Exam 1 Review: Biochemistry
Bonding and Properties of Water
1. Rank the following types of bonds from strongest to weakest in living (or
aqueous) systems:
Hydrogen bond
interaction
-
ionic bond
van der Waals
-
-
covalent bond
-
hydrophobic
1. Covalent bond
2. Ionic bond/hydrogen bond
3. Ionic bond/hydrogen bond
PG. 18
4. Hydrophobic interaction
5. van der Waals interactions
2. Draw a water molecule including partial positive and negative charges.
PG. 21
3. Water is known as the universal solvent because of its ability to dissolve
charged and polar solutes. Why aren’t other liquids, such as oil, excellent
solvents?
Water is able to dissolve solute (ie. salt) because it is polar. Polar substances
contain partial positive and negative charges, which are attracted to charged
solute (ie. Na+ and Cl-). This attraction allows the solute to be surrounded by
water and dissolve. PG. 19
Other liquids, including oil, are non-polar. Non-polar molecules do not contain
charges (they are neutral) and, therefore, are not attracted to charged solute.
When a non-polar liquid is mixed with charges solute, no interaction occurs. The
solute is not surrounded by the liquid (solvent) and it does not dissolve. PG. 22
4. Based on the valence shell diagram of Nitrogen, how many bonds
will Nitrogen form? Explain.
Nitrogen has 5 valence electrons (electrons located in the outer
shell). In order to be stable, elements need 8 valence electrons. To achieve
this, Nitrogen can bond (share electrons!) with other elements. Nitrogen will
form 3 bonds (5+3=8) to become stable. PG.
19
Enzymes
1. Identify the type of inhibition in the diagram.
A. Competitive inhibition PG. 50
B. Non-competitive inhibition / Allosteric Inhibition PG. 50
2. Circle the correct word to complete the paragraph.
Enzymes speed up reactions by (increasing/decreasing) activation energy.
Activation energy is the energy needed to start exergonic reactions so that
energy can be released (net). Without enzymes, chemical reactions in living
systems would be too (slow, spontaneous). PG. 29 and 46
3. Fill in the graphs below. Then, provide a biochemical explanation for the
shape of each curve.
Explanation:
Enzyme activity
Each enzyme has a
as the temp.
Too
(molecules
and the
move faster -> more
enzyme denatures. PG. 52
collisions). Too hot,
Explanation:
will
increase
specific pH range.
increases
high or too low,
and the enzyme will
denature. PG. 52
4. Label the diagram below with the following terms:
Activation energy with enzyme
Initial energy
Final energy
Energy released
Catalyzed reaction
Activation energy without enzyme
Uncatalyzed reaction
5. (a) What concept is
being shown?
Feedback Inhibition through
allosteric inhibition. PG.
51
(b) Describe what is happening in your own words. Be sure to include the
PURPOSE of this process.
The end product is serving as an allosteric (non-competitive) inhibitor for
enzyme 1. If a lot of end product is present, it will accumulate and bind to
enzyme 1 more often. When the end product is bound, the shape of the active
site changes and the substrate cannot fit. If the green substrate can’t
bind, the purple molecule cannot be made. If there is no purple, no blue can
be made. If there is no blue, the end product cannot be made. This helps to
ensure that there is not too much end product produces – it controls itself!
This is feedback inhibition (also known as end-product inhibition). PG. 51
Proteins
Match each description/image with the correct level of protein structure:
a. Primary Structure
PG. 42-44
c. Tertiary Structure
b. Secondary Structure
d. Quaternary Structure
d 1. Results from interactions between two separate polypeptide chains.
C 2.
D 3.
A 4. The specific sequence of amino acids, as determined by the RNA base pairs.
B 5. Either a beta-pleated sheet or an alpha-helix, depending on the hydrogen
bonding pattern of the polypeptide backbone.
A 6.
B 7.
C 8. Complex shape resulting from hydrogen bonding, hydrophobic interactions,
ionic bonds, and disulfide bridges between R-groups