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cells
structural units of all living things
cells
basic structural unit of living organisms
collective activities of its cells
the activity of an organism depends on the _____
principle of complementary
what principle states that the activities of the cell are dictated by their structure
structure (anatomy)
the activities of cells are dictated by their _______
every disease
the loss of cell homeostasis underlies _________
60 percent water
living cells are about0 ______ percent water
generalized cell
demonstrates the typical features of the cell
plasma membrane, nucleus, and the cytoplasm
main regions of the cell
nucleus
is the control center of the cell
DNA
the genetic material
self-destruct
a cell that has lost of ejected its nucleus is destined to ___________
nuclear envelope or membrane
double membrane barrier of the nucleus
more freelly
substances may pass through the nuclear envelope much __________ than elswhere because of its relatively larger pores
nucleoplasm
the nuclear membrane encloses a jellylike fluid called
nucleolus, nucleoli
_____ contains one or more small, dark-staining, essentially round bodies called _____
ribosomes
nucleoli are sites where cell structures called ____________ are assembled
chromatin
a loose network of “beads on a string’ (DNA) around proteins called “histones”
chromosomes
in cell division, chromatin forms dense, rodlike bodies called _________ as the chromatin threads coil
plasma membrane
transparent barrier that contains cell contents and separates them from the surrounding environment
fluid mosaic model
showcases the two phospholibid bylayer or the plasma membrane
glycolipids
what do you call the phospolipids with sugar group attached to them
phospholipid molecule heads
they lie on both the inner and outer surfaces of the cell as water is prominent or a main component of both intracellular and extracellular fluids
nonpolar fatty acid tails
these avoid water and line up in the center of the membrane
water soluble
the hydrophobic makeup of the membrane interior makes the plasma membrane relatively impermeable to most ________
cholesterol
helps stabilize the plasma membrane and keep it flexible
proteins
responsible for the most specialized functions of the membrane
enzymes
some proteins are enzymes
proteins protruding from the surface of the cell
______ are receptors for hormones or other
chemical messengers or are binding sites for
anchoring the cell to fibers or to other structures inside or outside the cell
transport
Most proteins that span
the membrane are involved in
channels (tiny pores)
some cluster together to form protein ______ through which water and small
water-soluble molecules or ions can move
carriers
other proteins act as ________ that bind to a substance and move it through the membrane.
glycoproteins, glycocalyx
because of their presence,
the cell surface is a fuzzy, sticky, sugar-rich area called ______
glycoproteins
determine your blood type, acting as receptors that certain bacteriam viruses, or toxins can bind to, and play a role in cell-to-cell recognition and interactions
epithelial cells
Although certain cell types—blood cells, sperm cells, and some phagocytic cells (which ingest bacteria and foreign debris)—are “footloose” in the body, many other types, particularly ______, are knit into tight communities.
glycoproteins
act as an adhesive or cellular glue
wavy contours
___________ of the membranes of adjacent cells fit together in a tongue and groove fashion
tight junctions
impermeable junctions that encircle the cells and bind them together into leakproof sheets
tight junction
In ______, adjacent
plasma membranes fuse together tightly
like a zipper and prevent substances from
passing through the extracellular space betweencells
tigh junctions
inn the small intestine, for example,
these junctions prevent digestive enzymes from seeping into the bloodstream.
desmosomes
anchoring junctions scattered like rivets along the sides of adjacent cells
desmosomes
prevent cells subjected to mechanical streess (heart muscle cells and skin cells) from being pull apart
gap junctions or communicating junctions
these junctions allow communication and are commonly found between embryonic cells and in the heart
connexons, transmembrane proteins
In gap junctions, the neighboring cells are connected by hollow cylinders composed of
proteins (called _______) that span the
entire width of the abutting membranes
(which are therefore called _____).
cytoplasm
cellular material outside the nucleus
cytoplasm
site of most cellular activities
cytosol
semitransparent fluid that suspends other elements of the cell
inclusions
chemical substances tha tmay or may not be present depending on the specific cell, where stored nutrients and cell products float around (lipid droplets common in fat cells, glycogen granules abundant in liver and muscle cells, pigments such as melanin and hair cells, this is where items are kept on hand until needed
organelles
specialized cellular compartments that are the metabollic machinery of the cell
mitochondria
enzymes dissolve in fluid within the mitochondria, carry the reactions where ozygen are used to break down food an d in this process, some energy escapes and is used to make ATP molecules
ribosomes
site of protein synthesis
ribosomes that float freely in the cytoplassm
manufacture proteins that function inside the cell and produces proteins that functon outside the cell
endoplasmic reticulum
continuous with the nuclear membrane; It serves as a mini circulatory system for the cell because it provides a network of channels for carrying substances (primarily proteins) from
one part of the cell to another.
rough
ER that is studded with ribosomes
rough ER
membrane factory
proteins
The _____ made on its ribosomes
migrate into the rough ER tunnels, where they fold
into their functional three-dimensional shapes.
