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Presentation on theme: "Review."— Presentation transcript:

1 Review


3 Review Hydrophobic (non polar) Hydrophilic (polar)

4 Polar Have a charge to them
Molecules with a positive and negative side Non-symmetrical Amino acids: amine, alcohol, amide functional group


6 Nonpolar No charge associated with a molecule
Electrons are evenly distributed creating no electrical field (charges cancel out each other) Symmetrical shape In amino acids (benzene ring/alkyl functional group)


8 Covalent bonds Share a pair of electrons
Both atoms are holding onto electrons Stable H — H H2 (hydrogen gas)

9 Nonpolar covalent bond
Pair of electrons shared equally by 2 atoms Methane (CH4)

10 Polar covalent bonds Pair of electrons shared unequally by 2 atoms
Oxygen has higher electronegativity and will pull electrons more H Oxygen + +


12 Amino acid

13 Hydrophobic R groups Composed mostly of carbon and hydrogen, and tend to be repelled from water Glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), proline (Pro), phenylalanine (Phe), methionine (Met), and tryptophan (Trp).

14 Polar amino acids Side chains that are not charged
Serine (Ser), threonine (Thr), cysteine (Cys), asparagine (Asn), glutamine (Gln), and tyrosine (Tyr)

15 Basic amino acids Arginine (Arg), lysine (Lys), and histidine (His)
Their side chains contain nitrogen and resemble ammonia, which is a base

16 Acidic amino acids Acidic R groups
Aspartate (Asp) and glutamic acid or glutamate (Glu)

17 Bonds Amino acids are linked together by peptide bonds

18 Primary (1°) structure Order of amino acids in chain
amino acid sequence determined by gene (DNA) slight change in amino acid sequence can affect protein’s structure & its function even just one amino acid change can make all the difference! lysozyme: enzyme in tears & mucus that kills bacteria

19 Secondary (2°) structure
“Local folding” folding along short sections of polypeptide interactions between adjacent amino acids H bonds weak bonds between R groups forms sections of 3-D structure -helix -pleated sheet

20 Tertiary (3°) structure
“Whole molecule folding” interactions between distant amino acids hydrophobic interactions cytoplasm is water-based nonpolar amino acids cluster away from water H bonds & ionic bonds disulfide bridges covalent bonds between sulfurs in sulfhydryls (S–H) anchors 3-D shape

21 Quaternary (4°) structure
More than one polypeptide chain bonded together only then does polypeptide become functional protein hydrophobic interactions hemoglobin collagen = skin & tendons

22 Protein structure (review)
R groups hydrophobic interactions disulfide bridges (H & ionic bonds) multiple polypeptides hydrophobic interactions amino acid sequence peptide bonds determined by DNA R groups H bonds

23 Protein denaturation Unfolding a protein
conditions that disrupt H bonds, ionic bonds, disulfide bridges temperature pH salinity alter 2° & 3° structure alter 3-D shape destroys functionality some proteins can return to their functional shape after denaturation, many cannot

24 Enzymes Lock and key: The key (substrate) has a specific shape (arrangement of functional groups and other atoms) that allows it and no other key to fit into the lock (the enzyme).

25 Enzymes Induced fit: The substrate is distorted (atoms are shifted, bonds are stretched, and reactive groups are brought close together). Only molecules with the correct functional groups in the correct configurations are able to be induced to fit the active site of the enzyme.

26 Enzyme Inhibition


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