1. Macromolecules DNA/RNA

2. The first macromolecule we will study is the DNA and RNA molecules. Strands of DNA wrapped around proteins make up the chromosomes discussed meiosis and mitosis. DNA stands for “deoxyribonucleic acid” and literally has one fewer oxygen atoms (deoxy) in it’s sugar component than it’s counterpart RNA “ribonucleic acid”. The main elements are carbon, hydrogen, oxygen, nitrogen and phosphorous.

3. importance DNA codes for the production of all proteins most organisms and many viruses. It has important features that make it useful for this: – It can make exact copies of itself (important to pass on protein making instructions to new cells/offspring) – It can easily be “opened up” to reveal it’s protein making instructions, and then put back together, through use of hydrogen bonding “H-bonding” (hydrogen of one molecule has a positive charge and is attracted to a negative O,N,or F of another molecule.)

4. RNA and DNA Both Ribonucleic acid and deoxyribonucleic acid are composed of a 5 carbon, sugar backbone (ribose and deoxyribose respectively), linked together in a chain not by an intermediate phosphate molecule. DNA is doubled stranded (two sides held together by H-bonds), while RNA is single stranded. DNA looks like a twisted up ladder, called a double helix.

5. Contrary to popular opinion Many people believe and say that sugar “dissolves” in water (this would be bad news for DNA/RNA as well as many other structures we have. When a substance, like salt NaCl dissolves, the water molecules break them apart into ions “Na+” and “Cl-”. We say they are soluble in water. Sugars do NOT do this

6. Sugar is insoluble In the case of simple sugars the individual molecules are separated and float around amongst the water molecules, but they are NOT pulled apart by it. They dissolute in the water. More complex sugars (many sugars bonded together) become more and more difficult to dissolute. (starch forms suspensions like pudding) carbohydrates and fiber do not dissolute.

7. The nucleotides Also attached to each sugar is a nucleic acid, also called a nitrogenous base (either a double ringed purine or a single ringed pyridimine), which are basically comprised of 5 or 6 sided sugars with some of the carbons having been replaced with nitrogen. DNA has Adenosine, Cytidine, Guanosine and Thymidine, RNA has the same first three, but Uracel instead of Thymidine. You don’t have to know the names, just the letters. One unit of phosphate, sugar and a base is called a nucleotide (page 229 of text)

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9. DNA Structure The purines of one DNA strand Hydrogen bond to a pyridimine of the corresponding strand.

10. Opposites attract Note the position of the charged atoms of the nucleotides. What would happen if a T tried to bond to a G? If a an A tried to bond to a C? The nucleotides can only H-bond according to the “base pairing sequence” A-T and C-G. This is what allows DNA to make exact copies of itself.

11. Draw and label Be able to draw and label a simple diagram of a DNA strand, and tell the main elements it is made up of ( see page 230 of text). Be able to explain the base pairing sequence of the nucleotides as well as define a nucleotide.

12. Assignment Concept check #1-3 page 231 Concept check #1,2 page 234