MCB 450 Learning Objectives Exam 1
UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS
1) What is it meant by the Central Dogma? - CORRECT ANSWER "The central dogma of
molecular biology deals with the detailed residue-byresidue transfer of sequential information. It
states that information cannot be transferred back from protein to either protein or nucleic acid."
-information flows from DNA to RNA (transcription) and then to protein (translation).
2) Know the four types of biological molecules & their general roles in cells - CORRECT ANSWER
1) Proteins
-Linear Polymers of L-Amino Acids that are Joined by Peptide Bonds2) Nucleic Acids (DNA/RNA)
-Information molecules in the cell
3) Carbohydrates (poly- & oligosaccharides)
-linear or branched polymers of monosaccharides (a.k.a. sugars)
4) Lipids (Fatty acids)
-water-insoluble molecules that are highly soluble in organic solvents
-Major component of membrane (phospholipids) • Long term energy storage • Protection against heat
loss (insulation) • Protection against physical shock • Protection against water loss • Chemical
messengers (hormones)
3) Definition of covalent bond?
Know the properties of the four types of covalent bonds. How are they formed? - CORRECT
ANSWER -bonds in which the electrons are shared by the participating atoms
1) Peptide Bond
-each amino acid is attached to another amino acid by a covalent bond.
2) Phosphodiester bond
-a covalent bond in RNA or DNA that holds a polynucleotide chain together by joining a phosphate
group at position 5 in the pentose sugar of one nucleotide to the hydroxyl group at position 3 in the
pentose sugar of the next nucleotide.
3) Glycosidic bond
-Carbohydrates are made up of monosaccharides linked together into polysaccharide chains by a type
of covalent bond known as a glycosidic bond.
,4) Ester Bond
-Triglycerides are lipids consisting of one glycerol molecule bonded with three fatty acid molecules.
4) Know the properties of water. - CORRECT ANSWER 1) water is a dipolar molecule with an
uneven distribution of electrons between the hydrogen and oxygen.
2) unequal e- sharing results in dipoles
3) it forms hydrogen bonds with each other and other polar molecules and acts as a (good) solvent.
The polarity of water and its ability to form hydrogen bonds renders it a solvent for any charged or
polar molecule.
4) Water is cohesive
5) What are polar, non-polar, and amphipathic molecules? - CORRECT ANSWER Polar- Have
electronegative difference between the 2 bonded atoms (hydrophilic)
Non-polar- Electrical charges are evenly distributed between the molecule (hydrophobic)
Amphipathic- Have polar or charged regions as well as non-polar regions.
6) What are the four types of weak, non-covalent interactions and their functions? - CORRECT
ANSWER 1) Hydrogen Bonds
-an attractive force between a partially positive charged hydrogen and a partially negative charged
atom (oxygen and nitrogen)
2) Ionic Bonds/ Electrostatic Interactions
-A weak interaction between ions having opposite charges. Also called ionic bond or salt bridge. NaCl
3) Van der Waals Interactions
-short range attractive interactions between molecules that are neither polar nor charged, Depend on
transient asymmetry in electrical charge induced between closely approaching atoms, Very weak
4) Hydrophobic Bonds/Interactions (hydrophobic effect)
-Aggregation of non-polar molecules results in an increase in randomness of water molecules;The
process in which nonpolar molecules in aqueous solutions are driven together because of the resulting
increase in entropy of water molecules
-Ex: membrane formation and Protein folding
, 7) What is it meant by Brownian (thermal) motion? - CORRECT ANSWER -Thermal motions
in an aqueous environment power biological interactions: allow molecules to diffuse about the cell,
collide, and react
-Collisions of water molecules with larger particles causes the particles to move about randomly
8) What are Kw and pH? Can you solve problems involving pH and Kw? - CORRECT ANSWER
Kw= the ionic product of water = [H+][OH-]
Ph= -log of H+ concentration
9) Understand how buffer works. - CORRECT ANSWER -Buffers are aqueous solutions that
resist changes in pH as acid or base are added
-Mixture of a weak acid (proton donor) and its conjugate base (proton acceptor) or a weak base and its
conjugate acid.
-Buffer capacity is generally best within ~ +/-1 pH unit of pKa
-Buffering maintains cellular pH & pH of body fluids
=WORKS best when pH=pKa
10) Know the relationship between pH and pKa (Henderson-Hasselbalch eq.) Be able to solve
problems using Henderson-Hasselbalch - CORRECT ANSWER
11) Use H-H equation to calculate how to make or change the pH of a buffer - CORRECT ANSWER
1. Describe the classification of the 20 amino acids commonly present in proteins based on their
polarities, structural side chains, properties and characteristics. - CORRECT ANSWER 1.
