[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:06.71,0:00:09.58,Default,,0000,0000,0000,,You're in line at the grocery store, when, uh oh!
Dialogue: 0,0:00:09.58,0:00:11.28,Default,,0000,0000,0000,,Somone sneezes on you.
Dialogue: 0,0:00:11.28,0:00:13.74,Default,,0000,0000,0000,,The cold virus is sucked inside your lungs
Dialogue: 0,0:00:13.74,0:00:16.49,Default,,0000,0000,0000,,and lands on a cell on your airway lining.
Dialogue: 0,0:00:16.49,0:00:19.04,Default,,0000,0000,0000,,Every living thing on Earth is made of cells,
Dialogue: 0,0:00:19.04,0:00:21.07,Default,,0000,0000,0000,,from the smallest one-celled bacteria,
Dialogue: 0,0:00:21.07,0:00:23.85,Default,,0000,0000,0000,,to the giant blue whale, to you.
Dialogue: 0,0:00:23.85,0:00:27.19,Default,,0000,0000,0000,,Each cell in your body is surrounded by a cell membrane,
Dialogue: 0,0:00:27.19,0:00:30.28,Default,,0000,0000,0000,,a thick flexible layer made of fats and proteins,
Dialogue: 0,0:00:30.28,0:00:33.48,Default,,0000,0000,0000,,that surrounds and protects the inner components.
Dialogue: 0,0:00:33.48,0:00:34.49,Default,,0000,0000,0000,,It's semipermiable,
Dialogue: 0,0:00:34.49,0:00:37.05,Default,,0000,0000,0000,,meaning that it lets some thing pass in and out
Dialogue: 0,0:00:37.05,0:00:38.40,Default,,0000,0000,0000,,but blocks others.
Dialogue: 0,0:00:38.40,0:00:41.50,Default,,0000,0000,0000,,The cell membrane is covered with tiny projections.
Dialogue: 0,0:00:41.50,0:00:42.75,Default,,0000,0000,0000,,They all have functions,
Dialogue: 0,0:00:42.75,0:00:44.73,Default,,0000,0000,0000,,like helping cells adhere to their neighbors,
Dialogue: 0,0:00:44.73,0:00:47.78,Default,,0000,0000,0000,,or binding to nutrients the cell will need.
Dialogue: 0,0:00:47.78,0:00:50.06,Default,,0000,0000,0000,,Animal and plant cells have cell membranes.
Dialogue: 0,0:00:50.06,0:00:52.05,Default,,0000,0000,0000,,Only plant cells have a cell wall,
Dialogue: 0,0:00:52.05,0:00:56.05,Default,,0000,0000,0000,,which is made of rigid cellulose that gives the plant structure.
Dialogue: 0,0:00:56.05,0:00:59.41,Default,,0000,0000,0000,,The virus cell that was sneezed in to you lungs is sneaky.
Dialogue: 0,0:00:59.41,0:01:00.58,Default,,0000,0000,0000,,Pretending to be a friend,
Dialogue: 0,0:01:00.58,0:01:03.55,Default,,0000,0000,0000,,it attaches to a projection on the cell membrane,
Dialogue: 0,0:01:03.55,0:01:06.95,Default,,0000,0000,0000,,and the cell brings it through the cell membrane and inside.
Dialogue: 0,0:01:06.95,0:01:08.33,Default,,0000,0000,0000,,When the virus gets through,
Dialogue: 0,0:01:08.33,0:01:10.22,Default,,0000,0000,0000,,the cell recognizes its mistake.
Dialogue: 0,0:01:10.22,0:01:12.17,Default,,0000,0000,0000,,An enemy is inside!
Dialogue: 0,0:01:12.17,0:01:14.01,Default,,0000,0000,0000,,Speical enzymes arrives at the scene
Dialogue: 0,0:01:14.01,0:01:16.22,Default,,0000,0000,0000,,and chop the virus to pieces.
