Biomolecules

BIOMOLECULES Carbohydrates Fats Proteins

Organic Compounds Carbohydrates A group that includes things like table sugars and starches. Includes Simple and Complex groups

Simple Carbohydrates Simple Monosaccharides Fructose Glucose Disaccharides Sucrose Lactose

Monosaccharides

Disaccharides

Glycogen: a Polysaccharide

Complex Carbohydrates Polysaccharides are long branching chains of simple sugars, specifically glucose. Starch is a storage carbohydrate in plants. Glycogen is a storage carbohydrate in animals. Liver and muscles

How the Body Uses Sugars Glycogen exists in the body as a reservoir of available energy that is stored in the chemical bonds within individual glucose monomers. Hydrolysis of glycogen, as occurs during periods of fasting, leads to release of the glucose monomers into the blood, thereby preventing blood glucose from decreasing to dangerously low levels. Glucose is often called “blood sugar” because it is the major monosaccharide found in the blood.

Lipids Lipids are molecules composed predominantly (but not exclusively) of hydrogen and carbon atoms. These atoms are linked by nonpolar covalent bonds. Thus, lipids are nonpolar and have a very low solubility in water. Lipids can be divided into four subclasses: fatty acids, triglycerides, phospholipids, and steroids. Solid at room temp = fat; Liquid at RT = oil

Triglycerides

polyunsaturated) fats are liquid at room temp. Unsaturated (mono- & polyunsaturated) fats are liquid at room temp. Trans fats have added hydrogen (hydrogenated) (p 29) Triglycerides: 3 FA + Glycerol Saturated Unsaturated Polyunsaturated

Trans Fats

Organic Compounds Lipids, Fats or Triglycerides Composed of Glycerol backbone plus 3 fatty acid chains Saturated Fats Contains only single bonds between the carbons on the fatty acid chains Solid at room temperature Unsaturated Fats Contains one or more double bonds between the carbons on the fatty acid chains Semi-solid or liquid at room temperature Mono, di- and polyunsaturated fats Will only dissolve in other lipids and insoluble in water. Like Dissolves in Like

Phospholipid

Phospholipids

Organic Compounds Phospholipids Modified triglycerides Phosphorous head and two fatty acid tails Amphipatic Hydrophilic, as well as Hydrophobic Found only in human cell membrane as a bi-layer Hydrophobic – Tails on the inside of the membrane Hydrophilic – Heads on the outside of the membrane

Cholesterol

Steroids Cholesterol decreases cell membrane permeability to small water-soluble molecules.

Steroids

Organic Compounds Steroids Parent compound is cholesterol. Used for the production of steroid hormones. Can dissolve in fatty substances. Dissolves through cell membrane and nuclear membrane and attaches directly to DNA Starts Transcription of proteins Such as enzymes Cholesterol can be produced through de-novo synthesis

Organic Compounds Proteins composes 10 – 30% of cell mass and is the basic structural material of the body. Some are structural. Bones, hair, connective tissue Some are functional. Antibodies, enzymes, protein hormones

Amino Acids

Organic Compounds Amino acids. The Building Blocks of Protein Composed of an amine groups a carboxyl group a “R” or Functional group. 20 different types of amino acids 9 Essential Must acquire these through the foods we eat 11 Non-essential Can be produced through de-novo synthesis

Peptide Bond

Peptide Bonds Most proteins contain from 1500 to 50,000 amino acids in the human body.

Primary Structure of a Polypeptide Chain 28

Conformation Interactions between side groups of each amino acid leads to bending, twisting, and folding of the chain into a more compact structure. The final shape of a protein is known as its conformation. 29

Amino acid interactions 30

Polypeptides: Conformations

Hemoglobin 32

Proteins Hydrogen bonds form and break quickly and can thereby change the protein shape and its function

Protein Structure Globular Proteins Compact, spherical proteins Have tertiary or quaternary structures Also known as functional proteins Antibodies Hormones Enzymes (catalysts) Membrane Transporters DNA Regulatory Proteins for transcription

Proteins Fibrous proteins are stable. Globular proteins are very unstable. Hydrogen bonds can form and break easily. Hydrogen bonds can break when: A PO4 group is added

Adenosine Triphosphate The transfer of a high energy phosphate group to an enzyme causes a change in confirmation The change in enzyme shape allows the enzyme to quickly catalyze the reaction

Protein Structure Change in shape of protein = Denatured Change in conformation = Change in configuration Denatured When globular proteins lose their shape they can’t perform their function any longer. pH drops. Temperature rises above normal levels.

Enzymes Enzymes are globular proteins that act as catalysts. A catalyst speeds up a chemical reaction but it itself is not used up Enzymes are recycled The function of a globular protein depends on the arrangement of the atoms

Mechanism of Enzymes Three Basic Steps The Enzyme binds with a substrate at its active site. The Enzyme-Substrate Complex is rearranged to form a product. The Enzyme releases the product and goes back to its original shape The Enzyme can be used again to catalyze another reaction

Enzymes The job of an enzyme is to lower the activation energy Some enzymes carry a helper of “cofactor” such as iron or copper. Vitamins, especially B complex.

Feedback Inhibition of Biochemical Pathways

Activation Energy Fig 4-3

Some more characteristics of enzymes: Usually end in –ase Inactive form: -ogen

Naming of Enzymes mostly suffix -ase first part gives info on function examples Kinase Phosphatase Peptidase Dehydrogenase

Protein Molecules Specificity The ability of a protein to bind to a certain ligand or a group of related ligands Some proteins are very specific about the ligands they bind, others bind to whole groups of molecules

Affinity The degree to which a protein is attracted to a ligand is referred to as its Affinity. High affinity proteins are more likely to bind a certain molecule than a low affinity protein