Biology 172 Lecture 3

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  1. Molecules with a preponderance of nonpolar covalent bonds cannot form _______ _____ from ________ ______ with water and is called __________
    • covalent bonds
    • hydrogen bonds
    • hydrophobic
  2. It takes a lot of energy to change the ________ of water
    Temperature
  3. Substances that give up protons during chemical reactions to increase the proton concentration in water are called _____
    acids
  4. Substances that lower the proton concentration during chemical reactions are called ________
    bases
  5. Chemical properties of water that support life
    • Cohesion (hydrogen bonds)
    • Moderation of temperature (high specific heat)
    • Solvent for polar compounds
  6. Most chemical reactions important for life take place in _________ _________
    aqueous solutions
  7. pH scale = -log[H+]
    • an acid increases [H+]
    • a base reduces [H+]
    • a buffer minimizes changes in [H+] and [OH-]
  8. In cells, naturally occurring molecules act as ________ to maintain ___________
    • buffers
    • homeostasis
  9. Functional groups _, _, _ dictate the types of reactions that organic molecules participate in
    • N
    • O
    • H
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  12. Monomers:
    Proteins
    Carbohydrates
    Nucleic Acids
    • Amino Acids
    • Monosaccharides
    • Nucleotides
  13. Polymers:
    Proteins
    Carbohydrates
    Nucleic Acids
    • Polypeptides (Proteins)
    • Polysaccharides
    • Nucleic Acids
  14. Proteins jobs
    • enzymes/ catalysis
    • structure
    • transport
    • signaling
    • defense
  15. Carbohydrates
    • fuel
    • building material
  16. Nucleic Acids
    • nucleotides (energy and signaling)
    • DNA = genetic info
    • RNA = intermediary between DNA and protein
  17. Lipids
    • fuel storage
    • membranes
    • hormones
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    In size and shape, proteins are the most diverse class of molecules know
  20. Proteins Composed of Amino Acids
    • 20 different types
    • each has a carboxyl group and amino group
    • differ in charge, polarity, and size, and 'R' group
  21. At pH ___ (in a cell) the amino and carboxyl groups are ______
    • 7.2
    • ionized
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    The side chain R groups are nonpolar.
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  26. Biological macromolecules (DNA, carbohydrates, proteins) are assembled into polymers by condensation reactions:
    Condensation reactions: monomer in, water out (dehydration)
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    What is this type of reaction called?
    what type of bond is formed?
    R-groups in this polypeptide?
    • Dehydration (from condensation)
    • Covalent (polar) bond
    • Polar
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    Linear sequence of amino acids linked by ______ _____
    Sequence is determined by _______ ________
    Amino acids linked by ________ ______
    • peptide bonds
    • genetic instructions
    • covalent bonds
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    why are polypeptide chains flexible?
    • 9 amino acids
    • Because the groups on either side of each peptide bond can rotate about their single bonds
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    Why is this important?
    Importance of primary structure
  31. 2. Protein Secondary Structure
    Interactions between atoms in backbone held together by hydrogen bonds
  32. Two main secondary structures
    • -alpha helixes
    • -beta sheets
    • Stable 3D structures that form through hydrogen bonding of the backbone amino and carbonyl groups
  33. Secondary Structure
    Hydrogen bonds form between _____ _______ of one amino acid and ________ on amino group of another animo acid
    • carbonyl oxygen
    • hydrogen
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  37. Noncovalent bonds help _______ _____
    proteins fold
  38. Electrostatic Interactions
    attractive forces between oppositely charged molecules H bonding : attraction between electropositive hydrogen atom and 2 electron attracting atoms, usually O or N
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    Folded conformation in aqueous solution
  40. Tertiary structure - overall 3-D shape of polypeptide. Held together by ....
    • interactions between atoms in R groups
    • -hydrophobic
    • -van der Waals
    • -hydrogen bonds
    • -ionic bonds
    • -disulfide bridges
  41. Quaternary structure
    • Shape of a complex of multiple polypeptide chains (subunits)
    • Held together by covalent, ionic, hydrogen, and/or hydrophobic interactions
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Biology 172 Lecture 3
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Biology 172 Exam Review Lecture 3
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