[00:06] someone sneezes on you. and lands on a cell on your airway lining. from the smallest one-celled bacteria
[00:21] Each cell in your body is surrounded by a cell membrane, that surrounds and protects the inner components.
[00:33] meaning that it lets some thing pass in and out The cell membrane is covered with tiny projections. or binding to nutrients the cell will need.
[00:47] Only plant cells have a cell wall, which is made of rigid cellulose that gives the plant structure. Pretending to be a friend,
[01:00] and the cell brings it through the cell membrane and inside. the cell recognizes its mistake. Special enzymes arrive at the scene
[01:14] They then send one of the pieces back where the cell displays it to warn neighboring cells and immediately goes into action.
[01:27] proteins that will attack and kill This process starts in the nucleus. the blueprint that tells our cells how to make everything
[01:40] A certain section of our DNA contains instructions Enzymes in the nucleus find the right section of DNA,
[01:52] called messenger RNA. The messenger RNA leaves the nucleus to carry out its orders. There can be as many as 10 million ribosomes
[02:05] all studded along a ribbon-like structure This ribosome reads the instructions from the nucleus. It takes amino acids and links them together one by one
[02:18] creating an antibody protein that will go fight the virus. The antibody heads to the golgi apparatus. Enclosed in a bubble made of the same material as the cell membrane,
[02:35] telling it how to get to the edge of the cell. the bubble surrounding the antibody fuses to the cell membrane. and it heads out to track down the virus.
[02:50] and its pieces recycled over and over again. Where did the cell get the energy to do all this? To make energy, the mitochondria takes oxygen,
[03:04] and adds electrons from the food we eat That process also creates a high energy molecule, called ATP which the cell uses to power all of its parts.
[03:18] They have chloroplasts with light energy from the sun a form of chemical energy.
[03:30] to keep things running smoothly, to keep you running smoothly. Scientists think there are about 37 trillion of them.