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Kursus i medicinsk celle- og vævsbiologi > Key terms > Flashcards

Key terms Flashcards

1
Q

bacteriorhodopsin

A

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.

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2
Q

cell cortex

A

Specialized layer of cytoplasm on the inner face of the

plasma membrane.

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3
Q

cholesterol

A

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

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4
Q

detergent

A

Soapy substance used to solubilize lipids and membrane

proteins.

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5
Q

fat droplet

A

Large cluster of hydrophobic fats or oils that forms inside

the cells.

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6
Q

glycocalyx

A

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

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7
Q

lipid bilayer

A

Thin pair of closely juxtaposed sheets, composed mainly of phospholipid molecules, that forms the structural basis for
all cell membranes.

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8
Q

membrane domain

A

Functionally and structurally specialized region in the membrane of a cell or organelle; typically characterized by
the presence of specific proteins.

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9
Q

membrane protein

A

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

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10
Q

phosphatidylcholine

A

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

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11
Q

phospholipid

A

A major type of lipid molecule in many cell
membranes. Generally composed of two fatty
acid tails linked to one of a variety of phosphatecontaining
polar groups.

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12
Q

plasma membrane

A

The protein-containing lipid bilayer that surrounds a living

cell.

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13
Q

saturated

A

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

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14
Q

unsaturated

A

Describes an organic molecule that contains one or more

double or triple bonds between its carbon atoms.

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15
Q

action potential

A

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.

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16
Q

active transport

A

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

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17
Q

antiport

A

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

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18
Q

axon

A

Long, thin extension that conducts electrical signals away

from a nerve cell body toward remote target cells.

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19
Q

Ca2+ pump

A

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

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20
Q

channel

A

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

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21
Q

dendrite

A

Short, branching structure that extends from the surface of

a nerve cell and receives signals from other neurons.

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22
Q

depolarization

A

A shift in the membrane potential, making it less negative

on the inside of the cell.

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23
Q

electrochemical gradient

A

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.

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24
Q

gradient-driven pump

A

A protein that uses energy stored in the electrochemical
gradient of ions to actively transport a solute across a
membrane.

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25
Q

H+ pump

A

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

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26
Q

ion channel

A

Transmembrane protein that forms a pore across the lipid
bilayer through which specific inorganic ions can diffuse
down their electrochemical gradients.

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27
Q

k+ leak channel

A

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

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28
Q

ligand gated channel

A

An ion channel that is stimulated to open by the binding of

a small molecule such as a neurotransmitter

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29
Q

mechanically-gated channel

A

An ion channel that allows the passage of select ions across

a membrane in response to a physical perturbation.

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30
Q

membrane potential

A

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

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31
Q

membrane transport protein

A

A protein associated with the lipid bilayer of a cell

membrane.

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32
Q

Na+ pump

A

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.

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33
Q

Nernst equation

A

An equation that relates the concentrations of an inorganic
ion on the two sides of a permeable membrane to the
membrane potential at which there would be no net
movement of the ion across the membrane.

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34
Q

nerve terminal

A

Structure at the end of an axon that signals to another

neuron or target cell.

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35
Q

Neuron

A

ormation as part of the nervous system; a nerve cell.

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36
Q

Neurotransmitter

A

Small signaling molecule secreted by a nerve cell at a
synapse to transmit information to a postsynaptic cell.
Examples include acetylcholine, glutamate, GABA, and
glycine.

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37
Q

Optogenetics

A

Technique that uses light to control the activity of neurons
into which light-gated ion channels have been artificially
introduced.

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38
Q

Osmosis

A

Passive movement of water across a cell membrane from
a region where the concentration of water is high (because
the concentration of solutes is low) to a region where the
concentration of water is low (and the concentration of
solutes is high).

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39
Q

Passive transport

A

oncentration gradient across a cell membrane via a
membrane transport protein, such as a channel or a
transporter.

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40
Q

Patch-clamp recording

A

Technique used to monitor the activity of ion channels in a
membrane; involves the formation of a tight seal between
the tip of a glass electrode and a small region of cell
membrane, and manipulation of the membrane potential
by varying the concentrations of ions in the electrode.

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41
Q

pump

A

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.

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42
Q

resting membrane potential

A

Voltage difference across the plasma membrane when a

cell is not stimulated.

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43
Q

symport

A

A transporter that transfers two different solutes across a

cell membrane in the same direction.

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44
Q

synapse

A

Specialized junction where a nerve cell
communicates with another cell (such as
a nerve cell, muscle cell, or gland cell),
usually via a neurotransmitter secreted by
the nerve cell.

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45
Q

synaptic vesicle

A

Small membrane-enclosed sac filled with neurotransmitter

that releases its contents by exocytosis at a synapse.

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46
Q

transmitter-gated ion channel

A

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.

