DNA

DNA. DNA is often called the blueprint of life. In simple terms, DNA contains the instructions for making proteins within the cell. Proteins control all chemical processes in the cell

Where is DNA found in the Cell?? Answer: The Nucleus DEOXYRIBONUCLEIC ACID Stores and passes on genetic information from one generation to another.

4 DNA by the Numbers Each cell has about 2 m of DNA. The average human has 75 trillion cells. The average human has enough DNA to go from the earth to the sun more than 400 times. DNA has a diameter of only m. The earth is 150 billion m or 93 million miles from the sun.

DNA,a type of nucleic acid, is a large polymer This means that DNA is very large molecule made up a LOT of individual monomers – single pieces What is a monomer of nucleic acids called? Answer: Nucleotide A single strand of DNA is made up of many MILLIONS of nucleotides

Nucleotide = sugar + phosphate + nitrogenous base

7 The Shape of the Molecule The basic shape is like a twisted ladder or zipper. This is called a double helix.

DNA Who figured it out? James Watson, Francis Crick and Rosalind Franklin are credited with discovering the double helix structure of DNA. Watson and Crick used Franklin’s x-ray data to write “The Double Helix”

WatsonCrick Franklin

What they figured out: DNA is a twisted ladder of 2 single strands attached in the middle Each strand is made up of only 4 different types of nucleotide units

12 nucleotide Single Strand of DNA

Double Strand of DNA The outer parts of the ladder (rail)are made of sugars (deoxyribose) bonded to each other by phosphates. The steps of the ladder are made of pairs of nitrogen bases.

DNA bonds Covalent bonds connect sugars and phosphates Hydrogen bonds link bases

DNA is made up of steps and rails of a ladder. This is a rail This is a step Green can only go with Red Purple can only go with Yellow Nitrogen Bases

DNA STRUCTURE 1.ADENINE = A 2.GUANINE = G 3.CYTOSINE = C 4.THYMINE = T THE NITROGEN BASES ARE REPRESENTED BY THEIR CAPITAL LETTER.

17 Chargaff’s Rule: Adenine and Thymine always join together A T Cytosine and Guanine always join together C G

DNA STRUCTURE There is only one way the nitrogen bases can join in the center of the DNA molecule Adenine pairs with Thymine Guanine pairs with Cytosine How to remember ?

We love DNA made of nucleotides Sugar, phosphate, and a base bonded down one side. Adenine and thymine make a lovely pair, Cytosine without guanine would feel very bare. Hydrogen bonds attach the bases just like we had planned. A double helix is the shape of our DNA strand.

DNA STRUCTURE QUESTIONS? Can C join with A? And G join with T? NO

ACTCATGGTCATG TGAGTACCAGTAC This is an example of a sequence of a single strand of DNA that may be found in your body. What would be the sequence of the other side of the DNA? ACTCATGGTCATG

The combinations of the nitrogen bases is the code that produces the information for a particular protein Because there can be so many different combinations of the bases the code can be limitless