3 Cells Flashcards
cell
the structural and functional unit of all living things
the structural and functional unit of all living things
cells
the three major regions/parts of all animal cells
nucleus
plasma membrane
cytoplasm
nucleus
plasma membrane
cytoplasm
the three major regions of all animal cells
the fluid between the cells
interstitial fluid
interstitial fluid
the fluid between the cells
orientation of the three main regions of the generalized cell
the nucleus is located near the center
it is surrounded by the semifluid cytoplasm
which in turn is enclosed by the plasma membrane which forms the outer cell boundry
nucleus
the control center of the cell; site of DNA
the control center of the cell
nucleus
what part of the cell is the site of the genes (DNA)?
nucleus
what is like the blueprint that contains all of the instructions needed for building the whole body?
DNA
what has the instructions for building proteins?
DNA
what happens to a cell that has lost or ejected its nucleus?
it is programmed to die
what are the three recognizable regions of the nucleus?
nuclear envelope
nucleoli
chromatin
nuclear envelope
nucleoli
chromatin
the three recognizable structures of the nucleus
what is bounded by the double membrane barrier of the nuclear membrane (nuclear envelope)?
the nucleus
nuclear membrane
binds the nucleus in its porous double barrier
binds the nucleus in its double barrier
nuclear membrane
the nucleus is bounded by what?
a double layer porous membrane called the nuclear membrane (nuclear envelope)
another name for nuclear membrane
nuclear envelope
another name for nuclear envelope
nuclear membrane
what is between the two membranes of the nuclear envelope?
a fluid-filled space (like a moat)
at various points where the two layers of the nuclear membrane fuse, what penetrates through the fused regions?
nuclear pores
nuclear pores
tiny holes in the double wall of the nuclear membrane
what is the jelly-like fluid in which nuclear elements are suspended
nucleoplasm
nucleoplasm
enclosed by the nuclear membrane; the jelly-like fluid in which other nuclear elements are suspended
nucleoli
one or more small, dark staining round bodies in the nucleus; the sites where ribosomes are assembled
one or more small, dark staining round bodies in the nucleus
nucleoli
assembly site for ribosomes
nucleoli
protein-synthesizing “factories”
ribosomes
ribosomes
assembled in the nucleoli and particularly abundant in the cytoplasm; protein-synthesizing “factories”
where are ribosomes particularly abundant?
the cytoplasm
what do the large nuclear pores of the nuclear membrane permit?
permit large molecules such as protein and RNA molecules to pass easily
the nuclear membrane is similar to other membranes except for what?
except it has particularly large nuclear pores to allow large molecules such as protein and RNA molecules to pass easily
when a cell is not dividing, its genetic material is in a threadlike form called this
chromatin
chromatin
the threadlike form a cells genetic material is in when it is not dividing
where is chromatin located?
it is scattered throughout the nucleus
what happens to chromatin when the cell is dividing to form two daughter cells?
the chromatin threads coil and condense to form dense, rodlike bodies called chromosomes
plasma membrane
the flexible, fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment
the flexible, fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment
plasma membrane
what does the structure of the plasma membrane consist of?
two lipid (fat) layers arranged “tail to tail” in which protein molecules float
the structure of this is two lipid (fat) layers arranged “tail to tail” in which protein molecules float
plasma membrane
why is the plasma membrane described in a “fluid mosaic model”?
because the proteins, some of which are free to move, form a constantly changing pattern, or mosaic
most of the lipid portion of the plasma membrane is what?
phospholipids (some with attached sugar groups)
besides phospholipids, a substantial amount of what else is found in the plasma membrane?
cholesterol
the general function of nucleoli?
nucleoli are the sites of synthesis of ribosomes, which are important in protein synthesis
what orients the polar heads and nonpolar tails of the phospholipid molecules in the lipid bilayer of the plasma membrane?
the polar heads are hydrophilic and orient outward and inward toward the intracellular and extracellular fluids; the nonpolar tails are hydrophobic and line up oriented inward
what does the cholesterol help do in the plasma membrane?
keeps the membrane fluid
what is the advantage of the hydrophilic/hydrophobic orientation of the phospholipids of the plasma membrane?
the self-orienting properties allow the membranes to reseal themselves when torn; makes the membrane relatively impermeable to most water-soluble molecules
what are responsible for most of the specialized functions of the plasma membrane?
the proteins scattered in the lipid bilayer
besides protecting the cell, what else does the plasma membrane do?
determines which substances may enter or leave the cell and in what amount
what determines which substances may enter or leave the cell and in what amount?
plasma membrane
most proteins that span the plasma membrane are involved in what activity?
transport
what is the major building material of the cell?
protein
living matter is over 60% what?
water
what percent of living matter is water?
