NUCLEIC ACIDS:

DNA & RNA

DNA• Deoxyribonucleic Acid (pg. 297)• ____________-(genes)• permanent• 1 meter in each human ________• “Double ______”

– Animation of DNA packaging– http://www.hhmi.org/biointeractive/media/DNAi_packaging_vo2-lg.mov

DNA• Backbone: alternating….

–__________ (deoxyribose)–__________

• Rungs: –Nitrogen _______

• ____________:–Sugar+Phosphate+Nbase

DNA

PHOSPHATE

DEOXYRIBOSESUGAR

NITROGEN BASE (2)

ALL 3 MAKE A

_____________

• Nitrogen bases: 4 types_________: • Adenine (__)• Guanine (__)(double ring)_________:• Cytosine (__)• Thymine (__) (single ring)

BASE PAIRING• In DNA samples of ___ organism:

–The % of G and C are _______–The % of A and T are _______

Organism %A %T %G %C

Human 30.9% 29.4% 19.9% 19.8%

Rat 28.6% 28.4% 21.4% 21.5%

Fish 27.8% 27.5% 22.2% 22.6%

Yeast 31.3% 32.9% 18.7% 17.1%

BASE PAIRING• Edwin Chargaff• ______________:

–A=____–G=____–Yet… no one knew why!

Watson and Crick• James _______ (US)• Francis ________(England)• April _______• Built cardboardwire models to determine 3-D structure of DNA

Watson and Crick• Using Rosalind_________ X-ray diffraction picture of DNA, they determined the

____________structure

Orientation• DNA strand is oriented ___to ___

Chromosome Structure• __________: DNA (neg

charge) coils around _____ proteins (pos charge)

• Nucleosomes group into _________

• Chromatin supercoils to make _____________