Biological Macromolecules: Nucleic Acids, Proteins, Lipids, and Carbohydrates

Vocabulary flashcards covering the structures, classifications, and functions of nucleic acids, proteins, lipids, and carbohydrates from the lecture notes.

Nucleic Acid

Polymers of nucleotides consisting of a sugar (ribose for RNA, deoxyribose for DNA), a phosphate group, and a nitrogenous base.

DNA (Deoxyribonucleic Acid)

Double-stranded nucleic acid containing the genetic code, composed of four nucleotides (A, T, G, C) held together by hydrogen bonds between complementary bases.

RNA (Ribonucleic Acid)

Single-stranded nucleic acid composed of four nucleotides (A, G, C, U) that exists in three main forms: messenger RNA, transfer RNA, and ribosomal RNA.

Messenger RNA

A form of RNA (mRNA) that encodes proteins.

Transfer RNA

A form of RNA (tRNA) that carries amino acids.

Ribosomal RNA

A form of RNA (rRNA) that forms the ribosomes.

Nitrogenous Bases

Molecules found in nucleic acids including Adenine (A), Guanine (G), Cytosine (C), Thymine (T) in DNA, and Uracil (U) in RNA.

Protein

Polymers of amino acids joined by peptide bonds formed through dehydration synthesis, containing more than $50$ amino acids.

Conjugated Protein

A protein that contains a prosthetic group, which is a non-amino moiety covalently bound to it (such as heme bound to globin chains in hemoglobin).

Hemoglobin Structure

A conjugated protein structure consisting of $\alpha$ chains, $\beta$ chains, iron, and heme groups.

Primary Protein Structure

The specific amino acid sequence of a protein.

Secondary Protein Structure

Coiled or folded protein shape held together by hydrogen bonds involving the backbone structure of the amino acid sequence, such as an $\alpha$-helix or $\beta$-pleated sheet.

Tertiary Protein Structure

The folding of secondary protein structures into globular or fibrous shapes.

Globular Proteins

Compact proteins formed by tertiary folding that are found in cell membranes and body fluids.

Fibrous Proteins

Slender filaments formed by tertiary folding that are found in muscle and connective tissue.

Quaternary Protein Structure

The structural level resulting from the association of two or more polypeptide chains.

Protein Conformation

The three-dimensional structure of a protein critical for its function, which can be triggered to change by voltage changes, binding, or dissociation.

Denaturation

A drastic conformity change in a protein that destroys its function, often caused by extreme heat or pH.

Lipids

Hydrophobic organic molecules composed mainly of long chains of carbon with hydrogen and oxygen attached.

Fatty Acid

Lipid monomers consisting of chains of $4$ to $24$ carbon atoms.

Saturated Fatty Acid

A fatty acid saturated with the maximum possible hydrogen atoms, containing only single bonds between carbon atoms.

Unsaturated Fatty Acid

A fatty acid with fewer than the maximum possible hydrogen atoms, containing at least one double bond between carbon atoms.

Cis Fatty Acid

An unsaturated fatty acid where hydrogen atoms attached to the carbon double bond are on the same side, making it easily broken down by metabolic enzymes.

Trans Fatty Acid

An unsaturated fatty acid where hydrogen atoms attached to the carbon double bond are on opposite sides, making it harder to metabolize and causing it to remain in circulation longer.

Triglyceride

A lipid formed by three fatty acids covalently bonded to glycerol by dehydration synthesis, functioning in energy storage, thermal insulation, space filling, binding organs together, and cushioning organs.

Phospholipids

Amphipathic lipids in which one fatty acid is replaced by a phosphate group, serving as the structural foundation of cell membranes and aiding in fat digestion.

Amphipathic

Describing a molecule that contains both hydrophilic and hydrophobic areas.

Cholesterol

A lipid that is an important component of cell membranes for membrane stability and lipid rafts, and a precursor for steroids and bile acids; synthesized mainly by the liver ($81\%$) with $19\%$ coming from diet.

Steroids

Lipids synthesized from cholesterol that contain a four-ring structure and function as chemical messenger hormones (e.g., cortisol, estrogen, testosterone).

Bile Acid

Steroids that aid in fat digestion and nutrient absorption.

Eicosanoids

Lipids that function as chemical messengers between cells.

Fat-Soluble Vitamins

Lipids including vitamins A, D, E, and K involved in blood clotting, wound healing, vision, and calcium absorption.

Carbohydrates

Hydrophilic organic molecules with a hydrogen to oxygen ratio of $2:1$ and a general formula of $\text{(CH}_2\text{O)}_n$.

Monosaccharides

Single carbohydrate monomers including glucose, galactose, and fructose.

Glucose

A monosaccharide known as blood sugar that serves as an energy source for most cells.

Galactose

A monosaccharide that is converted to glucose and metabolized.

Fructose

A monosaccharide known as fruit sugar that is converted to glucose and metabolized.

Disaccharides

Carbohydrates composed of two monosaccharide monomers, including sucrose, lactose, and maltose.

Sucrose

A disaccharide (cane sugar) composed of glucose and fructose that is digested to glucose and fructose.

Lactose

A disaccharide (milk sugar) composed of galactose and glucose that is important for infant nutrition and digested to glucose and galactose.

Maltose

A disaccharide (malt sugar) composed of $2$ glucose units that is a product of starch digestion and further digested to glucose.

Oligosaccharides

Carbohydrates composed of $3$ to $50$ monosaccharide monomers.

Polysaccharides

Carbohydrates consisting of long chains of monosaccharides, including cellulose, starch, and glycogen.

Cellulose

A structural polysaccharide of plants that functions as dietary fiber in humans.

Starch

A polysaccharide used for energy storage in plant cells and as an energy source in the human diet.

Glycogen

A polysaccharide used for energy storage in animal cells (located in the liver, muscle, brain, uterus, and vagina).

Conjugated Carbohydrates

Molecules formed by carbohydrates covalently bonded to other large organic molecules, including glycolipids, glycoproteins, and proteoglycans.

Glycoprotein

A conjugated carbohydrate that serves as a component of the cell surface coat and mucus.

Glycolipid

A conjugated carbohydrate that serves as a component of the cell surface coat.

Proteoglycan

A conjugated carbohydrate involved in cell adhesion and lubrication, serving as a supportive filler of some tissues and organs.