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47
Q

transporter

A

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

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48
Q

voltage-gated channel

A

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.

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49
Q

voltage-gated Na+ channel

A

rotein 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.

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50
Q

autophagy

A

Mechanism by which a cell “eats itself,” digesting molecules

and organelles that are damaged or obsolete.

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51
Q

clathrin

A

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).

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52
Q

coated vesicle

A

Small membrane-enclosed sac that wears a
distinctive layer of proteins on its cytosolic
surface. It is formed by pinching-off of a
protein-coated region of cell membrane.

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53
Q

endocytosis

A

Process by which cells take in materials through an
invagination of the plasma membrane, which surrounds
the ingested material in a membrane-enclosed vesicle. (See
also pinocytosis and phagocytosis.)

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54
Q

endomembrane system

A

Interconnected network of membrane-enclosed organelles
in a eukaryotic cell; includes the endoplasmic reticulum,
Golgi apparatus, lysosomes, peroxisomes, and endosomes.

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55
Q

endoplasmic reticulum

A

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

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56
Q

endosome

A

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

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57
Q

exocytosis

A

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.

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58
Q

golgi apparatus

A 
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.
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59
Q

lysosome

A

Membrane-enclosed organelle that breaks down worn-out
proteins and organelles and other waste materials, as well
as molecules taken up by endocytosis; contains digestive
enzymes that are typically most active at the acid pH found
inside these organelles.

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60
Q

membrane-enclosed organelle

A

Any organelle in a eukaryotic cell that is surrounded by a
lipid bilayer—for example, the endoplasmic reticulum, Golgi
apparatus, and lysosome.

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61
Q

nuclear envelope

A

Double membrane surrounding the nucleus. Consists of

outer and inner membranes, perforated by nuclear pores.

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62
Q

nuclear pore

A

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

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63
Q

peroxisome

A

Small membrane-enclosed organelle that contains enzymes

that degrade lipids and destroy toxins.

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64
Q

phagocytic cell

A

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

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65
Q

phagocytosis

A

The process by which particulate material is engulfed
(“eaten”) by a cell. Prominent in predatory cells, such as
Amoeba proteus, and in cells of the vertebrate immune
system, such as macrophages.

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66
Q

pinocytosis

A

Type of endocytosis in which soluble materials are taken
up from the environment and incorporated into vesicles for
digestion. (Literally, “cell drinking.”)

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67
Q

rab protein

A

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.

68
Q

receptor-mediated endocytosis

A

Mechanism of selective uptake of material by animal cells
in which a macromolecule binds to a receptor in the plasma
membrane and enters the cell in a clathrin-coated vesicle.

69
Q

rough endoplasmic reticulum

A

Region of the endoplasmic reticulum
associated with ribosomes and involved in
the synthesis of secreted and membranebound
proteins.

70
Q

secretion

A

Production and release of a substance from a cell.

71
Q

signal sequence

A

Amino acid sequence that directs a protein to a specific

location in the cell, such as the nucleus or mitochondria.

72
Q

SNARE

A

One of a family of membrane proteins responsible for the
selective fusion of vesicles with a target membrane inside
the cell.

73
Q

tethering protein

A

Filamentous transmembrane protein involved in the

docking of transport vesicles to target membranes

74
Q

transport vesicle

A

Membrane vesicle that carries proteins from one
intracellular compartment to another—for example, from
the endoplasmic reticulum to the Golgi apparatus.

75
Q

unfolded proteins response

A

Molecular program triggered by the accumulation of
misfolded proteins in the endoplasmic reticulum. Allows
cells to expand the endoplasmic reticulum and produce
more of the molecular machinery needed to restore proper
protein folding and processing.

76
Q

vesivular transport

A

Movement of material between organelles in the eukaryotic

cell via membrane-enclosed vesicles.

77
Q

active site

A

Region on the surface of an enzyme that binds to a substrate

molecule and catalyzes its chemical transformation.

78
Q

allosteric

A

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
ligand affinity.

79
Q

alpha helix

A

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.

80
Q

amino acid sequence

A

The order of the amino acid subunits in a protein chain.

Sometimes called the primary structure of a protein.

81
Q

antibody

A

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.

82
Q

antigen

A

Molecule or fragment of a molecule that is recognized by

an antibody.

83
Q

Beta sheet

A 
olding 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.
84
Q

binding site

A

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.

85
Q

C-terminus

A

The end of a polypeptide chain that carries a free carboxyl

group (–COOH).

86
Q

chromatography

A

Technique used to separate the individual molecules in a
complex mixture on the basis of their size, charge, or their
ability to bind to a particular chemical group. In a common
form of the technique, the mixture is run through a column
filled with a material that binds the desired molecule, and
it is then eluted from the column with a solvent gradient.

87
Q

coiled-coil

A

Stable, rodlike protein structure formed when two or more

α helices twist repeatedly around each other.

