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

5. The normal pH of blood is:
   • b. Just slightly basic
6. What molecules are responsible for the homeostatic control of blood pH?
   • c. Buffers
7. Which of the following could be considered an energy molecule?
   • e. All of the above (Glycogen, Glucose, ATP, Fatty acids)
8. If an atom gained 2 electrons, what would its resulting charge be?
   • c. Negative 2
9. 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)