Chapter 3; Cellular Form and Function Flashcards
Cytology
scientific study of cells
cellulae
little cells
cytoplasm
fluid within cells
spontaneous generation
the living things arise form nonliving matter
cell theory
the theory that all things are made of cells
squamous
thin, flat, scaly shape, often with a huge bulge where the nucleus is
cuboidal
squarish-looking in frontal sections and about equal in height and width
columnar
distinctly taller than wide
polygonal
having irregularly angular shapes with four or more sides
stellate
having multiple pointed processes projecting from the body of a cell
spheroidal to ovoid
round to oval
discoid
disc-shaped
fusiform
spindle-shaped, elongated, with a thick middle and tapered ends
fibrous
long, slender, and threadlike
micrometer
one millionth of a meter, one thousandth of a millimeter
empty magnification
if enlargement fails to reveal any ore useful detail
scanning electron microscope (SEM)
produces dramatic three-dimensional images at high magnification and resolution
vascular corrosion
visually stunning application of SEM
plasma (cell) membrane
a microscopic membrane of lipids and proteins which forms the external boundary of the cytoplasm of a cell
organelles
diverse structures that perform various metabolic tasks for the cell
inclusions
foreign matter or stored cell products
cytosol or intracellular fluid (ICF)
clear gel inside the cytoskeleton, organelles, and inclusions
extracellular fluid (ECF)
fluids not contained in the cells
tissue fluid (intersitital)
the ECF located amid the cells
intracellular face
the side that faces the cytoplasm
extracellular face
side that faces outward
glycocalyx
a carbohydrate coating on the cell surface with multiple functions described shortly
integral proteins
penetrate into the phospholipid layer or all the way through it
transmembrane proteins
those that pass through completely through
peripheral proteins
do not protrude into the phospholipid layer but adhere to one face of the membrane
receptors
cell communicators
second-messenger systems
when a messenger binds to a surface receptor, it may trigger changes within the cell that produce a second messenger in the cytoplasm
enzymes
carry out the final stages of starch and protein digestion in the small intestine, help produce second messengers, and break down hormones and other signaling molecules
enzymes
carry out the final stages of starch and protein digestion in the small intestine, help produce second messengers, and break down hormones and other signaling molecules
channel proteins
proteins that move through channels
leak channels
channels that are always open and allow materials to pass through continually
gates (gated channels)
channels that open and close under different circumstances and allow solutes through at some times, but not others
ligand-gated channels
respond to chemical stimuli
voltage-gated channels
respond to changes in electrical potential across the plasma membrane
mechanically gated channels
respond to physical stress on a cell
channelopathies
defects in channel proteins are responsible for a family of disease
carriers
transmembrane proteins that bind to glucose, electrolytes, and other solutes and transfer them to the other side of the membrane
pumps
carriers that sometimes consume ATP in the process of transfer
cell-identify markers
glycoproteins contribute to the glycocalyx that enables our bodies to tell which cells belong to it and which are foreign invaders
cell-adhesion molecules
cells adhere to one another and to extracellular material through membrane proteins
G protein
named for the ATP-like chemical, guanosine triphosphate (GTP), from which they get their energy
adenylate cyclase
when activated by the receptor, a G protein relays the signal to another membrane protein
cyclic AMP
adenylate cyclase removes two phosphate groups from ATP and converts it to cAMP
kinases
cyclic AMP then activates cytoplasmic enzymes
glycocalyx
fuzzy coat made of the carbohydrate moieties glycolipids and glycoproteins
microvilli
extensions of the plasma membrane that serve primarily to increase a cell’s surface area
brush border
on some cells, they are very dense and appear as a fringe
terminal web
actin filaments attach to the inside of the plasma membrane at the tip of the microvillus, and at its base they extend a little way into the cell and anchor the microvillus to a protein mesh
primary cilium
a few micrometers long whose function is unknown
ciliopathies
cilia that are responsible for several hereditary disease
ventricles
internal cavities
efferent ductules
short ducts
power stroke
each cilium bends stiffly forward and produces a power stroke that pushes along the mucus or other matter
recovery stroke
occurs after a power stroke that restores it to the upright position, ready to flex again
chloride pumps
in the apical plasma membrane that produce the layer by pumping CI- into ECF
axoneme
the structural basis for ciliary movement
microtubules
an array of thin protein cylinders
basal body
anchors the cilium
dynein arms
helps the dynein “crawl” up the adjacent pair of microtubules
flagellum
the whip-like tail of the sperm
9+2 structure
two central microtubules surrounded by a ring of nine microtubule pairs
9+0 structure
the primary cilia, which cannot move, lack the two central microtubules but still have the nine peripheral pairs
pseudopods
cytoplasm-filled extensions of the cell varying in shape from fine, filamentous processes to blunt fingerlike ones
amoeba
a freshwater organism that crawls and captures food by means of pseudopods
neutrophils
white blood cells that crawl about like amebae by means of fingerlike pseudopods
macrophages
tissue cells that are derived from certain white blood cells-reach out with thin filaments pseudopods to snare bacteria and cell debris and “reel them in” to be digested by cleaned up
selectively permeable
allows some things through
carrier-mediated
use a membrane protein to transport substances from one side of the membrane to the other, but some transport processes do not involve carriers
simple diffusion
the net movement of particles from a place of high concentration to a place of lower concentration as a result of their constant, spontaneous motion
dialysis membranes
membranes in which dialysis diffusion occurs for kidney patients
temperature
diffusion is driven by the kinetic energy of the particles, and temperature is a measure of that kinetic energy
molecular weight
heavy molecules move more sluggish and diffuse more slowly
“steepness” of the concentration gradient
the steepness of a gradient refers to the concentration difference between two points
membrane surface area
the apical surface of cells specialized for absorption
