Bio 178 Lecture 4 The Chemical Building Blocks of Life

Outline Macromolecules Proteins Nucleic Acids Lipids (Mon) Carbohydrates (Mon)

Reading Chapter 3 Quiz Material Questions on P 60 Chapter 3 Quizzes on Text Website (

Chemistry of Carbon - Organic Molecules Biological molecules are composed primarily of C atoms bonded to H, O, N, & S. Hydrocarbons - Store a lot of energy! Functional Groups The part of a molecule responsible for its chemical properties. Organic molecules Have a C based core with attached functional groups.

Functional Groups

Macromolecules Types Carbohydrates, lipids, proteins, & nucleic acids. Polymer A long chain of similar molecules. Making and Breaking Macromolecules Dehydration synthesis Hydrolysis

Proteins Composition Polymers of amino acids. Amino Acids Carboxyl Group Amino Group Functional groups can be polar, non-polar, electrically charged, aromatic, or have unique properties.

Protein Synthesis

Protein Structure Bonds that stabilize Protein Structure Hydrogen bond Disulfide bridge Ionic bond

Fig. 3.7b(TE Art) C CS C O O N N C H H C CS H H Disulfide bridge 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Levels of Protein Structure Primary Secondary Motifs Tertiary Domains Quaternary

Primary Structure Unique aa seq of a protein Determined by genetic information

Secondary Structure of a Protein Coiling or folding of the polypeptide chain as the result of hydrogen bonds at regular intervals along the polypeptide backbone

Motifs (Supersecondary structure) A distinctive, usually recurrent structural element (secondary protein structures) such as a simple protein motif consisting of two alpha helices. Examples:  turn        barrel

Tertiary Structure The overall 3D shape of the polypeptide chain. Hydrophobic regions will be on the inside. Due to interactions between the R groups. Stability of tertiary structure is determined by how well non-polar R groups (will be different sizes) fit into the protein interior.

Domains Portion of a polypeptide chain that folds independently of the rest of the polypeptide chain (can be excised and still fold correctly). Domains often have different functions within the protein (eg. DNA binding region).

Quaternary Structure The spacial arrangement of the polypeptide chains (subunits) when a protein is composed of 2 or more polypeptide chains.

Protein Folding Chaperone Proteins Enable new proteins to fold correctly. Example - heat shock proteins. Scientific evidence suggests that the primary function of chaperones is to prevent protein aggregation (of incompletely folded proteins). Chaperone Proteins and Disease Can chaperones prevent protein misfolding diseases? Why do these defense mechanisms fail in patients with these diseases?

Human Brain with Spongiform Encephalopathy

Normal (Good) PrPC Prion (Bad) PrPSc Normal Protein Folding is Critical to Function

Protein Denaturation A change in the shape of the protein. Caused by a change in temperature or polarity of the protein’s environment.

Protein Functions FunctionClassExamplesUse Enzyme catalysis EnzymesProteases Break down protein DefenseImmunoglobulinsAntibodies Mark foreign substances Transport Long distance transporters Hemoglobi n Transport O 2 and CO 2 Transport Short distance transporters Proton pump Transports protons across membranes

FunctionClassExamplesUse SupportFibersCollagen Forms cartilage MotionMuscle Actin & Myosin Muscle Contraction RegulationHormonesInsulin Glucose Transport Storage Ion Binding Ferritin Calmodulin Stores Iron Binds Calcium Protein Functions

Fig. 3.4 Structural Proteins

Nucleic Acids Composition Polymers of nucleotides (5-C sugar, phosphate group, & nitrogenous base). Types DNA (deoxyribonucleic acid) RNA (ribonucleic acid) Functions DNA - Genetic instructions. Occurs in the nucleus. RNA - Direct protein synthesis. Made in the nucleus, travels to the cytoplasm.

A Nucleotide is a monomer of a nucleic acid

Nitrogenous Bases