Final Exam Vocab

Question 1

The basic unit from which a living organism is made; an aqueous solution of chemicals, enclosed by a membrane, that has an ability to self-replicate.

Answer 1

cell

Question 2

Double-stranded polynucleotide formed from two separate chains of covalently linked deoxyribonucleotides. It serves as the cell’s store of genetic information that is transmitted from generation to generation.

Answer 2

DNA

Question 3

Molecule produced by the transcription of DNA; usually single-stranded, it is a polynucleotide composed of covalently linked ribonucleotide subunits. Serves a variety of informational, structural, catalytic, and regulatory functions in cells.

Answer 3

RNA

Question 4

Macromolecule built from amino acids that provides cells with their shape and structure and performs most of their activities.

Answer 4

protein

Question 5

Process of gradual modification and adaptation that occurs in living organisms over generations.

Answer 5

evolution

Question 6

The total genetic information carried by all the chromosomes of a cell or organism; in humans, the total number of nucleotide pairs in the 22 autosomes plus the X and Y chromosomes.

Answer 6

genome

Question 7

Instrument for viewing extremely small objects. Some use a focused beam of visible light and are used to examine cells and organelles. Others use a beam of electrons and can be used to examine objects as small as individual molecules.

Answer 7

microscope

Question 8

The protein-containing lipid bilayer that surrounds a living cell.

Answer 8

plasma membrane

Question 9

Contents of a cell that are contained within its plasma membrane but, in the case of eukaryotic cells, outside the nucleus.

Answer 9

cytoplasm

Question 10

Instrument used to visualize a specimen that has been labeled with a fluorescent dye; samples are illuminated with a wavelength of light that excites the dye, causing it to fluoresce.

Answer 10

fluorescence microscope

Question 11

Large macromolecular complex, composed of RNAs and proteins, that translates a messenger RNA (mRNA) into a polypeptide chain.

Answer 11

ribosome

Question 12

Instrument that passes a beam of electrons through a specimen to reveal and magnify the structures of very small objects, such as organelles and large molecules.

Answer 12

electron microscope

Question 13

A discrete structure or subcompartment of a eukaryotic cell that is specialized to carry out a particular function. Examples include mitochondria and the Golgi apparatus.

Answer 13

organelle

Question 14

An organism whose cells have a distinct nucleus and cytoplasm.

Answer 14

eukaryote

Question 15

Major category of living cells distinguished by the absence of a nucleus; includes the archaea and the eubacteria (commonly called bacteria).

Answer 15

prokaryote

Question 16

Microscopic organism that is a member of one of two divisions of prokaryotes; some species cause disease. The term is sometimes used to refer to any prokaryotic microorganism, although the world of prokaryotes also includes archaea, which are only distantly related.

Answer 16

bacterium

Question 17

Microscopic organism that is a member of one of the two divisions of prokaryotes; often found in hostile environments such as hot springs or concentrated brine.

Answer 17

archaeon

Question 18

In biology, refers to the prominent, rounded structure that contains the DNA of a eukaryotic cell. In chemistry, refers to the dense, positively charged center of an atom.

Answer 18

nucleus

Question 19

Long, threadlike structure composed of DNA and proteins that carries the genetic information of an organism; becomes visible as a distinct entity when a plant or animal cell prepares to divide.

Answer 19

chromosome

Question 20

Membrane-enclosed organelle, about the size of a bacterium, that carries out oxidative phosphorylation and produces most of the ATP in eukaryotic cells.

Answer 20

mitochondrion

Question 21

Specialized organelle in algae and plants that contains chlorophyll and serves as the site for photosynthesis.

Answer 21

chloroplast

Question 22

The process by which plants, algae, and some bacteria use the energy of sunlight to drive the synthesis of organic molecules from carbon dioxide and water.

Answer 22

photosynthesis

Question 23

Labyrinthine membrane-enclosed compartment in the cytoplasm of eukaryotic cells where lipids and proteins are made.

Answer 23

endoplasmic reticulum (ER)

Question 24

Membrane-enclosed organelle in eukaryotic cells that modifies the proteins and lipids made in the endoplasmic reticulum and sorts them for transport to other sites.

