MEMBRANE TRANSPORT Flashcards
Cells use different mechanisms
to transport molecules across
the plasma membrane based on
- energy requirements
- nature of the molecules being transportedf
two main types of membrane transport within the cell
active and passive transport
The membrane remains flexible due to phospholipid movement and cholesterol
regulation.
fluidity
The inner and outer layers contain different proteins and lipid compositions suited for
distinct functions.
asymmetry
Importance of glycoprotein, glycolipid, peripheral protein, and integral protein
- Allows dynamic changes for growth,
division, and signaling. - Enables membrane transport by
controlling the movement of
molecules. - Supports cell recognition and immune
responses.
[IMPORTANCE]
Allows dynamic changes for _____, _____, and _________.
growth
division
signalling
Enables _____ ________ by
controlling the movement of
molecules.
membrane transport
refers to
the movement of substances
across cell membranes, a crucial
process for maintaining cellular
function and homeostasis,
involving both passive and active
mechanisms.
membrane transport
relies on concentration
gradients, allowing molecules to move
from high to low concentration without
ATP input.
passive transport
concentration gradient
high to low concentration
moves molecules against
their concentration gradient (low → high
concentration) and requires ATP or
another energy source.
active transport
types of passive transport
- simple diffusion
- osmosis
- facilitated diffusion
Molecules Transported in Simple Diffusion:
Oxygen
(O2), Carbon dioxide (CO2), small
lipids.
Example: Oxygen diffuses into
cells during respiration, while CO2
diffuses out.
simple diffusion
the passive movement of water
molecules across a semi-
permeable membrane.
osmosis
direction of movement in osmosis
Water
moves from a region of low
solute concentration to high
solute concentration.
3 types of solution in osmosis
- hypertonic
- isotonic
- hypotonic
High solute outside
Water exits cell
Cell shrinks
hypertonic
Equal solute
No net water movement
Cell remains stable
isotonic
Low solute outside
Water enters cell
Cell swells and may burst
hypotonic
The passive movement of Passive Transport
molecules through a membrane
protein (carrier or channel) since
they cannot pass through the
lipid bilayer directly.
facilitated diffusion
molecules transported in facilitated diffusion
glucose, amino acids, ions
- Glucose transporters (GLUT)
help glucose enter cells. - Ion channels (Na+, K+, Cl−)
regulate nerve impulses.
examples of facilitated diffusion
Transport proteins (pumps) use
ATP to move molecules directly
against the gradient.
primary active transport
