Biological Macromolecules: Carbohydrates, Lipids, Proteins, Nucleic Acids

Carbohydrates

Large complex molecules usually composed of repeating units of smaller molecules linked by covalent bonds.

Polymers

Long molecules consisting of many similar smaller building blocks called monomers.

Monomer

One of the repeating units that make up a polymer.

Starch

A polymer of glucose, serving as energy storage in plants.

Glycogen

A polymer of glucose, serving as energy storage in animals.

Cellulose

A polymer of glucose, providing structural support in plant cell walls.

Monosaccharides

Single sugar units such as glucose, fructose, and galactose.

Disaccharides

Two monosaccharides joined by a glycosidic linkage.

Polysaccharides

Long chains of monosaccharides linked by glycosidic bonds.

Hydroxyl group

A functional group (-OH) that can exist in different positions on glucose.

Alpha position

The configuration of the hydroxyl group on carbon 1 of glucose in starch and glycogen.

Beta position

The configuration of the hydroxyl group on carbon 1 of glucose in cellulose.

Dehydration synthesis

The process by which polymers are built, involving the removal of water to form covalent bonds.

Fatty Acids

Long hydrocarbon chains with a carboxyl group (-COOH) at one end.

Triglycerides

Lipids made of glycerol and three fatty acids, serving as energy storage.

Phospholipids

Lipids that form cell membranes, consisting of two fatty acids and a phosphate group.

Steroids

Lipids characterized by a carbon skeleton with four fused rings.

Waxes

Lipids that provide protective coatings, typically long-chain fatty acids.

Hydrophobic

Insoluble in water, characteristic of lipids.

Organic molecules

Compounds primarily made of carbon, hydrogen, and oxygen.

Isomers

Molecules with the same molecular formula but different structures.

Quick energy source

The primary function of monosaccharides.

Saturated fatty acids

Straight chains, pack tightly. Solid at room temperature (butter, lard).

Unsaturated fatty acids

At least one double bond between carbons. Liquid at room temperature (oils).

Cis double bonds

Create kinks (a bend in the hydrocarbon chain caused by a cis double bond (C=C)) that prevent tight packing.

Monounsaturated fatty acids

One double bond between carbon atoms.

Polyunsaturated fatty acids

More than one double bond between carbon atoms.

Trans fatty acids

Unsaturated, but with trans double bonds (no kink). Behave like saturated fats (solid at room temperature). Often artificially produced, linked to health risks.

Hydrogenation

A chemical process that adds hydrogen to unsaturated fatty acids, converting double bonds into single bonds. This makes oils more solid at room temperature and can create trans fats, which are linked to health risks.

Lipid bilayers

A double layer of phospholipids that forms the cell membrane. Hydrophilic phosphate heads face outward toward water, and hydrophobic fatty acid tails face inward, away from water.

Sterols

A type of lipid with a four-ring carbon structure and a hydroxyl (-OH) group. Examples include cholesterol, testosterone, and estrogen.

Cholesterol

Part of animal cell membranes and a precursor for other steroids, but high levels can cause fatty deposits in blood vessels.

Medical uses of steroids

Steroids can be used as medications to reduce inflammation (corticosteroids), treat hormone deficiencies (like testosterone or estrogen replacement), support immune system disorders, and aid in certain chronic conditions like asthma or arthritis.

Proteins

A macromolecule made of amino acid monomers linked by peptide bonds. The chain folds into a specific 3D shape to perform functions like catalyzing reactions (enzymes), providing structural support, transporting molecules, and signaling.

Amino acids

There are 20 common amino acids that make up proteins. Essential amino acids (cannot be made by the body, must come from food, 8 total) include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine.

Non-essential amino acids

Made by the body: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, tyrosine.

Amino acid

A molecule that contains an amino group (-NH₂), a carboxyl group (-COOH), a hydrogen atom (-H), and an R group (side chain) that varies between amino acids and determines its properties.

Peptide bond

A covalent bond formed between the carboxyl group of one amino acid and the amino group of another, linking amino acids together.

Polypeptide

A chain of amino acids linked together by peptide bonds, forming a polymer.

Protein

A macromolecule composed of one or more polypeptides that fold into specific three-dimensional shapes, determining their function.

Primary structure

The linear sequence of amino acids in a polypeptide chain.

Secondary structure

Local folding of a polypeptide into shapes like alpha helices or beta sheets, stabilized by hydrogen bonds.

Tertiary structure

The overall three-dimensional shape of a single polypeptide, stabilized by interactions between R groups.

Quaternary structure

The arrangement of multiple polypeptide chains into a functional protein.

Denaturation

The process in which a protein loses its natural three-dimensional shape, disrupting its function.

Causes of denaturation

Factors that can lead to denaturation include heat, changes in pH, chemicals (e.g., alcohol, detergents), and heavy metals.

Effects of denaturation

A protein unfolds or changes shape, often becoming nonfunctional.

Nucleic acids

Macromolecules that store and transmit genetic information, made of nucleotide monomers.

Nucleotide

The building block of nucleic acids, consisting of a phosphate group, a five-carbon sugar, and a nitrogen-containing base.

Phosphate group

A component of nucleotides that can be one, two, or three phosphates.

Five-carbon sugar

A sugar component of nucleotides, which is deoxyribose in DNA and ribose in RNA.

Nitrogenous base

A component of nucleotides that can be either a purine or pyrimidine.

Pyrimidines

Nitrogenous bases with a single-ring structure, including cytosine (C), uracil (U), and thymine (T).

Purines

Nitrogenous bases with a double-ring structure, including adenine (A) and guanine (G).

DNA Base Pairing Rules

Adenine (A) pairs with Thymine (T) via 2 hydrogen bonds; Cytosine (C) pairs with Guanine (G) via 3 hydrogen bonds.

RNA Base Pairing Rules

Adenine (A) pairs with Uracil (U) via 2 hydrogen bonds; Cytosine (C) pairs with Guanine (G) via 3 hydrogen bonds.

Uracil (U)

A nitrogenous base found only in RNA.

Thymine (T)

A nitrogenous base found only in DNA.

Cytosine (C)

A nitrogenous base found in both DNA and RNA.

Adenine (A)

A nitrogenous base found in both DNA and RNA.

Guanine (G)

A nitrogenous base found in both DNA and RNA.