Membrane transport ppt BIOCHEMISTRY
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Transcript of Membrane transport ppt BIOCHEMISTRY
MEMBRANE TRANSPORT
Dr. Vijay Marakala, MBBS, MD.
Assistant professor BIOCHEMISTRY SIMS & RC
MEMBRANE TRANSPORT• Cell membrane is the boundary between inside &
outside…
IN foodcarbohydratessugars, proteinsamino acidslipidssalts, O2, H2O
OUT wasteammoniasaltsCO2
H2O products
IN
OUT
Can it be an impenetrable boundary? NO!
MEMBRANE TRANSPORT• Biological membrane are semipermeable
Channel proteins
Carrier proteins
Lipid bilayer interstices
Passive transport Active
transport
PASSIVE TRANSPORT• Transport of solute molecules from high concentration to low
concentration across membrane• It is a down hill transport and requires no energy
Simple diffusion
Facilitated diffusion
2 types
SIMPLE DIFFUSION• Move from HIGH to LOW concentration
– “passive transport”– no energy needed
Diffusion
Through the channel protein and lipid bilayer
interstices.E.g., Transport of O2, CO2, N2, ethanol and
urea
SIMPLE DIFFUSION
Passive transport protein
Lower concentration
Higher concentration of
Protein channel
FACILITATED DIFFUSION
E.g., Transport of glucose and most amino acids
Through carrier protein
conformational change
ACTIVE TRANSPORT• Molecule moves against a concentration gradient.• Needs an external energy (ATP)
Primary active transport• Energy is derived directly from hydrolysis of
ATP
Secondary active transport• ATP provides the energy for transport
indirectly
Two types
PRIMARY ACTIVE TRANSPORT
Sodium-Potassium pump
High Na+
Low Na+
Low K+
High K+
SECONDARY ACTIVE TRANSPORT• ATP provides the energy for transport indirectly.• Uses an energy of an electrochemical gradient or membrane
potential produced originally by primary active transport process by using ATP
Co-transport or Symport
Both the substances move across in same direction
Sodium- glucose cotransport
Counter transport or antiport
Each substance moves in opposite direction
Sodium-calcium counter transport
VOLTAGE GATED CHANNELS
Voltage gated channels are opened by membrane depolarization
Membrane potential change (voltage difference) switches the ion channel to open
Voltage gated sodium channels
Voltage gated potassium channels
IONOPHORE
TRANSPORT OF MACROMOLECULES
ENDOCYTOSISPinocytosis
(cellular drinking)
Phagocytosis (cellular eating)
EXOCYTOSIS
Exocytic vesicles
Vesicle forming
ENDOCYTOSIS
Vesicle
Fluid outside cell
Protein
Cytoplasm
EXOCYTOSIS
AQUAPORINS• Water moves rapidly into & out of cells
– evidence that there were water channels
1991 | 2003
Peter AgreJohn Hopkins
Roderick MacKinnonRockefeller