04.16.2020 - Thursday - Science -
Left side of today’s science notebook.
As always, define the terms that are CAPITALIZED if you’re unfamiliar with them.
- Current Events: Link - https://www.cnn.com/cnn10
- One note on the Coronavirus. Specifically; The potential spread of the virus when people who have the virus do not have symptoms.
- One note on World War One era aircraft. (Time permitting, we do a mini-unit on the forces of flight.)
II. LIFE! One of the definitions of life, that we discussed in class, the the ability to REPRODUCE.
A. “Where we’ve been and where we’re going.”
1. Going back about 14.5 billion years ago, just after the BIG BANG, there was - mostly - only one type of ELEMENT in the universe …. HYDROGEN.
2. As GRAVITY pulled together hydrogen, STARS formed. There were no planets, yet, because there wasn’t any heavy ELEMENTS with which to build planets this long ago!
3. Those first stars, eventually, blew up! When a star gets to the end of its’ life it can explode in a huge blast we call a SUPERNOVA!
4. Why do we care about SUPERNOVA explosions billions of years ago? It turns out that these explosions helped make all those heavier elements that are needed for things like planets and, eventually, life.
5. The element, HYDROGEN, was a basic building block of bigger and heavier elements like OXYGEN, CARBON, NITROGEN - and others - that are needed for the big MOLECULES that make us. Remember the “Big Four?” The four most important elements for life? We remembered it in class with C - H - O - N. Carbon, Hydrogen, Oxygen, and Nitrogen.
6. About ten billions years after the BIG BANG, our SOLAR SYSTEM began to form. Earth, along with the other planets that orbit our sun, are made from some of those big, heavy elements that were released when those first generation of stars blew themselves apart billion of years ago. When you hear scientists say; “We are made of ‘star stuff.’ This is what they mean. The big atoms that make our DNA were first formed inside stars!
7. It’s worth noting that those last six points took us humans tens of thousands of years to figure out! The tool for figuring this out was SCIENCE!
III. Here on Earth, DNA is an extremely long molecule. That, by itself, isn’t life. But … here’s the thing …. It’s a molecule that can make copies of itself!
A. DNA is a long molecule that, usually, hangs out (resides in) the NUCLEUS of EUKARYOTE cells. In case your forgot, us ANIMALS are eukaryotes. It means we have cells that have a nucleus and other ORGANELLES. (Specialized parts inside our cells that perform certain functions - Remember “Cell City?”)
IV. The LIFE CYCLE of a cell consists of four, main, stages:
B. DNA “copying”
C. Preparing for division
D. Mitosis - CELL DIVISION.
OK … That was quite a bit of recap with some new stuff there at the end. There will be a “color-in” assignment on the right side of today’s notes. Take care you amazing group of eukaryotic cells! scf