The Molecular Basis of Inheritance Chapter 16 The Molecular Basis of Inheritance

EXPERIMENT RESULTS Living S cells (control) Living R cells (control) Fig. 16-2 How did this experiment rule out the possibility that the R cells could have simply used the capsules of the dead S cells to become pathogenic? Mixture of heat-killed S cells and living R cells Living S cells (control) Living R cells (control) Heat-killed S cells (control) EXPERIMENT RESULTS Figure 16.2 Can a genetic trait be transferred between different bacterial strains? Mouse dies Mouse healthy Mouse healthy Mouse dies Living S cells

EXPERIMENT Empty protein shell Radioactivity (phage protein) in liquid Fig. 16-4-3 What did Hershey and Chase’s experiment prove? EXPERIMENT Empty protein shell Radioactivity (phage protein) in liquid Radioactive protein Phage Bacterial cell Batch 1: radioactive sulfur (35S) DNA Phage DNA Centrifuge Radioactive DNA Pellet (bacterial cells and contents) Figure 16.4 Is protein or DNA the genetic material of phage T2? Batch 2: radioactive phosphorus (32P) Centrifuge Radioactivity (phage DNA) in pellet Pellet

Sugar–phosphate backbone 5 end Sugar (deoxyribose) 3 end Fig. 16-5 What does Chargaff’s rules state? Sugar–phosphate backbone 5 end Nitrogenous bases Thymine (T) Adenine (A) Figure 16.5 The structure of a DNA strand Cytosine (C) ____________________________ Describe the structure and its components Phosphate Sugar (deoxyribose) 3 end Guanine (G)

(b) Franklin’s X-ray diffraction photograph of DNA Fig. 16-6b How did Photo 51 contribute to the quest to uncover the of DNA? Figure 16.6 Rosalind Franklin and her X-ray diffraction photo of DNA (b) Franklin’s X-ray diffraction photograph of DNA

____________ __________ bond ____________ 1 nm 3.4 nm __________ Fig. 16-7a describe the key features of the DNA structure including the directionality of the molecule. ____________ __________ bond ____________ 1 nm 3.4 nm Figure 16.7 The double helix __________ 0.34 nm _________ (a) Key features of DNA structure (b) Partial chemical structure

Identify the purines and pyrimidine. How do they differ in structure? Fig. 16-8 Identify the purines and pyrimidine. How do they differ in structure? ___________ (A) _____________ (T) Figure 16.8 Base pairing in DNA __________ (G) ___________ (C)

(b)____________________________ Fig. 16-9-3 Describe the replication process. What does semiconservative model indicate? What does replication ensure? A T A T A T A T C G C G C G C G T A T A T A T A A T A T A T A T G C G C G C G C (a) _______________ (b)____________________________ (c)________________________________________________________________________________________________________________________ Figure 16.9 A model for DNA replication: the basic concept

(a) Conservative model Fig. 16-10 Describe how the work of Meselson and Stahl. Which model did it support and why? First replication Second replication Parent cell (a) Conservative model (b) Semiconserva- tive model Figure 16.10 Three alternative models of DNA replication (c) Dispersive model

____________________ Fig. 16-13 fill in the blanks Which end do the nucleotides get added to? Define Anti-parallel elongation, how does this relate to the bi-directionality of the molecule. ______________ ____________________ 3 ______________ 5 3 RNA _________ Figure 16.13 Some of the proteins involved in the initiation of DNA replication 5 5 3 ______________

Nucleoside triphosphate Fig. 16-14 Describe the process occurring here. Compare dATP to ATP. What happens to the dATP as it joins the DNA strand New strand 5 end Template strand 3 end 5 end 3 end Sugar A T A T Base Phosphate C G C G G C G C DNA polymerase 3 end A T A Figure 16.14 Incorporation of a nucleotide into a DNA strand T 3 end C Pyrophosphate C Nucleoside triphosphate 5 end 5 end

Overall directions of replication Fig. 16-15a Distinguish between the leading strand and the lagging strand. Explain how they work in the replication process. Overview Origin of replication Leading strand Lagging strand Primer Lagging strand Leading strand Figure 16.15 Synthesis of the leading strand during DNA replication Overall directions of replication

Origin of replication 3 5 RNA primer 5 “Sliding clamp” 3 5 Fig. 16-15b What is an Okazaki Fragment? How are they joined together? Which direction do they move toward? Origin of replication 3 5 RNA primer 5 “Sliding clamp” 3 5 DNA pol III Parental DNA 3 5 Figure 16.15 Synthesis of the leading strand during DNA replication 5 3 5

Be able to explain what is happening in this diagram. Fig. 16-16b6 Be able to explain what is happening in this diagram. 3 5 5 3 Template strand 3 5 RNA primer 3 1 5 3 Okazaki fragment 5 3 5 1 3 5 3 2 1 5 5 3 Figure 16.6 Synthesis of the lagging strand 3 5 2 1 5 3 3 1 5 2 Overall direction of replication

Table 16-1 Review the chart and be able to identify the protein and its functional role in the replication process

Nuclease DNA polymerase DNA ligase Fig. 16-18 How does DNA repair and proofread itself. Nuclease DNA polymerase Figure 16.18 Nucleotide excision repair of DNA damage DNA ligase

What do repeated rounds of replication begin to produce? Fig. 16-19 Examine the diagram What do repeated rounds of replication begin to produce? What is the role of telomeres? What are they connected to? 5 Ends of parental DNA strands Leading strand Lagging strand 3 Last fragment Previous fragment RNA primer Lagging strand 5 3 Parental strand Removal of primers and replacement with DNA where a 3 end is available 5 3 Second round of replication Figure 16.19 Shortening of the ends of linear DNA molecules 5 New leading strand 3 New lagging strand 5 3 Further rounds of replication Shorter and shorter daughter molecules

Nucleosomes, or “beads on a string” (10-nm fiber) Fig. 16-21a Be able to discuss the progressive levels of DNA coiling and folding. Identify the histones, nucleosomes, looped domains and Metaphase chromosomes and chromatin? What are their functions? Nucleosome (10 nm in diameter) DNA double helix (2 nm in diameter) H1 Histone tail Histones Figure 16.21a Chromatin packing in a eukaryotic chromosome DNA, the double helix Histones Nucleosomes, or “beads on a string” (10-nm fiber)

Condensin and DNA (yellow) Outline of nucleus Condensin (green) Fig. 16-22 What role does histone phosphorylation play in chromosome behavior during meiosis? Answer What if Question pg. 322 RESULTS Condensin and DNA (yellow) Outline of nucleus Condensin (green) DNA (red at periphery) Figure 16.22 What role does histone phosphorylation play in chromosomal behavior during meiosis? Normal cell nucleus Mutant cell nucleus