Answer 24

Golgi apparatus

Question 25

Contents of the main compartment of the cytoplasm, excluding membrane-enclosed organelles such as the endoplasmic reticulum and mitochondria. Also used to refer to the cell fraction remaining after membranes, cytoskeletal components, and other organelles have been removed.

Answer 25

cytosol

Question 26

System of protein filaments in the cytoplasm of a eukaryotic cell that gives the cell shape and the capacity for directed movement. Its most abundant components are actin filaments, microtubules, and intermediate filaments.

Answer 26

cytoskeleton

Question 27

A free-living, nonphotosynthetic, single-celled, motile eukaryote.

Answer 27

protozoan

Question 28

A living thing selected for intensive study as a representative of a large group of species. Examples include the mouse (representing mammals), the yeast (representing a unicellular eukaryote), and E. coli (representing bacteria).

Answer 28

model organism

Question 29

Describes genes, chromosomes, or any structures that are similar because of their common evolutionary origin. Can also refer to similarities between protein sequences or nucleic acid sequences.

Answer 29

homologous

Question 30

A molecule that releases a proton when dissolved in water; this dissociation generates hydronium (H3O+) ions, thereby lowering the pH.

Answer 30

acid

Question 31

The smallest particle of an element that still retains its distinctive chemical properties; consists of a positively charged nucleus surrounded by a cloud of negatively charged electrons.

Answer 31

atom

Question 31

Small organic molecule containing both an amino group and a carboxyl group; it serves as the building block of proteins.

Answer 31

amino acid

Question 32

Activated carrier that serves as the principal carrier of energy in cells; a nucleoside triphosphate composed of adenine, ribose, and three phosphate groups.

Answer 32

ATP

Question 33

Region on the surface of an enzyme that binds to a substrate molecule and catalyzes its chemical transformation.

Answer 33

active site

Question 34

Describes a protein that can exist in multiple conformations depending on the binding of a molecule (ligand) at a site other than the catalytic site; such changes from one conformation to another often alter the protein’s activity or ligan affinity.

Answer 34

allosteric

Question 35

Folding pattern, common in many proteins, in which a single polypeptide chain twists around itself to form a rigid cylinder stabilized by hydrogen bonds between every fourth amino acid.

Answer 35

alpha helix

Question 36

The order of the amino acid subunits in a protein chain. Sometimes called the primary structure of a protein.

Answer 36

amino acid sequence

Question 37

Protein produced by B lymphocytes in response to a foreign molecule or invading organism. Binds to the foreign molecule or cell extremely tightly, thereby inactivating it or marking it for destruction.

Answer 37

antibody

Question 38

Molecule or fragment of a molecule that is recognized by an antibody.

Answer 38

antigen

Question 39

Folding pattern found in many proteins in which neighboring regions of the polypeptide chain associate side-by-side with each other through hydrogen bonds to give a rigid, flattened structure.

Answer 39

beta sheet

Question 40

Region on the surface of a protein, typically a cavity or groove, that interacts with another molecule (a ligand) through the formation of multiple noncovalent bonds.

Answer 40

binding site

Question 41

A large aggregate of phase-separated macromolecules that creates a region with a special biochemistry without the use of an encapsulating membrane.

Answer 41

biomolecular condensate

Question 42

Small molecule that binds tightly to an enzyme and helps it to catalyze a reaction.

Answer 42

coenzyme

Question 43

Covalent cross-link formed between the sulfhydryl groups on two cysteine side chains; often used to reinforce a secreted protein’s structure or to join two different proteins together.

Answer 43

disulfide bond

Question 44

A protein that catalyzes a specific chemical reaction.

Answer 44

enzyme

Question 45

A form of metabolic control in which the end product of a chain of enzymatic reactions reduces the activity of an enzyme early in the pathway.

Answer 45

feedback inhibition

Question 46

Intracellular signaling protein whose activity is determined by its association with either GTP or GDP. Includes both trimeric G proteins and monomeric GTPases, such as Ras.

Answer 46

GTP-binding protein

Question 47

General term for a small molecule that binds to a specific site on a macromolecule.

