Chapter 5 5 Nucleic Acids AP Biology Objectives

Chapter 5. 5 Nucleic Acids AP Biology

Objectives: § Describe the structure of a nucleotide. § Compare and contrast the structure and § § § function of DNA and RNA. Identify the 5’ end and 3’ end of a nucleic acid and the direction complementary nucleotides are added. Give the base-pairing rules in DNA and RNA. Vocabulary: nucleotide, nitrogen base, complementary AP Biology

Nucleic Acids Information storage AP Biology

Nucleic Acids § Function: u genetic material § 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 AP Biology proteins

G T A AP Biology A C G T C G A T C A

Nucleic Acids § Examples: u RNA (ribonucleic acid) § single helix u DNA (deoxyribonucleic acid) § double helix § Structure: u AP Biology monomers = nucleotides DNA RNA

Nucleotides § 3 parts nitrogen base (C-N ring) u pentose sugar (5 C) u § ribose in RNA § deoxyribose in DNA u phosphate (PO 4) group Are nucleic acids charged molecules? AP Biology Nitrogen base I’m the A, T, C, G or U part!

Types of nucleotides § 2 types of nucleotides different nitrogen bases u purines u § double ring N base § adenine (A) § guanine (G) u AP Biology pyrimidines § § single ring N base cytosine (C) thymine (T) uracil (U) Purine = AG Pure silver!

Nucleic polymer § Backbone sugar to PO 4 bond u phosphodiester bond u § 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? AP Biology

Pairing of nucleotides § Nucleotides bond between DNA strands H bonds u purine : : pyrimidine u A : : T u § 2 H bonds u G : : C § 3 H bonds Matching bases? Why is this important? AP Biology

DNA molecule § Double helix u H bonds between bases join the 2 strands § A : : T § C : : G H bonds? Why is this important? AP Biology

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? AP Biology

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 AP Biology

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 AP Biology

1953 | 1962 Watson and Crick … and others… AP Biology

Maurice Wilkins… and… AP Biology 1953 | 1962

Rosalind Franklin (1920 -1958) AP Biology

Interesting note… § Ratio of A-T: : G-C affects stability of DNA molecule u u 2 H bonds vs. 3 H bonds 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) AP Biology

Another interesting note… § ATP Adenosine triphosphate u modified nucleotide § adenine (AMP) + Pi + AP Biology +

Macromolecule Review AP Biology

Carbohydrates § Structure / monomer u monosaccharide § Function energy u raw materials u energy storage u structural compounds u glycosidic bond § Examples u AP Biology glucose, starch, cellulose, glycogen

Lipids § Structure / building block u glycerol, fatty acid, cholesterol, H-C chains § Function energy storage u membranes u hormones u § Examples u AP Biology ester bond (in a fat) fat, phospholipids, steroids

Proteins § Structure / monomer amino acids u levels of structure u § Function enzymes u transport u signals u defense u structure u receptors u peptide bond § Examples u AP Biology digestive enzymes, membrane channels, insulin hormone, actin

Nucleic acids § Structure / monomer u nucleotide § Function u information storage & transfer § Examples u AP Biology DNA, RNA phosphodiester bond

Ghosts of Lectures Past (storage) AP Biology 2007 -2008

Building the polymer AP Biology

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 50 th anniversary in 2003!) AP Biology

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? AP Biology