06_01_Hereditary info'jpg

1
Chromatin Structure and Replication While we
will not cover DNA structure in class formally,
you should review materials in the beginning of
Chapter 5 on the fundamental structures of DNA
and chromosomes. In Chapter 6, you will not be
responsible for the details of homologous and
nonhomologous Recombination, and retroviruses.
Questions in this chapter you should be able to
answer Chapter 5- s 1, 3, 4A,B, 5, 7, 8, 10A,
11, 13, 14, 17 Chapter 6- s 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 15, 16, 17, 19, 20
2
From Chapter 5 What is Chromatin? What is the
structure of Nucleosomes?
Jmol Nucleosome model
Figures 5-21, 22,23
3
What are functions of nucleosomes? Supercoiling
of DNA heterochromatin vs euchromatin Ge
ne regulation
5.2 chromosome coil.mov
4
Why is DNA replication said to be
semiconservatve? Where does DNA
replication begin on a chromosome?
DNA 5 3 Orientation
5
06_09_Replic.forks.jpg
Answer Question 6-1A How long until forks 4 and 5
meet? Distance between bases is 0.34
nm Replication rate is 100 bases / sec
6
In what direction does DNA replication
occur? What happens if a base mismatch occurs?
Where does energy for addition of nucleotide
come from?
7
Why does DNA replication only occur in the 5 to
3 direction?
Should be PPP here
8
How is DNA synthesized on 3 end behind
advancing replication fork?
9
Why does DNA synthesis begin with an RNA
primer? How are Okasaki fragments Synthesized
and connected? What are the key proteins
involved? (next slide)
10
06_17_group proteins.jpg
Question 6-3 What would be the end products if
an enzyme were missing? -- polymerase? --
ligase? -- primase? -- nuclease?
6.5 replication fork.mov animation
6.4 replication_1 Computer animation
11
Why is a special replication mechanism needed for
telomeres? What serves as the template?
12
DNA replication occurs with great
fidelity? Somatic cell DNA stability and
reproductive-cell DNA stability are essential.
Why?
13
What are some common types of chemical mutations?
14
During DNA replication, how is a base mismatch
repaired? How is the new (mutated) DNA
strand Identified?
How is damaged DNA repaired? What are three
steps?
Excision Resynthesis Ligation
15
The elegant Meselson and Stahl experiment 1)
Grew bacterial cells in medium containing only
15N (dense) -- all DNA contained 15N 3) Then
allowed cells to divide in medium containing
14N 4) Looked at density of DNA using density
gradient centrifugation after 0, 1, 2, etc.
rounds of cell division. -- What did they see?
How do we know that DNA replication is
semi-conservative?
LL HH
16
Transposable elements and repetitive DNA How
much of the DNA codes for genes? What is rest
of DNA? Repetitive DNA Noncoding
non-repetitive DNA What are transposable
elements? e.g., LINEs SINEs?
Figures 9-25 9-26
17
06_32_mobile genetic.jpg
What is a transposable element?
18
How do transposable elements move?
19
How does a retrotransposon move?
e.g., L1 or Alu
20
Transposable elements have accumulated in genomes
of different species