Answer 47

ligand

Question 48

Enzyme that severs the polysaccharide chains that form the cell walls of bacteria; found in many secretions including saliva and tears, where it serves as an antibiotic.

Answer 48

lysozyme

Question 49

The end of a polypeptide chain that carries a free a-amino group.

Answer 49

N-terminus

Question 50

Covalent chemical bond between the carbonyl group of one amino acid and the amino group of a second amino acid.

Answer 50

peptide bond

Question 51

Linear polymer composed of multiple amino acids. Proteins are composed of one or more long polypeptide chains.

Answer 51

polypeptide chain

Question 52

Repeating sequence of the atoms (-N-C-C-) that form the core of a protein molecule and to which the amino acid side chains are attached.

Answer 52

polypeptide backbone

Question 53

The amino acid sequence of a protein.

Answer 53

primary structure

Question 54

Macromolecule built from amino acids that provides cells with their shape and structure and performs most of their activities.

Answer 54

protein

Question 55

Segment of a polypeptide chain that can fold into a compact, stable structure and that often carries out a specific function.

Answer 55

protein domain

Question 56

Enzyme that catalyzes the transfer of a phosphate group from ATP to a specific amino acid side chain on a target protein.

Answer 56

protein kinase

Question 57

Enzyme that catalyzes the removal of a phosphate group from a protein, often with high specificity for the phosphorylated site.

Answer 57

protein phosphatase

Question 58

The covalent addition of a phosphate group to a side chain of a protein, catalyzed by a protein kinase; serves as a form of regulation that usually alters the activity or properties of the target protein.

Answer 58

protein phosphorylation

Question 59

Complete structure formed by multiple, interacting polypeptide chains that form a larger protein molecule.

Answer 59

quaternary structure

Question 60

Regular local folding pattern of a polymeric molecule. In proteins, it refers to alpha helices and beta sheets.

Answer 60

secondary structure.

Question 61

Portion of an amino acid not involved in forming peptide bonds; its chemical identity gives each amino acid unique properties.

Answer 61

side chain

Question 62

A molecule on which an enzyme acts to catalyze a chemical reaction.

Answer 62

substrate

Question 63

Complete three-dimensional structure of a fully folded protein.

Answer 63

tertiary structure

Question 64

A family of enzymes (typically multisubunit) that use the energy of ATP hydrolysis to alter the arrangement of nucleosomes in eukaryotic chromosomes, changing the accessibility of the underlying DNA to other proteins.

Answer 64

chromatin-remodeling complex

Question 65

Specialized DNA sequence that allows duplicated chromosomes to be separated during M phase; can be seen as the constricted region of a mitotic chromosome.

Answer 65

centromere

Question 66

Complex of DNA and proteins that makes up the chromosomes in a eukaryotic cell.

Answer 66

chromatin

Question 67

Long, threadlike structure composed of DNA and proteins that carries the genetic information of an organism; becomes visible as a distinct entity when a plant or animal cell prepares to divide.

Answer 67

chromosome

Question 68

A ring-shaped SMC protein complex that organizes interphase chromosomes into a long series of large chromatin loops; in addition, a special subset of cohesins holds together the sister chromatids after DNA has been replicated.

Answer 68

cohesin

Question 69

A ring-shaped SMC protein complex that compacts duplicated chromosomes for segregation by forming both loops and loops within loops.

Answer 69

condensin

Question 70

One of the two main states in which chromatin exists within an interphase cell. Prevalent in gene-rich areas, its less compact structure allows access for proteins involved in transcription.

Answer 70

euchromatin

Question 71

Highly condensed region of an interphase chromosome; generally gene-poor and transcriptionally inactive.

Answer 71

heterochromatin

Question 72

One of a small group of abundant, highly conserved proteins around which DNA wraps to form nucleosomes, structures that represent the most fundamental level of chromatin packing.

Answer 72

histone

Question 73

Enzyme that catalyzes the covalent addition of a small molecule, such as a methyl or acetate group, to a specific amino acid side chain on a histone.

Answer 73

histone-modifying enzyme

Question 74

Large structure within the nucleus where ribosomal RNA is transcribed and ribosomal subunits are assembled.

