Biology 241 - Human Physiology Review

Macromolecules and Their Functions

  • Proteins
    • Enzymes: Catalyze biological reactions.
    • Receptors: Bind to signaling molecules.
    • Regulation of movement across membranes.
    • Anatomical structure.
    • Emergency energy source.
  • Carbohydrates
    • Monomers (e.g., glucose) used to produce ATP.
    • Polymers (e.g., glycogen) store energy.
  • Lipids
    • Monomers (fatty acids) can be used to make ATP.
    • Polymers store energy.
    • Phospholipids build cell membranes.
    • Steroids are found in cell membranes and act as hormones.
  • Nucleic Acids
    • Monomers (ATP, GTP) serve as direct energy sources.
    • DNA contains instructions for protein synthesis.
    • RNA transports information from DNA to ribosomes for protein synthesis.

Atomic Structure

  • Nucleus: Contains protons (positive charge) and neutrons (neutral charge).
  • Electrons: Negatively charged particles that orbit the nucleus in shells.
  • Valence Shell: The outermost electron shell.
  • Neutral Atom: Contains an equal number of protons and electrons.

Chemical Bonding

Why Atoms Form Bonds

  • Atoms form bonds to achieve a stable valence shell, typically with eight electrons (octet rule).

Ionic Bond Formation

  • Process: One atom donates one or more electrons to another atom.
  • Donor Atom: Becomes positively charged (cation).
  • Acceptor Atom: Becomes negatively charged (anion).
  • Bonding: Electrostatic attraction between oppositely charged ions.

Covalent Bond Formation

  • Process: Atoms share one, two, or three electrons to achieve a stable valence shell.
  • Stability: Atoms are physically connected and become unstable if separated.

Polar vs. Non-Polar Covalent Bonds

  • Polar Covalent Bond: Unequal sharing of electrons, resulting in partial charges on atoms. Allows the molecule to mix with water.
  • Non-Polar Covalent Bond: Equal sharing of electrons, resulting in no charged regions on the molecule.

Hydrophobic vs. Hydrophilic Molecules

  • Hydrophilic Molecules: Dissolve in water due to their charged nature, which attracts water molecules (water-soluble).
  • Hydrophobic Molecules: Do not dissolve in water because they are non-polar and have no attraction to water molecules (lipid-soluble).

Dehydration Synthesis

  • Process: Formation of a polymer by removing a hydroxyl group (OH) from one monomer and a hydrogen (H) from another.
  • OH + H othe H_2O
  • Result: Water molecule is released, and the monomers bond together.

Hydrolysis

  • Process: Breaking a polymer bond by adding water.
  • Water Splits: A water molecule splits into a hydrogen ion (H) and a hydroxyl group (OH).
  • Monomer Attachment: The hydroxyl group attaches to one monomer, and the hydrogen ion attaches to the other, breaking the bond.

Macromolecule Characteristics

Carbohydrates

  • Tend to have a ring structure of carbons with hydroxyl groups (-OH) attached to each carbon.

Amino Acids

  • Central carbon atom bound to:
    • An amino group (-NH2)
    • A carboxyl group (-COOH)
    • A hydrogen atom (H)
    • An R-group (variable side chain that determines the amino acid's identity)

Fatty Acids

  • Long chain of carbon atoms with attached hydrogen atoms.
  • A carboxyl group (-COOH) at one end.
  • Saturated Fatty Acids: Have single bonds between carbon atoms and are saturated with hydrogen atoms.
  • Unsaturated Fatty Acids: Have one or more double bonds between carbon atoms.

Nucleic Acids

  • Composed of a sugar ring, a phosphate group, and a nitrogenous base.

Protein Structure

Primary Structure

  • The linear sequence of amino acids in a polypeptide chain.

Secondary Structure

  • Formed by interactions between the oxygen, nitrogen, and hydrogen atoms of the polypeptide backbone.
  • Alpha-helices: Coiled structure.
  • Beta-pleated sheets: Folded structure.

Tertiary Structure

  • Formed by interactions between the R-groups of amino acids.
  • Creates a three-dimensional structure; may be the active structure for some proteins.

Quaternary Structure

  • Involves the assembly of two or more polypeptide chains (tertiary structures).
  • Not all proteins have quaternary structure.

Multiple Choice Answers (with brief explanations)

  1. Which of the following can be dissolved, or broken, in water:
    • e. More than one of the above (Ionic bonds, Polar covalent bonds, Hydrogen bonds)
  2. Which of the following molecules would dissolve in water:
    • e. More than one of the above (Protein, Glucose)
  3. Decomposition reactions:
    • b. Cause a break down of a polymer
  4. Ions can be generated by:
    • c. Giving up of an electron

Multiple Choice Answers Continued

  1. The normal pH of blood is:
    • b. Just slightly basic
  2. What molecules are responsible for the homeostatic control of blood pH?
    • c. Buffers
  3. Which of the following could be considered an energy molecule?
    • e. All of the above (Glycogen, Glucose, ATP, Fatty acids)
  4. If an atom gained 2 electrons, what would its resulting charge be?
    • c. Negative 2
  5. Which of the following protein structures would be considered the active form?
    • e. More than one of the above (Tertiary and Quaternary)

Matching

Monomers and Polymers

  1. The monomer of a protein:
    • C. Amino Acids
  2. A monomer of triglycerides:
    • F. Fatty Acid
  3. A monomer of carbohydrates:
    • A. Glucose
  4. A monomer of nucleic acids:
    • G. ATP
  5. A polymer of carbohydrates:
    • K-B,E. More than one of the above (Starch, Glycogen)
  6. A polymer of nucleic acids:
    • H. DNA
  7. A polymer of lipids:
    • K-I,J. More than one of the above (Triglyceride, Steroid)

Functions of Biomolecules

  1. A source of energy in the cell:
    • J- A,B,C,E,F. More than one of the above (Protein, Monosaccharides, ATP, Glycogen, Fatty acids)
  2. Used as energy storage in adipose tissue:
    • F. Fatty acids
  3. Used as energy storage in muscle and liver tissue:
    • E. Glycogen
  4. Used as enzymes in chemical reactions:
    • A. Protein
  5. Used as receptors on cell membranes:
    • A. Protein
  6. Used to form cell membranes:
    • G. Phospholipids
  7. Used as immediate energy supply for cellular function:
    • C. ATP
  8. Used as a storage of the directions for making proteins:
    • D. DNA
  9. Used as a “copy” of the directions for making proteins:
    • H. RNA
  10. May be used as a hormone:
    • J-A,I. More than one of the above (Protein, Steroids)

True/False

  1. Covalent bonds are easier to break than ionic bonds.
    • F (False)
  2. Most macromolecules are made up of more than one bond type.
    • T (True)
  3. When a protein is in primary structure, it is an active protein.
    • F (False)
  4. Ions are produced when one atom gives electrons to another.
    • T (True)
  5. Water can only dissolve things that are not charged.
    • F (False)
  6. Lipids are essentially nonpolar.
    • T (True)
  7. Hydrogen bonds occur between polar molecules.
    • T (True)
  8. Denatured proteins have their tertiary or quaternary structures disrupted.
    • T (True)
  9. Conformational changes in a protein are usually destructive.
    • T (True)
  10. All steroids are hormones.
    • T (True)
  11. All hormones are steroids.
    • F (False)
  12. Hydrolysis is a type of dissociation reaction.
    • T (True)
  13. Carbohydrates, proteins and lipids use dehydration synthesis to form polymers.
    • T (True)
  14. pH is a measure of hydrogen ions in solution.
    • T (True)
  15. A solution is usually defined as the amount of water that is present.
    • F (False)