dna structure notes qq#1: – what do you know about the structure of dna? – be as detailed as...
TRANSCRIPT
DNA Structure Notes
• QQ#1:–What do you know about the structure of DNA?
–Be as detailed as Possible
Deoxyribose Nucleic Acid: Structure NotesMicrosoft ClipArt GalleryCalled a double
helix (a spiral ladder)
DNA is a Polymer• DNA’s Monomers: • repeating subunits called NUCLEOTIDES
• Nucleotides consist of three parts:• Phosphate Group• Sugar Group• Nitrogenous Base
QQ#2
What are the three parts of the nucleotide?
Nucleotide Structure
Copy theDiagram In your notes:
• The phosphate bonds to what is called the 5’ (five prime) carbon of the sugar molecule.
• The base bonds with the sugar at the 1’ carbon. – Can be one of four bases:• Adenine, Thymine, Cytosine, Guanine
Discuss: How do you
think these may link
together to form a
polymer?
DNA’s Repeating Structure DNA is directional
The nucleotides are connected together by a phosphodiester bond between phosphate groups at the 3’ and 5’ carbon on the the sugar molecule.
These bonds create one side of the strand of DNA.
The other (complementary) strand runs in the opposite direction connected in the middle by the bases called anti-parallel chain
Bases In general
bases can accept hydrogen ions or more generally, donate a pair of valence electrons when bonding
The opposite of an acid
Categories of Bases pyrimidines – one ring
Cytosine and Thymine purines – two rings
Adenine and Guanine
• QQ#4:–Can you think of a way to remember which bases are purines and which are pyrimidines?
Categories of Bases
pyrimidines – one ring
Cytosine and Thymine
purines – two rings
Adenine and Guanine
Hydrogen Bonds• A Purine always bonds with
a Pyrimidine• Bases are connected across
middle of helix:• Adenine forms (2) h-bonds
with Thymine• Guanine forms (3) h-bonds
with Cytosine• These bonds hold the two
strands of DNA together and cause the twisting to occur
• The entire code that instructs our cells depends on the order of Adenine, Guanine, Thymine, Cytosine
• The specific bonding angles of the nucleotides forces the helix shape.
• Within the helix there is a major and minor groove
Major and Minor Grooves
• Caused by bonding angles
• Major groove allows proteins to bond: important for replication.
• Each full twist of the helix has 10 nucleotides
Putting it All together
http://www.youtube.com/watch?v=ZGHkHMoyC5I
Exit Slip
• On a separate scratch piece of paper, answer the following questions.1. What do you know now about DNA structure?2. Compare this knowledge with what you knew before?3. Why is the structure of DNA important to the essential questions: In what way(s) does your DNA define you?4. Predict how the structure of DNA relates to how all organisms have the same exact DNA in all cells