Glossary
Aldose
A monosaccharide (simple sugar) containing an aldehyde group, typically at the end of its carbon chain.
Example:
Glucose is an aldose sugar, meaning it has a carbonyl group at the end of its chain, which is crucial for its role in cellular respiration.
Amino Acids
The monomeric building blocks of proteins, each containing an amino group, a carboxyl group, a hydrogen atom, and a unique R group, all attached to a central carbon atom.
Example:
There are 20 common amino acids that can be linked in countless combinations to form diverse proteins.
Carbohydrates
Organic compounds composed of carbon, hydrogen, and oxygen, serving as primary energy sources and structural components in living organisms.
Example:
When you eat pasta, your body breaks down the complex carbohydrates into simpler sugars for immediate energy.
Cholesterol
A crucial steroid found in animal cell membranes, regulating membrane fluidity and serving as a precursor for other steroids like hormones.
Example:
While often associated with health concerns, cholesterol is vital for maintaining the integrity of animal cell membranes and synthesizing vitamin D.
DNA
Deoxyribonucleic acid, a double-stranded nucleic acid that carries the genetic instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses.
Example:
The human genome is entirely encoded within the sequence of bases in DNA molecules located in the nucleus of each cell.
Ester bonds
Covalent bonds formed between a hydroxyl group and a carboxyl group, notably found linking fatty acids to glycerol in triglycerides and phospholipids.
Example:
The formation of a fat molecule involves three ester bonds connecting the fatty acid chains to the glycerol backbone.
Fats (Triglycerides/Triacylglycerols)
Lipids composed of a glycerol molecule joined to three fatty acid chains via ester bonds, primarily functioning in long-term energy storage.
Example:
Animals store excess energy as fats (triglycerides) in adipose tissue, providing insulation and a reserve fuel supply.
Fatty Acids
Long hydrocarbon chains with a carboxyl group at one end, which can be saturated or unsaturated and are components of many lipids.
Example:
Omega-3 fatty acids are essential nutrients that the human body cannot produce on its own and must be obtained from the diet.
Glucose
A common monosaccharide with the formula C6H12O6, serving as the primary source of energy for most living organisms through cellular respiration.
Example:
After a meal, your blood glucose levels rise as carbohydrates are digested, signaling the pancreas to release insulin.
Glycerol
A three-carbon alcohol molecule that serves as the backbone for triglycerides and phospholipids, with a hydroxyl group attached to each carbon.
Example:
In the synthesis of a fat molecule, three fatty acids attach to the three hydroxyl groups of a single glycerol molecule.
Glycosidic bond
A covalent bond formed between two monosaccharides by a dehydration reaction, linking them to form disaccharides or polysaccharides.
Example:
Lactose, the sugar in milk, is a disaccharide formed by a glycosidic bond between glucose and galactose.
Hydrophilic Head
The water-attracting portion of a phospholipid, consisting of the glycerol and phosphate group, which faces the aqueous environment.
Example:
The hydrophilic head of a phospholipid allows the cell membrane to interact with water-based solutions both inside and outside the cell.
Hydrophobic Tail
The water-repelling portion of a phospholipid, consisting of the two fatty acid chains, which forms the interior of the cell membrane bilayer.
Example:
The nonpolar hydrophobic tails of phospholipids cluster together in the interior of the cell membrane, away from water.
Ketose
A monosaccharide (simple sugar) containing a ketone group, typically located in the middle of its carbon chain.
Example:
Fructose, found in fruits, is a ketose sugar, distinguished by its carbonyl group being within the carbon chain rather than at the end.
Lipids
A diverse group of hydrophobic macromolecules, primarily composed of hydrocarbons, important for energy storage, insulation, and cell membrane structure.
Example:
Butter and oils are examples of lipids that provide concentrated energy and help absorb fat-soluble vitamins.
Macromolecules
Large organic molecules essential for life, built from smaller organic subunits. They include carbohydrates, lipids, proteins, and nucleic acids.
Example:
DNA, a macromolecule, carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms.
Monomer
A small molecule that can chemically bond with other monomers to form a polymer.
