University:
Sam Houston State University
Course:
BIOL 1406 | General Biology I
Academic year:

2024
Views:

197

Pages:

10
Author:

5CelestialChronicle

AMINO ACIDS – THE TEENAGERS OF MOLECULES Amino Acids are similar to teenagers.  Some amino acids are attracted to each other; others are repelled by each other  In general, there are a couple of factors that affect how amino acids shape the protein.  AMINO ACID CHARGE The first of these factors is charge  An amino acid can be negatively charged, positively charged, or neutral (no charge)  Opposite charges attract; a negative will move closer to a positive charge and form a bond  Similar charges repel each other; two positive charges will move away from each other   Ditto for two negative charges AMINO ACID HYDROPHOBICITY  Hydrophobicity is a long word that simply means whether or not a molecule is attracted to or repelled by water For example, oil is hydrophobic – it does not mix with water  Salt is hydrophilic – it easily dissolves in water  Hydrophobic – water hating (it has a ‘phobia’ of water)  Hydrophilic – loves water (Philadelphia is the city of Brotherly Love)  Hydrophobic amino acids will move to the inside to get away from water  Hydrophilic amino acids will move to the outside to move towards water  CYSTEINE BONDS Cysteines are one of the 20 amino acids  Cysteines are like the obnoxious couples that are always together – they can’t stand to be apart  Two cysteines will always move closer to each other  When they move close, they will form what is called a “disulfide bond” or “disulfide bridge”  1 Hydrogen bond СН 2 1 о н. . о 1 С-ОН 1 СН2 Hydrophoblc interactions (clustering of hydrophoblc / groups away from water) 1 and van der Waals сн interactions / "С С ---Polypeptide Нз Нз с С backbone Н з , / Нз сн 1 -CH 2 -S-S�CH 2Disulfide bridge о 1 -CH 2 -CH 2 -CH2 -CH 2 -NH 3+ -o-C-CH2lonic bond SUMMARY  So, three major factors affect how amino acids change from a straight line to a 3D protein Charge – like charges repel, opposite charges attract  Hydrophobicity – some amino acids are attracted to water and move to the outside; others are repelled by water and move to the inside  Cysteine bonds – two cysteine amino acids will form a disulfide bond together  cys - - - + Hydrophilic Amino Acids on the Outside Hydrophobic Amino Acids on the Inside Disulfide Bond between Cys - + Neg & Pos attraction cys SHAPES OF PROTEINS  There are two kinds of shapes that can result because of the factors that affect protein shapes α helix (pronounced “alpha helix”)  β sheet (pronounced “beta sheet”) 