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Transcript
Biological Macromolecules The monomers of each Common polymers You read the following phrase in a research article: “Individuals who exercise will lose weight faster than individuals who do not exercise.” This statement is an example of: 1. 2. 3. 4. data collection A theory A hypothesis A prediction 4 Biological Macromolecules 1. Carbohydrates Monosaccharides, Disaccharides & Polysaccharides 2. Lipids (Fats) Glycerides & Sterols 3. Proteins Enzymes, structures, membrane proteins 4. Nucleic acids DNA, RNA Monomers -> Polymers • Monomer: simple molecule • Polymer: strings of similar, simple monomers • Recall: – Dehydration synthesis – Hydrolysis Unity • ALL polymers are made from very few monomers – All proteins from 20 Amino Acids – Most polysaccharides from 3 monosaccharides • ALL organisms build the same polymers – We build and store the same glycogen molecules in our muscles as do sharks – Redwoods & sword ferns make same cellulose Carbohydrates (sugar, starch & fiber) • • • • • Monomers = Monosaccharides Polymers = Polysaccharides CH2O Hydroxyl & carbonyl groups Arrangement of atoms alters taste Common food sugars Carbohydrates 1. Mono and di-saccharides • Simple Sugars 1. Polysaccharides – Starches • • Amylose; Amylopectin (starches) Glycogen – Structural polysaccharides • • • Cellulose; hemicellulose Chitin Peptidoglycan Carbohydrates • Polysaccharides – Energy storage: Starch & Glycogen – Structure: Cellulose, chitin & peptidoglycan Lipids • Glycerides • Phospholipids • Sterols • Hydrophobic Triglycerides • Glycerol - an alcohol • Fatty acids - carboxyl group with hydrocarbon chain • Energy storage (9 kcal/gram), insulation, padding Saturated & Unsaturated Phospholipid • Both hydrophobic & hydrophilic • Structural molecules (ALL cell membranes are made of these) Steroids • Hydrophobic • Signaling – hormones • Structural – Stiffen cell membranes Proteins • Monomers = Amino Acids (AA) – AA = carboxyl group, R (functional) group, amino group • Polymers = Proteins – (3 - 100K) linked by peptide bonds • Most abundant molecules of human body (~ 2 million; 20% of body weight) Protein Function • Support - Structural proteins in cell membranes • Movement - Contractile proteins move muscles and cells • Transport - Transport proteins bind insoluble compounds and molecules to allow transport in bloodstream • Buffering - Buffer against detrimental pH changes • Metabolic regulation - Enzymes accelerate chemical reactions • Coordination & Control - Hormones • Defense - Antibodies, clotting proteins (globulin), keratin Making a protein • Join amino group to carboxyl group • Peptide bond – Any chain of two or more amino acids joined together are peptides • “R” side chain = functional group Protein structure 1. Primary (covalent, peptide bond) – AA sequence 2. Secondary (H-bonding) – – α-helices β-pleated sheets 3. Tertiary (H- bonding) 4. Quaternary – Additions of other polypeptides Primary structure • Polypeptide chain: linear sequence of AA Secondary structure • Common macrostructures formed by H-bonding between functional groups of AA. • α-helices: common in fibrous proteins • pleated sheets: common in globular proteins Tertiary Structure Quaternary Structure • Final, assembled & functional protein • Consist of: – Multiple polypeptides joined by hydrogen bonds OR, – Single functional polypeptide Various protein shapes Concept Check This lysozyme protein is found in tears & protects the eye from bacterial infections. Which of the following best describes the outside of the molecule? 1. The R-groups on the surface of the molecule are mostly hydrophobic. 2. The R-groups on the surface of the molecule are mostly hydrophilic. 3. The R-groups on the surface of the molecule are mostly non-polar. 4. The R-groups on the surface of the molecule are constantly changing between non-polar and polar as the protein chain bends and folds. Example: Hemoglobin • HbA, HbB, HbE • Multiple Hb proteins exist; only two producenormal O2 binding to RBC’s Hemoglobin • HbA, HbB, HbE • Small changes in AA sequence result in major functional changes – Less functional protein produced; Fewer competent RBC’s are made; HbE – Defective protein is produced: RBC’s sickle (collapse); HbS • Each altered phenotype results from a single AA change Denaturation • Loss of function due to shape change – Caused by changes in pH or temperature Nucleic Acids • Polymers that serve as recipes for proteins • DNA (deoxyribonucleic acid): double stranded polymer; duplicate, read in reverse (think of this entire molecule as a cookbook) • RNA (ribonucleic acid): single stranded polymer; usually, a short transcript (copy) of a tiny portion of a single strand of DNA (recipe) • Monomers = nucleotides Nucleotides • 5 nucleotides – DNA: Adenine, Thymine, Guanine, Cytosine – RNA: Adenine, Uracil, Guanine, Cytosine • Consist of Phosphate, Sugar, Nitrogenous base – The base is variable • Where are they joined? What reaction joins them? RNA • Single polynucleotide strand • Repeated Sugar phosphate ladder • Base protrudes from sugar • Many varieties: – mRNA, tRNA, rRNA RNA • Single polynucleotide strand • Repeated Sugar phosphate ladder • Base protrudes from sugar • Many varieties: – mRNA, tRNA, rRNA • 3-D shape also due to Hbonds DNA • Double stranded ladder • Each base binds to one specific counterpart – A-T; C-G (base pairs) • What type of bonds hold base pairs (bp) together? • thousands - millions of bp in length – Codes for hundreds - thousands of genes Concept Check When proteins are heated, they denature. If moderate heat was applied to this molecule of DNA what part of the molecule would break apart first? (Use your knowledge of chemical bonds.) 1. The nucleotides along each side would break apart. 2. The sugar-phosphate backbone would separate from the nitrogen bases. 3. The nitrogen base pairs would separate in the interior of the molecule.