Example:
Glucose is a monomer that can be linked together to form complex carbohydrate polymers like starch or cellulose.
Monosaccharides
The simplest form of carbohydrates, often called simple sugars, which serve as the basic building blocks for more complex carbohydrates.
Example:
During digestion, complex starches are broken down into individual monosaccharides like glucose, which can then be absorbed into the bloodstream.
Nucleic Acids
Macromolecules that store and transmit genetic information, primarily DNA and RNA, composed of nucleotide monomers.
Example:
DNA and RNA are the two main types of nucleic acids that are fundamental to heredity and protein synthesis.
Nucleotide
The monomeric building block of nucleic acids, consisting of a 5-carbon sugar (deoxyribose or ribose), a phosphate group, and a nitrogenous base.
Example:
ATP (adenosine triphosphate) is a modified nucleotide that serves as the primary energy currency of the cell.
Peptide Bonds
Covalent bonds that link amino acids together in a polypeptide chain, formed by a dehydration reaction between the carboxyl group of one amino acid and the amino group of another.
Example:
During protein synthesis, ribosomes form peptide bonds between incoming amino acids, elongating the polypeptide chain.
Phospholipids
Lipids composed of a glycerol backbone, two fatty acids, and a phosphate group, forming the primary component of cell membranes.
Example:
The cell membrane is a bilayer of phospholipids, with their hydrophilic heads facing the aqueous environments inside and outside the cell.
Polymer
A large molecule (macromolecule) composed of many repeated smaller subunits (monomers) linked together.
Example:
Starch is a polymer made up of many glucose monomers joined together, serving as energy storage in plants.
Polypeptide
A polymer of many amino acids linked together by peptide bonds; one or more polypeptides fold into a specific three-dimensional structure to form a functional protein.
Example:
Insulin is a small polypeptide hormone that regulates blood sugar levels.
Proteins
Complex macromolecules made of amino acid subunits, performing a vast array of functions including catalysis, transport, structure, and defense.
Example:
Enzymes, antibodies, and structural components like collagen are all types of proteins that carry out essential tasks in the body.
R group
The variable side chain of an amino acid, which determines its unique chemical properties (e.g., polar, nonpolar, acidic, basic) and influences protein folding.
Example:
The specific sequence and properties of the R groups along a polypeptide chain dictate how the protein will fold into its functional 3D shape.
RNA
Ribonucleic acid, a single-stranded nucleic acid involved in various roles in gene expression, including messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).
Example:
During protein synthesis, messenger RNA carries the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm.
Saturated Fatty Acids
Fatty acids that contain no double bonds between carbon atoms in their hydrocarbon chain, allowing them to pack tightly and be solid at room temperature.
Example:
Butter contains a high proportion of saturated fatty acids, which is why it remains solid at room temperature.
Steroids
A class of lipids characterized by a carbon skeleton consisting of four fused rings, functioning as hormones and structural components.
Example:
Testosterone and estrogen are steroids that act as signaling molecules, regulating various physiological processes in the body.
Sterols
A subgroup of steroids that contain a hydroxyl (-OH) functional group, such as cholesterol.
Example:
Ergosterol, a type of sterol, is found in fungi and is a target for some antifungal medications.
Structure determines function
A fundamental principle in biology stating that the specific arrangement of atoms in a molecule or the shape of a biological component dictates its role and activity.
Example:
The unique folded shape of an enzyme, its structure, allows it to bind to specific substrates and catalyze a particular reaction, defining its function.
Sugar-phosphate backbone
The structural framework of DNA and RNA, formed by alternating sugar and phosphate groups linked by phosphodiester bonds, from which the nitrogenous bases project.
Example:
The double helix of DNA is stabilized by the strong sugar-phosphate backbone on the outside, protecting the genetic information within.
Unsaturated Fatty Acids
Fatty acids that contain one or more double bonds between carbon atoms in their hydrocarbon chain, causing kinks that prevent tight packing and make them liquid at room temperature.
Example:
Olive oil is rich in unsaturated fatty acids, contributing to its liquid state and health benefits.