The Cell - Anatomy and Physiology Laboratory Flashcards
fundamental unit of life
cell
Cells of the human body are classified as
eukaryotic
is a thin phospholipid bilayer in which
various proteins are embedded or attached
plasma membrane
hydrophilic
water-loving
hydrophobic
water-fearing
The phospholipids are composed of
hydrophilic (“water-loving”) phosphate heads and hydrophobic (“water-fearing”) lipid tails.
Two types of proteins are associated with the phospholipid bilayer:
Integral proteins and peripheral proteins
are embedded at least partially within
the cell membrane
integral proteins
are located on the interior or exterior surface of the cell membrane.
peripheral proteins
Some integral proteins, called _________________________, span the entire width of the phospholipid bilayer.
transmembrane proteins
A plasma membrane is
selectively permeable
allows the passage of some substances but not others
selectively permeable
Nonpolar molecules such as_____________________________________ pass freely through the membrane
oxygen, carbon dioxide, and steroid hormones
water-soluble substances, such as _____________________________________________ are unable to pass freely through the membrane.
amino acids, sugars, proteins, nucleic acids, and many ions
can serve as transport channels through which substances move from one side of the membrane to the other.
Integral proteins
Cells depend on the ____________________ to import substances such as nutrients, oxygen, and hormones, and to export substances such as carbon dioxide and other waste products.
selectively permeable plasma membrane
Both integral and peripheral proteins can serve as _______________________ and they also play major roles in cell-to-cell recognition and intercellular joining.
receptors and enzymes
A cell’s membrane transport mechanisms are of two types:
passive and active
in which substances cross the membrane without the cell expending any energy,
passive
requires the cell to expend energy in the form of the high-energy molecule ATP.
active
Among passive transport mechanisms the most common
are
diffusion and osmosis
Passive transport mechanisms can be either
unassisted or assisted
The unassisted net movement of molecules from an area of higher concentration to an area of lower concentration is called
simple diffusion
requires the assistance of either a channel protein (channel- mediated facilitated diffusion) or a carrier protein (carrier-mediated facilitated diffusion)
facilitated diffusion
assistance of a channel protein
channel- mediated facilitated diffusion
assistance of a carrier protein
carrier-mediated facilitated diffusion
is a special type of diffusion involving the passive movement of a solvent (usually water) from an area of higher water concentration (and thus lower solute concentration) to an area of lower water concentration (and thus higher solute concentration) across a selectively permeable membrane, either through the phospholipid bilayer or through a specific channel protein called an aquaporin
Osmosis
substances are driven through a selectively permeable membrane by hydrostatic pressure.
filtration
Two common energy-requiring transport mechanisms are termed
active transport and vesicular transport
is the movement of molecules from an area of lower concentration to an area of higher concentration and is accomplished with the expenditure of energy.
Active transport
is a classic example of an active transport mechanism
sodium-potassium pump
of a cell consists of a variety of specialized structures called organelles suspended in a fluid portion called the cytosol, which is largely water containing a variety of solutes such as sugars, proteins, and ions. Organelles perform specific functions to maintain homeostasis within the cell.
cytoplasm
is largely water containing a variety of solutes such as sugars, proteins, and ions.
cytosol