Definition
Glucose and fructose are both simple sugars with the same molecular formula () but different structures: glucose contains an aldehyde functional group (), while fructose contains a ketone functional group () along with several hydroxyl () groups in both — this structural difference is exactly what makes them isomers of each other with slightly different properties (e.g. fructose tastes sweeter).
Maltose comes from the breakdown of starch (e.g. in germinating grain); lactose is found naturally in milk; fructose is found naturally in fruits and honey.
Two examples of polymeric (complex) carbohydrates: starch and cellulose — both are long chains of glucose units joined together, differing in how those units link, which gives them very different properties (starch is digestible and used for energy storage in plants; cellulose is not digestible by humans and forms structural plant cell walls).
Definition
Proteins are built from amino acids, linked by a peptide linkage formed between the carboxyl group () of one amino acid and the amine group () of the next, releasing a water molecule each time (a condensation reaction) — repeating this many times over builds up a long polypeptide chain.
Three important functions of proteins in the body: acting as enzymes (biological catalysts, speeding up reactions), providing structural support (e.g. collagen, keratin), and transporting substances around the body (e.g. haemoglobin carrying oxygen) — proteins are not primarily used as the body's main energy source (that's carbohydrates and fats), which is the one major function they generally don't perform.
An adult should consume approximately – grams of protein per day, though the precise recommended amount varies with body weight and activity level.
Denaturation is a permanent change in a protein's structure (and so its function) caused by heat, extreme pH, or certain chemicals — two examples: cooking an egg (heat denatures the egg-white protein, changing it from clear/runny to white/solid), and milk curdling when an acid is added (denaturing the milk proteins).
Definition
A fat contains the ester functional group (), since a fat (triglyceride) is formed by esterification between three fatty acid molecules and one glycerol molecule, releasing three water molecules: glycerol fatty acid triglyceride .
Fatty acids serve as the building blocks of lipids in essentially the same structural role that amino acids serve for proteins — just as many amino acids link together to build a protein, fatty acids (combined with glycerol) link together to build fats.
Stearic acid (a simple fatty acid) is obtained mainly from animal fats. Lauric acid is obtained mainly from coconut oil/palm kernel oil; palmitic acid is obtained mainly from palm oil (and animal fats).
Commercial products obtained from oils and fats include soap, cosmetics, candles, margarine, and biodiesel.
Definition
Vitamin A deficiency causes night blindness (and other vision problems, since vitamin A is essential for the eye's light-sensing pigments).
Vitamin C's sources include citrus fruits, and its deficiency causes scurvy (symptoms including bleeding gums and poor wound healing, since vitamin C is needed for healthy connective tissue).
Vitamin D's sources include sunlight exposure (the skin synthesizes it) and certain foods (like fortified milk and fatty fish) — it's essential for calcium absorption and bone health.
Vitamin K helps in blood clotting, since it's needed to activate certain clotting factor proteins in the blood.
Fatigue and depression can be caused by a deficiency of vitamin B (or related B vitamins), which is important for nerve function and red blood cell production.
Definition
DNA (deoxyribonucleic acid) stores an organism's genetic information and instructions for building and maintaining it, passed from parent to offspring. RNA (ribonucleic acid) mainly carries out DNA's instructions, helping translate the genetic code into proteins.
Compared to RNA, a DNA molecule is double-stranded (RNA is typically single-stranded) and more chemically stable, making it well-suited to long-term storage of genetic information, while RNA's temporary, working-copy role suits its single-stranded, less stable structure.
Definition
Genetic engineering terms: changing an organism's genome by deleting or inserting a region of DNA is called gene editing/genetic modification. Creating an exact genetic replica of a cell, tissue, or organism is called cloning.
Gene therapy is a medical technique that treats or prevents disease by introducing, removing, or altering genetic material within a patient's cells — e.g. inserting a working copy of a gene to replace a faulty one causing a genetic disorder.
Definition
A pregnancy test detects the hormone hCG (human chorionic gonadotropin), which is produced early in pregnancy and appears in urine.
Early cancer detection commonly uses biopsy and imaging/screening tests (along with specific biomarker blood tests for certain cancers) to identify abnormal cell growth before symptoms become severe.
Three basics of healthy eating: eating a balanced diet with adequate proportions of carbohydrates, proteins, fats, vitamins, and minerals; controlling portion sizes to maintain a healthy weight; and staying well-hydrated with sufficient water intake.
Quick Recap
- ●Glucose () and fructose () are isomers (); starch and cellulose are polymeric carbohydrates from glucose units
- ●Proteins: amino acids linked by peptide bonds ( peptide ); functions: enzymes, structure, transport (not primary energy)
- ●Fats: ester functional group; glycerol fatty acids triglyceride ; fatty acids are lipids' building blocks (like amino acids for proteins)
- ●Vitamins: A (night blindness), C (scurvy), D (sunlight, bones), K (blood clotting), B (fatigue/depression if deficient)
- ●DNA: stores genetic info, double-stranded, stable. RNA: carries out instructions, single-stranded. Cloning exact replica; gene therapy treating disease via genetic material
- ●Pregnancy test detects hCG hormone; healthy eating balanced diet portion control hydration
