MODULE 16

• Active transport is the movement of molecules across a cell membrane from a region of their lower concentration to a region or their higher concentration - in the direction against some gradient or other obstructing factor (often a concentration gradient).
• Active transport is the movement of molecules across a cell membrane from a region of their lower concentration to a region or their higher concentration - in the direction against some gradient or other obstructing factor (often a concentration gradient).
• Active transport requires the assistance of a type of protein called a carrier protein, using energy supplied by ATP or Adenosine Triphosphate to affect the transport.
• Proteins do much of the work in active transport.
• In active transport, proteins are positioned to cross the membrane so one part is on the inside of the cell and one part is on the outside.
• Protein can only able to move molecules and ions in and out of the cell when they cross the bilayer.
• The membrane proteins are very specific.
• A common example of active transport, or moving a substance against its gradient, is the maintaining of a balance of sodium and potassium inside and outside a cell.
• Too much sodium inside the cell would cause cell death.
• The cell membrane must actively regulate how much sodium is allowed in through the membrane.
• Active transport is the process by which dissolved molecule move across a cell membrane from a lower to a higher concentration.
• In humans, active transport takes place during the digestion of food in the small intestine.
• Carbohydrates are broken down into simple sugars such as glucose.
• Active transport is the term used to descrive the processes of moving materiale through the cell membrane that requires the use of energy.
• Sodium-Potassium pump is a type of active transport.
• Active transport is important because some molecules are transported this way such as sodium, potassium, hydrogen, amino acids, and glucose.
• Glucose is the simpliest sugar being usee by the brain cells for its functions.
• Sodium is used to balance the water level in the body, so much salts would make a person very fat, he has retained water in the cells, amino acids are protein base, necessary for growth and repair of tissuew.
• Potassium is needed for effectice muscle function especially the heart, without this active transport, there will be lots of problems in the body.
• Exocytosis moves materials out of cell in vesicle.
• In exocytosis, vesicle combines with plasma membrane.
• In exocytosis, material is emptied to the outside.
• In endocytosis, substances engulfed by being enclosed in a membranous vesicle.
• Endocytosis 2 types

  • Phagocytosis - cell eating
  • Pinocytosie - cell drinking
• In Bulk/Vesicular Transport, most molecules, including proteins, are too large to pass directly through membranes.
• In Bulk/Vesicular transport, large molecules are loaded into small membrane-wrapped containers called vesicles.
• Vesicles are constantly forming - especially at the plasma membrane, the Endoplasmic Reticulum, and the Golgi.
• Once formed, vesicles deliver their contents to destinations within or outside of the cell.
• A vesicle forms when the membrane bulges out and pinches off.
• Vesicles travel to its destination then merges with another membrane to release its cargo.
• Vesicular transport is the predominant mechanism for exchange of proteins and lipids between membrane-bound organelles in eukaryotic cells.
• Inside the cells, Golgi-derived vesicles are involved in several vesicular transport steps, incluring bidirectional transport within the Golgi and recycling to the Endoplasmic Reticulum.
• Vesicles or other bodies in the cytoplasm move macromolecules or large particles across the plasma membrane.
• There are two types of vesicle transport, endocytosis and exocytosis.
• Endocytosis and exocytosis are active transport processes, requiring energy.
• Endocytosis is the case when a molecule causes the cell membrane to bulge inward, forming a vesicle.
• Phagocytosis is the type of endocytosis where an entire cell is engulfed.
• Pinocytosis is when the external fluid is engulfed.
• Receptor-mediated endocytosus occurs when the material to be transported binds to certain specific molecules in the membrane.
• Example of receptor-mediated endocytosis include the transport of insulin and cholesterol into animal cells.