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Chapter 2 – Biochemistry Assignment KEY
Part A - Short Answers – 0.5 Marks OFF for each INCORRECT blank
TOTAL = 30
1. The atomic number for carbon is _6_; therefore, carbon has __6_protons and
_6_electrons.
2. At pH of 7, [H+] = [OH-]. Below pH 7, which of these is greater? __[H+]__Bases have a
pH that is __greater__than 7.
3. The primary structure of a protein is a polymer of __amino acids__;the secondary
structure is characterized by the alpha __helix__;the tertiary structure is its __3D
globular__shape; and the quarternary structure is the association of more than
__one___polypeptide chains.
4. The molecule that cells "burn" during respiration to produce ATP is __glucose__
5. An unsaturated fatty acid contains less __hydrogen atoms__than a saturated one.
6. Both DNA and RNA are polymers of __nucleotides__, each of which contains a
nitrogenous __base__, a 5-carbon _sugar_, and a __phosphate group.
7. The molecule below is what type of molecule? _amino acid__. What is the formula of the
"R" group? __CH3S__. Which side, left or right is the amino group? _right___ Which
side, left or right is the acid group? ___left___
H
O
C
C
H
N
HO
H
H C H
S H
8. What are the four most common atoms in organic molecules? __H, C, O, N___
9. What are the four classes of organic compounds? __CARBOHYDRATES, LIPIDS,
PROTEINS, NUCLEIC ACIDS_
10. The molecule below belongs to what class of molecule? __CARBOYDRATES_ The
hydrolysis of this molecule would produce what molecule? _GLUCOSE
O
O
O
O
O
11. Of the biological classes of molecules, which is:
a) most concerned with energy transformations __CARBOHYDRATES (NUCLEIC ACIDS
OK BECAUSE OF ATP)___
b) the class that forms enzymes _PROTEINS___
c) makes up genes __NUCLEIC ACIDS__
d) the class that is capable of storing the most energy per gram LIPIDS
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 U1 Assign. - Page 1 of 3
12. What type of molecule is the molecule below? _FATTY ACID (HYDROCARBON)_.
Molecules made of these molecules joined to glycerol would be at what state at room
temperature? _LIQUID_
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
13. The molecule at left is what type of molecule? __NUCLEOTIDE__ Label the parts of this
molecules:
A = __PHOSPHATE GROUP__
NH2
B = __PENTOSE SUGAR__
C
N
N
H
C = __NITROGENOUS BASE__
N
H
O
O-
P
N
5'
O
CH2
O
O-
A
H
H
H
H
3'
B
OH H
14. Nucleotides on a single strand are connected together by bonds that form between the
_SUGAR__ of one nucleotide and the _PHOSPHATE GROUP__ of the other nucleotide.
15. Three molecules composed of nucleotides are __DNA, RNA, ATP__
16. __PHOSPHOLIPIDS_ are lipids containing phosphorous that are particularly important in
the formation of cell membranes.
17. Which element is most characteristic of proteins? _NITROGEN___
18. Use the following words to describe the making of a protein (an expression may be used
more than once):
 tertiary structure, hydrophobic interactions, water,-COOH, polypeptide chain,
Dehydration synthesis, -NH2, secondary structure, hydrogen bonding, covalent bonds,
helix, primary structure, peptide bonds
__DEHYDRATION SYNTHESIS__ between amino acids joins _-COOH (ACID)_ groups
to __-NH2 (AMINO)_ groups (in the process __H2O (WATER)_ molecules are removed)
to form a __POLYPEPTIDE CHAIN_. The bonds so formed are called _PEPTIDE
BONDS_. The sequence of amino acids is called the _PRIMARY STRUCTURE_. The
_SECONDARY STRUCTURE_ is often in the form of an alpha helix, which is due to
__HYDROGEN BONDS_ between amino acids in the chain. The TERIARY
STRUCTURE__ is the three dimensional shape of the protein as it folds back on itself.
This structure is held together by __HYDROGEN_, _IONIC__, and _COVALENT
BONDS_ between R groups. The shape of the protein is determined by its _PRIMARY
STRUCTURE_. The function of the protein is determined by its PRIMARY
STRUCTURE_.
19. A protein that has lost its precise three dimensional shape has become _DENATURED_.
20. Two main functions of carbohydrates in living systems are in _SHORT_-term energy
sources, and structural components of cell _WALLS_ in plants.
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U1 Assign. - Page 2 of 3
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21. _STARCH_ has few side branches of glucose chains, and is the storage form of glucose
in plants.
22. __GLYCOGEN_ has many side branches of glucose chains, and is the storage form of
glucose in _ANIMALS_. The __LIVER_ is the main organ that produces, breaks down,
and stores this polysaccharide.
23. "Roughage" or "Fibre" in our diet is actually due to the presence of __CELLULOSE_,
another polymer of glucose found only in _PLANT CELL WALLS_.
24. A pentose sugar contains _5_ carbons, while a hexose sugar contains _6_.
25. Lipids are organic compounds that are _INSOLUABLE_ in water. In the body, they serve
as __LONG_-term energy storage molecules.
26. Neutral fats are composed of two types of molecules: __FATTY ACIDS_ and
_GLYCEROL_(like oils, butter, etc.).
27. Saturated fatty acids have no __DOUBLE_ bonds between carbon atoms, and tend to be
solid at room temperature. ___UNSATURATED FATTY ACIDS__are most often found in
vegetable oils, and account for the fact that they are liquid at room temperature.
28. A phospholipid is a lipid made of glycerol, 2 fatty acids, and a phosphate group. It is the
primary component of membranes. The phosphate "head" is _POLAR
(HYDROPHILIC)_, the tail is _NONPOLAR (HYDROPHOBIC)_.
29. _STEROIDS (STEROID HORMONES)__ are small lipids containing rings that are all
derived from cholesterol.
30. _NUCLEIC ACIDS (DNA)_ stores genetic information.
31. What type of molecule is the molecule drawn below? __PHOSPHOLIPID_
O
CH3
CH2
CH2
CH2
CH2
CH2 CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH
CH2
CH
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2 CH2 CH2
CH2
CH2
CH2
C
O
CH2
C
O
CH
O
C
O
O
H2
P
O
CH2
CH3
N+ CH3
CH3
CH2
O-
32. What is the best one-word description for the molecule
H H O H H
O
to the right? _DIPEPTIDE_
H
N
C
C
N
C
C
Circle the bond that was created when this molecule
O H
R
R
was formed. What is the name of this type of bond?
_PEPTIDE BOND_
33. a) To what sub-class of molecules does the molecule below belong? __STEROIDS__
b) Why are these molecules grouped with lipids? __THEY ARE WATER
INSOLUABLE__
HO
34. What type of molecule is the one to the right? _NUCLEIC ACID_
What is its full name? _ADENOSINE TRIPHOSPHATE (ATP)_.
Circle the bond that stores the most energy.
N
N
N
N
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U1 Assign. – page 3 of 3
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