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Chapter 14.1-14.4 Proteins. Heather Bobber, Zoë Berkheimer, and Tyler Sterling. 14.1: Functions of Proteins. Most important biological compound Greek “ proteios ” – “of first importance” Functions Structure Skin, bones, hair, and nails Ex. Collagen and Keratin Catalysis
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Chapter 14.1-14.4Proteins Heather Bobber, Zoë Berkheimer, and Tyler Sterling
14.1: Functions of Proteins • Most important biological compound • Greek “proteios” – “of first importance” • Functions • Structure • Skin, bones, hair, and nails • Ex. Collagen and Keratin • Catalysis • Enzymes that speed up reactions in living organisms • Movement • Muscles are made of myosin and actin
Functions (continued) • Transport • Transport nutrients in cells • Ex. Hemoglobin carries oxygen in blood from the lungs to the cells • Hormones • Some proteins are hormones • Ex. Insulin, erythropoietin, and human growth hormones • Protection • Antibodies and fibrinogen which is involved in blood clotting • Storage • Proteins store materials • Ex. Ferritin stores iron in the liver
Functions (continued) • Regulation • Controls the expression of genes and manufacturing of proteins in cells • One cell has 9000 different proteins while the human body has 100,000. • There are 2 types of proteins • Fibrous proteins: insoluble in water and are used for structural purposes. • Globular proteins: soluble in water and are used for nonstructural purposes.
14.2: Amino Acids • Proteins are chains of amino acids • Amino Acid- An organic compound containing an amino group and a carboxyl group • In nature there are 20 common amino acids called alpha amino acids
Amino Acids (continued) • There are 4 groups of chains based on their polarity • Non-polar, polar but neutral, acidic, and basic • Non-polar is hydrophobic • The other three are hydrophilic • Most amino acids are L-isomers and D-amino acids are rare in nature.
14.3: Zwitterions • Zwitterions: compounds with a positive charge on one atom and a negative charge on another atom • Zwitter – German “hybrid” • Amino acids are zwitterions • Ionic compounds • Solids, high melting points • Fairly soluble in water
Zwitterions Continued • Amino acids are negative ions at high pH and positive at low pH • Isoelectric point – pH at which the sample of amino acid or protein has an equal number of positive and negative charges
14.4: Characteristics of Amino Acids • The side chain gives unique properties to amino acids • Example: Cysteine can be easily dimerized to cystine • Some amino acids have acidic or basic properties • Glutamic acid and Aspartic acid have carboxylic acid groups on side chain • Histidine, lysine, and arginine have basic side chains • Phenylalanine, tryptophan, and tyrosine have aromatic rings in their side chains, making them key precursors to neurotransmitter • Tryptophan is converted to serotonin • Tyrosine is converted to adrenaline