The Chemical Context of Life
Which subatomic particle has a positive charge?
Proton
Water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as _____.
Hydrogen Bonds
What name is given to the following reaction?
glucose + glucose → maltose + water
Dehydration reaction
Bacterial cells are prokaryotic. Unlike a typical eukaryotic cell, they _____.
a. lack a nucleus
b. have a smaller nucleus
c. lack a plasma membrane
d. have membrane-bound internal organelles
a. lack a nucleus
Explain why argon, which is a noble gas, does not react with other elements.
Argon already has a filled valence electron shell. Atoms that have unpaired electrons in their valence shells will bond with other atoms to fulfill the octet rule.
Which answer best describes why does ice float in liquid water?
a) The high surface tension of liquid water keeps the ice on top.
b) Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.
c) The high surface tension of liquid water keeps the ice on top.
d) The crystalline lattice of ice causes it to be denser than liquid water.
b) Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.
The presence of uracil is found in which nucleic acid?
RNA
Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through which cellular junction?
Gap junctions
An uncharged atom of argon has an atomic number of 18 and an atomic mass of 40. This atom has _____ protons, _____ neutrons, and _____ electrons.
18; 22; 18
Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; what are enantiomers?
Molecules that are mirror images of each other.
The shape of a protein is determined by _____.
a.the interaction between R-groups of a chain of amino acids
b. Hydrogen bonds along the backbone of the polypeptide
c. the sequence of amino acids
d. all of the above
d. all of the above
Motor proteins provide for molecular motion in cells by interacting with which cellular structure?
Cytoskeleton
To create an ionic bond, you need the presence of cations and anions. How are cations and anions created?
Cations have donated electrons, resulting in the atom having more protons than electrons and giving rise to a positive charge. Anions have received electrons, resulting in the atom having less protons than electrons and giving rise to a negative charge.
Which functional group is nonpolar and is involved in gene expression?
Methyl
The term insoluble fiber on food packages refers to which polysaccharide? Why is this carbohydrate insoluble?
Starch (alpha configuration) is largely helical. Cellulose molecules (β configuration) are straight and unbranched. Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyze beta linkages in cellulose.
Mitochondria are found in what type of cells?
plant and animal cells
Explain the difference between nonpolar and polar covalent bonds while using the term electronegativity.
Nonpolar = atoms have similar electronegativity values; equal sharing of electrons; no charge
Polar = atoms have different electronegativity values; unequal sharing of electrons; partial charges result
Explain why ATP is a good source of energy for a cell.
ATP has three phosphate groups that are negatively charged. The forcing of these negatively charged phosphates to bond involves a lot of energy. When hydrolysis occurs, one phosphate group is removed and thus releasing that potential energy.
Explain the difference between unsaturated and saturated fats in regards to their molecular structure.
Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds.
Unsaturated fatty acids have one or more double bonds.
Provide the pathway a newly synthesized protein destined for secretion from a eukaryotic cell will follow.
rough ER → transport vesicle → Golgi → transport vesicle → plasma membrane