Chapter 2 Flashcards
(23 cards)
What are covalent bonds?
Bonds between atoms with shared pairs of electrons
What are non-covalent bonds?
Attractive forces that are weaker.
1) ionic
2) H+ bonds
3) Hydrophobic/ Van de Waals
What are ionic bonds?
Attractions between charged atoms.
Are weakened in water.
May be significant with large molecules
What are hydrogen bonds?
Occurs when covalently bound H+ has a partial positive charge and attracts electrons of a second atom.
What are hydrophobic/ Van de waals forces?
1) Occur when non polar molecules associate and minimize their exposure to polar molecules
2) Attractions between non polar molecules due to dipole formation
What are fats composed of?
glycerol linked by three ester bonds to three fatty acids
What are the polar charged amino acids?
Aspartic acid, glutamic acid, lysine, arginine, histidine
What are the polar uncharged amino acids?
Serine, threonine, glutamine, asparagine, tyrosine
What are the non polar amino acids?
Alanine, valine, leucine, isoleucine, methionine, phenylalanine, tryptophan
What are the amino acids with unique side chains and what are their properties?
1) Glycine: (R=H)- small R group, flexible backbone so useful in protein hinges, not sterically hindered.
2) Proline: R group forms ring w amino group; hydrophobic amino acid that does no fit into orderly secondary structure, works well in hinges.
3) Cysteine: reactive R, -SH; forms disulfide (-S-S-) bridge with other cysteines often at some distance.
What are some post-translational modifications that can occur with amino acids?
1) Phosphorylation of Tyr, Thr, Ser
2) Acetylation of Lys
What is the primary structure of proteins?
Sequence of amino acids in the polymer
What is the secondary structure of proteins?
Conformation of adjacent amino acids into a-helix, B-sheet, hinges, turns, loops, or finger-like extensions.
What is tertiary structure?
conformation of the entire polymer, stabilized by non covalent bonds, can be fibrous or globular.
What are conformational changes?
Non-random movements triggered by the binding of a specific molecule.
What is quaternary structure?
Proteins composed of subunits
What is an example of a protein-protein interaction?
Multiprotein complex-when different proteins become physically associated
Two alternate pathways for protein folding:
1) Proteins may assume their native conformation through a series of steps
2) May fold along pathways without intermediate forms
* * Smaller proteins with single domains fold faster than large ones
What is Creutzfeld-Jakob disease?
Results from misfolded protein in the brain. Normal protein PrP^c, ->misfolded-> PrP^Sc. Mad cow, kuru, scrapie
What is Alzheimer’s?
Involves misfolded proteins that accumulate in the brains of affected individuals. Amyloid precursor (APP) is cleaved by two secretes enzymes. *In Alz one cleavage product is AB42, a protein that misfolds and self-associates into amyloid plaques
What are molecular chaperones?
“helper proteins” to prevent nonselective interactions during protein folding to achieve proper 3D conformation.
What is the proteome?
entire inventory of an organism’s proteins.
What is proteomics?
Uses advanced technologies to perform large-scale studies on diverse proteins. Separated by gel electrophoresis, identified using mass spec, high speed
