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Biology Lecture 5
Amino Acids and Proteins
19
Biology
Undergraduate 1
10/11/2009

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Term
Amino Acids
Definition
  • joined by polypeptide bonds
  • always occure by formation of a covalent bond between an amino group and carboxyl group through dehydration
  • building blocks of proteins
  • 20 naturally occuring amino acids
  • their R groups is what makes them all different
Term
Amino group
Definition
nitrogen atom bonded to two hydrogen atoms and a carbon skeleton
Term
alpha helix
Definition

hydrogen bond between every 4 peptide bonds

chain must fold to bring chain close enough to form h bonds

Term
beta pleated sheets
Definition
bonding is between different segments of the polypeptide that come to lie parrallel to each other
Term
carboxyl group
Definition
an oxygen atom double bonded to a carbon atom which is also bonded to an O-H group
Term
Catalyst
Definition
chemical agents that selectively speed up reactions without being consumed in the reaction
Term
denaturation
Definition
  • When a protein loses its native shape because of a change in PH, salt concentration, temperature ect.
  • protein becomes biologically inactive
  • often occures when it goes from an aqueous environment to an organic solvent
  • agents that distrub hydrogen or ionic bonds or disulfide bridges that maintain a proteins shape
  • may occure in excessive heat
Term
disulfide bridges
Definition
  • covalent bonds that form where two cysteine monomers, amino acids with sulfhydryl groups on their side chains are brought close together by the folding of the protein
  • the sulfur of one cyteine bonds to the sulfur of the second, and the disulfide bridge rivets parts of the protein together.
Term
Enzyme
Definition
a macromolecule serving as a catalyst, a chemical agent that changes the rate of the reaction without being consumed by the reaction
Term
Hydrophobic interactions
Definition
non-polar amino acids cluster in interior away from water, are not actually bonded together
Term
peptide bond
Definition
bond that occurs when two amino acids are positioned so that the carboxyl group of one is adjacent to the amino group of the other, they become joined by a dehydration reaction.
Term
polypeptide
Definition
polymers of amino acids
Term
primary structure
Definition
  • sequence of amino acids in chain
  • chain goes from amino end to carboxyl end
Term
proteins
Definition
consists of one or more polypeptides, each coiled and folded into a specific 3-dimensional structure
Term
Quaternary structure
Definition
  • not all proteins require this
  • polypeptides wrap around together
  • 3-chains called collagen
    • ex: hemaglobin
Term
Secondary structure
Definition
  • repeated interactions between peptide bonds that are hydrogen bonds
    • alpha helix
    • b pleated sheet
Term
sickle-cell anemia
Definition
  • hereditary disorder caused by the substitution of one amino acid (valine) for a normal one (glutamic acid) at a particular position in the promary structure of hemoglobin, the protein that carries oxygen in red blood cells
  • cells crystalize deforming into a sickle shape
Term
tertiary structure
Definition
  • results from irregular interactions between R groups
    • h-bonds between polar r groups
    • ionic bonds between charged r groups
    • disulfide bridges
    • hydrophobic interactions
Term
urea
Definition
a soluble nitrogenous waste produced in the liver bya metabolic cycle that combines ammonia with carbon dioxide
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