Hydrophobic amino acids (9 Amino acids)
-nonpolar R groups
-even distribution of e-s
-does not gain or lose protons
-does not participate in hydrogen or ionic bonds
-Mainly Hydrocarbon Side chains
2. Polar amino acids
UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS
1) What is it meant by the Central Dogma? - CORRECT ANSWER "The central dogma of
molecular biology deals with the detailed residue-byresidue transfer of sequential information. It
states that information cannot be transferred back from protein to either protein or nucleic acid."
-information flows from DNA to RNA (transcription) and then to protein (translation).
2) Know the four types of biological molecules & their general roles in cells - CORRECT ANSWER
1) Proteins
-Linear Polymers of L-Amino Acids that are Joined by Peptide Bonds2) Nucleic Acids (DNA/RNA)
-Information molecules in the cell
3) Carbohydrates (poly- & oligosaccharides)
-linear or branched polymers of monosaccharides (a.k.a. sugars)
4) Lipids (Fatty acids)
-water-insoluble molecules that are highly soluble in organic solvents
-Major component of membrane (phospholipids) • Long term energy storage • Protection against heat
loss (insulation) • Protection against physical shock • Protection against water loss • Chemical
messengers (hormones)
3) Definition of covalent bond?
Know the properties of the four types of covalent bonds. How are they formed? - CORRECT
ANSWER -bonds in which the electrons are shared by the participating atoms
1) Peptide Bond
-each amino acid is attached to another amino acid by a covalent bond.
2) Phosphodiester bond
-a covalent bond in RNA or DNA that holds a polynucleotide chain together by joining a phosphate
group at position 5 in the pentose sugar of one nucleotide to the hydroxyl group at position 3 in the
pentose sugar of the next nucleotide.
3) Glycosidic bond
-Carbohydrates are made up of monosaccharides linked together into polysaccharide chains by a type
of covalent bond known as a glycosidic bond.
,4) Ester Bond
-Triglycerides are lipids consisting of one glycerol molecule bonded with three fatty acid molecules.
4) Know the properties of water. - CORRECT ANSWER 1) water is a dipolar molecule with an
uneven distribution of electrons between the hydrogen and oxygen.
2) unequal e- sharing results in dipoles
3) it forms hydrogen bonds with each other and other polar molecules and acts as a (good) solvent.
The polarity of water and its ability to form hydrogen bonds renders it a solvent for any charged or
polar molecule.
4) Water is cohesive
5) What are polar, non-polar, and amphipathic molecules? - CORRECT ANSWER Polar- Have
electronegative difference between the 2 bonded atoms (hydrophilic)
Non-polar- Electrical charges are evenly distributed between the molecule (hydrophobic)
Amphipathic- Have polar or charged regions as well as non-polar regions.
6) What are the four types of weak, non-covalent interactions and their functions? - CORRECT
ANSWER 1) Hydrogen Bonds
-an attractive force between a partially positive charged hydrogen and a partially negative charged
atom (oxygen and nitrogen)
2) Ionic Bonds/ Electrostatic Interactions
-A weak interaction between ions having opposite charges. Also called ionic bond or salt bridge. NaCl
3) Van der Waals Interactions
-short range attractive interactions between molecules that are neither polar nor charged, Depend on
transient asymmetry in electrical charge induced between closely approaching atoms, Very weak
4) Hydrophobic Bonds/Interactions (hydrophobic effect)
-Aggregation of non-polar molecules results in an increase in randomness of water molecules;The
process in which nonpolar molecules in aqueous solutions are driven together because of the resulting
increase in entropy of water molecules
-Ex: membrane formation and Protein folding
, 7) What is it meant by Brownian (thermal) motion? - CORRECT ANSWER -Thermal motions
in an aqueous environment power biological interactions: allow molecules to diffuse about the cell,
collide, and react
-Collisions of water molecules with larger particles causes the particles to move about randomly
8) What are Kw and pH? Can you solve problems involving pH and Kw? - CORRECT ANSWER
Kw= the ionic product of water = [H+][OH-]
Ph= -log of H+ concentration
9) Understand how buffer works. - CORRECT ANSWER -Buffers are aqueous solutions that
resist changes in pH as acid or base are added
-Mixture of a weak acid (proton donor) and its conjugate base (proton acceptor) or a weak base and its
conjugate acid.
-Buffer capacity is generally best within ~ +/-1 pH unit of pKa
-Buffering maintains cellular pH & pH of body fluids
=WORKS best when pH=pKa
10) Know the relationship between pH and pKa (Henderson-Hasselbalch eq.) Be able to solve
problems using Henderson-Hasselbalch - CORRECT ANSWER
11) Use H-H equation to calculate how to make or change the pH of a buffer - CORRECT ANSWER
1. Describe the classification of the 20 amino acids commonly present in proteins based on their
polarities, structural side chains, properties and characteristics. - CORRECT ANSWER 1.
Hydrophobic amino acids (9 Amino acids)
-nonpolar R groups
-even distribution of e-s
-does not gain or lose protons
-does not participate in hydrogen or ionic bonds
-Mainly Hydrocarbon Side chains
2. Polar amino acids
