DNA Structure Function You Tube Index DNA Structure

DNA Structure & Function

You Tube Index DNA Structure (in order of usefulness) • DNA Structure – http: //glencoe. mcgrawhill. com/sites/9834092339/student_view 0/chapter 14/dna _structure. html • Good (factual, but dry) – http: //www. youtube. com/watch? v=tkn. Yr. U 98 r. Bk&feature =fvwrel • Structure & Prot synthesis – http: //www. youtube. com/watch? v=FUA 6_Ucw 3 i 4 For history of discovery of DNA and structure see the Powerpoint “DNA History”

Watson & Crick (credited with discovery of STRUCTURE of DNA, though their work relied heavily on the work of others)

!!! DNA Functions • Carries genetic code for life processes • Can replicate to continue life… • Lengths of DNA (genes) code for production of proteins that are – structural – functional – & are 95% of human body!

!!! DNA Packaging

Role of DNA Terms (over the course of this AS & others you will understand all of these terms) • • Genome – all the DNA in a cell • Genes – sections of DNA coding for the production of proteins • • Chromosomes • • Chromatid • Nucleus • • Nuclear Membrane • Chromatin • DNA • • Nucleotides - the repeating unit of • DNA • • Protein • • m. RNA • Prokaryote – cells / organisms without a nucleus Eukaryote – cells / organisms with a nucleus Protein synthesis – process where protein is manufactured Mitochondria – organelle (“little organ”) in a cell where energy (ATP) is produced Cytoplasm Enzymes Metabolism Cell division Centromere

!!! Nucleic Acids • Two types: – DNA – Deoxyribose nucleic acid (location: nucleus) – RNA – Ribose nucleic acid (location: nucleus + cytoplasm) • Made of repeating units: nucleotides • Nucleotide made of: – Nitrogen base – A 5 -carbon sugar (deoxyribose in DNA, ribose in RNA) – Phosphate group

Sweet Difference

!!! DNA Structure The two strands are “anti parallel” One strand runs from 3’ to 5’ the other 5’ to 3’

DNA Structure • Shape: double helix (like a twisted ladder)

!!! • 4 bases: – Adenine – Guanine DNA Structure T – Thymine C – Cytosine In RNA the base U (Uracil) replaces thymine • “Rungs” - Bases held together by hydrogen bonds – A pairs with T (two bonds) – G pairs with C (three bonds) • “Backbone” – Sugars joined to phosphates * by “phosphodiester” bonds! • Complementary vs template – Since you find a C opposite a G… etc the second strand is said to be complementary to the first. - And: the first strand can be used as a template to make a new complementary strand

* Pyrimidines vs Purines • The “pyrimidine bases” are: – C & T (one ring structure) • The “purines” are: – A & G (double ring structure) To remember: purines = two rings

Length of DNA in organisms • Only 4 bases BUT one DNA molecule = millions of bases long • Human: 6 billion base pairs • Bacteria: ~ 4. 3 million bases • Viruses…. .

ΦX 174 Bacteriophage DNA Sequence Bacteriophage = virus affecting bacteria 9 genes, each codes for one protein. Genes overlap, one genes is highlighted. Human genome = 1 million times longer

How much DNA in humans? • ~ 100, 000, 000 cells in the human body • 2 m of DNA in each cell (3 -5 cm per chromosome) • DNA length in kilometres: – 200, 000, 000 km • How many times to the moon? (moon = 184, 000 km) – 1, 086, 957 times • How many times to the sun & back? (= 300, 000 km) – 667 times

DNA Structure END