Cell Biology and Macromolecules

Study Notes

Cell biology is a branch of biology that studies the structure and function of the cell
Cell biology focuses on physiological properties, metabolic processes, signaling pathways, the life cycle, chemical composition, and the interactions of the cell with their environment
Includes the processes of mitosis and meiosis
Molecular biology focuses on molecules of life, primarily nucleic acids and proteins
Cell biology focuses on how these molecules are used by the cell for survival, reproduction, and normal cell function

The most abundant biological macromolecules are proteins, nucleic acids, and polysaccharides
These are all polymers composed of multiple covalently linked small molecules, called monomers

Proteins are polymers of amino acids, linked by a peptide bond
The order in which amino acids occur in a polypeptide chain is specific to each protein
Proteins are large and highly complex macromolecules

Proteins are the working molecules of a cell, carrying out the program of activities encoded by genes
Proteins are constructed by the polymerization of 20 different amino acids into linear chains
Proteins differ in kind, number, and arrangement of amino acids they contain
The structures and functions of proteins are determined by the properties of the amino acids, specifically their side chains
Side chains vary in size, shape, charge, hydrophobicity, and reactivity

Structural proteins provide structural rigidity to the cell
Transport proteins control the flow of materials across cellular membranes
Regulatory proteins act as sensors and switches to control protein activity and gene function
Signaling proteins include cell surface receptors and other proteins that transmit external signals to the cell interior
Motor proteins cause motion

Primary structure: The linear arrangement of amino acid residues in a polypeptide chain
Secondary structures: Result from the folding of localized parts of a polypeptide chain, forming alpha helix and beta sheet configurations
Tertiary structure: The three-dimensional structure of a single polypeptide chain, resulting from interactions between amino acid side chains
Quaternary structure: The arrangement of multiple polypeptide chains (subunits) to form a functional protein complex