MODULE 3 | Transport Mechanisms through Membranes Flashcards
is
generally not permeable to
proteins, nucleic acids, and
other molecules needed for
the structure and function of
the cell
Plasma membrane
• is the net movement of molecules and ions across a
membrane from higher to lower concentration
(down a concentration gradient)
PASSIVE TRANSPORT
• does not require metabolic energy
PASSIVE TRANSPORT
Examples/types of passive transport:
a) DIFFUSION
b) OSMOSIS
c) FACILITATED DIFFUSION
Solutes, such as ions or molecules, tend to
move from an area of higher concentration of
a solute to an area of lower concentration of
that same solute in solution.
Diffusion
•This movement occurs as a result of the
random and constant motion characteristic of
all molecules, and is independent from the
motion of other molecules.
Diffusion
is the diffusion of water across a
selectively permeable membrane, such as
the cell membrane, from a region of higher
water concentration to the area of lower
water concentration
Osmosis
is the diffusion of solutes through channel
proteins in the plasma membrane. Water can
pass freely through the plasma membrane
without the aid of specialized proteins.
FACILITATED DIFFUSION
• The movement of substances across the cell membrane
from regions of lower concentration to those of higher
concentration against a concentration gradient.
ACTIVE TRANSPORT
Requires metabolic energy
ACTIVE TRANSPORT
Active Transport is achieved through:
a) Protein Pumps
b) Vesicular Transport
1. Endocytosis
2. Exocytosis
Transport
proteins in the plasma membrane
transfer solutes such as small ions
(Na+, K+, Cl-, H+), amino acids,
and monosaccharides.
Protein Pumps
Vesicles or other bodies in
the cytoplasm move macromolecules or large particles
across the plasma membrane.
VESICULAR TRANSPORT
•Types of vesicular transport
•Endocytosis
•Exocytosis
is the uptake of material through
the cell membrane by the formation of a vesicle.
Endocytosis
