ESSENTIAL CELL BIOLOGY CHAPTER
#1,2,4,5,7&8 EXAM QUESTIONS AND
ANSWERS
homologous - ANSWER-Describes organs or molecules that are similar because of
their common evolutionary origin. Specifically it describes similarities between protein
sequences or nucleic acid sequences.
micrometer
(μm) - ANSWER-Unit of measurement often applied to cells and organelles. Equal to
10^-6 meter.
microscope - ANSWER-Instrument for viewing extremely small objects. Light
microscope utilizes a focused beam of visible light and is used to examine cells and
organelles. An electron microscope utilizes a beam of electrons and can be used to
examine objects as small as individual molecules.
mitochondrion - ANSWER-Membrane-enclosed organelle, about the size of a
bacterium, that carries out oxidative phosphorylation and produces most of the ATP in
eukaryotic cells.
model organism - ANSWER-An organism selected for intensive study as a
representative of a large group of species. Examples are the mouse (representing
mammals), the yeast (representing a unicellular eucaryote), and Escherichia coli
(representing bacteria).
nanometer
(nm) - ANSWER-Unit of length commonly used to measure molecules and cell
organelles. Equal to 10^-9 meters.
nucleus - ANSWER-The major organelle of a eukaryotic cell, which contains DNA
organized into chromosomes. Also, when referring to an atom, the central mass built
from neutrons and protons.
organelle - ANSWER-A discrete structure or subcompartment of a eukaryotic cell
(especially one that is visible in the light microscope) that is specialized to carry out a
particular function. Examples include mitochondria and the Golgi apparatus.
procaryote - ANSWER-Major category of living cells distinguished by the absence of a
nucleus. Procaryotes comprise the archaea and the eubacteria (commonly called
bacteria), two of the three domains of life.
, protein - ANSWER-The major macromolecular constituent of cells. Each protein is
composed of one or more linear chains of amino acids linked together by peptide bonds
in a specific sequence. The amino acid chain is folded into a 3D shape that is unique to
the given protein and determines its function.
protozoan - ANSWER-A member of the protozoan--free-living, non photosynthetic,
single celled, motile eucaryotic organisms. Many protozoans live by feeding on other
organisms.
ribosome - ANSWER-Particle composed of ribosomal RNAs and ribosomal proteins that
associate with messenger RNA and catalyzes the synthesis of protein.
RNA
(ribonucleic acid) - ANSWER-A (usually) single-stranded polynucleotide in the form of a
chain of covalently linked ribonucleotide subunits. It is synthesized when an RNA
polymerase copies the nucleotide sequence of DNA. RNA serves a variety of functions
in cells: messenger RNA, microRNA, ribosomal RNA, transfer RNA.
acid - ANSWER-In the context of cell biology, an organic molecule that dissociates in
water to generate hydronium (H3O+) ions (thereby producing a low pH).
amino acid - ANSWER-Organic molecule containing both an amino group and a
carboxyl group. α-Amino acids (those in which the amino and carboxyl groups are linked
to the same carbon atom) serve as the building blocks of proteins.
atom - ANSWER-The smallest particle of an element that still retains its distinctive
chemical properties.
atomic weight - ANSWER-Mass of an atom expressed in daltons.
ATP
(adenosine 5'-triphosphate) - ANSWER-Nucleoside triphosphate composed of adenine,
ribose, and three phosphate groups that is the principal carrier of chemical energy in
cells. The terminal phosphate groups are highly reactive in the sense that their
hydrolysis, or transfer to another molecule, is accompanied by the release of a large
amount of free energy.
Avogadro's number - ANSWER-The number of molecules in a quantity of substance
equal to its molecular weight in grams. Approximately 6x10^23.
base - ANSWER-Molecule that accepts a proton in solution. Also used to refer to the
purine and pyrimidines in DNA and RNA, which are organic bases.
buffer - ANSWER-Any weak acid or base that can release or take up protons, and
thereby serve to maintain the pH under a variety of conditions.
