Download Barron`sChapter 3The Cell – Vocabulary

Chapter 3: The Cell - Vocabulary
actin filaments
Muscular protein filament in sarcomeres; its
movement shortens sarcomeres, yielding muscle
contraction. Actin filaments play role in movement of
cell + organelles.
amphipathic
Molecule that has both positive and negative pole.
apoptosis
Programmed cell death involving cascade of specific
cellular events leading to death + destruction of cell.
aquaporins
Channel proteins through which water can diffuse
across membranes.
autocrine signals
Diffuse from one part of cell to another part of same
cell.
autophagy
Process by which cell continually renews itself by
breaking down + recycling cell parts.
blood
Fluid circulated by heart through closed system of
vessels.
bulk flow
Overall movement of fluid in one direction in
organism.
carriers
Carry particles across membrane by active transport.
catalase
Enzyme produced in all cells that decomposes
hydrogen peroxide (H2O2), a by-product of cell
respiration.
cells
Smallest units that display properties of life;
composed of organelle-containing cytoplasm
surrounded by plasma membrane.
cell membrane receptors
Span entire thickness of membrane; therefore, they
are in contact w/ both extracellular environment +
cytoplasm.
cellulose
Polysaccharide that is major complex carbohydrate in
plant cell walls.
cell walls
Structures that surround plant, protistan, fungal, or
bacterial cell + maintain cell’s shape + rigidity.
centrioles
Cell organelles, existing in pairs, that occur in
centrosome + may help organize mitotic spindle for
chromosome movement during animal cell division.
centrosomes
Central microtubule organizing centers of cells. In
animal cells, it contains two centrioles.
Chapter 3: The Cell - Vocabulary
chitin
Strong, but flexible, nitrogenous polysaccharide
found in exoskeleton of arthropods and in cell walls
of fungi.
cholesterol molecules
Embedded in interior of phospholipid bilayer in order
to stabilize membrane.
chromatin network
Network of DNA strands + associated proteins
observed within nucleus that is not dividing.
cilia
Short, hair-like projections from plasma membrane,
occurring usually in larger numbers.
cleavage furrows
Shallow grooves in cell surface in animal cell where
cytokinesis is taking place.
coated vesicles
Receptors carrying ligands that migrated + clustered
along membrane + turned inwards.
contractile vacuoles
Found in many freshwater protists; used to pump out
excess water.
countercurrent exchange
Fluids flow side-by-side in opposite directions, as in
exchange of fluid in kidneys
cristae
Short, finger-like projections formed by folding of
inner membrane of mitochondria.
cyclic AMP (cAMP)
ATP-related compound that acts as second messenger
in peptide hormone transduction; it initiates activity
of metabolic machinery.
cytoplasmic streaming
Involvement of cytoskeleton with flow of cytoplasm.
desmosomes
Intracellular junctions that connect cytoskeletons of
adjacent cells.
diffusion
Movement of molecules or ions from region of higher
to lower concentration; it requires no energy and
tends to lead to equal distribution.
electron transport chain (ETC)
Passage of electrons along series of membrane-bound
electron carriers from higher to lower energy level;
energy released is used for synthesis of ATP.
endocrine signals
Hormones; travel anywhere in blood to reach target
cells.
estrogen
Female sex hormone that helps maintain sexual
organs and secondary sex characteristics; example of
hydrophobic chemical messenger.
Chapter 3: The Cell - Vocabulary
eukaryotic cells
Type of cell that has membrane-bounded nucleus +
membranous organelles; found in organisms within
domain Eukarya.
exocytosis
Process in which intracellular vesicle fuses w/ plasma
membrane so that vesicle’s contents are released
outside cell.
facilitated diffusion
Diffusion that involves protein channels.
first messenger
Chemical signal such as peptide hormone that binds
to plasma membrane receptor protein + alters
metabolism of cell b/c second messenger is activated.
flagella
Long, slender extension used for locomotion by some
bacteria, protozoans, and sperm.
fluid mosaic model
Model for plasma membrane based on changing
location + pattern of protein molecules in fluid
phospholipid bilayer.
food vacuoles
Formed by phagocytosis of foreign material.
G-protein-coupled receptors
Example of cell surface receptors.
gap junctions
Junction between cells formed by joining of 2
adjacent plasma membranes; it lends strength +
allows ions, sugars, & small molecules to pass
between cells.
gated channels
Open + close in response to variables such as turgor
pressure of cell.
Golgi apparatus
Organelle consisting of sacs + vesicles that process,
package, & distribute molecules about or from cell.
heart
Muscular organ whose contraction causes blood to
circulate in body of animal.
hydrolytic enzymes
Digestive enzymes; found in lysosomes.
hydrophilic protein channels
Required by facilitated diffusion; passively transports
specific substances across plasma membrane.
hydrophilic signalling molecules
Cannot diffuse through membrane; however, they
can bind to part of receptor on cell surface that
changes shape on cytoplasmic side of same receptor.
hypertonic
Higher solute concentration than cytoplasm of cell;
causes cell to lose water by osmosis.
hypotonic
Lower solute concentration than cytoplasm of cell;
causes cell to gain water by osmosis.