60%
a cell is composed of primarily which elements?
C Carbon
H Hydrogen
O Oxygen
N Nitrogen
what is the plasma membrane composed of?
a lipid bilayer containing proteins
what kind of proteins are many of the proteins in the lipid bilayer of the plasma membrane?
glycoproteins
what do the proteins in the plasma membrane do?
Act as enzymes or carriers in membrane transport
Form membrane channels
Provide receptor sites for hormones & other
chemicals (inc. bacteria, virus, toxins)
Play a role in cell-to-cell recognition & interactions
during development and immune reactions
glycoprotein
branching sugar groups attached to most of the proteins abutting the extracellular space “sugar-proteins”
branching sugar groups attached to most of the proteins abutting the extracellular space
glycoproteins
“sugar-proteins”
glycoproteins
create a fuzzy, sticky, sugar-rich area on the cell surface called glycocalyx
glycoproteins
what is the purpose of protein channels (tiny pores formed by clustered proteins) in the plasma membrane?
water and small water-soluble molecules or ions can move through
the three ways cells are typically bound together
Glycoproteins in the glycocalyx act as an adhesive
Wavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion
Special membrane junctions are formed which vary structurally depending on their roles
glycocalyx
the fuzzy, sticky, sugar-rich surface of the plasma membrane caused by the presence of glycoproteins
the three common types of membrane junctions
Tight junctions
Desmosomes
Gap junctions
Impermeable junctions that bind cells together into leak-proof sheets that prevent substance from passing through the extracellular space between cells.
Tight junctions
Tight junctions
Impermeable junctions that bind cells together into leak-proof sheets that prevent substance from passing through the extracellular space between cells.
In these types of membrane junctions, adjacent plasma membranes fuse together tightly like a zipper.
Tight junctions
In the small intestine, these types of membrane junctions prevent digestive enzymes from seeping into the bloodstream.
Tight junctions
Desmosomes
Anchoring membrane junctions scattered like rivets along the sides of abutting cells.
Anchoring membrane junctions scattered like rivets along the sides of abutting cells.
Desmosomes
what type of membrane junctions prevent cells subjected to mechanical stress (like skin cells) from being pulled apart?
Desmosomes
Structurally, these membrane junctions are buttonlike thickenings of adjacent plasma membranes (plaques), which are connected by fine protein filaments
Desmosomes
desmosomes, structurally
membrane junctions are buttonlike thickenings of adjacent plasma membranes (plaques), which are connected by fine protein filaments. Thicker protein filaments (“guy wires”) form the internal connection between the inner walls.
In desmosomes, Thicker protein filaments extend from the plaques inside the cells to the plaques on the cell’s opposite sides, forming an internal system of strong ________________
strong “guy wires”.
“guy wires”
In desmosomes, Thicker protein filaments extend from the plaques inside the cells to the plaques on the cell’s opposite sides, forming an internal system of strong “guy wires”
gap junctions
the neighboring cells are connected by hollow cylinders composed of proteins (called connexons) that span the entire width of the abutting membranes
in these membrane junctions, the neighboring cells are connected by hollow cylinders composed of proteins that span the entire width of the abutting membranes
gap junctions
connexons
in gap junctions, hollow cylinders composed of proteins create water-filled channels that span the entire width of the abutting cell
in gap junctions, hollow cylinders composed of proteins create water-filled channels that span the entire width of the abutting cell
connexons
what kind of membrane junctions function mainly to allow communication?
gap junctions
what kind of membrane junctions are commonly seen in the heart and between embryonic cells?
gap junctions
In which membrane junctions can chemical molecules, such as nutrients or ion, pass directly through the water-filled connexon channels from one cell to another?
gap junctions
microvilli
tiny finger-like extensions of the plasma membrane that project from an exposed cell surface to increase the surface area of the cell for absorption
tiny finger-like extensions of the plasma membrane that project from an exposed cell surface to increase the surface area of the cell for absorption
microvilli
