3.5 Active Transport, Endocytosis, and Exocytosis
KEY CONCEPT Cells use energy to transport materials
that cannot diffuse across a membrane.
Active Transport
Defined: Molecules move from a LOW to a HIGH
concentration
ATP energy opens/closes protein channel
• ATP = Adenosine Triphosphate
Acts like a pump
3.5 Active Transport, Endocytosis, and Exocytosis
Active transport requires energy input from a cell
and enables a cell to move a substance against its
concentration gradient.
• Passive transport requires no energy from the cell.
• Active transport is
powered by chemical
energy (ATP).
• Active transport occurs
through transport protein
pumps.
• Cells use active transport
to maintain homeostasis.
3.5 Active Transport, Endocytosis, and Exocytosis
A cell can import and export large materials or large
amounts of material in vesicles during the
processes of endocytosis and exocytosis.
• Cells use energy to transport material in vesicles.
• Endocytosis is the process of
taking material into the cell.
• Phagocytosis is a type of
endocytosis.
Endocytosis
Endocytosis: Process in which the plasma membrane
takes in substances (2 types)
• 1) Phagocytosis: when a cell engulfs a solid particle
• 2) Pinocytosis: when a cell engulfs a liquid particle
Unfortunately, viruses can also enter our cells this way
Endocytosis & the lysosome
3.5 Active Transport, Endocytosis, and Exocytosis
A cell can import and export large materials or large
amounts of material in vesicles during the
processes of endocytosis and exocytosis.
• Cells use energy to transport material in vesicles.
• Exocytosis is the process of
expelling material from the
cell.
Exocytosis
Defined: Process when substances are expelled
from the cell
Proteins, nutrients, and waste exit by exocytosis
Vesicle carry & release objects through the
plasma membrane
Contractile vacuole of a Paramecium
Water being pumped out of this
cell to prevent bursting
Quick Review
Diffusion is the
movement of particles
from high to low
concentrations
Some methods of
movement don’t require
energy (Passive
Transport)
Some methods of
movement require
energy (Active
transport)
Farts smell because of
diffusion