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NUCLEIC ACIDS

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Below is one of the molecules that makes up DNA. What functional groups do you see in the molecule: 1.Hydroxyl 2.Carboxyl 3.Amino 4.Phosphate

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Functions of DNA Control the processes of heredity by which cells and organisms reproduce proteins

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Types of Nucleic Acids 1.DNA (deoxyribonucleic acid): double- stranded 2.RNA (ribonucleic acid): single- stranded

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Nucleic Acid Structure The monomer units of DNA are known as nucleotides All nucleotides have three parts in common: a.Phosphate backbone b.Pentose sugar (ribose or deoxyribose) c.Nitrogen base

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Deoxyribose Sugar (DNA) Has 5 carbons and 3 oxygens Carbon atoms are numbered 1', 2', 3', 4', and 5' Distinguishes from the numbering of the atoms of the purine and pyrmidine rings 5'-carbons link to the phosphate groups 3'-carbons link to the hydroxyl groups

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Direction of the nucleotides in one strand is opposite to their direction in the other strand: the strands are antiparallel. Asymmetric ends of DNA strands are called the 5 (five prime) and 3 (three prime) ends 5' end having a terminal phosphate group 3' end having a terminal hydroxyl group

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Nitrogen Bases Weak hydrogen bonds connect complementary nitrogen bases Two types: a.Pyrimidines: form hexagon shaped rings 1.Cytosine 2.Thymine (only DNA) 3.Uracil (only RNA)

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b.Purines: combination of a pentagon shaped ring and a hexagon shaped ring 1.Adenine 2.Guanine

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Nitrogen Base Pairing Adenine and Thymine must form two hydrogen bonds to be stable while Guanine and Cytosine must form three Makes the base pairing system an extremely simple: the A-T and C-G pairs are the only ones physically possible

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Lets Practice How to Form DNA!

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We will use our hands to represent a nucleotide. SUGAR PHOSPHATE NITROGEN BASE

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The four different Nitrogen Bases for DNA are abbreviated using the following letters. Adenine Thymine Guanine Cytosine A T G C

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Using your two hands, please show how you think two nucleotides will/should bond together. Did you put your hands like this???

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Time to find out why this is wrong!!!

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Adenine and Guanine are larger molecules known as PURINES LOOK! TWO RINGS!!!

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THYMINE and CYTOSINE are smaller molecules known as PYRIMIDINES LOOK! Only one ring!!

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Now, when using our hands to represent the nucleotides, we must modify the nitrogen base in order to represent these PURINES and PYRIMIDINES. How would you represent a large PURINE? How would you represent a small PYRIMIDINE? Full Finger Half Finger

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In DNA, a PURINE always bonds with a PYRIMIDINE when forming a rung of the DNA ladder. LOOK! A long finger pairs with a short finger! In other words, a purine pairs with a pyrimidine.

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In DNA, Adenine always pairs with Thymine using two hydrogen bonds. A T

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In DNA GUANINE always pairs with CYTOSINE using three hydrogen bonds. G C

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Time to use your brain and hands in order to review nucleotide structure and type. USING YOUR HAND, SHOW ME THYMINE USING YOUR HAND SHOW ME ADENINE SHOW ME CYTOSINE SHOW ME HOW CYTOSINE AND THYMINE BOND TO FORM A RUNG ON THE LADDER THEY DONT

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OK Now that you recognize nucleotide type and structure, its time to start building the polymer from these monomers.

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The molecules marked W are best described as: 1.Monomers 2.Polymers 3.Isomers 4.isotopes

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Reactions A and B are respectively known as: A B 1.Dehydration, hydrolysis 2.Condensation, hydrolysis 3.Polymerization, decomposition 4.Hydrolysis, dehydration

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Molecule(s) X are most likely: 1.Carbohydrates 2.Monomers 3.Polymers 4.Water 5.Starch

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If molecule W is a nucleotide, molecule marked Y is most likely: 1.Protein 2.Starch 3.DNA 4.Galactose 5.Fructose

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In order to make a molecule of DNA, you would need to create many rungs to the DNA ladder. Look. Many Rungs. Etc

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What part of the nucleotide alternates to form the sides of the DNA ladder? Etc Sugar, Phosphate. Etc

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What makes up the RUNGS of the ladder? The Nitrogen Bases

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Go Ahead! Stack you hand on top of your partners hands building two rungs of the DNA ladder.

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Why is this WRONG????

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The sides of the DNA ladder run in opposite directions. One side is actually flipped and the nucleotides are upside down!

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TRY IT!!!

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Because the sides of the DNA run in opposite directions, DNA is said to be ANTIPARALLEL.

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In this DNA molecule, the THUMB part or better known as the PHOSPHATE GROUP, is said to be the 5 prime (5) end. 5 prime

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The hand or sugar part of the DNA molecule makes up the 3 prime (3) end of the DNA ladder. 3 Prime

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If you link enough nucleotides together, the DNA molecule begins to take on the characteristic shape known as the Double Helix