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MICR 3033 EXAM 1 QUESTIONS
WITH CORRECT SOLUTIONS
Describe a hydrogen bond. - correct-answer - positively charged hydrogen is
attracted to negatively charged atoms, intermolecular forces hold these bonds
together
A carbon atom contains six protons and six neutrons. What are its atomic
number, atomic weight, and how many electrons does it have? How many
additional electrons must it add to fill its outermost shell? - correct-answer -
atomic number: 6
atomic weight: 12
electrons: 6
additional electrons: 4
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How is an ionic bond formed? - correct-answer - One atom completely loses an
electron while the other completely gains that electron creating two charged
molecules
What are the differences between an ionic and covalent bond? - correct-answer -
Ionic bond: donates electrons, creates charged molecules, very polar
Covalent: shares electrons, equally distributed charges, not very polar
Why are polar covalent bonds and the resulting permanent dipoles so important
in biology? - correct-answer - Stabilize protein. Hold molecules in position during
chemical reactions. Allows for the formation of the phospholipid bilayer
Why are substances such as sugars soluble in water and others such as lipids not?
- correct-answer - Sugars have hydrophilic exteriors which lipids have hydrophobic
exteriors. Polar substances are soluble in water because they charged and
integrate the lattice by attracting hydrogen bonds from water molecules.
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Nonpolar substances, such as lipids, are not soluble in water because they repel
hydrogen bonds and disrupt the water lattice structure.
Why does an acid donate protons when in water? - correct-answer - Water
contains an electronegative atom (Oxygen). This atom is polar covalently bonded
to two hydrogens, making it a partial negative charge. The acid will donate a
proton to the Oxygen on the water molecule.
If non-covalent interactions are so weak in a water environment , how can they
possibly be important for holding molecules together in cells? - correct-answer -
While these bonds may be weak, there are so many of them that exist at one time
that together, they form a very strong bond.
How glucose, mannose, and galactose differ from each other? - correct-answer -
they are different because of different placement of hydroxyl (-OH) groups on the
molecules
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they are isomers: they share the same structural formula but are stereochemically
different , have different biochemical properties
Describe the formation (condensation) and disruption (hydrolysis) of a glycoside
bond - correct-answer - A glycoside bond occurs with the condensation of two
hydroxyl groups (one from each sugar), releasing a water molecule.
A glycosidic bond is formed by a condensation reaction when an -OH group on
one sugar is bonded on an -OH group on another while the molecule of water is
expelled as the bond. The bonds created can be broken by the reverse process
(hydrolysis) in which a mol of water is consumed.
Describe the differences between a linear molecule such as cellulose and a non-
linear molecule such as starch - correct-answer - Linear molecule (cellulose): A
straight chain, no branching
MICR 3033 EXAM 1 QUESTIONS
WITH CORRECT SOLUTIONS
Describe a hydrogen bond. - correct-answer - positively charged hydrogen is
attracted to negatively charged atoms, intermolecular forces hold these bonds
together
A carbon atom contains six protons and six neutrons. What are its atomic
number, atomic weight, and how many electrons does it have? How many
additional electrons must it add to fill its outermost shell? - correct-answer -
atomic number: 6
atomic weight: 12
electrons: 6
additional electrons: 4
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How is an ionic bond formed? - correct-answer - One atom completely loses an
electron while the other completely gains that electron creating two charged
molecules
What are the differences between an ionic and covalent bond? - correct-answer -
Ionic bond: donates electrons, creates charged molecules, very polar
Covalent: shares electrons, equally distributed charges, not very polar
Why are polar covalent bonds and the resulting permanent dipoles so important
in biology? - correct-answer - Stabilize protein. Hold molecules in position during
chemical reactions. Allows for the formation of the phospholipid bilayer
Why are substances such as sugars soluble in water and others such as lipids not?
- correct-answer - Sugars have hydrophilic exteriors which lipids have hydrophobic
exteriors. Polar substances are soluble in water because they charged and
integrate the lattice by attracting hydrogen bonds from water molecules.
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Nonpolar substances, such as lipids, are not soluble in water because they repel
hydrogen bonds and disrupt the water lattice structure.
Why does an acid donate protons when in water? - correct-answer - Water
contains an electronegative atom (Oxygen). This atom is polar covalently bonded
to two hydrogens, making it a partial negative charge. The acid will donate a
proton to the Oxygen on the water molecule.
If non-covalent interactions are so weak in a water environment , how can they
possibly be important for holding molecules together in cells? - correct-answer -
While these bonds may be weak, there are so many of them that exist at one time
that together, they form a very strong bond.
How glucose, mannose, and galactose differ from each other? - correct-answer -
they are different because of different placement of hydroxyl (-OH) groups on the
molecules
, 4|Page
they are isomers: they share the same structural formula but are stereochemically
different , have different biochemical properties
Describe the formation (condensation) and disruption (hydrolysis) of a glycoside
bond - correct-answer - A glycoside bond occurs with the condensation of two
hydroxyl groups (one from each sugar), releasing a water molecule.
A glycosidic bond is formed by a condensation reaction when an -OH group on
one sugar is bonded on an -OH group on another while the molecule of water is
expelled as the bond. The bonds created can be broken by the reverse process
(hydrolysis) in which a mol of water is consumed.
Describe the differences between a linear molecule such as cellulose and a non-
linear molecule such as starch - correct-answer - Linear molecule (cellulose): A
straight chain, no branching
