im confused about biology?

Question

please explain to me about active and passive transport
i know passive transport is like high concentration to low concetration so it doesnt really require energy then theres diffusion, facilitated diffusion, and osmosis
for active trasnport theres like endocytosis and exocytosis but i dont understand the difference and what they are then endocytosis is split into pinocytosis and phagocytosis (which is like eating the cell??? please explain!!) thanks

Answer 1

Active transport is moving a molecule against its concentration gradient, which requires energy. Molecules want to move from areas of high concentration to areas of low concentration, which is passive transport, which normally doesnt require energy.

In cells active transport can happen across the semi-permiable membrane. Molecules that are too large to "fit" into the membrane must be "carried" across to the other side of the membrane, which require energy. Some other molecules that require active transport across membranes is large molecules, polar molecules, and some complex sugars.

Passive transport doesnt require energy, so small molecules, like water, oxygen, and non polar molecules can diffuse across the membrane without using energy. Some simple sugars can diffuse across the membrane without using energy.

Answer 2

Active transport is done in a couple of different ways. One is by special proteins in the plasma membrane that grab a molecule on the low concentration side and change shape to fling the molecule out on the high concentration side. It requires energy to change shape.

The other kind of active transport is called bulk transport: endocytosis and exocytosis.
1. Endocytosis means that the plasma membrane wraps around the material until it forms a vacuole which pinches off inside the cell. That's how it takes in materials that are too big to get in any other way. Endo means in, and cyto means cell. If the material taken in is a solid particle (like a bacterial cell or a paramecium), then that kind of endocytosis is called phagocytosis. If the material taken in is a liquid (like a droplet of oil) then that kind of endocytosis is called pinocytosis.
2. Exocytosis is what happens when larger materials have to be sent out of the cell - usually large undigested bits from big food particles or cell products like secretions. A vacuole or vesicle with the material moves toward the plasma membrane until it touches. Then the membrane of the vesicle or vacuole joins up with the plasma membrane and the contents are pushed out.

I'm going to find some animations that will help you understand, and I'll come back to this answer to add the websites.

This one shows both endo- and exocytosis.
http://trc.ucdavis.edu/biosci10v/bis10v/week2/endocytosis.mov

This one shows both types of bulk transport happening in a cell. http://www.pleasanton.k12.ca.us/avhsweb/thiel/apbio/notes/chp8/exocytosis_endocytosis.mov

Answer 3

You seem to understand passive transport. Endocytosis is taking things into the cell; exocytosis is pushing things out. Pinocytosis is a drinking/sucking process, and Phagocytosis is making a vacuole for the thing the cell is taking in by folding the membrane.