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The human body in medieval and modern science

By |2018-04-25T17:09:55-07:00September 6th, 2017|Biology, Science|

Chinese drawing of the organs (about 1200) Between the Middle Ages and modern times, doctors have learned a lot of new things about how human bodies work. The Islamic doctor Al-Tabari, in the early 800s, learned that light bounces off objects into your eyes. Al-Tabari's student Al Razi figured out that a fever is your body's way of fighting illness, not [...]

Proterozoic Eon – eukaryotes to worms

By |2018-04-21T11:56:39-07:00June 24th, 2017|Biology, Geology|

Two and a half billion years ago, the Archaean Eon ended and the Proterozoic Eon began. Trillions of prokaryote cells lived in Earth's oceans. Some of these cells could photosynthesize their energy from sunlight, water, and carbon dioxide. These photosynthesizing cells pooped out a lot of oxygen. By about 2.3 billion years ago, the iron [...]

How do eukaryote flagella move cells?

By |2019-06-01T13:23:00-07:00May 29th, 2017|Biology|

Human sperm cells with flagella (under a microscope): Eukaryote flagella Not the old kind of flagella About two billion years ago, the first eukaryote cells evolved from the earlier prokaryote cells.  These eukaryote cells also evolved a new way to move themselves around. What are prokaryotes? What are eukaryotes? Eukaryote project All our [...]

What is a prokaryote – Cell biology

By |2018-09-11T05:51:18-07:00May 29th, 2017|Biology|

A prokaryote (seen through a microscope) What does "prokaryote" mean? The simplest living cells are called prokaryotes, which is Greek for "before the nucleus" - these are cells that were so simple that they didn't have a nucleus. When did the first prokaryotes evolve? The first prokaryotes probably evolved from even simpler cells [...]

What is mitosis? Sexual reproduction – Biology

By |2017-05-29T00:31:28-07:00May 29th, 2017|Biology|

Eukaryote cells generally reproduce themselves using a method called mitosis. When a eukaryote cell senses that there is plenty of food around, it splits into two new cells that together can eat more food. But it's pretty complicated for eukaryote cells to divide. They have a lot of DNA molecules, to control all the different parts [...]

What are mitochondria? Parts of a cell – Biology

By |2017-05-29T00:26:07-07:00May 29th, 2017|Biology|

A mitochondrion (seen through a microscope) About two billion years ago, in the Proterozoic, there were only prokaryotic cells on Earth. Mitochondria probably started out as independent cells that were especially good at digesting food. These cells were extra good at digesting because they had evolved to have two membranes. The inside membrane, [...]

Golgi body game – Directing molecules – Parts of a cell activities

By |2017-05-28T17:49:54-07:00May 28th, 2017|Biology|

Taken with an electron microscope at the University of Melbourne, Australia Here's an active game where you can act out what a Golgi body does. Form into groups of eight, and find a big area, like one half of the gym, to be the cell. One player is a lysosome; she just stands [...]

Cell digestion – Parts of a cell – Cell Biology

By |2019-05-07T14:54:58-07:00May 28th, 2017|Biology|

Amoeba - a one-celled organism - Cell digestion How do cells get energy? All cells have to have some way to get energy from outside themselves, or they will starve to death. The earliest, simplest cells, about 3.5 billion years ago, got their food by drifting around in the ocean until they came [...]