Lecture Notes on Proteins, Enzymes, ATP, and Nucleotides

Vocabulary flashcards covering protein structure (primary to quaternary), protein types and functions, enzymes, ATP/ADP dynamics, glycolysis and respiration, and nucleotides/nucleic acids.

Primary structure

The linear sequence of amino acids in a polypeptide.

Secondary structure

Periodic folding patterns of the polypeptide, such as alpha helices and beta sheets.

Tertiary structure

The overall 3D folding of a single polypeptide, held in place by disulfide bonds and ionic/hydrogen bonds.

Quaternary structure

The arrangement of two or more polypeptide chains into a functional protein (e.g., hemoglobin has four subunits).

Globular proteins

Soluble, compact proteins typically found in body fluids and membranes.

Conjugated protein

A protein that contains a non-amino acid moiety (prosthetic group) essential for its function.

Heme group

Iron-containing prosthetic group that binds to certain proteins (like Hb) to enable function.

Hemoglobin

A four-subunit conjugated protein that carries oxygen in the blood.

Ligand

A molecule that binds to a protein (often a receptor) to modulate function.

Channel proteins

Proteins that form pores in membranes to allow specific substances to pass.

Carrier proteins

Proteins that transport substances across membranes.

Glycoproteins

Proteins with attached carbohydrate groups; involved in recognition and protection; antibodies are glycoproteins.

Antibodies

Proteins that recognize and bind antigens as part of the immune response.

Enzyme

A protein that acts as a catalyst to speed up chemical reactions; usually specific and named with the suffix -ase.

Substrate

The molecule that an enzyme acts upon at its active site.

Active site

The region of an enzyme where the substrate binds and the reaction occurs.

Activation energy

The minimum energy required to start a chemical reaction; enzymes lower this barrier.

Kinase

An enzyme that transfers a phosphate group to a substrate (phosphorylation).

Phosphorylation

Addition of a phosphate group, typically from ATP, to a molecule.

ATP

Adenosine triphosphate; the cell’s main energy currency; hydrolysis to ADP + Pi releases energy.

ADP

Adenosine diphosphate; product of ATP hydrolysis with two phosphates.

ATPase

An enzyme that hydrolyzes ATP to ADP and Pi, releasing energy.

Glycolysis

Glucose is broken down to pyruvate in the cytosol, producing a small amount of ATP; can be anaerobic or aerobic.

Aerobic respiration

Metabolic pathway requiring oxygen; occurs in mitochondria and yields about 30 ATP per glucose.

Anaerobic fermentation

Glucose breakdown without oxygen, producing lactate or ethanol with minimal ATP yield.

Mitochondria

Cellular organelles that generate most of the cell’s ATP under aerobic conditions.

Nucleotide

Organic molecule with a nitrogenous base, a sugar, and a phosphate group; building block of nucleic acids.

Nucleic acids

Polymers of nucleotides (DNA and RNA) that store and transmit genetic information.

GTP

Guanosine triphosphate; an energy donor similar to ATP used in signaling and some reactions.

cAMP

Cyclic adenosine monophosphate; a second messenger in cellular signaling.

Dehydration synthesis

A chemical reaction that forms bonds by removing water; often energy-requiring.