dna: the other macromolecule
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DNA: The Other MacroMolecule. Basic Structure. DNA is a long chain polymers of small compound called nucleotides. Draw this picture in box in your notes. What is a Nucleotide?. Nucleotide contains: 5-carbon sugar called deoxyribose Phosphate group - PowerPoint PPT PresentationTRANSCRIPT
DNA: The Other MacroMolecule
Basic Structure
• DNA is a long chain polymers of small compound called nucleotides.
• Draw this picture in box in your notes
What is a Nucleotide?
Nucleotide contains:5-carbon sugar called
deoxyribosePhosphate groupOne Nitrogenous
base (there are 4 types)
How are the molecules positioned?
• Sugar and phosphate make up backbone (sides of ladder)
• Nitrogenous bases make up steps of ladder
• Bases are always paired (Chargaff’s rule)
• Draw a nucleotide in the box and label its parts.
There are two types of Nitrogen Bases:
• Make up the “steps” or rungs of the DNA ladder– One Step= Purine + Pyrimidine
• Purines– Double ring structure– Adenine– Guanine
• Pyrimidines– Single-ring structure– Cytosine– Thymine (in DNA only)
Watch the following videos to help you get a better
understanding of DNA and nucleotides
• http://www.youtube.com/watch?v=qy8dk5iS1f0
• http://www.youtube.com/watch?v=rromYAt1Lfw
How do they pair up to for the rungs of the ladder?
• Adenine (Purine) binds with Thymine (pyrimidine) or vice versa
• A-T or T-A.
• Cytosine (Purine) binds with Guanine (pyrimidine) or vise versa
• C-G or G-C.
• Held together by weak hydrogen bonds.
• Base pairs join together in complement.
• Draw that pairing
How does it all fit into your cells?
• Chromatin wrapped around proteins called histones.
• Chromatin condenses to form chromosomes during replication
DNA Replication
• The enzyme helixase “unzips”the helix by breaking the hydrogen bonds.
• DNA polymerase moves along the “exposed” strands, adding nuleotides. A new helix is made. You now have two.
• Polymerase proofreads, backtracks, and fixs errors in base pairs.
• Errors not corrected are called mutations
DNA Replication, now that’s easy!
• http://www.youtube.com/watch?v=zdDkiRw1PdU
• http://www.youtube.com/watch?v=cDlKrLJjRlY&feature=related cartoon
• http://www.youtube.com/watch?v=gI-TGzZNzVE remix of cartoon
Draw this in box for replication.Be sure to label old and new strands.
• Where might you draw in helixase?
• Polymerase?
How different are We?
• The difference between 2 people, 2-10 million nucleotides.
• That’s only 1% of our total DNA!• DNA replication only takes about 6
hours to happen.
Who discovered DNA and its structure?
• Rosalind Franklin and Maurice Wilkins• Rosalind Franklin, 1950s, Brit scientist who
studied DNA• Used X-ray diffraction technique to learn
about structure of DNA • She noticed an X-shaped pattern• This indicated that DNA had a helical
structure• She did not get a chance to publish her
research…and her idea was basically stolen
You’ve been ripped off, once again it’s a Man world!
• http://www.youtube.com/watch?v=7SN7aAkdt-0
Who got the credit? Crick and Watson
• 23-year old American Biologist James Watson went to work with English Physicist Francis Crick
• Used information from Rosalind Franklin and Maurice Wilkins (1950’s)– These two scientists used Rosalind
Franklin’s x-ray crystallography images to begin to piece together the DNA structure
– Showed that there were 2 strands twisted around each other
These guys got all the credit for discovering the structure of DNA
• http://www.youtube.com/watch?v=OiiFVSvLfGE
Watch the video on Secrets of the Sequence
• Do the accompanying worksheet called the Human Genome Project
• http://www.youtube.com/watch?v=sf0YXnAFBs8