Proteins
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Transcript of Proteins
Regents Biology
Proteins
insulin
collagen (skin)
hemoglobin
Examples muscle fingernails, claws skin hair enzymes
example: pepsin
hormones example: insulin
Regents Biology
Proteins Function:
many, many functions hormones
insulin
movementmuscle
immune systemprotect against germs
enzymeshelp chemical reactions
Regents Biology
Proteins
Building block =
aminoacid
aminoacid–
aminoacid–
aminoacid–
aminoacid–
—N—H
H
H|
—C—|
C—OH
||O
variable group
amino acids
20 different amino acids
Regents Biology
Amino acid chains Proteins
amino acids chained into a polymer
Each amino acid is different some “like” water & dissolve in it
some “fear” water & separate from it
Regents Biology
Water-fearing amino acids Hydrophobic
“water fearing” 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 pepsin
3-D protein structure
collagen
Proteins fold & twist into 3-D shape
hemoglobingrowthhormone
Regents Biology
Proteins (Polypeptides)Proteins (Polypeptides)
Four levels of protein Four levels of protein structure:structure:
A.A. Primary StructurePrimary Structure
B.B. Secondary Structure Secondary Structure
C.C. Tertiary Structure Tertiary Structure
D.D. Quaternary Structure Quaternary Structure
Regents Biology
Primary Structure
Amino acids bonded together by peptide bonds peptide bonds (straight chains)(straight chains)
aa1 aa2 aa3 aa4 aa5 aa6
Peptide Bonds
Amino Acids (aa)
Regents Biology
Secondary StructureSecondary Structure3-dimensional folding
arrangement of a primary primary structurestructure into coilscoils and pleatspleats held together by hydrogen hydrogen bondsbonds.
Two examples:Two examples:Alpha HelixAlpha Helix
Beta Pleated SheetBeta Pleated Sheet
Hydrogen BondsHydrogen Bonds
Regents Biology
Tertiary StructureTertiary StructureSecondary structuresSecondary structures bentbent and
foldedfolded into a more complex 3-D more complex 3-D arrangementarrangement of linked polypeptides
Bonds: H-bonds, ionic, disulfide Bonds: H-bonds, ionic, disulfide bridges (S-S)bridges (S-S)
Call a “subunit”.“subunit”.Alpha HelixAlpha Helix
Beta Pleated SheetBeta Pleated Sheet
Regents Biology
Quaternary StructureQuaternary StructureComposed of 2 or more “subunits”Globular in shapeForm in Aqueous environmentsExample: enzymes (hemoglobin)enzymes (hemoglobin)
subunitssubunits