passive and active transport
TRANSCRIPT
Passive and Active Transport
Passive and Active Transport
FOS 3 Infectious Disease Unit
FOS 3 Infectious Disease Unit
Homeostasis When organisms adjust internally to
changing external environments One way to maintain homeostasis is by
controlling the movement of substances across the cell membrane.
Transport Across Membranes
Active transport is pumping against the concentration gradient
3 types of Passive TransportDiffusion, Osmosis and Facilitated Diffusion
Diffusion Diffusion is movement from an area of high
concentration to low concentration Diffusion is passive transport: NO energy is
required!
Passive Transport- Diffusion Oxygen, Carbon
dioxide, water and amino acid molecules are small enough to diffuse.
Proteins, carbohydrates, and other ions are too large to diffuse.
Passive Transport-Diffusion
Passive Transport
Simple Diffusion Across Bilayers
Pas
sive
Tra
nsor
t- O
smos
isMore water
Less water
Osmosis: Water down Conc. Gradient
Tonicity
More solute in than out
Passive Transport- Facilitated Diffusion
Some ions diffuse through channel proteins. The pores can always be open or open in response to a stimulus. No energy is required so this is still passive transport.
Passive Transport- Facilitated Diffusion
Passive Transport- Facilitated Diffusion
Passive Transport- Facilitated Diffusion Transport of substances through the cell
membrane down a concentration gradient aided by carrier or channel proteins.
Active Transport Transport against the concentration
gradient that requires energy
Active Transport: Sodium-Potassium Pump
Electrochemical Gradient An electrochemical gradient is a
concentration gradient with ions: These ions want to move down their
concentration gradient These ions also want to move towards the
opposite charge found on the other side of the membrane.
This attraction for the other side of the membranes (membrane potential) can be harnessed to do work.
Active Transport- Electrogenic Pump
Active Transport- Cotransport
Movement “Across” Membrane
Endocytosis and Exocytosis These are mechanisms that involve
movement into and out of the lumen of the endomembrane.
NOT movement directly across the membrane
Substances enter the endomembrane system but not the cytoplasm!
Endocytosis Phagocytosis
Taking up solids Allows digestion in confined space
Phagocytosis Pictures
Exo
cyto
sis
Hormones Chemicals secreted by cells that act to
regulate the activity of other cells in the body.
Four Functions: Regulate processes, like growth and
development Coordinate production, use and storage of
energy. Maintaining Homeostasis React to stimuli outside the body
Hormones Two types:
Amino Acid Hormones Steroid Hormones
Lipid hormones
Hormones- Amino Acid How they work:
Bind to a receptor protein on the Cell Membrane, the receptor membrane changes shape
The shape changes causes a second messenger which causes a change in the target cell
Hormones-Steroid Hormones How it works:
Steroid Hormone is release, it diffuses through the cell membrane
There is a hormone receptor in the cytoplasm. The hormone and receptor bind
The hormone receptor complex enters the nucleus and either activates or inactivates transcription of a gene.
Insulin Insulin Receptors in cell membranes are
transmembrane receptors Insulin binds and activates the receptor This increases the affinity for glucose
transporters and allows more glucose into the cell.