membrane permeability
diffusion through a membrane depends on how permeable it is to the particles
osmosis
the net flow of water from one side of a selectively permeable membrane to the other
hydration sphere
formed by the accumulation of water on the high-solute side is that when water molecules encounter a solute particles
aquaporins
channel proteins for water
hydrostatic pressure
when water is heavier on one side than the other
osmotic pressure
when hydrostatic pressure is required on one side to halt osmosis
reverse osmosis
a process in which a mechanical pressure applied to one side of the system can override osmotic pressure
capillary filtration
the heart drives water out of the smallest blood vessels by reverse osmosis
osmolarity
osmotic concentration
milliosmoles per liter (mOsm/L)
a unit of measure that expresses the quantity of nonpermeating particles per liter of solution
tonicity
the ability of a solution to affect the fluid volume and pressure in a cell
hypotonic
a lower concentration of nonpermeating solutes than the intracellular fluid (ICF)
hypertonic
one with a higher concentration of nonpermeating solutes than the ICF
isotonic
total concentration of nonpermeating solutes is the same as in the ICF
carrier-mediated transport
a solute binds to a carrier in the plasma membrane, which then changes shape and releases the solute to the other side
specificity
when a certain enzyme carrier cannot transport their stuff
saturation
solute concentration increases
transport maximum
the carriers are saturated-no more are available to handle the increased demand and transport levels off at a rate
uniport
carries only one type of solute
cotransport
some carriers move two or more solutes through a membrane simultaneously in the same direction
symport
carrier protein that performs
countertransport
other carriers move two or more solutes in opposite directions
antiport
carrier protein during countertransport
sodium-potassium pump
continually removes Na+ from the cell and brings in K+
facilitated diffusion
carrier-mediated transport of a solute through a membrane down its concentration gradient
primary active transport
a process in which a carrier moves a substance through a cell membrane up its concentration gradient using energy provided by ATP
secondary active transport
requires an energy input, but depends only indirectly on ATP
regulation of cell volume
certain anions are confined to the cell and cannot penetrate the plasma membrane
resting membrane potential
all living cells have an electrical charge difference across the plasma membrane
heat production
when the weather turns chilly, we turn up not only the furnace in our home but also the “furnace” in our body
vesicular transport
move large particles, droplets of fluid, or numerous molecules at once through the membrane, contained in bubble like vesicles of membrane
vesicles
structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer
endocytosis
vesicular processes that bring matter into a cell
exocytosis
those that release material from a cell
phagocytosis
process of engulfing particles
phagosome
a vesicle in the cytoplasm surrounded by a unit membrane
phagolysosome
a lysosome merges with the phagosome, converting it to phagolysosome
pinocytosis
process of taking in droplets of ECF containing molecules of some use to the cell
pinocytotic vesicles
is a mode of endocytosis in which small particles suspended in extracellular fluid are brought into the cell through an invagination of the cell membrane,
clathrin
pit coated with a peripheral membrane protein
low-density lipoproteins
protein-coated droplets of cholesterol and other lipids of cholesterol and other lipids in the blood
clathrin coated vesicles
most prominent form of traffic from the plasma membrane to endosomes (endocytosis), a pathway by which ligands enter cells.
exocytosis
a process of discharging material from a cell
microfilaments (thin filaments)
about 6 nm thick and are made of the protein actin
terminal web (membrane skeleton)
fibrous mat on the cytoplasmic side of the plasma membrane
intermediate filaments
thicker and stiffer than microfilaments
microtubules
are cylinders made of 13 parallel strands called protofilaments
centrosome
microtubules radiate from an area of the cell
tubulin
each protofilament is a long chain of globular proteins
organelles
internal structures of a cell that carry out specialized metabolic tasks
membranous organelles
structures that are surrounded by membranes
nucleus
largest organelles and usually the only one clearly visible with the light microscope
anuclear
no nucleus
multinuclear
2-50 nuclei
nuclear envelope
double membrane
nuclear pore complex
ring of proteins
nuclear lamina
a narrow but densely fibrous zone composed of intermediate filaments
nuclear pores
structure that is made up of a collection of 30 different proteins called nucleoporins that assemble to form the complete nuclear pore complex (NPC).
chomatin
fine threadlike matter composed of DNA and protein
neucloli
one or more dark-staining masses
endoplasmic reticulum (ER) (little network within the cytoplasm)
interconnected channels called cisterns enclosed by a unit membrane
cisterns or cisternae
interconnected channels
rough ER
cisternae are parallel, flattened sacs covered with granules called ribosomes
smooth ER
cisternae are more tubular, branch more extensively and lack ribosomes
ribosomes
small granules of protein and RNA found in the nucleoli, in the cytosol, and on the outer surfaces of the rough ER and nuclear envelope
Golgi complex
a small system of cisternae that synthesize carbohydrates and put the finishing touches on protein and glycoprotein synthesis
Golgi vesicles
bud off the swollen rim of a cisterna and are abundant in Golgi complex
secretory vesicles
stores the cell product for later release
lysosome
a package of enzymes bounded by a membrane
autophagy
lysosomes also digest and dispose of surplus or nonvital organelles and other cell components in order to recycle their nutrients to more important cell needs
autolysis
the digestion of surplus cells by their own lysosomal enzymes
peroxisomes
resemble lysosomes but contain different enzymes and are produced by the ER rather than the Golgi complex
proteasome
protein disposal is the function of another structurally simple organelle
mitochondria
organelles specialized for synthesizing ATP
cristae
the inner membrane usually has folds that project like shelves across the organelle
matrix
the space between the cristae
centriole
short cylindrical assembly of microtubules, arranged in nine groups of three microtubules each
inclusions
two kinds, accumulated cell products and foreign bodies and other debris