Answer 74

nucleolus

Question 75

Beadlike structural unit of a eukaryotic chromosome composed of a short length of DNA wrapped around an octameric core of histone proteins; includes a nucleosomal core particle (DNA plus histone protein) along with a segment of linker DNA that ties the core particles together.

Answer 75

nucleosome

Question 76

A large ring-shaped structure that contains two Structural Maintenance of Chromosomes (SMC) protein subunits at its core; the ring these proteins form is large enough for nucleosomes to pass easily through it. Cohesins and condensins are two major types.

Answer 76

SMC ring complex

Question 77

During protein synthesis, an enzyme that attaches the correct amino acid to a tRNA molecule to form a “charged” aminoacyl-tRNA.

Answer 77

aminoacyl-tRNA synthetase

Question 78

Set of three consecutive nucleotides in a transfer RNA molecule that recognizes, through base-pairing, the three-nucleotide codon on a messenger RNA molecule; this interactions helps to deliver the correct amino acid to a growing polypeptide chain.

Answer 78

anticodon

Question 79

Group of three consecutive nucleotides that specifies a particular amino acid or that starts or stops protein synthesis; applies to the nucleotides in an mRNA or in a coding sequence of DNA.

Answer 79

codon

Question 80

Segment of a eukaryotic gene that is transcribed into RNA and dictates the amino acid sequence of part of a protein.

Answer 80

exon

Question 81

Noncoding sequence within a eukaryotic gene that is transcribed into an RNA molecule but is then excised by RNA splicing to produce an mRNA.

Answer 81

intron

Question 82

RNA molecule that specifies the amino acid sequence of a protein.

Answer 82

messenger RNA (mRNA)

Question 83

An RNA molecule that is the final product of a gene and does not code for a protein. These RNAs serve as enzymatic, structural, and regulatory components for a wide variety of processes in the cell.

Answer 83

noncoding RNA

Question 84

The addition of multiple adenine nucleotides to the 3’ end of a newly synthesized mRNA molecule.

Answer 84

polyadenylation

Question 85

Enzyme that degrades proteins by hydrolyzing their peptide bonds.

Answer 85

protease

Question 86

RNA molecule that forms the structural and catalytic core of the ribosome.

Answer 86

ribosomal RNA (rRNA)

Question 87

An RNA molecule with catalytic activity.

Answer 87

ribozyme

Question 88

Enzyme that catalyzes the synthesis of an RNA molecule from a DNA template using ribonucleoside triphosphate precursors.

Answer 88

RNA polymerase

Question 89

RNA molecules containing on the order of 200 nucleotides that participate in RNA splicing.

Answer 89

small nuclear RNA (snRNA)

Question 90

Process in which intron sequences are excised from RNA molecules in the nucleus during the formation of a mature messenger RNA.

Answer 90

RNA splicing

Question 91

Large assembly of RNA and protein molecules that splices introns out of pre-mRNA in the nucleus of eukaryotic cells.

Answer 91

spliceosome

Question 92

Small RNA molecule that serves as an adaptor that “reads” a codon in mRNA and serves as the source of the amino acid added to the growing polypeptide chain.

Answer 92

transfer RNA (tRNA)

Question 93

Small protein that can be covalently attached to other proteins; a major role is to mark target proteins for degradation by the proteasome.

Answer 93

ubiquitin

Question 94

Process by which a pluripotent cell undergoes a progressive, coordinated change to a more specialized cell type, brought about by large-scale changes in gene expression.

Answer 94

differentiation

Question 95

The enzymatic addition of methyl groups to cytosine bases in DNA; this covalent modification generally turns off genes by attracting proteins that block gene expression.

Answer 95

DNA methylation

Question 96

Somatic cell that has been reprogrammed to resemble and behave like a pluripotent embryonic stem (ES) cell through the artificial introduction of a set of genes encoding particular transcription regulators.

Answer 96

induced pluripotent stem (iPS) cell

Question 97

Small noncoding RNA that controls gene expression by base-pairing with a specific mRNA to regulate its stability and its translation.

Answer 97

microRNA (miRNA)

Question 98

Short length of RNA produced from double-stranded RNA during the process of RNA interference. It base-pairs with complementary sequences in other RNAs, leading to the inactivation or destruction of the target RNA.

