Lecture 3: Biological Molecules

Flashcards about Biological Molecules

Organic Compounds

Carbon-based molecules, containing at least one carbon atom covalently bonded to a hydrogen atom.

Inorganic Compounds

All compounds other than organic compounds (can also contain carbon atoms).

Monomer

Single, small molecule that can combine with identical or similar molecules to form polymers.

Polymer

A chain of many monomers.

Hydrophilic molecules

"Water loving", polar molecules that easily dissolve in water.

Hydrophobic molecules

"Water-fearing", non-polar molecules that do not dissolve in water.

Functional groups

Atoms or groups of atoms covalently bonded to a carbon backbone that are directly involved in chemical reactions.

Hydroxyl group

Polar; found in carbohydrates, alcohols, and amino acids.

Carboxyl group

Acidic; organic molecules containing carboxyl groups are called carboxylic acids; found in amino acids and fatty acids.

Amino group

Basic; organic molecules containing amino groups are called amines; found in amino acids.

Phosphate group

Acidic; organic molecules containing phosphate groups are called phosphates; give molecules negative electrical charge; found in nucleic acids, phospholipids, and ATP.

Carbohydrates

Organic molecules composed of carbon, hydrogen, and oxygen atoms.

Monosaccharides

Simple sugars that are the monomers of carbohydrates.

Disaccharides

A double sugar made from two monosaccharides held together by a covalent bond.

Polysaccharides

Complex carbohydrates formed by joining hundreds of thousands of monomers into linear or branched macromolecules.

Starch

A branched polysaccharide that functions as an energy storage molecule in plants, algae, and some bacteria.

Glycogen

A branched polysaccharide that functions as an energy storage molecule in animals and some bacteria.

Cellulose

A linear polysaccharide made up of glucose monomers that is a structural component of cell walls of plants and many algae.

Chitin

An important structural component of cell walls of Fungi and exoskeletons of insects, spiders, and crustaceans.

Lipids

Non-polar organic molecules that are hydrophobic and insoluble in water.

Triglycerides

A lipid consisting of a 3-carbon glycerol molecule and long hydrocarbon chains called fatty acids.

Saturated fatty acid

Contains the maximum number of hydrogen atoms extending from the carbon backbone and no double covalent bonds between carbon atoms.

Unsaturated fatty acid

Contains fewer than the maximum number of hydrogen atoms and one or more double covalent bonds between a few carbon atoms in the hydrocarbon tail.

Phospholipids

A type of structural lipid found in cell membranes, similar to triglycerides but contain only two fatty acid chains.

Nucleic acids

Macromolecules that store information and provide instructions for building proteins.

Nucleotides

Monomers that compose both DNA and RNA.

Sugar-phosphate backbone

A linear polynucleotide with a repeating pattern of sugar-phosphate-sugar-phosphate.

Proteins

Polymers composed of carbon, hydrogen, oxygen, nitrogen, and usually sulfur atoms, playing many roles in cells.

Amino acids

Monomers from which proteins are built, each consisting of a carbon atom attached to an amino group, a carboxyl group, and a side chain (R group).

Primary structure of a protein

The sequence of amino acids in a protein.

Secondary structure of a protein

Coils (α-helices) or accordion-like structures (β-pleated sheets) formed by polypeptide chains due to ionic bonds, hydrogen bonds, and hydrophobic/hydrophilic characteristics.

Tertiary structure of a protein

Complex three-dimensional shape of a polypeptide formed by further folding; interactions involve covalent bonds between R groups of amino acids, hydrogen bonds, ionic bonds, and other molecular interactions.

Quaternary Structure of a protein

Complex proteins composed of two or more polypeptide chains linked together by disulfide bridges or other bonds.

ATP (Adenosine triphosphate)

The main, short-term, recyclable energy supply for cells, composed of ribose, adenine, and three phosphate groups.

Protein denaturation

Occurs when the shape of a protein is disrupted, causing loss of its biological function.

Enzymes

Proteins that speed up chemical reactions; biological catalysts.

Substrate

The reactant an enzyme acts on.

Active site

The specific region of an enzyme that binds the substrate and catalyzes the reaction.

Cofactors

Non-protein helpers that may be bound tightly to the enzyme as a permanent resident, or may bind loosely and reversibly along with the substrate.

Coenzyme

An organic molecule serving as a cofactor.

Noncompetitive inhibitors

Bind to the enzyme, but not at the active site, and change the shape of the enzyme, preventing the substrate from binding.

Competitive inhibitors

Bind to the active site of an enzyme, competing with the substrate.

Inhibitors

A compound that mimics the substrate and competes for the active site.

Metabolism

The totality of an organism’s chemical reactions.

Metabolic pathway

Begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product; each step is catalyzed by a specific enzyme.

Catabolic pathways

A process that leads to the release of energy.

Anabolic pathways

Consume energy to build complicated molecules from simpler ones.

First law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

Second law of thermodynamics

Every energy transfer or transformation increases the entropy (disorder) in the universe.

Entropy

A measure of disorder, or randomness.

Free energy

Energy available to do work.

Exergonic reactions

Reactions that release energy.

Endergonic reactions

Reactions that require energy input.

Energy of Activation

Energy that must be overcome in order for a chemical reaction to occur.