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Chapter 16.1

Chapter 16.1. Functions of Proteins. SWBAT: Classify proteins by their functions in the cells. Proteins. Proteins are polymers of amino acids chemically bonded to each other All proteins in humans are made up from 20 different amino acids Protein Subclasses are:

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Chapter 16.1

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  1. Chapter 16.1 Functions of Proteins SWBAT: Classify proteins by their functions in the cells

  2. Proteins Proteins are polymers of amino acids chemically bonded to each other All proteins in humans are made up from 20 different amino acids Protein Subclasses are: • structural, contractile, transport, hormones, enzymes, immunoprotein, AA storage Identification: many end with –in, -en, -ase

  3. Table 16.1 – page 534

  4. Chapter 16.2 Amino Acids SWBAT: know the structure of an amino acid and be familiar with the classification of amino acids

  5. Anatomy of an Amino Acid • AA are all the same with regard to • Central carbon • Amino group • Carboxyl group • Hydrogen • Differ with regard to the R-side chain

  6. Amino Acids NH3+ COO- Remember that amines are bases and can accept a proton Remember that carboxylic acids are acids and can lose a proton This form of the amino acid is called a zwitterion…which has no net charge (one positive and one negative). At normal body pH (~7.4) the functional groups are

  7. Amino Acid (R) Group Side Chain (R) Group can be: Alkyl Hydroxyl Thiol Amino Carboxyl Aromatic Cyclical Amide

  8. Classification of Amino Acids Polar Amino Acid Non-polar Neutral (not charged) Positively charged (Basic) Charged Negatively charged (Acidic)

  9. Nonpolar Amino Acids All are nonpolar amino acids R can be: • Alkyl side chain • Aromatic side chain

  10. Polar Amino Acids • R can be: • Hydroxyl (-OH) • Thiol (-SH) • Amide (-CONH2) All can H-bond with water

  11. Acidic Amino Acids • R will be: • Carboxylic acid (-COOH) Can ionize as a weak acid

  12. Basic Amino Acids R group will contain: an amino group that ionizes as a weak base All are polar amino acids…

  13. Amino Acid Stereoisomers • All of the alpha amino acids (except glycine) are chiral – can exist as D or L enantiomers • Fisher projections with –COOH at the top and (R) group at bottom • L isomer – NH2 group on left • D isomer – NH2 group on right L-serine D-serine In biological systems, only L amino acids are in proteins

  14. Homework: pg 534 16.1 – 16.2pg 537 16.3 – 16.12

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