BrainPOP
BrainPOP
  • 4 months ago
Transcript
00:00Hey, I need one of those 8x2 pieces.
00:07No, no, 8x2.
00:128 dots long and 2 dots wide.
00:17Dear Tim and Moby,
00:19My sister said that my body is made of cells.
00:22Is that true and what are cells anyway?
00:26From Jenny.
00:28Well, your sister is right.
00:30You are made of cells.
00:32She's made of cells too.
00:34In fact, all living things are made of one or more cells.
00:38If you could look at yourself through a microscope,
00:40you could see that you're divided into millions of tiny...
00:44tiny sections.
00:46These sections are called cells and they're the basic unit of life.
00:50They come in lots of types and live with other cells like them
00:53in groups called tissues.
00:55When two or more tissues combine,
00:57they form organs like the heart and brain.
01:00Every single part of your body is really millions of cells working together.
01:05Each cell is basically a sack of jelly-like fluid called cytoplasm.
01:11The sack surrounding it is called the cell membrane.
01:14It lets good stuff in and keeps bad stuff out.
01:18Floating around in the cytoplasm are organelles.
01:21Just like the body has organs for different functions,
01:24the cell has organelles for all its functions.
01:26Like mitochondria extract energy from nutrients
01:30and ribosomes create proteins,
01:32molecules used to build pretty much everything in the body.
01:35Then there's the nucleus, which is kind of like the cell's brain.
01:39It's a membrane pouch that holds an organism's genetic material,
01:43the biological instructions passed down from its parents.
01:46These instructions are encoded in a substance called DNA.
01:50In plant and animal cells, DNA is contained in a nucleus.
01:54We call these kinds of cells eukaryotic.
01:57The other type of cell, prokaryotic, has no nucleus.
02:01Genetic information in prokaryotic cells just sort of floats free in the cytoplasm.
02:06Most prokaryotes are single-celled bacteria,
02:10like Lactobacillus acidophilus, which is used to make yogurt.
02:14Nope, not all cells look like these.
02:17In any given organism, different cells carry out very specialized functions.
02:22As a result, they can look very different.
02:25Some types of bone cells are star-shaped.
02:28Muscle cells have to be stretchy.
02:30Nerve cells can be over a meter long, so they can carry signals across the body.
02:35This bacterium has little hairs growing out of its membrane to help it move around.
02:40Red blood cells are sort of shaped like little bowls.
02:44And plant cells have a rigid cell wall that maintains their shape.
02:49You have about 40 trillion eukaryotic cells in your body,
02:52and about as many prokaryotic cells.
02:55Your intestines and other body parts are home to all kinds of helpful bacteria.
03:01Laugh all you want, but humans like me couldn't live without them.
03:06Okay, whether they're eukaryotic or prokaryotic,
03:09almost all cells have the ability to divide.
03:12In eukaryotes, the process is called mitosis.
03:15The cell makes a copy of its nucleus.
03:18Then its cell membrane splits to form two separate cells.
03:22This is how you grow.
03:27Hey, hey, cut that out.
03:32Holy cats!
03:33I'm beside myself.
03:35What are we gonna do?
03:36Twice as much homework!
03:38Jinx!
03:42You