Dialogue: 0,0:01:16.22,0:01:18.04,Default,,0000,0000,0000,,They then send one of the pieces back
Dialogue: 0,0:01:18.04,0:01:19.38,Default,,0000,0000,0000,,through the cell membrane,
Dialogue: 0,0:01:19.38,0:01:22.06,Default,,0000,0000,0000,,where the cell displays it to warn neighboring cells
Dialogue: 0,0:01:22.06,0:01:23.72,Default,,0000,0000,0000,,about the invader.
Dialogue: 0,0:01:23.72,0:01:25.33,Default,,0000,0000,0000,,A near by cell sees the warning
Dialogue: 0,0:01:25.33,0:01:27.81,Default,,0000,0000,0000,,and immediately goes in to action.
Dialogue: 0,0:01:27.81,0:01:29.42,Default,,0000,0000,0000,,It needs to make antibodies,
Dialogue: 0,0:01:29.42,0:01:31.19,Default,,0000,0000,0000,,proteins that will attack and kill
Dialogue: 0,0:01:31.19,0:01:33.07,Default,,0000,0000,0000,,the invading virus.
Dialogue: 0,0:01:33.07,0:01:35.66,Default,,0000,0000,0000,,This process starts in the nucleus.
Dialogue: 0,0:01:35.66,0:01:37.67,Default,,0000,0000,0000,,The nucleus contains our DNA,
Dialogue: 0,0:01:37.67,0:01:40.39,Default,,0000,0000,0000,,the blueprint that tells our cells how to make everything
Dialogue: 0,0:01:40.39,0:01:43.29,Default,,0000,0000,0000,,our bodies need to function.
Dialogue: 0,0:01:43.29,0:01:46.13,Default,,0000,0000,0000,,A certain section of our DNA contains instructions
Dialogue: 0,0:01:46.13,0:01:49.28,Default,,0000,0000,0000,,that tell our cells how to make antibodies.
Dialogue: 0,0:01:49.28,0:01:52.33,Default,,0000,0000,0000,,Enzymes in the nucelus find the right section of DNA,
Dialogue: 0,0:01:52.33,0:01:54.14,Default,,0000,0000,0000,,then create a copy of these instructions,
Dialogue: 0,0:01:54.14,0:01:56.43,Default,,0000,0000,0000,,called messenger RNA.
Dialogue: 0,0:01:56.43,0:02:00.42,Default,,0000,0000,0000,,The messenger RNA leaves the nucleus to carry out its orders.
Dialogue: 0,0:02:00.42,0:02:03.47,Default,,0000,0000,0000,,The messenger RNA travels to a ribosome.
Dialogue: 0,0:02:03.47,0:02:05.91,Default,,0000,0000,0000,,There can be as many as 10 million ribosomes
Dialogue: 0,0:02:05.91,0:02:07.30,Default,,0000,0000,0000,,in a human cell,
Dialogue: 0,0:02:07.30,0:02:09.14,Default,,0000,0000,0000,,all studded along a ribbon-like structure
Dialogue: 0,0:02:09.14,0:02:11.67,Default,,0000,0000,0000,,called the endoplasmic riticulumn.
Dialogue: 0,0:02:11.67,0:02:14.91,Default,,0000,0000,0000,,This ribosome reads the instructions from the nucleus.
Dialogue: 0,0:02:14.91,0:02:18.09,Default,,0000,0000,0000,,It takes amino acids and links them together one by one
Dialogue: 0,0:02:18.09,0:02:22.00,Default,,0000,0000,0000,,creating an antibody protein that will go fight the virus.
Dialogue: 0,0:02:22.00,0:02:23.24,Default,,0000,0000,0000,,But before it can do that,
Dialogue: 0,0:02:23.24,0:02:25.78,Default,,0000,0000,0000,,the antibody needs to leave the cell.
Dialogue: 0,0:02:25.78,0:02:28.65,Default,,0000,0000,0000,,The antibody heads to the golgi appartatus.
Dialogue: 0,0:02:28.65,0:02:31.72,Default,,0000,0000,0000,,Here it's packed up for delivery outside the cell.