#1,2,4,5,7&8 EXAM QUESTIONS AND
ANSWERS
homologous - ANSWER-Describes organs or molecules that are similar because of
their common evolutionary origin. Specifically it describes similarities between protein
sequences or nucleic acid sequences.
micrometer
(μm) - ANSWER-Unit of measurement often applied to cells and organelles. Equal to
10^-6 meter.
microscope - ANSWER-Instrument for viewing extremely small objects. Light
microscope utilizes a focused beam of visible light and is used to examine cells and
organelles. An electron microscope utilizes a beam of electrons and can be used to
examine objects as small as individual molecules.
mitochondrion - ANSWER-Membrane-enclosed organelle, about the size of a
bacterium, that carries out oxidative phosphorylation and produces most of the ATP in
eukaryotic cells.
model organism - ANSWER-An organism selected for intensive study as a
representative of a large group of species. Examples are the mouse (representing
mammals), the yeast (representing a unicellular eucaryote), and Escherichia coli
(representing bacteria).
nanometer
(nm) - ANSWER-Unit of length commonly used to measure molecules and cell
organelles. Equal to 10^-9 meters.
nucleus - ANSWER-The major organelle of a eukaryotic cell, which contains DNA
organized into chromosomes. Also, when referring to an atom, the central mass built
from neutrons and protons.
organelle - ANSWER-A discrete structure or subcompartment of a eukaryotic cell
(especially one that is visible in the light microscope) that is specialized to carry out a
particular function. Examples include mitochondria and the Golgi apparatus.
procaryote - ANSWER-Major category of living cells distinguished by the absence of a
nucleus. Procaryotes comprise the archaea and the eubacteria (commonly called
bacteria), two of the three domains of life.
, protein - ANSWER-The major macromolecular constituent of cells. Each protein is
composed of one or more linear chains of amino acids linked together by peptide bonds
in a specific sequence. The amino acid chain is folded into a 3D shape that is unique to
the given protein and determines its function.
protozoan - ANSWER-A member of the protozoan--free-living, non photosynthetic,
single celled, motile eucaryotic organisms. Many protozoans live by feeding on other
organisms.
ribosome - ANSWER-Particle composed of ribosomal RNAs and ribosomal proteins that
associate with messenger RNA and catalyzes the synthesis of protein.
RNA
(ribonucleic acid) - ANSWER-A (usually) single-stranded polynucleotide in the form of a
chain of covalently linked ribonucleotide subunits. It is synthesized when an RNA
polymerase copies the nucleotide sequence of DNA. RNA serves a variety of functions
in cells: messenger RNA, microRNA, ribosomal RNA, transfer RNA.
acid - ANSWER-In the context of cell biology, an organic molecule that dissociates in
water to generate hydronium (H3O+) ions (thereby producing a low pH).
amino acid - ANSWER-Organic molecule containing both an amino group and a
carboxyl group. α-Amino acids (those in which the amino and carboxyl groups are linked
to the same carbon atom) serve as the building blocks of proteins.
atom - ANSWER-The smallest particle of an element that still retains its distinctive
chemical properties.
atomic weight - ANSWER-Mass of an atom expressed in daltons.
ATP
(adenosine 5'-triphosphate) - ANSWER-Nucleoside triphosphate composed of adenine,
ribose, and three phosphate groups that is the principal carrier of chemical energy in
cells. The terminal phosphate groups are highly reactive in the sense that their
hydrolysis, or transfer to another molecule, is accompanied by the release of a large
amount of free energy.
Avogadro's number - ANSWER-The number of molecules in a quantity of substance
equal to its molecular weight in grams. Approximately 6x10^23.
base - ANSWER-Molecule that accepts a proton in solution. Also used to refer to the
purine and pyrimidines in DNA and RNA, which are organic bases.
buffer - ANSWER-Any weak acid or base that can release or take up protons, and
thereby serve to maintain the pH under a variety of conditions.
