Lecture Notes VOCAB: Bonds, Carbohydrates, Fats/Lipids, Enzymes (Video)

Vocabulary flashcards covering core terms from bonds, carbohydrates, fats/lipids, and enzymes as presented in the video notes.

Atom

The basic unit of matter: a nucleus containing positively charged protons and neutral neutrons, surrounded by a cloud of negative electrons.

Proton

Positively charged subatomic particle located in the nucleus.

Neutron

Electrically neutral subatomic particle located in the nucleus.

Electron

Negatively charged subatomic particle orbiting the nucleus.

Valence electron

Electrons in the outermost electron shell that participate in bonding.

Intramolecular bonds

Bonds between atoms within the same molecule (e.g., ionic, covalent, non-polar covalent).

Ionic bond

Electrostatic attraction between metal cations and non-metal anions; occurs when electronegativity difference > 1.7; compounds dissociate in polar solvents.

Covalent bond

Bond formed by sharing electrons between two atoms; usually between non-metals; can be nonpolar or polar depending on electronegativity difference (< or ≥ 0 but typically <1.7 for covalent).

Non-polar covalent bond

Covalent bond with approximately equal sharing of electrons (electronegativity difference near 0).

Polar covalent bond

Covalent bond with unequal sharing of electrons; one atom attracts electrons more strongly; greater polarity as electronegativity difference increases.

Electronegativity

The tendency of an atom to attract electrons in a chemical bond.

Ionic compound dissociation

Ionic compounds separate into ions when placed in polar solvents (like water).

Hydrophilic

Polar or ionic substances that dissolve in water or other polar solvents.

Hydrophobic

Nonpolar substances that do not readily dissolve in water.

Glucose

Hexose aldose sugar; main product related to photosynthesis and cellular respiration.

Galactose

Hexose aldose sugar; epimer of glucose; monomer of lactose.

Fructose

Hexose sugar; ketose form.

Aldose

Carbohydrate containing an aldehyde group at the end of the carbon backbone.

Ketose

Carbohydrate containing a ketone group (often at carbon 2 in the chain).

Ribose

Pentose sugar (C5H10O5); found in RNA, ATP, NAD+.

Deoxyribose

Pentose sugar (C5H10O4) with one fewer oxygen than ribose; sugar in DNA.

Pentose

Five-carbon sugar.

Hexose

Six-carbon sugar.

Anomeric carbon

C1 of a sugar; the carbon whose OH orientation defines α or β anomers.

α (alpha) anomer

Hydroxyl group at carbon 1 is oriented downward.

β (beta) anomer

Hydroxyl group at carbon 1 is oriented upward.

Monosaccharide

A single sugar unit (e.g., glucose, fructose, galactose).

Disaccharide

Two monosaccharides linked by a glycosidic bond (e.g., maltose, lactose, sucrose).

Polysaccharide

A polymer composed of many monosaccharide units.

Glucose vs. Galactose (C4 difference)

Glucose has OH at C4 down; Galactose has OH at C4 up.

Glycosidic bond

Bond linking sugar units in disaccharides and polysaccharides.

Disaccharides (examples)

Maltose (glucose + glucose), Lactose (galactose + glucose), Sucrose (glucose + fructose).

Maltose

Disaccharide formed from two α-glucose units.

Lactose

Disaccharide formed from β-galactose and β-glucose; digested by lactase.

Sucrose

Disaccharide formed from α-glucose and fructose; digested by sucrase; transported as sucrose in phloem.

Amylose

Unbranched component of starch; α-1,4 linkages; 300–600 glucose units.

Amylopectin

Branched component of starch; mainly α-1,4 with α-1,6 branches.

Starch

Polysaccharide storage carbohydrate in plants; composed of amylose and amylopectin.

Glycogen

Branched polysaccharide for short-term glucose storage in animals (liver and muscles); mainly α-1,4 with α-1,6 branches.

Cellulose

Structural polysaccharide in plant cell walls; composed of β-glucose with β-1,4 linkages; indigestible by humans but digestible by some decomposers with cellulase.

β-glucose

Sugar form in cellulose; linked by β-1,4 bonds.

α-1,4 linkage

Glycosidic bond between glucose units in starch and glycogen.

β-1,4 linkage

Glycosidic bond between glucose units in cellulose.

Membrane polysaccharides concept

Use of ether bonds and glycosidic linkages in complex carbohydrates and plant structures.

Ether bond

Bond consisting of carbon–oxygen–carbon in some polymers; a type of linkage in organic molecules.

Dehydration synthesis

Reaction that builds larger molecules by removing water; anabolic.

Hydrolysis

Reaction that breaks polymers into monomers by adding water; catabolic.

Triglyceride

A lipid with three fatty acids esterified to glycerol; main long-term energy storage molecule.

Saturated triglyceride

Triglyceride with maximum hydrogens (no double bonds); solid at room temperature; typically animal fats.

Unsaturated triglyceride

Triglyceride with one or more double bonds; has kinks; liquid at room temperature; typically plant oils.

Cis-fatty acids

Hydrogens on the same side of the double bond; naturally occurring; causes kinks.

Trans-fatty acids

Hydrogens on opposite sides of the double bond; often industrially produced; straighter chains; associated with plaques.

Phospholipids

Main component of biological membranes; hydrophilic phosphate-choline head and hydrophobic fatty acid tails; form micelles or liposomes.

Lecithin

A phospholipid that acts as an emulsifier in foods.

Micelle

Spherical arrangement of phospholipids in water with tails inward and heads outward.

Liposome

Vesicle formed by a phospholipid bilayer used to transport molecules in cells.

Phospholipid bilayer

Two-layer membrane structure forming cell membranes.

Steroids

Lipids with interlocking carbon ring structures; include hormones; can increase membrane fluidity; gonane is the steroid nucleus.

Gonane

The core four-ring carbon skeleton of steroids.

Enzyme

Biological catalyst that speeds up chemical reactions without being consumed; usually proteins (or sometimes RNA in some cases).

Suffix -ase

Most enzyme names end with -ase (e.g., amylase, protease).

Active site

The region of an enzyme where the substrate binds.

Substrate

The reactant(s) that bind to the enzyme's active site.

Lock and key model

A model where substrate fits the active site exactly like a key fits a lock.

Induced-fit model

A model where the enzyme active site becomes more complementary to the substrate as binding occurs.

Competitive inhibitor

Inhibitor with a shape similar to the substrate that competes for the active site.

Allosteric site

A site on an enzyme away from the active site where allosteric effectors bind.

Non-competitive inhibitor

Inhibitor that binds to the allosteric site and changes the enzyme's shape, reducing activity.

Allosteric effector

Molecule that binds to the allosteric site to modulate enzyme activity.

Feedback inhibition

Regulatory mechanism where the product inhibits an earlier step to control production.

Precursor activation

Mechanism where product formation occurs only when enough substrate is available.

Chymotrypsinogen

Zymogen (inactive enzyme) produced in the small intestine that is activated to α-chymotrypsin.

α-Chymotrypsin

Active proteolytic enzyme in the small intestine; active site includes serine and histidine; catalyzes peptide bond hydrolysis.

Active-site residues (Serine and Histidine)

Serine (Ser195) and Histidine (His57) participate in catalysis via hydrogen bonding and proton transfer.