Chapter 3: The Cell - Vocabulary
integral proteins
Proteins embedded in plasma membrane; have nonpolar regions that completely span hydrophobic
interior of membrane.
intracellular digestion
Digestion that occurs within cell.
ion channel receptors
Example of cell surface receptors.
isotonic
Solution that is equal in solute concentration to that
of cytoplasm of cell; causes cell to neither gain nor
lose water by osmosis.
ligands
Molecules that bind specifically to receptor site of
another molecule.
ligand receptor complex
Either immediately activates pathway in cytoplasm or
migrates to nucleus, where it acts as transcription
factor + switches genes on/off.
lysosomes
Membrane-bounded vesicle that contains hydrolytic
enzymes for digesting macromolecules.
microfilaments
Assembled from actin filaments; help support shape
of cell.
microtubules
Small, cylindrical organelles composed of tubulin
protein around empty central core; present in
cytoplasm, centrioles, cilia, and flagella.
microtubule organizing centers (MTOCs)
Non-membranous structures that lie outside nuclear
membrane; organize spindle fibers + give rise to
spindle apparatus during cell division.
middle lamella
Formed when plant cell divides; thin, gluey layer
formed between two new plant cells.
nitrous oxide (NO)
Example of hydrophobic chemical messenger.
nuclear envelopes
Double membranes that surround nucleus in
eukaryotic cells + is connected to endoplasmic
reticulum; have pores that allow substances to pass
between nucleus and cytoplasm.
osmosis
Diffusion of water through differentially permeable
membrane.
osmotic potential
Tendency of water to move across permeable
membrane into solution.
paracrine signals
Send messages to nearby cells by diffusion.
Chapter 3: The Cell - Vocabulary
passive transport
Movement of molecules down concentration gradient
from region of high concentration to region of low
concentration until equilibrium is reached; examples
include diffusion + osmosis.
peripheral proteins
Proteins that occur on cytoplasmic side of plasma
membrane; loosely bound to surface of membrane.
peroxisomes
Enzyme-filled vesicle in which fatty acids + amino
acids are metabolized to hydrogen peroxide (H2O2)
that is broken down to harmless products.
phagocytosis
Process by which amoeboid-type cells engulf large
substances, forming intracellular vacuole.
phospholipid bilayer
Describes plasma membrane structure: 2 layers of
phospholipids; hydrophobic tails face inwards, while
hydrophilic heads face outwards.
pinocytosis
Process by which vesicle formation brings
macromolecules into the cell.
plasma membranes
Membranes surrounding the cytoplasm that consist
of phospholipid bilayer w/ embedded proteins;
function to regulate entrance/exit of molecules from
cell.
plasmodesmata
In plants, cytoplasmic strands that extend through
pores + in cell wall + connect the cytoplasm of two
adjacent cells.
plasmolysis
Contraction of cell contents due to loss of water.
pores
Allows for transport of molecules, such as mRNA, that
are too large to diffuse directly through nuclear
envelope.
primary cell walls
Cell walls that are located immediately outside plasma
membrane.
protein kinase receptors
Example of cell surface receptors.
pseudopods
Cytoplasmic extension of amoeboid protists; used for
locomotion + engulfing food.
pumps
Carry particles across membrane via active transport.
quorum sensing
Phenomenon that allows simple bacterial cells to
secrete molecules that enable them to respond to
changes in their population density.
receptors
Type of membrane protein that binds to specific
molecules in environment, providing mechanism for
cell to sense + adjust to its surroundings.
Chapter 3: The Cell - Vocabulary
receptor-mediated endocytosis
Selective uptake of molecules into cell by vacuole
formation after they bind to specific receptor proteins
in plasma membrane.
rough endoplasmic reticulum
Membranous system of tubules, vesicles, & sacs in
cells; has attached ribosomes.
secondary cell walls
Produced by some cells; secondary cell walls located
underneath primary cell walls.
second messenger
Chemical signal such as cyclic AMP that causes cell to
respond to the first messenger—hormone bound to
plasma membrane receptor protein.
secrete
To release substance by exocytosis from cell that may
be gland or part of gland.
selectively permeable
Describes plasma membrane; only certain molecules
are allowed to pass through.
signal transduction pathway
Coordinates activities within, between, and among
individual cells; supports entire organism.
simple diffusion
Diffusion that does not involve protein channels.
sodium-potassium pump
Carrier protein in plasma membrane that moves
sodium ions out of + potassium ions into animal cells;
important in nerve + muscle cells.
solute
Substance dissolved in solvent, forming solution.
solvent
Liquid portion of solution; serves to dissolve solute.
spindle fibers
Help separate chromosomes during mitosis + meiosis;
consist of microtubules organized into 9 triplets w/ no
microtubules in center.
steroid hormones
Type of hormone that has same complex of four
carbon rings, but each one has different side chains.
synaptic signalling
Occurs in animal nervous system; neurotransmitters
are signalling molecules.
testosterone
Male sex hormone that helps maintain sexual organs
and secondary sex characteristics; example of
hydrophobic chemical messenger.
theory of endosymbiosis
States that eukaryotic cells emerged when
mitochondria + chloroplasts, once free-living
prokaryotes, took up permanent residence inside
other larger cells, about 1.5 billion years ago.
Chapter 3: The Cell - Vocabulary
thylakoids
Flattened sacs within granum whose membranes
contain chlorophyll + where light reactions of
photosynthesis occur.
thyroid hormones
Example of hydrophobic chemical messenger.
tight junctions
Junction between cells when adjacent plasma
membrane proteins join to form impermeable barrier.
transcription factors
In eukaryotes, proteins required for initiation of
transcription by RNA polymerase.
turgid
Another word for “swollen”.
turgor pressure
Pressure of cell contents against cell wall; in plant
cells, determined by water content of the vacuole +
provides internal support.
urinary bladder
Organ where urine is stored.
water potential
Potential energy of water; measure of capability to
release/take up water relative to another substance.