Bio 178 Lecture 4 The Chemical Building Blocks of Life.
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Transcript of Bio 178 Lecture 4 The Chemical Building Blocks of Life.
Bio 178 Lecture 4The 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 (www.mhhe.com/raven7)
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 moleculesHave 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
ProteinsComposition
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 StructureBonds that stabilize Protein Structure
• Hydrogen bond
• Disulfide bridge
• Ionic bond
Fig. 3.7b(TE Art)
C C S
CO
ON
N
C
H
HCCS
H
H
Disulfidebridge
2
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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 StructureThe spacial arrangement of the polypeptide chains (subunits) when a protein is composed of 2 or more polypeptide chains.
Protein FoldingChaperone 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 DenaturationA change in the shape of the protein.
Caused by a change in temperature or polarity of the protein’s environment.
Protein Functions
Function Class Examples Use
Enzyme catalysis
Enzymes ProteasesBreak down
protein
Defense Immunoglobulins AntibodiesMark foreign substances
TransportLong distance transporters
Hemoglobin
Transport O2 and CO2
TransportShort distance transporters
Proton pump
Transports protons across
membranes
Function Class Examples Use
Support Fibers CollagenForms
cartilage
Motion MuscleActin & Myosin
Muscle Contraction
Regulation
Hormones InsulinGlucose
Transport
Storage Ion BindingFerritin
Calmodulin
Stores IronBinds
Calcium
Protein Functions
Fig. 3.4
Structural Proteins
Nucleic AcidsCompositionPolymers 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