Nucleic acids 2006-2007
Nucleic Acids Information storage 2006-2007
Nucleic Acids Function: u genetic material DNA stores information w genes w blueprint for building proteins n DNA RNA proteins transfers information w blueprint for new cells w blueprint for next generation proteins
A C T G A T G A C C A T G
Nucleic Acids Examples: u RNA (ribonucleic acid) single helix u DNA (deoxyribonucleic acid) double helix Structure: u monomers = nucleotides DNA RNA
Nucleotides 3 parts u nitrogen base (C-N ring) u pentose sugar (5C) ribose in RNA deoxyribose in DNA u phosphate (PO 4 ) group Nitrogen base I m the A,T,C,G or U part! Are nucleic acids charged molecules?
Types of nucleotides 2 types of nucleotides u different nitrogen bases u purines double ring N base adenine (A) guanine (G) u pyrimidines single ring N base cytosine (C) thymine (T) uracil (U) Purine = AG Pure silver!
Nucleic polymer Backbone u sugar to PO 4 bond u phosphodiester bond new base added to sugar of previous base polymer grows in one direction u N bases hang off the sugar-phosphate backbone Dangling bases? Why is this important?
Pairing of nucleotides Nucleotides bond between DNA strands u H bonds u purine :: pyrimidine u A :: T 2 H bonds u G :: C 3 H bonds Matching bases? Why is this important?
DNA molecule Double helix u H bonds between bases join the 2 strands A :: T C :: G H bonds? Why is this important?
Copying DNA Replication u 2 strands of DNA helix are complementary have one, can build other have one, can rebuild the whole Matching halves? Why is this a good system?
When does a cell copy DNA? When in the life of a cell does DNA have to be copied? u cell reproduction mitosis u gamete production meiosis
DNA replication It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material. James Watson Francis Crick 1953
1953 1962 Watson and Crick and others
Maurice Wilkins and 1953 1962
Rosalind Franklin (1920-1958)
Interesting note Ratio of A-T::G-C affects stability of DNA molecule u 2 H bonds vs. 3 H bonds u biotech procedures more G-C = need higher T to separate strands u high T organisms many G-C u parasites many A-T (don t know why)
Another interesting note ATP Adenosine triphosphate u modified nucleotide adenine (AMP) + P i + P i + +
HELIXHELIX
Macromolecule Review 2006-2007
Carbohydrates Structure / monomer u monosaccharide Function u energy u raw materials u energy storage glycosidic bond u structural compounds Examples u glucose, starch, cellulose, glycogen
Lipids Structure / building block u glycerol, fatty acid, cholesterol, H-C chains Function u energy storage u membranes u hormones Examples u fat, phospholipids, steroids ester bond (in a fat)
Proteins Structure / monomer u amino acids u levels of structure Function u enzymes defense u transport structure u signals receptors Examples u digestive enzymes, membrane channels, insulin hormone, actin peptide bond
Nucleic acids Structure / monomer u nucleotide Function u information storage & transfer Examples u DNA, RNA phosphodiester bond
Let s build some DNA, baby!
Ghosts of Lectures Past (storage) 2007-2008
Building the polymer
RNA & DNA RNA u single nucleotide chain DNA u double nucleotide chain N bases bond in pairs across chains u spiraled in a double helix double helix 1 st proposed as structure of DNA in 1953 by James Watson & Francis Crick (just celebrated 50th anniversary in 2003!)
Information polymer Function u series of bases encodes information like the letters of a book u stored information is passed from parent to offspring need to copy accurately u stored information = genes genetic information Passing on information? Why is this important?