05.12.2020 - Science - Tuesday -
- Current Events: https://www.cnn.com/cnn10
- A note on the dinosaur story: One of the most important pieces of evidence for natural selection and evolution is the fossil record. We know about the dinosaurs, that existed more than 65 million years ago, because of fossil evidence.
II. We recognize SIX KINGDOMS of life … To categorize living things we put them in groups so we can more easily study their history and how they’re related to other living things. The classification system begins at a very “high” level and becomes very detailed.
III. This is how we get SCIENTIFIC NAMES or TAXA. Usually, scientists use the last two on this list to be specific about which SPECIES they are describing.
IV. For example, every living thing falls into one of three DOMAINS.
A. Eukarya: Living things that have cells with a nucleus.
B. Bacteria: Once-celled organisms that have cells with no nucleus.
C. Archaea: The is the newest classification of domains. These used to be classified as bacteria but they are now seen as their own domain. Sometimes they are called extremophiles.
1. Off the coast of California and in places like Yellowstone National Park, there are hot springs. Places where water - that has seeped into cracks in the Earth - comes close to rock that is very hot and the water is forced to the surface as geysers or ocean hot springs. Think about camping … yes camping. If you collect water from a lake or stream, and want to be sure it’s OK to drink, you might boil it for a few minutes to kill any parasites and bacteria. This works well for water that you might collect on a trail or near a lake. Extremophiles are bacteria that actually live in the boiling temperatures and thrive there. Life was thought to not be able to exist in such “extreme” environments.
This makes the search for life beyond Earth even more exciting because there are places in our own solar system where such extreme conditions, with all the chemicals necessary for life, might exist! For example, one of the moons of Jupiter, is called Io. (It’s one of the four Galilean moons - so called because these moons were discovered by Galileo Galilei in the seventeenth century. It’s difficult to overstate how important this discovery was. He showed that the Earth was not the center of the universe. The moons of Jupiter were even important in calculating the speed of light!). The moon Io seems to have a layer of salty water (more water than Earth has!) That is covered by ice. Because Io is so close to Jupiter, the gravity from Jupiter makes the moon flex and makes it very hot on the inside, probably creating hot spring like on Earth. This might be a place where life could exist.
V. As an example of classification of a common species … let’s take a cat for example. Notice how we use LATIN.
A. Domain: Eukarya - (Has cells with a nucleus)
B. Kingdom: Animalia - (Animals)
C. Phylum: Chordata: - (Is an animal with a backbone.)
D. Class: Mammalia - (Is a mammal.)
E. Order: Carnivora - (Is a carnivore.)
F. Family: Felidae
G: Genus: Felis
H. Species: Cats
VI. This connects with genetics because we used to put living things in categories based on their STRUCTURE. Now we can look at the DNA from a living thing and determine how closely it is related to another living thing. The ability to look at DNA to help categorize living things has changed the classifications of hundreds of plants and animals.