Answer 98

small interfering RNA (siRNA)

Question 99

Having both hydrophobic and hydrophilic regions, as in a phospholipid or a detergent molecule.

Answer 99

amphipathic

Question 100

Pigmented protein found in abundance in the plasma membrane of the salt-loving archaeon Halobacterium halobium; pumps protons out of the cell, fueled by light energy.

Answer 100

bacteriorhodopsin

Question 101

Specialized layer of cytoplasm on the inner face of the plasma membrane. In animal cells, it is rich in actin filaments that govern cell shape and drive cell movement.

Answer 101

cell cortex

Question 102

Short, rigid lipid molecule present in large amounts in the plasma membranes of animal cells, where it makes the lipid bilayer less flexible.

Answer 102

cholesterol

Question 103

Protective layer of carbohydrates on the outside surface of the plasma membrane formed by the sugar residues of membrane glycoproteins, proteoglycans, and glycolipids.

Answer 103

glycocalyx

Question 104

Common phospholipid present in abundance in most cell membranes; uses choline attached to a phosphate as its head group.

Answer 104

phosphatidylcholine

Question 105

Describes an organic molecule that contains a full complement of hydrogen; in other words, no double or triple carbon-carbon bonds.

Answer 105

saturated

Question 106

Describes an organic molecule that contains one or more double or triple bonds between is carbon atoms.

Answer 106

unsaturated

Question 107

Cell junction that helps hold together epithelial cells in a sheet of epithelium; actin filaments inside the cell attach to its cytoplasmic face.

Answer 107

adherens junction

Question 108

Thin mat of extracellular matrix, secreted by epithelial cells, upon which these cells sit.

Answer 108

basal lamina

Question 109

A member of a family of Ca2+-dependent proteins that mediates the attachment of one cell to another in animal tissues.

Answer 109

cadherin

Question 110

Long, thin polysaccharide fiber that helps strengthen plant cell walls.

Answer 110

cellulose microfibril

Question 111

Triple-stranded, fibrous protein that is a major component of the extracellular matrix and connective tissues; it is an abundant main protein in animal tissues, and different forms can be found in skin, tendon, bone, cartilage, and blood vessels.

Answer 111

collagen

Question 112

An undifferentiated cell type derived from the inner cell mass of an early mammalian embryo and capable of differentiating to give rise to any of the specialized cell types in the adult body.

Answer 112

embryonic stem (ES) cell

Question 113

Sheet of cells covering an external surface or lining an internal body cavity.

Answer 113

epithelium

Question 114

Complex network of polysaccharides (such as glycosaminoglycans or cellulose) and proteins (such as collagen) secreted by cells. A structural component of tissues that also influences their development and physiology.

Answer 114

extracellular matrix

Question 115

Cell type that produces the collagen-rich extracellular matrix in connective tissues such as skin and tendon. Proliferates readily in wounded tissue and in tissue culture.

Answer 115

fibroblast

Question 116

Extracellular matrix protein that helps cells attach to the matrix by acting as a “linker” that binds to a cell-surface integrin molecule on one end and to a matrix component, such as collagen, on the other.

Answer 116

fibronectin

Question 117

In animal tissues, specialized connection between juxtaposed cells through which ions and small molecules can pass from one cell to another.

Answer 117

gap junction

Question 118

Polysaccharide chain that can form a gel that acts as a “space filler” in the extracellular matrix of connective tissues; helps animal tissues resist compression.

Answer 118

glycosaminoglycan (GAG)

Question 119

Structure that anchors epithelial cells to the basal lamina beneath them.

Answer 119

hemidesmosome

Question 120

One of a family of transmembrane proteins present on cell surfaces that enable cells to make a break attachments to the extracellular matrix, helping them to crawl through a tissue.

Answer 120

integrin

Question 121

The spread of cancer cells from the initial site of the tumor to form secondary tumors at other sites in the body.

Answer 121

metastasis

Question 122

A gene that, when activated, can potentially make a cell cancerous. Typically a mutant form of a normal gene (proto-oncogene) involved in the control of cell growth or division.

