1: Molecules and Fundamentals of Biology

A comprehensive set of 87 flashcards covering key concepts in biological molecules and structures.

Matter

Anything that takes up space and has mass.

Element

A pure substance that has specific chemical and physical properties and can't be broken down into a simpler substance.

Atom

The smallest unit of matter that still retains the chemical properties of the element.

Molecule

Two or more atoms joined together.

Intramolecular forces

Attractive forces that act on atoms within a molecule.

Intermolecular forces

Attractive forces that exist between molecules.

Monomers

Single molecules with the capability of polymerizing.

Polymers

Substances made of many monomers linked together.

Polymerization

The continuous bonding of one monomer to another, forming a polymer.

Dehydration (condensation) reaction

A polymerization reaction that results in the release of water.

Hydrolysis

A depolymerization reaction which utilizes water to break bonds.

Carbohydrates

Molecules used for both fuel and structural support, containing carbon, hydrogen, and oxygen.

Monosaccharides

Carbohydrate monomers; their formula is (CH2O)n.

Ribose

A five-carbon monosaccharide.

Fructose

A six-carbon monosaccharide.

Glucose

A six-carbon monosaccharide.

Disaccharides

Molecules composed of two monosaccharides joined together by a glycosidic bond.

Polysaccharides

Long polymers containing multiple monosaccharides held together by glycosidic bonds.

Starch

An energy storage polysaccharide of glucose monomers used by plants.

Glycogen

An energy storage polysaccharide of glucose monomers held together and used by animals.

Cellulose

Structural support polysaccharides made of many glucose monomers, important for plant cell walls.

Amino acids

Protein monomers composed of carbon, hydrogen, nitrogen, and oxygen.

Polypeptides (proteins)

Strands of many amino acids held together by peptide bonds.

Peptide bonds

Bonds between the carboxyl group of one amino acid and the amino group of another.

Primary structure

The simple amino acid sequence resulting from mRNA translation.

Secondary structure

Folding patterns of the primary amino acid sequence, including α-helices and β-pleated sheets.

Tertiary structure

Three-dimensional structure resulting from interactions between R groups.

Hydrophobic interactions

Congregation or interaction of nonpolar molecules.

Disulfide bonds

Covalent bonding between two sulfur atoms.

Quaternary structure

A structure formed when multiple polypeptide chains come together.

Conjugated proteins

Proteins composed of amino acids and non-protein components.

Metalloproteins

Proteins which contain a metal ion cofactor.

Glycoproteins

Proteins that contain a carbohydrate group.

Protein denaturation

The loss of protein function and higher-order structures due to factors like temperature or pH.

Catalysts

Substances that increase reaction rates by decreasing activation energy without shifting equilibrium.

Transition state

An unstable intermediate between reactants and products.

Enzymes

Biological catalysts, most of which are proteins.

Active sites

Receptor regions on an enzyme that are specific for a substrate.

Specificity constant

A measure of enzyme binding efficiency for a specific substrate.

Induced fit theory

The theory that active sites mold to fit the substrate upon binding.

Lock and key model

An outdated theory suggesting active sites are rigid and substrates fit them perfectly.

Ribozymes

RNA molecules that are capable of acting as enzymes.

Cofactor

A non-protein molecule that helps enzymes function.

Coenzyme

An organic cofactor, such as a vitamin.

Holoenzyme

The complex formed when an enzyme binds its cofactor.

Apoenzyme

An enzyme without a bound cofactor.

Prosthetic groups

Cofactors that are tightly or covalently bound to their enzyme.

Phosphatase

An enzyme that cleaves a phosphate group off of a substrate molecule.

Phosphorylase

An enzyme that directly adds a phosphate group to a substrate by breaking bonds.

Kinase

An enzyme that indirectly adds a phosphate group to a substrate by transferring it from ATP.

Allosteric site

A substrate binding location that is separate from the active site.

Competitive inhibitor

A molecule that directly competes with reaction substrates for an enzyme’s active site.

Noncompetitive inhibitor

A molecule that binds at the enzyme’s allosteric site, changing the active site.

V max

The maximum reaction velocity.

Saturation

When all enzyme active sites are occupied.

Michaelis constant (KM)

The substrate concentration required to reach half of the maximum velocity (½ Vmax).

Feedback loops

Descriptions of how the product of a reaction affects the rate of that same reaction.

Negative feedback loop

When reaction products slow or inhibit the original reaction.

Positive feedback loop

When reaction products activate or increase the original reaction.

Fatty acid tails

Long hydrocarbon tails with hydrophobic properties.

Hydrophobic

A property of repelling water.

Hydrophilic

A property of attracting water.

Lipophilic

A property of attracting lipids.

Amphipathic

A molecule containing both hydrophobic and hydrophilic parts.

Saturated

A hydrocarbon chain without any double bonds.

Unsaturated

A hydrocarbon chain with one or more double bonds.

Triglyceride (triacylglycerol)

A lipid containing a glycerol backbone and three fatty acids.

Glycerol backbone

Three carbons that serve as anchors for fatty acid chains.

Phospholipids

Lipids composed of a glycerol backbone, one phosphate group, and two fatty acid tails.

Cholesterol

An amphipathic lipid component of cell membranes and precursor to steroid hormones.

Lipoproteins

Round complexes of lipids and proteins that carry lipophilic molecules through the blood.

Waxes

Simple lipids with long fatty acid chains connected to alcohols.

Carotenoids

Lipid derivatives containing long carbon chains with conjugated double bonds, functioning as pigments.

Sphingolipids

Lipids with a backbone containing aliphatic amino alcohols.

Glycolipids

Lipids in plasma membranes with carbohydrate groups bound instead of a phosphate group.

Nucleic acids

A diverse molecule class composed of sugar monomers used for genetic storage and transfer.

Nucleoside

A molecule made of one ribose/deoxyribose sugar and one nitrogenous base.

Nucleotide

A molecule made of one sugar, one nitrogenous base, and phosphate group(s).

RNA (ribonucleic acid)

A single-stranded molecule containing ribose sugar nucleotides.

DNA (deoxyribonucleic acid)

An antiparallel double helix molecule containing deoxyribose sugars.

Sugar-phosphate backbone

A structural chain of alternating sugars and phosphates held together by phosphodiester bonds.

Phosphodiester bonds

Bonds formed by a condensation reaction to link nucleotides.

Nucleic acid polymerization

The process where nucleic acids elongate as nucleoside triphosphates are added to the 3’ hydroxyl group.

mRNA (messenger RNA)

A single-stranded molecule from DNA transcription that carries protein-creation information.

tRNA (transfer RNA)

RNA that carries amino acids to ribosomes during protein synthesis.

rRNA (ribosomal RNA)

RNA that complexes with proteins to form the ribosome enzyme.

miRNA (microRNA)

RNA capable of silencing gene expression by base-pairing to mRNA.

dsRNA (double stranded RNA)

A genetic information reservoir used by some viruses.

Hypothesis

A proposed explanation of scientific phenomena based on prior knowledge that requires further testing.

Theory

An explanation of scientific phenomena accepted due to extensive testing and repetitive results.

Protobionts

Abiotic, lipid capsules that emerged as precursors to cells.

Central dogma of genetics

The principle that information is passed from DNA to RNA to proteins.