Membranes and Protein Trafficking: Part 1 - The Plasma Membrane PDF

Membranes and Protein trafficking: Part 1 The Plasma membrane  are enrolled University. Membranes and Protein trafficking– part 1 The plasma membrane LO: Understand the basic composition of the plasma membrane and transport of molecules across.  The plasma membran...

Membranes and Protein trafficking: Part 1 The Plasma membrane  are enrolled University. Membranes and Protein trafficking– part 1 The plasma membrane LO: Understand the basic composition of the plasma membrane and transport of molecules across.  The plasma membrane Plasma membrane Cell Biology Figure 1.2  The plasma membrane https://www.khanacademy.org/science/ap-biology/cell-structure-and-function/plasma-membranes  Lipids The main constituents of membrane bilayers are Phosphoglycerides (also called glycerophospholipids) The alcohol head groups give phosphoglycerides their names: phosphatidic acid [PA] (no head group) phosphatidylglycerol [PG] (glycerol head group) phosphatidylethanolamine [PE] (ethanolamine head group) phosphatidylcholine [PC] (choline head group) phosphatidylserine [PS] (serine head group) phosphatidylinositol [PI] (inositol head group) Cell Biology Figure 13.2  Integral membrane proteins Transport of metabolites and communication of information across otherwise impermeable membranes is mediated by integral membrane proteins These membrane- spanning proteins represent ~25% of protein- coding genes in all organisms and they serve numerous crucial functions, including: ion and nutrient transport, signalling, pathogenesis, defence and adhesion Cell Biology Figure 13.9 Hegde RS, Keenan RJ. The mechanisms of integral membrane protein biogenesis. Nat Rev Mol Cell Biol. 2022 Feb;23(2):107- 124. doi: 10.1038/s41580-021-00413-2. Epub 2021 Sep 23. PMID: 34556847.  Hydrophobic chains can anchor a protein to a membrane by inserting into the lipid bilayer Cell Biology Figure 13.10  The plasma membrane transport Proton pump (chemiosmosis): Uses ATP. moves protons (H+) out of cell from low to high concentration. ATP-binding cassette (ABC) transporters: are an example of ATP-dependent pumps. These pumps can move substrates in (influx) or out (efflux) of cells. Sodium-potassium pump: Moves 3 Na + out of cell & 2 K+ into cell. Both Na+ and K+ are moved from low to high concentration. Na-Cl carrier: It transports calcium out of the cell in exchange for sodium ions, typically in the ratio 3 Na+ to 1 Ca2+, driven by the electrochemical gradient for Na+ across the plasma membrane K-channel: potassium channels have an essential role in neuronal excitability, duration of action potential, secretion of hormones, smooth muscle relaxation, and From: Cell Biology repolarization of cardiac muscles  Membrane pumps Pumps are enzymes that use energy from adenosine triphosphate (ATP) (active transport), or light to move ions and other solutes across membranes at relatively modest rates Cell Biology Figure 21.25  Membrane carriers Uniporter = one compounds Antiporter = exchange two compounds in opposite direction Cell Biology Figure 15.1  Membrane channels Cell Biology Figure 16.5  CONNECT 0 /flindersunlversity O@flinders ® @flindersu niversity CD)school/f Iinders-university/ O@flindersuniversity l=linders University a c k nowled ges the Traditional Own ers a n d Custodians of the lands ,on which its c a m pus es a re located , t h es e a re t h e Traditional Lands of the Arremte, Dagoma111 First !Nations of the South East, First Peoples of the River Murray & Mallee region, J a w o yn , K a u r n a , h r r a k i a , Ngadjuri, Ngarrindje i, Ramindjeri, Wa ru m u n gu , Wardaman and Yolngu people. W e honour their Elders past, pres,ent and emerging. rl.·. Flinders Flinders.edu.au University