Answer 122

oncogene

Question 123

Cell-cell junction that connects one plant cell to the next; consists of a channel of cytoplasm lines by membrane.

Answer 123

plasmodesmata

Question 124

Capable of giving rise to any type of cell or tissue.

Answer 124

pluripotent

Question 125

Molecule consisting of one or more glycosaminoglycan chains attached to a core protein; these aggregates can form gels that regulate the passage of molecules through the extracellular medium and guide cell migration.

Answer 125

proteoglycan

Question 126

Gene that when mutated or overexpressed can help transform a normal cell into a cancerous one.

Answer 126

proto-oncogene

Question 127

Cell-cell junction that seals adjacent epithelial cells together, preventing the passage of most dissolved molecules from one side of the epithelial sheet to the other.

Answer 127

tight junction

Question 128

Member of a family of extracellular signal molecules that regulates cell proliferation and migration during embryonic development and that helps to maintain stem cells in a proliferative state.

Answer 128

Wnt protein

Question 129

Mechanism by which a cell “eats itself,” digesting molecules and organelles that are damaged or obsolete.

Answer 129

autophagy

Question 130

Protein that makes up the coat of a type of transport vesicle that buds from either the Golgi apparatus (on the outward secretory pathway) or from the plasma membrane (on the inward endocytic pathway).

Answer 130

clathrin

Question 131

Process by which cells take in materials through an invagination of the plasma membrane, which surrounds the ingested material in a membrane-enclosed vesicle.

Answer 131

endocytosis

Question 132

Membrane-enclosed compartment of a eukaryotic cell through which material ingested by endocytosis passes on its way to lysosomes.

Answer 132

endosome

Question 133

Process by which most molecules are secreted from a eukaryotic cell. These molecules are packaged in membrane-enclosed vesicles that fuse with the plasma membrane, releasing their contents to the outside.

Answer 133

exocytosis

Question 134

Double membrane surrounding the nucleus. Consists of outer and inner membranes, perforated by nuclear pores.

Answer 134

nuclear envelope

Question 135

Channel through which secreted large molecules move between the nucleus and the cytoplasm.

Answer 135

nuclear pore

Question 136

Small membrane-enclosed organelle that contains enzymes that degrade lipids and destroy toxins.

Answer 136

peroxisome

Question 137

A cell such as a macrophage or neutrophil that is specialized to take up particles and microorganisms by phagocytosis.

Answer 137

phagocytic cell

Question 138

The process by which particulate material is engulfed by a cell. Prominent in predatory cells and in cells of the vertebrate immune system, such as macrophages.

Answer 138

phagocytosis

Question 139

Type of endocytosis in which soluble materials are taken up from the environment and incorporated into vesicles for digestion.

Answer 139

pinocytosis

Question 140

One of a family of small GTP-binding proteins present on the surfaces of transport vesicles and organelles that serves as a molecular marker to help ensure that transport vesicles fuse only with the correct membrane.

Answer 140

Rab protein

Question 141

Region of the endoplasmic reticulum associated with ribosomes and involved in the synthesis of secreted and membrane-bound proteins.

Answer 141

rough endoplasmic reticulum

Question 142

Enzyme that catalyzes the formation of cyclic AMP from ATP; an important component in some intracellular signaling pathways.

Answer 142

adenylyl cyclase

Question 143

Enzyme that phosphorylates target proteins in response to an increase in Ca2+ ion concentration through its interaction with the Ca2+-binding protein calmodulin.

Answer 143

CaM-kinase

Question 144

Small Ca2+-binding protein that modifies the activity of many target proteins in response to changes in Ca2+ concentration.

Answer 144

calmodulin

Question 145

Small intracellular signaling molecule generated from ATP in response to hormonal stimulation of cell-surface receptors.

Answer 145

cyclic AMP

Question 146

Small messenger molecule produced by the cleavage of membrane inositol phospholipids in response to extracellular signals. Helps activate protein kinase C.

Answer 146

diacylglycerol (DAG)

Question 147

A membrane-bound GTP-binding protein involved in intracellular signaling; composed of three subunits, this intermediary is usually activated by the binding of a hormone or other ligand to a transmembrane receptor.

