1. THE MOLECULAR BASIS OF INHERITANCE
CHAPTER 16
THE MOLECULAR BASIS
OF INHERITANCE

2. 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.

3. 16.1 TRANSFORMATION OF BACTERIA

4. 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

5. 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

9. 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

11. 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

12. 16.10 ORIGINS OF REPLICATION

13. 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

14. 16.13 SYNTHESIS OF LEADING AND LAGGING STRAND DURING DNA REPLICATION

15. A SUMMARY OF DNA REPLICATION

16. 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

18. 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