THE MOLECULAR BASIS OF INHERITANCE CHAPTER 16 THE MOLECULAR BASIS OF INHERITANCE

I. DNA AS THE GENETIC MATERIAL THE SEARCH FOR THE GENETIC MATERIAL LED TO DNA: SCIENCE AS A PROCESS EXPERIMENTS WITH BACTERIA AND LATER, WITH PHAGES PROVIDED THE FIRST STRONG EVIDENCE THAT THE GENETIC MATERIAL IS DNA.

16.1 TRANSFORMATION OF BACTERIA

B. WATSON AND CRICK DISCOVERED THE DOUBLE HELIX : SCIENCE AS A PROCESS WATSON AND CRICK DISCOVERED THAT DNA IS A DOUBLE HELIX. (1950S) AMERICAN: JAMES WATSON & BRITISH PHYSICIST: FRANCIS CRICK INCORPORATED IDEAS OF OTHER SCIENTIST TO PUT TOGETHER A BRASS AND WIRE MODEL OF DNA (1962) AWARDED THE NOBEL PRIZE IN SCIENCE

DNA STRUCTURE TWO ANTIPARALLEL SUGAR-PHOSPHATE CHAINS WIND AROUND THE OUTSIDE OF THE MOLECULE. THE NITROGENOUS BASES PROJECT INTO THE INTERIOR, WHERE THEY HYDROGEN BOND IN COMPLEMENTARY PAIRS CHARGAFF’S RULE: ADENINE WITH THYMINE; GUANINE WITH CYTOSINE

II. DNA REPLICATION AND REPAIR DURING DNA REPLICATION, BASE-PAIRING ENABLES EXISTING DNA STRANDS TO SERVE AS TEMPLATES FOR NEW COMPLEMENTARY STRANDS DNA REPLICATION IS SEMICONSERVATIVE: THE PARENT MOLECULE UNWINDS, AND EACH STRAND THEN SERVES AS A TEMPLATE FOR THE SYNTHESIS OF A NEW HALF-MOLECULE ACCORDING TO BASE PAIRING RULES

A LARGE TEAM OF ENZYMES AND OTHER PROTEINS CARRIES OUT DNA REPLICATION REPLICATION BEGINS AT ORIGINS OF REPLICATION Y-SHAPED REPLICATION FORKS FORM AT OPPOSITE ENDS OF A REPLICATION BUBBLE, WHERE THE TWO DNA STRANDS SEPARATE

16.10 ORIGINS OF REPLICATION

DNA POLYMERASE CATALYZE THE SYNTHESIS OF NEW DNA STRANDS DNA SYNTHESIS AT A REPLICATION FORK YIELDS A CONTINOUS LEADING STRAND AND SHORT, DISCONTINOUS SEGMENTS OF LAGGING STRAND THE FRAGMENTS ARE THEN JOINED TOGETHER BY DNA LIGASE

16.13 SYNTHESIS OF LEADING AND LAGGING STRAND DURING DNA REPLICATION

A SUMMARY OF DNA REPLICATION

ENZYMES PROOFREAD DNA DURING ITS REPLICATION AND REPAIR DAMAGE TO EXISTING DNA IN MISMATCH REPAIR, PROTEINS PROOFREAD REPLICATING DNA AND CORRECT ERRORS IN BASE PAIRING IN EXCISION REPAIR, REPAIR ENZYMES FIX DNA DAMAGED BY PHYSICAL AND CHEMICAL AGENTS

THE ENDS OF DNA MOLECULES POSE A SPECIAL FUNCTION. THE ENDS OF THE LINEAR DNA MOLECULES OF EUKARYOTIC CHROMOSOMES, CALLED TELOMERES, GET SHORTER WITH EACH REPLICATION THE ENZYME TELOMERASE, PRESENT IN CERTAIN CELLS, CAN REEXTEND THE ENDS