(e)+Active+Transport

by DHK
= **1. What is active transport? What is required and where does this occur?** = ==== Active transport is the transportation of materials inside the cell by using an energy. This usually happens when cells have to move materials in an opposite direction, against a concentration gradient. This occurs inside the cell membrane ==== =**2. Copy the following into your notes. We will cover this in more detail later.** = ====ATP is the small energy carrying molecule that is used within cells of __ALL__ living things. Once the energy is used, it becomes ADP. This is recharged back into ATP inside the mitochondria, during respiration.==== **﻿** =**3. G** **ive 2 reasons why cells must use active transport at times, instead of diffusion? ****﻿** =
 * When cells move materials from low to high concentration, they require specific proteins. These proteins have an ability to bind to specific molecules (ex: glucose). Making these proteins move require energy which is an active transport.
 * In plants, they need to absorb salts from the soil but they exist in very thin solution. Active transport enables these cells to take the salts from this weak solution, also against the direction of the concentration gradient.

=**4. Describe the functioning of protein pumps.** =

The function of protein pumps is to pump out or in solutes or ions from a low concentration to high concentration by using ATP (energy). **More explanation on active transport in this video** media type="youtube" key="STzOiRqzzL4" height="345" width="420" align="center"

=5. The Golgi apparatus & endoplasmic reticulum are within the cell away from the plasma membrane. Explain how cells use vesicles as an intermediary for materials that they export annotated diagrams!). What is a vesicle? What feature of membranes allows vesicles to form?=

Visicle is a bubble-like membranous structure that stores and transports cellular products, and digests metabolic wastes within the cell. the membrane of endoplasmic reticulum allows vesicles to from and when it moves to Golgi apparatus, the membrane of Golgi apparatus allows vesicles to enter inside.

=**6. Define endocytosis and exocytosis. Draw a series of diagrams to describe these processes**= Endocytosis is a process where substance can able to go inside the cell without passing through the cell membrane.



Exocytosis is a process where intracellular vesicle (membrane bounded sphere) moves to the plasma membrane and subsequent fusion of the vesicular membrane and plasma membrane ensues

=7. Distinguish between pinocytosis & phagocytosis.=

Pinocytosis is when plasma membrane forms an invagination. Whatever substance is found within the area of invagination is brought into the cell. In general, this material will be dissolved in water and thus this process is also referred to as "cellular drinking" to indicate that liquids and material dissolved in liquids are ingested by the cell.

Phagocytosis is a form of endocytosis. The cell changes shape by sending out projections which are called "Pseudpodia (false feet). The phagocytic cell get attracted to a particle like bacteria or virus by chemical attractant and this process is called "chemotaxis" (movement toward a source of chemical attractant). Then the phagocytic cell sends out membrane projections to contact with some particle. The pseudopodia then surround the particle and when the plasma membrane of projection meet membrane, fusion occurs. As a results, it forms an intracellular vesicle.



=8. What is a contractile vacuole? Explain what it does, why and how it works.=

Contractile vacuole is a membrane-bound organelle found in certain protists that pumps fluid in a cyclical manner from within the cell to the ouside by filling and contracting to release its contents on the surface of the cell. The function of this is to maintain osmotic quilibrium. It also forces water out of the pores to reduce osmotic pressure and prevents the cell from bursting. = 9. Make a special note on sodium / potassium pumps, as we meet these lots all through the IB curriculum =

**Explanation on sodium / potassium pumps in this video** media type="youtube" key="yz7EHJFDEJs" height="345" width="420" align="center"


 *  **The sodium/potassium pump** is a good example of **active transport** of molecules across a membrane. In this example, active transport is coupled to ATP hydrolysis to obtain enough free energy to transport the ions against their concentration gradient. This ion pump is an example of antiport membrane transport, where the transported molecules are pumped across the membrane in opposite directions (as opposed to synport). The sodium gradient is generated for use by cotransport systems, such as the active transport of glucose from the extracellular environment into the inside of the cell. The non-equilibrium state of the sodium gradient is essentially free energy to be used for the import of molecules against their own concentration gradient. ||