SBI 4U
Mrs. Holterman
Name: ____________________
Date: ____________________
Chemistry Intro (Or Review?)
Use your textbook or the internet to find the answers to the following questions:
1. Why is Carbon all-important to life on earth?
Carbon can form 4 stable bonds. It reacts, but is not overly reactive. It can
form bonds with almost all elements (other than the noble gases). It can form
long chains with other carbons.
2. a) Draw a general organic molecule with a carbon backbone.
b) What features make the above molecule organic?
It has both Carbon and hydrogen
3. What is the simplest explanation of “functional group” in biochemistry?
A functional group is a bunch of atoms bonded together that give
characteristic features to a carbon backbone. See the different types in
question 4.
4. For each type of functional group listed, describe its effect on a non-polar carbon backbone and
relate this effect to the chemical structure of the functional group. Note: the carbon
backbone is non-polar because it is symmetrical, so although the C-H bond is
polar (Carbon and Hydrogen have different electronegativities, being at
different ends of the periodic table), the overall molecule is non-polar.
(-OH) A hydroxyl group is polar because Oxygen and Hydrogen
have different electronegativities, so a hydroxyl makes the carbon backbone more
soluble in water. Example of hydroxyl:
Hydroxyl,
SBI 4U
Mrs. Holterman
Name: ____________________
Date: ____________________
Carboxyl, (-COOH) Carboxyl consists of both hydroxyl and carbonyl, so it is
VERY polar. It can also donate its electron, making the carbon backbone
somewhat acidic (low pH). Note: pH is a measure of how many Hydrogen ions
there are in a solution. Low pHs (under 7) are considered acidic, high pHs ( over 7)
are considered basic. A pH of 7 is considered neutral. Example of carboxyl:
Carbonyl, (CO or COH): Carbonyl is somewhat polar, so it makes the carbon
backbone a bit more soluble in water. Example of carbonyl:
Sulfhydryl, (-SH): Sulfhydryl is polar, so it makes the carbon backbone more
soluble in water. Sulfhydryls in a protein can stabilize its structure. Example of
sulfhydryl:
(-PO4): Phosphates are non-polar when neutral because they are
symmetrical, however, as ions, they are polar. (Don’t stress over this part too
much because we won’t spend any time on it!) Phosphates in cells are often used
in energy transfer (we will revisit this later!) Example of a neutral phosphate:
Phosphate,
Amino (-NH2 or -NH3+) Amino groups are polar, but also basic because they
can accept electrons. They increase the pH of a solution. Example of an amino:
SBI 4U
Mrs. Holterman
Name: ____________________
Date: ____________________
5. Describe the changes in chemical bonding that occur in each type of chemical reaction listed here:
Dehydration synthesis/condensation
Two molecules are involved. One gives up a hydrogen, the other gives up a
hydroxyl. The C/N that lost the OH/H form a bond together, and the OH/H form
water.
Hydrolysis
One large molecule and water are involved. The large molecule splits in two. One
part takes the H from water, and the other takes the OH from water. (It is the
reverse of dehydration synthesis.)
Redox reaction
Two molecules are involved. One gives up electrons (and usually H in
biochemistry), the other receives electrons/hydrogens. The one that gets the
electrons/hydrogens is « reduced » (ends up with a more negative charge), while
SBI 4U
Mrs. Holterman
Name: ____________________
Date: ____________________
the molecule that gives up electrons is « oxidized » (ends up with a more positive
charge).
Neutralization
An acid (pH less than 7) reacts with a base (pH more than 7) to yield an ionic
compound and water.
6. Describe the differences between these types of isomers that can be found in a cellular
environment:
Optical isomer, Geometric isomer, Structural isomer
Isomers refer to two molecules with same chemical formulas (example: C6H12O6)
but the atoms are arranged differently.
A structural isomer has a very different shape because the atoms bond
differently. Example: (both are C6H12O6)
Geometric isomers are usually found on ring structures with two or more copies
of a functional group. The functional groups can be diagonal to each other or
facing the same direction:
Notice how the two highlighted
hydroxyl groups of glucose both point
down, while in galactose, one points
up and the other points down.
SBI 4U
Mrs. Holterman
Name: ____________________
Date: ____________________
Optical isomers can occur where a molecule has two different functional groups.
All bonds are the same, but they take up 3D space differently (which is why we
built models of them in class).
The solid triangles refer to bonds coming out of the page, while the striped
triangles refer to bonds going into the page.
Notice that in order for CH3 and COO- to be pointed into the page in both
molecules, the NH3+ groups point in opposite directions (right versus left). Believe
it or not, this makes a difference in your cells!!