BIO 121 Chapter 6 Review Questions and Correct Answers
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Course
BIO 121
Institution
BIO 121
Actin A globular protein that links into chains, two of which twist helically about each other, forming microfilaments (actin filaments) in muscle and other kinds of cells.
Active transport The movement of a substance across a cell membrane, with an expenditure of energy, against its concentration...
BIO 121 Chapter 6 Review Questions
and Correct Answers
Actin ✅A globular protein that links into chains, two of which twist helically about each
other, forming microfilaments (actin filaments) in muscle and other kinds of cells.
Active transport ✅The movement of a substance across a cell membrane, with an
expenditure of energy, against its concentration or electrochemical gradient; mediated
by specific transport proteins.
Adenosine triphosphate (ATP) ✅An adenine-containing nucleoside triphosphate that
releases free energy when its phosphate bonds are hydrolyzed. This energy is used to
drive endergonic reactions in cells.
Amphipathic ✅Having both a hydrophilic region and a hydrophobic region.
Aquaporin ✅A channel protein in the plasma membrane of a plant, animal, or
microorganism cell that specifically facilitates osmosis, the diffusion of water across the
membrane.
Capsule ✅A sticky layer that surrounds the cell wall of some prokaryotes, protecting
the cell surface and sometimes helping to glue the cell to surfaces.
Carbohydrate ✅A region along which the density of a chemical substance increases or
decreases.
Cell fractionation ✅The disruption of a cell and separation of its parts by centrifugation.
Central vacuole ✅A membranous sac in a mature plant cell with diverse roles in
reproduction, growth, and development.
Centriole ✅A structure in the centrosome of an animal cell composed of a cylinder of
microtubule triplets arranged in a 9 + 0 pattern. A centrosome has a pair of centrioles.
Centrosome ✅Structure present in the cytoplasm of animal cells, important during cell
division; functions as a microtubule-organizing center. A centrosome has two centrioles.
Chloroplast ✅An organelle found in plants and photosynthetic protists that absorbs
sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide
and water.
, Chromosome ✅A cellular structure carrying genetic material, found in the nucleus of
eukaryotic cells. Each chromosome consists of one very long DNA molecule and
associated proteins. (A bacterial chromosome usually consists of a single circular DNA
molecule and associated proteins. It is found in the nucleoid region, which is not
membrane bounded.)
Cilium ✅A short cellular appendage containing microtubules. A motile cilium is
specialized for locomotion and is formed from a core of nine outer doublet microtubules
and two inner single microtubules (the "9 + 2" arrangement) ensheathed in an extension
of the plasma membrane. A primary cilium is usually nonmotile and plays a sensory and
signaling role; it lacks the two inner microtubules (the "9 + 0" arrangement).
Collagen ✅A glycoprotein in the extracellular matrix of animal cells that forms strong
fibers, found extensively in connective tissue and bone; the most abundant protein in
the animal kingdom.
Concentration gradient ✅A region along which the density of a chemical substance
increases or decreases.
Contractile vacuole ✅A membranous sac that helps move excess water out of certain
freshwater protists.
Crista ✅An infolding of the inner membrane of a mitochondrion that houses electron
transport chains and molecules of the enzyme catalyzing the synthesis of ATP (ATP
synthase).
Cytoplasm ✅The contents of the cell, exclusive of the nucleus and bounded by the
plasma membrane.
Cytoskeleton ✅A network of microtubules, microfilaments, and intermediate filaments
that branch throughout the cytoplasm and serve a variety of mechanical, transport, and
signaling functions.
Cytosol ✅The semifluid portion of the cytoplasm.
Desmosome ✅A type of intercellular junction in animal cells that functions as a rivet.
Diffusion ✅The spontaneous movement of a substance down its concentration
gradient, from a region where it is more concentrated to a region where it is less
concentrated.
Dynein ✅In cilia and flagella, a large contractile protein extending from one
microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes in dynein
shape that lead to bending of cilia and flagella.
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