Regents Biology Proteins

Regents Biology Proteins: Multipurpose molecules

Regents Biology Proteins  Building block = amino acid amino acid – amino acid – amino acid – amino acid – —N——N— H H H | —C— | C—OH || O variable group amino acids  20 different amino acids used in the body There’s 20 of us… like 20 different letters in an alphabet! Can make lots of different words

Regents Biology Proteins  Function:  many, many functions  hormones  signals from one body system to another  insulin  movement  muscle  immune system  protect against germs  enzymes  catalysts in chemical reactions

Regents Biology collagen (skin) Proteins insulin Examples  Muscle  Repair and rebuild cells  Skin, hair, fingernails, claws  collagen, keratin  Pepsin  digestive enzyme in stomach  Insulin  hormone that controls blood sugar levels pepsin

Regents Biology Amino acid chains  Proteins  amino acids chained into a polymer called a polypeptide  Each amino acid is different  some “like” water & dissolve in it  some “hate” water & separate from it amino acid

Regents Biology Water-hating amino acids  Hydrophobic  “water hating” amino acids  try to get away from water in cell  the protein folds

Regents Biology Water-loving amino acids  Hydrophillic  “water loving” amino acids  try to stay in water in cell  the protein folds

Regents Biology Sickle cell anemia I’m hydrophilic! But I’m hydrophobic! Just 1 out of 146 amino acids!

Regents Biology Protein Formation: 1. Amino acids link up to form long chains called polypeptides 2. Polypeptide chains twist or spiral 3. The spiraled chain then folds into subunits 4. The protein forms its final shape by linking together multiple subunits

Regents Biology A.Primary Structure (1°) peptide bonds.  Amino acids bonded together by peptide bonds. aa1aa2aa3aa4aa5aa6 Peptide Bonds Amino Acids (aa)

Regents Biology B.Secondary Structure (2°) primary structurecoilspleats hydrogen bonds  3-dimensional folding arrangement of a primary structure into coils and pleats held together by hydrogen bonds.

Regents Biology B.Secondary Structure (2°) Two examples: Alpha Helix Beta Pleated Sheet Hydrogen Bonds

Regents Biology Alpha Helix Beta Pleated Sheets

Regents Biology C.Tertiary Structure (3°)  Secondary structuresbendfold more complex 3-D arrangement  Secondary structures bend and fold into a more complex 3-D arrangement. “subunit”.  Called a “subunit”.

Regents Biology C.Tertiary Structure (3°) Alpha Helix Beta Pleated Sheet

Regents Biology Subunit: Alpha Helix & Beta Pleated Sheets joined together

Regents Biology D.Quaternary Structure (4°)  Composed of 2 or more “subunits”. enzymes (hemoglobin)  Example: enzymes (hemoglobin) 3° subunits

Regents Biology Subunits

Regents Biology pepsin For proteins: SHAPE matters! collagen  Proteins fold & twist into 3-D shape  that’s what happens in the cell!  Different shapes = different jobs hemoglobin growth hormone

Regents Biology It’s SHAPE that matters!  Proteins do their jobs, because of their shape  Unfolding a protein destroys its shape  wrong shape = can’t do its job  unfolding of proteins = “denature”  temperature  pH (acidity)  salinity folded unfolded “denatured” With protein, it’s not the size, but the SHAPE that matters!

Regents Biology Quick review: With a partner 1. What is denaturing? 2. What is the role of hydrophobic and hydrophilic amino acids in protein formation ? 3. List at least 4 protein functions.