DNA Structure

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Essential Question What is DNA made of and how does it code for a genetic trait?

Deoxyribonucleic Acid DNA stands for...       Deoxyribonucleic Acid

DNA FACTS established by: James Watson and Francis Crick   

DNA Structure DNA consists of two molecules that are arranged into a ladder-like structure called a double helix. A molecule of DNA is made up of millions of tiny subunits called nucleotides.

What is a nucleotide? Each nucleotide consists of: Phosphate group Pentose Sugar (Deoxyribose) Nitrogenous base (A,T,G,C)

Nucleotides The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”.

Nitrogenous Bases Color code the following nitrogenous bases on the next slide.

Nitrogenous Bases A Adenine T Thymine C Cytosine G Guanine

Key Phosphate Deoxyribose (sugar)

Base-Pair Rule Adenine <==> Thymine Guanine <==> Cytosine The sides of the DNA ladder are phosphate & sugar held together by  hydrogen bonds

Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand.

Make sure you are in present mode to see this animation. C T G G A T C

DNA Structure To crack the genetic code found in DNA we need to look at the sequence of bases. The bases are arranged in triplets called codons. A G G - C T C - A A G - T C C - T A G T C C - G A G - T T C - A G G - A T C

Base Pair Rule One side: A T A T C A T G C G G G Other side: T A T A G Fill in the “other side” on your own so you can check your work afterwards on which base pairs up with the other.

DNA Structure A gene is a section of DNA that codes for a protein. Each unique gene has a unique sequence of bases. This unique sequence of bases will code for the production of a unique protein. It is these proteins and combination of proteins that give us a unique phenotype.

How the Code Works The combination of A,T,G,C determines what traits you might have. Ex: C A T C A T   =  purple hair T A C T A C  =  yellow hair

Think of the bases of DNA like letters. Letters form words Think of the bases of DNA like letters. Letters form words.... Words form sentences....                 *endless                combinations

DNA Gene Protein Trait

Let's Review What We Know About DNA Copy the missing parts of the questions. 1.  DNA stands for:   _________________________ 2.  What is the shape of DNA? _______________ 3.  Who established the structure of DNA?  ____________ 4.  Adenine always pairs with _______________ 5.  The sides of the DNA ladder are deoxyribose and _____ 6.  Guanine always pairs with _____________ 7.  What is the complimentary sequence:   A A T  G  C A 8.  The two sides of DNA are held together by _______ bonds. 9.  DNA is composed of repeating subunits called ______________________ 10.  What are the 4 bases that make up the rungs of the DNA ladder? _______________________________________

Add in the following words in the correct places on your diagram: chromosomes gene DNA cell

       

Use the image to  complete the following:  Circle a nucleotide and label it.  Label the name of the sugar (______________)  and phosphate. Label the bases that are not already labeled.

Summary Write 2 questions that start with a “Why” on page 1 & 2 of notes. Write a 3 sentence summary that answers the essential question. Turn in to basket. Pick up 12-1 DNA, complete & turn in to basket. Study for DNA quiz on Friday.