Wednesday, April 29, 2020

04.29.2020 - Science Notes -

04.29.2020 - Wednesday - Science - 
Remember to, as always, define CAPITALIZED terms with which you are unfamiliar.

  1. Current Events:  CNN !0 link …
    1. One note on UFO’s … Yes, “Unidentified Flying Objects.”  The reason for a note on UFO’s is that, very often, people have wondered if UFO’s are a sign that some kind of EXTRATERRESTRIAL LIFE is visiting Earth, perhaps in an advanced spacecraft.  In science class we have a reading in our text about UFO’s. While UFO’s are, sometimes, unexplained, as scientists we have to look at them critically and there’s no reason to think they’re from other planets.
    2. One note on exploring the oceans - while vast regions of the oceans remain unexplored the show - today - focuses on new techniques for exploring.
II.  Chromosomes, genes, and DNA.
A.  In the clip, that we watched in class, from the science fiction movie Jurassic Park the geneticists use DNA from dinosaurs to recreate entire animals.
B.. While mosquitos did exist during the MESOZOIC period - and they did feed on dinosaurs - the DNA from dinosaurs is long gone. Trying to recreate a whole dinosaur would be like trying to recreate an entire novel of thousands of pages with only the scraps of a few of the pages available. There’s too much missing information.

III.  DNA - the long molecule that carries genetic information - is a DOUBLE HELIX. 
A.  The DNA instructs the cell on ho to build PROTEINS.
B.  PROTEINS are made up of smaller blocks called AMINO ACIDS.  
C.  There are 20 different types of AMINO ACIDS.

IV.  Human DNA contains the instructions for making thousands of different types of PROTEINS.

V.  The BASE PAIRS of DNA are made of four different types of molecules. They are abbreviated with the letters A - T - C - G.  (Adenine, Thymine, Cytosine, and Guanine.) 
A.  (aside) - In this class you don’t need to remember the names of the four bases, just remember the letters for now.
VI.  The BASE PAIRS always fit together, or pair up, in the following ways …
A.     Adenine always pairs with Thymine.    ( A - T )
B.     Cytosine always pairs with Guanine.      ( C - G )

VII. A section of DNA that codes for (tells the cell how to make) a single protein is called a GENE.
A.  Humans have more than 20,000 GENES!
B.  (aside) There is DNA in our cells that doesn’t seem to “code” for proteins. It’s called “non-coding” DNA and we really don’t know what it does!

VII.  DNA is organized into CHROMOSOMES. Humans have 23 pairs of chromosomes.
A.  Different SPECIES may have very different numbers of chromosomes.
B.  Notice we said 23 PAIRS of chromosomes. Animals get half of their chromosomes from their mother and the other half from their father.
C.  The DNA from your parents gets mixed, which is why each person is unique!
D.  Humans have 46 pairs of chromosomes.

OK class … that is a ton of information! We’ll go into this in more detail and go through the “rules” for how genes mix to give us specific TRAITS. For now, our job is to be sure we know those Key Terms (CAPITALIZED TERMS) as we’ll be using them this unit. - 

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