SMi Source Lesson Biology: Cytokine Primer

  • SMi Source lesson Biology: Cytokine Primer has the following microlearning topics

  • 1. Cytokines as Proteins

    2. Cytokines as Intercellular Messengers

    3. Cytokines in Physiology and Disease

    4. Cytokine Examples

  • Lesson Biology: Cytokine Primer teaches these concepts

  • Cytokines: A Primer, Cytokines as Proteins, Cytokines

    Cytokines: A Primer, Cytokines as Proteins, Cytokines are Proteins

    Cytokines: A Primer, Cytokines as Proteins, Proteins are Linear Polymers of Amino Acids

    Cytokines: A Primer, Cytokines as Proteins, Proteins are the Products of Genes

    Cytokines: A Primer, Cytokines as Proteins, Protein Structure and Stability: Temperature

    Cytokines: A Primer, Cytokines as Proteins, Protein Structure and Stability: Addition of Acid

    Cytokines: A Primer, Cytokines as Proteins, Protein Structure and Stability: Addition of Alkali

    Cytokines: A Primer, Cytokines as Proteins, Protein Structure and Stability: Denaturation

    Cytokines: A Primer, Cytokines as Proteins, Protein Structure and Stability: Amino Acids

    Cytokines: A Primer, Cytokines as Proteins, Protein Structure and Stability: Molecular Interactions

    Cytokines: A Primer, Cytokines as Proteins, Protein Structure and Stability: Levels of Structure

    Cytokines: A Primer, Cytokines as Proteins, Protein Structure and Stability: Conditions that Affect Protein Structure

    Cytokines: A Primer, Cytokines as Proteins, Protein Structure and Stability: Oxidizing or Reducing Agents

  • Lesson Biology: Cytokine Primer addresses these key points

  • Cytokines

    • A class of intercellular signaling molecules

    Cytokines

    • Proteins that act as messengers between cells
    • Especially important for the immune system

    Proteins are Linear Polymers of Amino Acids

    • Molecules made up of chains of smaller units called monomers joined head-to-tail by strong covalent bonds
    • Complex machinery in the cell translates DNA into protein

    Amino Acids

    • Monomers of the protein polymer 
    • Linked by peptide bonds to form the polypeptide chain
    • Any one of 20 amino acids may be incorporated into each position of the polypeptide chain
    • Each point is determined by the gene that codes for the protein

    Proteins are the Products of Genes

    • Information specifying any particular protein molecule is contained within a specific gene
    • Information encoded in molecules of DNA, which make up the chromosomes found in the nucleus

    Increasing temperature causes

    • The atoms of the protein molecule to move around more and more
    • A protein's native structure can be disrupted
      • Denaturation

    Addition of acid to a protein solution

    • Causes several side chains that are normally negatively charged to lose their charge
    • Other amino acids that were previously uncharged may become positively charged
    • Affects the surface of the protein, and may completely alter the structure
    • Higher concentrations of acid can promote cleavage of the polypeptide chain

    Low concentrations of alkali

    • Alter the three-dimensional structure of the polypeptide by changing the charge of its amino acid side chains

    High concentrations of alkali

    • Able to cleave the polypeptide chain

    Denaturation

    • Chemical properties of a protein's surface are altered
    • Disrupts or completely abolishes a protein's normal interactions with other molecules

    Amino Acids

    • Polypeptide is a flexible molecule
    • Doesn't remain extended
    • Folds into a precise three-dimensional structure

    Protein's native form

    • One stable conformation for the polypeptide in its natural environment within a cell

    Side chain

    • Branches off the main chain of the polypeptide
    • Chemical properties specific to the particular amino acid
    • Bear a positive or negative electric charge, or uncharged
    • Repelled by water or affinity for water molecules
    • End up on the surface of the protein affect the chemical characteristics of the region of the surface at which they are found

    Pairs of Amino Acids

    • May form a strong ionic interaction within a protein
    • May form a strong covalent bond in which two sulfur atoms are joined, creating a disulfide bridge across the protein

    Molecular Interactions

    • Pockets or other surface shape features may fit and bind to a target molecule
    • Charged or water-repelling side chains may be located in just the right spots on the surface to maximize binding or promote a chemical reaction

    Interactions between amino acids

    • Aren't directly joined within an individual protein chain
    • Weaker than the covalent bonds that hold the amino acids together head-to-tail in the chain
    • Thus, it's difficult to break the protein up into its constituent amino acids
    • Allows a single protein molecule to bind to and affect many other target molecules

    Levels of Structure

    Primary Structure

    • Sequence of amino acids

    Secondary Structure

    • Regions of the protein chain that take on structures such as alpha helices and beta sheets

    Tertiary Structure

    • Secondary structures that assemble into organized bunches to form domains

    Quaternary Structure

    • Level of structure describing spatial arrangement of two or more polypeptide chains in a complex

    Characteristics of the solution in which a protein molecule is

    • Dissolved
    • In a cell
    • In the bloodstream
    • In a vial

    Surrounding conditions affect the characteristics and sometimes the structure of a given protein.

    Oxidizing or reducing agents

    • Affects the side chains of some amino acids, particularly cysteine

    Diatomic oxygen from the air can be transformed into highly reactive oxygen species

    • Peroxides
    • Free radicals

    Reactive oxygen species

    • Generated by exposing a solution to light

    Peroxides and free radicals

    • Present in the formulation excipients

    Cysteine

    • Side chain can be oxidized by reactive oxygen species, prevents it from forming a disulfide bond

    Disulfide

    • Can be broken by reducing agents like mercaptans.
    • Reducing agents can be generated by breakdown of additives to protein solutions such as surfactants