Dialogue: 0,0:02:31.72,0:02:35.12,Default,,0000,0000,0000,,Enclosed in a bubble made of the same material as the cell membrane,
Dialogue: 0,0:02:35.12,0:02:38.80,Default,,0000,0000,0000,,the golgi apparatus also gives the antibody directions,
Dialogue: 0,0:02:38.80,0:02:41.36,Default,,0000,0000,0000,,telling it how to get to the edge of the cell.
Dialogue: 0,0:02:41.36,0:02:42.18,Default,,0000,0000,0000,,When it gets there,
Dialogue: 0,0:02:42.18,0:02:45.98,Default,,0000,0000,0000,,the bubble surrounding the antibody fuses to the cell membrane.
Dialogue: 0,0:02:45.98,0:02:47.95,Default,,0000,0000,0000,,The cell ejects the antibody,
Dialogue: 0,0:02:47.95,0:02:50.58,Default,,0000,0000,0000,,and it heads out to track down the virus.
Dialogue: 0,0:02:50.58,0:02:52.39,Default,,0000,0000,0000,,The leftover bubble will be broken down
Dialogue: 0,0:02:52.39,0:02:53.98,Default,,0000,0000,0000,,by the cell's lysosomes
Dialogue: 0,0:02:53.98,0:02:56.92,Default,,0000,0000,0000,,and its pieces recycled over and over again.
Dialogue: 0,0:02:56.92,0:03:00.08,Default,,0000,0000,0000,,Where did the cell get the energy to do all this.
Dialogue: 0,0:03:00.08,0:03:02.40,Default,,0000,0000,0000,,That's the roll of the mitochondria.
Dialogue: 0,0:03:02.40,0:03:04.72,Default,,0000,0000,0000,,To make energy, the mitochondria takes oxygen,
Dialogue: 0,0:03:04.72,0:03:07.37,Default,,0000,0000,0000,,this is the only reason we breathe it,
Dialogue: 0,0:03:07.37,0:03:09.39,Default,,0000,0000,0000,,and adds electrons from the food we eat
Dialogue: 0,0:03:09.39,0:03:11.46,Default,,0000,0000,0000,,to make water molecules.
Dialogue: 0,0:03:11.46,0:03:13.88,Default,,0000,0000,0000,,That process also creates a high energy molecule,
Dialogue: 0,0:03:13.88,0:03:18.24,Default,,0000,0000,0000,,called ATP, which the cell uses to power all of its parts.
Dialogue: 0,0:03:18.24,0:03:20.96,Default,,0000,0000,0000,,Plant cells make energy a different way.
Dialogue: 0,0:03:20.96,0:03:22.10,Default,,0000,0000,0000,,They have chloroplasts
Dialogue: 0,0:03:22.10,0:03:24.20,Default,,0000,0000,0000,,that combine carbon dioxide and water
Dialogue: 0,0:03:24.20,0:03:26.05,Default,,0000,0000,0000,,with light energy from the sun
Dialogue: 0,0:03:26.05,0:03:27.77,Default,,0000,0000,0000,,to create oxygen and sugar,
Dialogue: 0,0:03:27.77,0:03:30.34,Default,,0000,0000,0000,,a form of chemical energy.
Dialogue: 0,0:03:30.34,0:03:32.29,Default,,0000,0000,0000,,All the parts of the cell have to work together
Dialogue: 0,0:03:32.29,0:03:34.53,Default,,0000,0000,0000,,to keep things running smoothly,
Dialogue: 0,0:03:34.53,0:03:36.65,Default,,0000,0000,0000,,and all the cells of your body have to work together
Dialogue: 0,0:03:36.65,0:03:38.95,Default,,0000,0000,0000,,to keep you running smoothly.
Dialogue: 0,0:03:38.95,0:03:40.52,Default,,0000,0000,0000,,That's a whole lot of cells.
Dialogue: 0,0:03:40.52,0:03:44.23,Default,,0000,0000,0000,,Scientists think there are about 37 trillion of them.