transport vesicles
the proteins made in th rough er then are dispatched to other aread of the cell in small sacs of membrane called ______
pancreas
rough er is abundant in cells that make and export proteins such as,
smooth er
because it lacks ribosome, it functions in lipid metabolism and detoxification of drugs and pesticides
liver, male testes that manufacture testosterone
smooth er are abundant in what cells
golgi apparatus
Its
major function is to modify, package, and ship
proteins (sent to it by the rough ER via transport
vesicles) in specific ways, depending on their final
destination
secretory vesicles
As proteins “tagged” for export accumulate in
the Golgi apparatus, the sacs swell. Then their
swollen ends, filled with protein, pinch off and
form ________ which travel
to the plasma membrane. When the vesicles reach
the plasma membrane, they fuse with it, the membrane
ruptures, and the contents of the sac are
ejected to the outside of the cell
lysosomes
Because lysosomal enzymes are capable
of digesting worn-out or nonusable cell structures
and most foreign substances that enter the cell,
________function as cellular “stomachs.”
white blood cells
lysosomes are abundant in ____
peroxisomes
are membranous sacs containing powerful oxidase
enzymes that use molecular oxygen
(O2) to detoxify a number of harmful or poisonous
substances, including alcohol and formaldehyde.
peroxisomes
their most important function is to
“disarm” dangerous free radicals. Free radicals
are highly reactive chemicals with unpaired electrons
that can damage the structure of proteins
and nucleic acids. Free radicals are normal byproducts
of cellular metabolism, but if allowed to
accumulate, they can have devastating effects on
cells
microfilaments
most involved in cell motility and in producing changes in cell shape
intermediate filaments
are strong stable and help desmosomes provide internal guy wires
microtubules
made up of repeating subunits of protein tubulin and determine the overall shape of the cell ; very important in cell division
centrioles
centrosome; generate microtubules and direct the formation of mitoic spindle curing cell division
cilia
whiplike cellular extensions that move substances along the cell surface
flagella
if the projections formed by the centrioles are longer, they are called
sperm cell
the only known flagellated cell
microvilli
They increase the cell’s surface
area tremendously and so are usually found on
the surface of cells active in absorption such as
intestinal and kidney tubule cells.
fibroblast
This cell has an elongated
shape, like the cable-like fibers that it secretes.
It has an abundant rough ER and a
large Golgi apparatus to make and secrete
the protein building blocks of these fibers.
erythrocyte
This cell carries
oxygen in the blood. Its biconcave disc
shape provides extra surface area for the
uptake of oxygen and streamlines the cell
so it flows easily through the bloodstream.
So much oxygen-carrying pigment is
packed in these that all other organelles
have been shed to make room.
fibroblast and erythrocytes
cells that connect body parts
epithelial ; cells that cover and line body organs
The hexagonal shape of this
cell is exactly like a “cell” in a honeycomb
of a beehive. This shape allows epithelial
cells to pack together in sheets. An epithelial
cell has abundant intermediate filaments
and desmosomes that resist tearing when
the epithelium is rubbed or pulled.
• Cells that move organs and body parts
cells that move organs and body parts :
Skeletal, cardiac, and smooth muscle cells.
These cells are elongated and filled with
abundant contractile filaments, so they can
shorten forcefully and move the bones,
pump blood, or change the size of internal
organs to move substances around the body
fat cells; cells that store nutrients
The huge spherical shape of a fat
cell is produced by a large lipid droplet in
its cytoplasm.
white blood cells such as the macrophage; cells that fights diseases
This cell extends long pseudopods
(“false feet”) to crawl through tissue
to reach infection sites. The many lysosomes
within the cell digest the infectious microorganisms
(such as bacteria) that it “eats.”
nerve cell ; cells that gather information and controls body functio
This cell has long processes
(extensions) for receiving messages
and transmitting them to other structures
in the body. The processes are covered
with an extensive plasma membrane, and
a plentiful rough ER synthesizes membrane
components and signaling molecules called
________
oocyte ; egg cell
The largest cell in the
body, this egg cell contains several copies
of all organelles, for distribution to the daughter cells that arise when the fertilized egg divides to become embryo
sperm cell
This cell is long and streamlined,
built for swimming to the egg for
fertilization. Its flagellum acts as a motile
whip to propel the sperm.
diffusion
the process by which
molecules (and ions) move away from areas where
they are more concentrated (more numerous) to
areas where they are less concentrated (with fewer
of them).
simple diffusion
The unassisted diffusion of solutes through
the plasma membrane (or any selectively permeable
membrane) is called
osmosis
Diffusion of water through a selectively permeable
membrane such as the plasma membrane is
specifically called
facilitated diffusion
provides
passage for certain needed substances (notably
glucose) that are both lipid-insoluble and too large
to pass through the membrane pores, or charged,
as in the case of chloride ions passing through a
membrane protein channel/protein carrier
filtration
is the process by which
water and solutes are forced through a membrane
(or capillary wall) by fluid, or hydrostatic, pressure.
In the body, hydrostatic pressure is usually
exerted by the blood. Like diffusion, _____ is a
passive process, and a gradient is involved. In f______,
however, the gradient is a pressure gradient
that actually pushes solute-containing fluid
from the higher-pressure area through
the filter to the lower-pressure area.
active ; solute pumping
Whenever a cell uses ATP to move substances
across the membrane, the process is
active transport
uses ATP to energize its
protein carriers, which are called solute pumps