Answer 147

G protein

Question 148

Intracellular signaling protein whose activity is determined by its association with either GTP or GDP. Includes both trimeric G proteins and monomeric GTPases, such as Ras.

Answer 148

GTP-binding protein

Question 149

Extracellular signal molecule that is secreted and transported via the bloodstream (in animals) or the sap (in plants) to target tissues on which it exerts a specific effect.

Answer 149

hormone

Question 150

Minor lipid component of plasma membranes that plays a part in signal transduction in eukaryotic cells; cleavage yields two small messenger molecules, IP3 and diacylglycerol.

Answer 150

inositol phospholipid

Question 151

Small intracellular signaling molecule that triggers the release of Ca2+ from the endoplasmic reticulum into the cytosol; produced when a signal molecule activates a membrane-bound protein called phospholipase C.

Answer 151

inositol 1,4,5-triphosphate (IP3)

Question 152

Mitogen-activated protein kinase. Signaling molecule that is the final kinase in a three-kinase sequence called the MAP-kinase signaling molecule.

Answer 152

MAP kinase

Question 153

Set of three functionally interlinked protein kinases that allows cells to respond to extracellular signal molecules that stimulate proliferation; includes a mitogen-activated protein kinase (MAP kinase), a MAP kinase kinase, and a MAP kinase kinase kinase.

Answer 153

MAP-kinase signaling module

Question 154

Intracellular signaling protein that toggles between an active and inactive state in response to receiving a signal.

Answer 154

molecular switch

Question 155

Small, single-subunit GTP-binding protein. Proteins of this family, such as Ras and Rho, are part of many different signaling pathways.

Answer 155

monomeric GTPase

Question 156

Locally acting gaseous signal molecule that diffuses across cell membranes to affect the activity of intracellular proteins.

Answer 156

nitric oxide (NO)

Question 157

Protein inside a eukaryotic cell that, on binding to a signal molecule, enters the nucleus and regulates transcription.

Answer 157

nuclear receptor

Question 158

Enzyme that phosphorylates inositol phospholipids in the plasma membrane, generating docking sites for intracellular signaling proteins that promote cell growth and survival.

Answer 158

phosphoinositide 3-kinase (PI 3-kinase)

Question 159

Enzyme associated with the plasma membrane that generates two small messenger molecules in response to activation.

Answer 159

phospholipase C

Question 160

Enzyme that catalyzes the transfer of a phosphate group from ATP to a specific amino acid side chain on a target protein.

Answer 160

protein kinase

Question 161

Enzyme that phosphorylates target proteins in response to a rise in diacylglycerol and Ca2+ ions.

Answer 161

protein kinase C (PKC)

Question 162

Enzyme that catalyzes the removal of a phosphate group from a protein, often with high specificity for the phosphorylated site.

Answer 162

protein phosphatase

Question 163

One of a large family of small GTP-binding proteins that helps relay signals from cell-surface receptors to the nucleus. Many human cancers contain an overactive mutant form of the protein.

Answer 163

Ras

Question 164

Enzyme-coupled receptor that phosphorylates target proteins on serine or threonine.

Answer 164

receptor serine/threonine kinase

Question 165

Enzyme-couple receptor in which the intracellular domain has a tyrosine kinase activity, which is activated by ligand binding to the receptor’s extracellular domain.

Answer 165

receptor tyrosine kinase (RTK)

Question 166

Enzyme that phosphorylates target proteins on serines or threonines.

Answer 166

serine/threonine kinase

Question 167

Conversion of an impulse or stimulus from one physical or chemical form to another. In cell biology, the process by which a cell responds to an extracellular signal.

Answer 167

signal transduction

Question 168

Hydrophobic signal molecule related to cholesterol; can pass through the plasma membrane to interact with intracellular receptors that affect gene expression in the target cell. Examples include estrogen and testosterone.

Answer 168

steroid hormone

Question 169

Enzyme that phosphorylates target proteins on tyrosines.

Answer 169

tyrosine kinase

Question 170

Traveling wave of electrical excitation caused by rapid, transient, self-propagating depolarization of the plasma membrane in a neuron or other excitable cell; also called a nerve impulse.

