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1. Label the components that make up the DNA. 2. Draw a box surrounding one nucleotide of the double helix and label this.

3 All life on earth uses a chemical called DNA to carry its genetic code or blueprint. In this lesson we be examining the structure of this unique molecule. By the way, can you make out what this is?

We study DNA for many reasons, e.g.,  its central importance to all life on Earth/ identifies organisms, HowStuffWorks Videos "Solved: DNA Analysis"  medical benefits such as cures for diseases or risks for genetic diseases na_testing_for_everyone/25395/index.html 4

 How is DNA similar to the Morse Code or any other secret codes?  How can we tell if organisms are related to each other and how organisms change over time?

 D=Deoxyribo  N=Nucleic  A=Acid  Deoxyribonucleic Acid 6

WHAT IS DNA?  DNA.  DNA is often called the blueprint of life.  In simple terms, DNA contains the instructions for making proteins within the cell. 7

CHROMOSOMES AND DNA?  Our genes are on our chromosomes.  Chromosomes are made up of a chemical called DNA. 8

THE SHAPE OF DNA?  DNA is a very long polymer.  The basic shape is like a twisted ladder or zipper.  This is called a double helix. 9

THE DOUBLE HELIX MOLECULE  The DNA double helix has two strands twisted together. 10

DNA DOUBLE HELIX Nitrogenous Base (A,T,G or C) “Steps of ladder” “Rails of ladder” Phosphate & Sugar Backbone

WHAT MAKES UP THE STRAND (RAILS) OF DNA?  The backbone of the molecule is alternating phosphates and deoxyribose sugar 12 phosphate deoxyribose bases

WHAT ARE THE FOUR NITROGENOUS BASES THAT MAKE UP THE STEPS OF THE LADDER?  Cytosine C  Thymine T  Adenine A  Guanine G THESE MAKE UP THE STEPS OF THE LADDER!!! 13 DNA has four different bases:

DNA is made up of repeating units called nucleotides 14 nucleotide

WHAT MAKES UP THE DNA NUCLEOTIDES? O O=P-O O 1. Phosphate Group Group N 3. Nitrogenous base (A, G, C, or T) (A, G, C, or T) CH2 O C1C1 C4C4 C3C3 C2C Sugar (deoxyribose)

A. Phosphate group B. Deoxyribose sugar C. Nitrogen base A. B. C.

CHARGAFF’S RULE:  DNA has specific pairing between the nitrogen bases:  Adenine Thymine  Adenine must pair with Thymine  GuanineCytosine  Guanine must pair with Cytosine about the same  Their amounts in a given DNA molecule will be about the same. G C TA

BASE-PAIRINGS CG H-bonds T A

TWO STRANDED DNA  Remember, DNA has two strands that fit together something like a zipper.  DNA was made of 2 long stands of nucleotides arranged in a specific way called the “Complementary Rule” 19

GENETIC DIVERSITY…  Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.

THE CODE OF LIFE…  The “code” of the chromosome is the SPECIFIC ORDER that bases occur. A T C G T A T G C G G…

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1. Which of the following bases pairs with adenine in DNA? a. Thymine b. Guanine c. Adenine d. Cytosine

2. If the template of a strand of DNA is 5' AGATGCATC 3’,the complementary strand will be — F 3' TCTACGTAG 5' G 5' CTACGTAGA 3' H 3' AGATGCATC 5' J 5' AGACGTCTA 3'

F Amount of adenine G Number of sugars H Sequence of nitrogen bases J Strength of hydrogen bonds

A. orders of nucleotides B. types of sugar molecules C. sized phosphate groups D. types of nitrogenous bases

F. DNA provides the shape and structure of the nucleus. G. DNA packages materials for transport through the nucleus. H. DNA carries materials into and out of the nucleus. J. DNA contains the blueprint for producing the whole organism.

Create a paper model of the double helix paying close attention to the components that make up the nucleotides!