88
Q

conformation

A

Precise, three-dimensional shape of a protein or other
macromolecule, based on the spatial location of its atoms
in relation to one another.

89
Q

coenzyme

A

Small molecule that binds tightly to an enzyme and helps it

to catalyze a reaction.

90
Q

cryoelectron microscopy

A

Technique for observing the detailed structure of a
macromolecule at very low temperatures after freezing
native structures in ice.

91
Q

disulfide bond

A

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.

92
Q

electrophoresis

A

Technique for separating a mixture of proteins or DNA
fragments by placing them on a polymer gel and subjecting
them to an electric field. The molecules migrate through
the gel at different speeds depending on their size and net
charge.

93
Q

enzyme

A

A protein that catalyzes a specific chemical reaction.

94
Q

feedback inhibition

A

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.

95
Q

fibrous protein

A

A protein with an elongated, rodlike shape, such as collagen

or a keratin filament.

96
Q

globular protein

A

Any protein in which the polypeptide chain folds into a

compact, rounded shape. Includes most enzymes.

97
Q

GTP-binding protein

A

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.

98
Q

helix

A

An elongated structure whose subunits twist in a regular

fashion around a central axis, like a spiral staircase.

99
Q

intracellular condensate

A

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

100
Q

intrinsically disordered sequence

A

Region in a polypeptide chain that lacks a definite structure.

101
Q

ligand

A

General term for a small molecule that binds to a specific

site on a macromolecule.

102
Q

lysozyme

A

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.

103
Q

mass spectrometry

A

Sensitive technique that enables the determination of the

exact mass of all of the molecules in a complex mixture.

104
Q

michaelis constant

A

The concentration of substrate at which an enzyme works
at half its maximum velocity; serves as a measure of how
tightly the substrate is bound.

105
Q

motor protein

A

Protein such as myosin or kinesin that uses energy derived
from the hydrolysis of a tightly bound ATP molecule to
propel itself along a protein filament or polymeric molecule.

106
Q

N-terminus

A

The end of a polypeptide chain that carries a free α-amino

group.

107
Q

nuclear magnetic resonance

A

Technique used for determining the three-dimensional

structure of a protein in solution.

108
Q

peptide bond

A

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

109
Q

polypeptide, polypeptide chain

A

Linear polymer composed of multiple amino acids. Proteins

are composed of one or more long polypeptide chains.

110
Q

polypeptide backbone

A

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.

111
Q

primary structure

A

The amino acid sequence of a protein.

112
Q

protein

A

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

113
Q

protein domain

A

Segment of a polypeptide chain that can fold into a compact,

stable structure and that often carries out a specific function.

114
Q

protein family

A

A group of polypeptides that share a similar amino acid
sequence or three-dimensional structure, reflecting a
common evolutionary origin. Individual members often
have related but distinct functions, such as kinases that
phosphorylate different target proteins.

115
Q

protein kinase

A

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

116
Q

protein machine

A

Assembly of protein molecules that operates as a
cooperative unit to perform a complex series of biological
activities, such as replicating DNA.

117
Q

protein phosphatase

A

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

118
Q

protein phosphorylation

A

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.

119
Q

quaternary structure

A

Complete structure formed by multiple, interacting

polypeptide chains that form a larger protein molecule.

120
Q

scaffold protein

A

Protein with multiple binding sites for other macromolecules,
holding them in a way that speeds up their functional
interactions.

121
Q

secondary structure

A

Regular local folding pattern of a polymeric molecule. In

proteins, it refers to α helices and β sheets.

122
Q

side chain

A

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

123
Q

substrate

A

A molecule on which an enzyme acts to catalyze a chemical

reaction.

124
Q

subunit

A

A monomer that forms part of a larger molecule, such as an
amino acid residue in a protein or a nucleotide residue in
a nucleic acid. Can also refer to a complete molecule that
forms part of a larger molecule. Many proteins, for example,
are composed of multiple polypeptide chains, each of which
is called a protein subunit.

125
Q

tertiary structure

A

Complete three-dimensional structure of a fully folded

protein.

126
Q

transition state

A

Transient structure that forms during the course of a
chemical reaction; in this configuration, a molecule has the
highest free energy; it is no longer the substrate, but is not
yet the product.

127
Q

turnover number

A

The maximum number of substrate molecules that an

enzyme can convert into product per second.

128
Q

Vmax

A

The maximum rate of an enzymatic reaction, reached when
the active sites of all of the enzyme molecules in a sample
are fully occupied by substrate.

129
Q

x-ray crystallography

A

Technique used to determine the three-dimensional
structure of a protein molecule by analyzing the diffraction
pattern produced when a beam of x-rays is passed through
an ordered array of the protein.

