11 o Dictates secondary and tertiary structure due to the chemical nature of

11 o dictates secondary and tertiary structure due to

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11
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o Dictates secondary and tertiary structure due to the chemical nature of the backbone and the R groups of the amino acids along the polypeptide. Secondary Structure- Regions stabilized by hydrogen bonds between atoms of the polypeptide backbone o Primary structure folded onto itself o Results from coiling or folding of the polypeptide o Held together by hydrogen bonds between amino groups and carboxyl groups of the amino acids (the polypeptide backbone) o Usually forms an helix or Pleated Sheet Tertiary Structure- Three dimensional shape stabilized by interactions between R groups/ A three dimensional polypeptide made by the interactions of secondary structures o Held together by interactions between R groups of the various amino acids o Hydrophobic interactions-as a polypeptide folds into its functional shape, amino acids with hydrophobic(nonpolar) R groups usually end up in clusters at the core of the protein, out of contact with water. A Hydrophobic interaction is 12
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caused by the exclusion of nonpolar substance by water molecules. Once non polar amino acid chains are close together van der Waals interactions help hold them together. o ionic bonds o hydrogen bonds- hydrogen bonds between polar R groups help stabilize tertiary structure. o Disulfide bridges- (S—S) covalent bonds between sulfhydryl groups. Form where two cysteine monomers, which have sulfhydryl groups on their R groups, are brought close together by the folding protein. The sulfur of one cysteine bonds to the sulfur of the second and the disulfide bridge rivets parts of the protein together. These are all weak interactions in the aqueous cellular environment, but their cumulative effect helps give the protein a unique shape. o Quaternary Structure- Association of two or more polypeptides (some proteins only)/ A three dimensional protein made up of multiple polypeptide subunits. 13
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o Two or more polypeptide chains aggregated into one functional macromolecule o Held together by hydrogen bonding, hydrophobic interactions, and disulfide bridges between subunits o Many proteins have quaternary structure. Denaturation- in proteins a process in which a protein loses it native shape due to the disruption of weak chemical bonds and interactions, thereby becoming biologically inactive; denaturation occurs under extreme (non-cellular) conditions of pH, salt concentration, or temperature Nucleic Acid- a polymer(polynucleotide) consisting of many nucleotide monomers; serves as a blueprint for proteins and through the actions of proteins, for all cellular activities. o Contain the elements C, H, O, N, P o Two Types: DNA(deoxyribonucleic acid) RNA(Ribonucleic acid) o ATP (Adenosine triphosphate) o Polynucleotide- consist of monomers called nucleotides.
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