Answer 170

action potential

Question 171

The movement of a solute across a membrane against its electrochemical gradient; requires an input of energy, such as that provided by ATP hydrolysis.

Answer 171

active transport

Question 172

Type of couple transporter that transfers two different ions or small molecules across a membrane in opposite directions, either simultaneously or in sequence.

Answer 172

antiport

Question 173

Channel that facilitates the transport of water, but not ions, across cell membranes; those found in the plasma membrane greatly increase a cell’s permeability to water.

Answer 173

aquaporin

Question 174

Long, thin extension that conducts electrical signals away from a nerve cell body toward remote target cells.

Answer 174

axon

Question 175

An active transporter that uses energy supplied by ATP hydrolysis to actively expel Ca2+ from the cell cytosol.

Answer 175

Ca2+ pump (or Ca 2+ ATPase)

Question 176

A protein that forms a hydrophilic pore across a membrane, through which selected small molecules or ions can passively diffuse.

Answer 176

channel

Question 177

Short, branching structure that extends from the surface of a nerve cell and receives signals from other neurons.

Answer 177

dendrite

Question 178

A shift in the membrane potential, making it less negative on the inside of the cell.

Answer 178

depolarization

Question 179

Driving force that determines which way an ion will move across a membrane; consists of the combined influence of the ion’s concentration gradient and the membrane potential.

Answer 179

electrochemical gradient

Question 180

A protein or protein complex that uses energy supplied by ATP hydrolysis, an ion gradient, or light to actively move protons across a membrane.

Answer 180

H+ pump

Question 181

Ion channel permeable to K+ that randomly flickers between an open and closed state; largely responsible for the resting membrane potential in animal cells.

Answer 181

K+ leak channel

Question 182

An ion channel that is stimulated to open by the binding of a small molecule such as a neurotransmitter.

Answer 182

ligand-gated channel

Question 183

An ion channel that allows the passage of select ions across a membrane in response to a physical perturbation.

Answer 183

mechanically gated channel

Question 184

Voltage difference across a membrane due to a slight excess of positive ions on one side and of negative ions on the other.

Answer 184

membrane potential.

Question 185

Any transmembrane protein that provides a passageway for the movement of select substances across a cell membrane.

Answer 185

membrane transport protein

Question 186

Transporter found in the plasma membrane of most animal cells that actively pumps Na+ out of the cell and K+ in using the energy derived from ATP hydrolysis.

Answer 186

Na+ pump

Question 187

Passive movement of water across a cell membrane from a region where the concentration of water is high to a region where the concentration of water is low.

Answer 187

osmosis

Question 188

The spontaneous movement of a solute down its concentration gradient across a cell membrane via a membrane transport protein, such as channel or a transporter.

Answer 188

passive transport

Question 189

Transporter that uses a source of energy, such as ATP hydrolysis or sunlight, to actively move a solute across a membrane against its electrochemical gradient.

Answer 189

pump

Question 190

Voltage difference across the plasma membrane when a cell is not stimulated.

Answer 190

resting membrane potential

Question 191

Part of an ion channel that determines which ions the channel can transport; located in the region where the channel is narrowest.

Answer 191

selectivity filter

Question 192

A transporter that transfers two different solutes across a membrane in the same direction.

Answer 192

symport

Question 193

Transmembrane receptor protein or protein complex that opens in response to the binding of a neurotransmitter, allowing the passage of a specific inorganic ion; its activation can trigger an action potential in a postsynaptic cell.

Answer 193

transmitter-gated ion channel

Question 194

Membrane transport protein that moves a solute across a cell membrane by undergoing a series of conformational changes.

Answer 194

transporter

Question 195

Channel protein that permits the passage of selected ions, such as Na+, across a membrane in response to changes in the membrane potential. Found primarily in electrically excitable cells such as nerve and muscle cells.

Answer 195

voltage-gated channel

Question 196

Protein in the plasma membrane of electrically excitable cells that opens in response to membrane depolarization, allowing Na+ to enter the cell. It is responsible for action potentials in these cells.

Answer 196

voltage-gated Na+ channel