130
Q

acetyl CoA

A

Activated carrier that donates the carbon atoms in its readily
transferable acetyl group to many metabolic reactions,
including the citric acid cycle and fatty acid biosynthesis;
the acetyl group is linked to coenzyme A (CoA) by a
thioester bond that releases a large amount of energy when
hydrolyzed.

131
Q

Acid

A

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

132
Q

Actin filament

A

Thin, flexible protein
filament made from
a chain of globular actin molecules; a major constituent of
all eukaryotic cells, this cytoskeletal element is essential for
cell movement and for the contraction of muscle cells.

133
Q

Actin-binding protein

A

Protein that interacts with actin monomers or filaments
to control the assembly, structure, and behavior of actin
filaments and networks.

134
Q

Activated carrier

A

A small molecule that stores energy or chemical groups
in a form that can be donated to many different metabolic
reactions. Examples include ATP, acetyl CoA, and NADH.

135
Q

activation energy

A

The energy that must be acquired by a molecule to undergo

a chemical reaction.

136
Q

adaptation

A

Adjustment of sensitivity following repeated stimulation;
allows a cell or organism to register small changes in a
signal despite a high background level of stimulation.

137
Q

Adenyl cyclase

A

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

138
Q

adherens junction

A

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

139
Q

ADP

A

Nucleoside diphosphate produced by hydrolysis of the

terminal phosphate of ATP.

140
Q

allele

A

An alternative form of a gene; for a given gene, many alleles
may exist in the gene pool of the species.

141
Q

alternative splicing

A

The production of different mRNAs (and proteins) from the

same gene by splicing its RNA transcripts in different ways.

142
Q

alu sequence

A

Family of mobile genetic elements that comprises about
10% of the human genome; this short, repetitive sequence is
no longer mobile on its own, but requires enzymes encoded
by other elements to transpose.

143
Q

amino acid

A

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

144
Q

aminoacyl-tRNA synthase

A

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

145
Q

amphipatic

A

Having both hydrophobic and hydrophilic regions, as in a

phospholipid or a detergent molecule

146
Q

anabolic pathway

A

Series of enzyme-catalyzed reactions by which large
biological molecules are synthesized from smaller subunits;
usually requires an input of energy.

147
Q

anabolism

A

Set of metabolic pathways by which large molecules are

made from smaller ones.

148
Q

anaphase

A

Stage of mitosis during which the two sets of chromosomes
separate and are pulled toward opposite ends of the dividing
cell.

149
Q

anaphase-promoting complex (APC/C)

A

A protein complex that triggers the separation of sister
chromatids and orchestrates the carefully timed destruction
of proteins that control progress through the cell cycle; the
complex catalyzes the ubiquitylation of its targets.

150
Q

antenna complex

A

In chloroplasts and photosynthetic bacteria, the part of
the membrane-bound photosystem that captures energy
from sunlight; contains an array of proteins that bind
hundreds of chlorophyll molecules and other photosensitive
pigments.

151
Q

anticodon

A

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

152
Q

apical

A

Describes the top or the tip of a cell, structure, or organ; in an epithelial cell, for example, this surface is opposite the
base, or basal surface.

153
Q

apoptosis

A

A tightly controlled form of programmed cell death that
allows excess cells to be eliminated from an adult or
developing organism.

154
Q

archaeon

A

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.

155
Q

Asexual reproduction

A

Mode of reproduction in which offspring arise from a
single parent, producing an individual genetically identical
to that parent; includes budding, binary fission, and
parthenogenesis.

156
Q

Aster

A

Star-shaped array of microtubules emanating from a

centrosome or from a pole of a mitotic spindle.

157
Q

Atom

A

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.

158
Q

atomic weight

A

The mass of an atom relative to the mass of a hydrogen
atom; equal to the number of protons plus the number of
neutrons that the atom contains

159
Q

ATP

A

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

160
Q

ATP synthase

A

Abundant membrane-associated enzyme complex that
catalyzes the formation of ATP from ADP and inorganic
phosphate during oxidative phosphorylation and
photosynthesis.

161
Q

Avogadro’s number

A

The number of molecules in a mole, the quantity of
a substance equal to its molecular weight in grams;
approximately 6 × 1023.

162
Q

bacterium

A

Microscopic organism that is a member of one of the 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 to each
other.

163
Q

Basal

A

Situated near the base; opposite of apical.

164
Q

Basal lamina

A

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

165
Q

Base

A

Molecule that accepts a proton when dissolved in water;
also used to refer to the nitrogen-containing purines or
pyrimidines in DNA and RNA.

166
Q

base pair

A

Two complementary nucleotides in an RNA or a DNA
molecule that are held together by hydrogen bonds—
normally G with C, and A with T or U.

167
Q

Bcl2family

A

Related group of intracellular proteins that regulates
apoptosis; some family members promote cell death, others
inhibit it

Kursus i medicinsk celle- og vævsbiologi (46 decks)

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