Download Chapter 5: Lipids and Nucleic Acids

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Chapter 5: Organic Compounds Questions pt. 1
Overview
1. What are the four classes of organic compounds/large biological molecules that make up living things? Give an
example of a specific compound in each of the four classes.
Class of organic compound:
Example:
Glucose, starch, cellulose
a) Carb’s
b) Lipids
c) Proteins
Phospholipids, cholesterol, olive oil, ear
wax
Enzymes, keratin, hemoglobin, receptor
prot. , Meats, nuts
DNA, RNA
d) Nucleic Acids
2. Explain the relationship between condensation/dehydration reactions and hydrolysis.
Condensation : form bonds between monomers
Hydrolysis: break bonds of polymers
3. a) What type of macromolecule is glycogen and starch? Carb.
b) How are they the same and how are they different?
Same: both a polymer of glucose
Different: way the glucose monomers bind together
4. Distinguish between saturated fats, monounsaturated fats, and polyunsaturated fats. Give an example of each.
Saturated Fats: all single C-C bonds, (ex:butter)
Monounsaturated Fats: 1 C=C double bond (ex: olive oil)
Polyunsaturated Fats: more than 1 C=C double bond (ex: soybean or corn oil)
5. List one piece of evidence showing that proteins are a very important macromolecule.
Acct. for more than 50% of the dry mass of most cells
6. a) What is the function of nucleic acids? Enable living org. to reproduce their complex components to 1
generation to the next
b) What determines the initial structure of a polypeptide (protein)? Sequence of DNA nucleotides
7. What type of macromolecule are glucose and ribose? IB: Be able to draw the ring structure of both.
Carbohydrate
GLUCOSE
Nucleic Acids
8) What are the subunits (building blocks) of nucleic acids called?
nucleotides
9) Fill in the blanks below illustrating the information flow in a cell:
DNA 
RNA

Proteins
10)What are the 3 parts of a nucleotide? Sketch the general structure of a nucleotide. Use the symbols on the
right.
1) Phosphate group 2) 5- C sugar 3) Nitrogenous base
11) Distinguish between purines and pyrimidines (how are they
different?) and list 2 purines and 3 pyrimidines.
Purines: larger; 6- C ring fused to a 5- C ring
(Ex: adenine “A” and Guanine “G”)
Pyrimidines: smaller; 6- C ring (Ex: Cytosine “C”, Thymine “T”,
and Uracil “U”)
12) Describe at least 2 ways in which RNA differs from DNA.
1) single stranded
2) different 5- C sugar in nucleotide (ribose)
3) DNA uses “T” base & RNA uses “U” base
13) Why is the base sequence for nucleic acids so important? Specifies the amino acid sequence of a protein
(makes 1 protein different than another)
Ex:
DNA “TAC” leads to amino acid “MET”
vs.
DNA “TGC” leads to amino acid “THR”
14) Why can we use DNA and proteins as tape measures of evolution?
Look for similar and differences in DNA seq. or amino acid seq.; how closely (or distantly) related are 2
species?
Lipids
15) Why are lipids grouped together?
All are hydrophobic
16) In the space below, list AND sketch (include labels) the separate components of a FAT.
1 Glycerol
(H,C,O)
3 Fatty Acid Chains
17) What is the NAME of the bond that links a fatty acid to a glycerol molecule? Which two functional groups are
involved in the formation of this bond?
Name: ester linkage
Two Functional Groups: hydroxyl & (-OH); carboxyl (-COOH)
18) a) Explain why unsaturated fats are generally liquids at room temperature.
The double bond causes a “kink” in the fatty acid chain which prevents the chains from packing close enough
together to form a solid
b) What is meant by “hydrogenated” vegetable oils? Why is this process done?
H’s are added to the unsat. veg. oil; turn the liquid into a solid at room temp. (Ex. Peanut butter)
19) What is “atherosclerosis”? deposits called plaques develop with in the walls of blood vessels, causing
inward bulges
What causes it? Saturated fats & maybe some hydrogenated fats
What is the result of this condition on an individual’s blood flow?
Bulges impede blood flow & reduce the resilience of blood vessels
20) In the space below, sketch and label a simplified diagram of a phospholipid symbol.
Head: Glycerol & Phosphate group +
2 Fatty acid chains in tail
21) a) Why is it that phospholipids show ambivalent behavior towards water?
Head is hydrophilic (due to charge of phosphate group) & has an affinity for H 20 BUT tail is hydrophobic (C
& H have equal electronegativity so are nonpolar) & is repelled by H20
b) Explain how phospholipids are arranged at the surface of a cell membrane. You may use a labeled sketch if
necessary.
Form a lipid bilayer with hydrophilic ends facing out & hydrophobic tails facing in
22) a) List two reasons why we need cholesterol in our bodies.
1) Component of animal cell membranes
2) Precursor from which other steroids are made (Ex: sex hormones)
b) Why is too much cholesterol in our diet bad for our health?
May contribute to artherosclerosis (which means clogging of arteries)