Cell Functions

What your cells do on a daily basis to keep themselves – and you – alive!

This happens mainly in the

Mitochondrion!

Cellular Respiration:All cells need energy to survive. Your cells perform cellular respiration, a series of chemical reactions that extracts energy gradually from glucose. The process is complex, but can be summarized as:

C6H12O6 + 6O2 6CO2 + 6H2O + ATP*Glucose + Oxygen Carbon dioxide + Water + Energy

Cell Transport: Phospholipid Bilayer:

Moving things in & out of the cell is the main job of the cell membrane.It is a double layer of fatty molecules called phospholipids. Gaps between the phospholipids let some things in, and keep other things out.The membrane is semipermeable.

Passive Transport:Some materials move through on

their own; the cell doesn’t use any of its energy to help the transport.

This is called passive transport.It can happen through membrane

pores, or special protein channels (facilitated diffusion).

Facilitated Diffusion:

Passive Transport:In order for passive transport to

happen, there has to be a concentration gradient:

High concentration outside of cellLow concentration inside the cellMolecules will tend to move from

high to low concentration. This is called Diffusion.

Diffusion:

As the sugar dissolves, the particles diffuse

through the water until they’re evenly

‘mixed’ or distributed.

Active Transport:Sometimes, the cell needs to

obtain a material that is:- A charged particle (an ion)- Rare, or Low in concentration- Too big to diffuse through the

membraneThis is when Active Transport is

used…

Active Transport:Active transport requires the cell

to use some of its energy in order to obtain & move materials in/out of the cell.

This may involve the proteins in the membrane, acting as pumps. They are able to change shape in order to move materials in/out of the cell.

Active Transport:… Goes against the concentration

gradient; it will move particles from Low Concentration areas to Higher Concentration areas.

A good example is the Sodium-Potassium Pump: It changes shape to release 3Na+ & bring in 2K+. The energy comes from ATP, a molecule cells derive from glucose metabolism.

Both Na+ & K+ are needed for several cell functions, but too much has a dehydrating effect…

… Keeping these two ions in balance is a constant job for all of your body’s cells… one of many, many jobs!

Active Transport:Sometimes, the cell needs to obtain

a material that is so large that it has to bend its entire membrane around it. This is called Endocytosis, & it takes energy.

(endo = into, cyto = cell, osis = process)

Taking in liquids = PinocytosisTaking in solids = Phagocytosis

(pino = to drink, phago = to eat)

Single-celled organisms, like Amoeba, rely on endocytosis a lot. Some of your white blood cells are phagocytes.

Active Transport:Sometimes, the cell needs to expel or

secrete a large quantity of a material. They do this by first producing the material (a hormone, a signalling chemical, or just a waste…), packaging it into a vacuole or vesicle, then fusing the vesicle to the cell membrane. The vesicle bursts, releasing the material. around it. This is called Exocytosis, & it usually involves the Golgi & RER.

(exo = out of, cyto = cell, osis = process)

In your body, a process like this would happen when white blood cells engulf, destroy & expel remnants of bacteria.

Remember: it’s all about energy use & concentration…