1. The Molecular Basis of Inheritance
Chapter 16
The Molecular Basis of Inheritance

2. EXPERIMENT RESULTS Living S cells (control) Living R cells (control)
Fig 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

3. EXPERIMENT Empty protein shell Radioactivity (phage protein) in liquid
Fig 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

4. Sugar–phosphate backbone 5 end Sugar (deoxyribose) 3 end
Fig. 16-5
What does Chargaff’s rules state?
Sugar–phosphate backbone  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)  end
Guanine (G)

5. (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

6. ____________ __________ 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

7. 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)

8. (b)____________________________
Fig 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

9. (a) Conservative model
Fig
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 Three alternative models of DNA replication
(c) Dispersive model

10. ____________________
Fig 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 Some of the proteins involved in the initiation of DNA replication 5 5 3
______________

11. Nucleoside triphosphate
Fig 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 Incorporation of a nucleotide into a DNA strand T
3 end C
Pyrophosphate C
Nucleoside triphosphate
5 end
5 end

12. Overall directions of replication
Fig a
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 Synthesis of the leading strand during DNA replication
Overall directions of replication

13. Origin of replication 3 5 RNA primer 5 “Sliding clamp” 3 5
Fig b 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 Synthesis of the leading strand during DNA replication 5 3 5

14. Be able to explain what is happening in this diagram.
Fig b6
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

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

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

17. What do repeated rounds of replication begin to produce?
Fig
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 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

18. Nucleosomes, or “beads on a string” (10-nm fiber)
Fig a 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)

19. Condensin and DNA (yellow) Outline of nucleus Condensin (green)
Fig 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 What role does histone phosphorylation play in chromosomal behavior during meiosis?
Normal cell nucleus
Mutant cell nucleus