; perform growth, repair, enzymes, antibodies, hormones, and function as channels/transporters.

Amino acids

Building blocks of proteins; about 20–22 common; each has an amino group, a carboxyl group, and a variable side chain (R) that determines identity and properties.

R group

The side chain of an amino acid that determines its identity and properties (polarity, size, charge).

Peptide bond

Covalent bond linking amino acids in a polypeptide; formed by dehydration synthesis.

Dehydration synthesis

Chemical reaction that forms a bond by removing a water molecule.

Hydrolysis

Chemical reaction that breaks bonds by adding water, releasing amino acids.

Dipeptide

Two amino acids linked by a peptide bond; the simplest peptide.

Polypeptide

A long chain of amino acids; proteins typically contain many amino acids; often around 500 amino acids.

Protein folding

The process by which a protein assumes its functional three-dimensional structure; misfolding can lead to loss of function and disease.

Hemoglobin

A protein in red blood cells that carries oxygen.

Antibodies

Proteins of the immune system that defend against pathogens.

Enzymes

Proteins that act as biological catalysts to accelerate chemical reactions.

Protein intake

Recommended daily protein amount; for example, an average child needs about 18 g per day; deficiencies can cause health issues.

Sickle cell disease

Genetic mutation altering the amino acid sequence of hemoglobin; structural change leads to disease.