Besdies diffusion and osmosis, in IBDP Biology we need to understand other aspects of transports within the body, such as endocytosis and exocytosis. Let's get started!

Role of protein pumps and ATP in active transport

• Molecules are moved against the concentration gradient from a region of their low concentration to a region of their high concentration.
• Active mean that the membrane protein 'pump' requires energy (ATP) to function
• The source of energy is ATP is produced in cell respiration
• Transported molecules enter the carrier protein in the membrane.
• The energy causes a shape change in the protein that allows it to move the molecule to the other side of the membrane.

• The sodium-potassium pump that creates electro-chemical gradient across the cell membrane of all cells.
• Cells are -ve charged on the inside relative to the outside.
• This pump is modified in the nerve cell to create some of the electrochemical phenomena seen in nerve cells.

Endocytosis and Exocytosis

1) Endocytosis- plasma membrane pulled inwards and pinched off.

2) Proteins are synthesised by ribosomes and enter RER (rough endoplasmic reticulum)

3) Vesicles bud off from RER and carry proteins to golgi apparatus

4) Golgi apparatus modifies proteins and vesicles bud off

5) Exocytosis- vesicles fuse with plasma membrane and expelles content

Exocytosis for extracellular components 

Used to produce plant cell wall:

• Maintains cell shape
• Allows high pressure to build up in cell without bursting
• High pressue prevents excessive water uptake by osmosis
• Turgor pressure makes cell rigid

Used to produce glycoproteins in animals. 

• This forms an extracellular matrix e.g.: around blood capillaries and alveoli in lungs.
• Support single layers of thin cells so they dont tear or perforate
• Cell to cell adhesion e.g: capillary walls adhere to alveolus wall 

That's all we need to know for the different transportation modes of endo/exocytosis and protein pumps! Good job!

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References:

• https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.ck12.org%2Fbiology%2Fexocytosis-and-endocytosis%2Flesson%2FExocytosis-and-Endocytosis-BIO%2F&psig=AOvVaw1Ormjtl0b7rcldLjJAdx2G&ust=1626365129436000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCKC667D44vECFQAAAAAdAAAAABAI
• https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.scienceabc.com%2Fpure-sciences%2Fwhat-are-endocytosis-phagocytosis-and-pinocytosis.html&psig=AOvVaw1tfYY_OAs5ppdZJkSnR00m&ust=1626365127545000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCOChq8z54vECFQAAAAAdAAAAABAm

Drafted by Venetia (Biology)