Biology 2120 recitation

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Biology 2120 recitation

• (Date)

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Todays schedule

• Lecture review
• Quiz
• Review Quiz

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• Lecture 9- Nuclear structure and DNA replication
• A The Big Picture 
• A The nucleus contains and protects most of a
  eukaryotic cell's DNA
• B The nuclear envelope is a double membrane
  structure
• C The outer membrane of the nuclear envelope is
  continuous with the endoplasmic reticulum Fig.
  18-26
• C Nuclear pore complexes regulate molecular
  traffic into and out of the nucleus Figs. 18-27,
  18-28, 18-29
• B The interior of the nucleus is highly
  organized and contains many subcompartments Fig.
  18-32
• C The nucleolus contains DNA that encodes
  ribosomal RNAs Fig. 18-33
• C The nuclear matrix helps to organize
  chromosomes Fig. 18-31
• C DNA replication occurs at sites called
  replication factories
• C RNA polymerase complexes, and spliceosomes
  are distinct structures within the nucleus

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A DNA replication is a complex, tightly
regulated process Fig. 19-13 B DNA polymerases
are enzymes that replicate DNA C DNA
polymerases add new deoxyribonucleotides to the
3 end of a DNA strand Fig. 19-7 C DNA
polymerases proofread their work Fig. 19-10A
DNA replication is a complex, tightly regulated
process Fig. 19-13 B DNA replication is
semi-discontinuous Fig. 19-9 C DNA replication
begins at sites on chromosomes called origins of
replication Fig. 19-5 C Specialized proteins
unwind and separate the two strands during
replication to form a replication fork Origin
Replication Complex, MiniChromosome Maintenance
proteins Fig. 19-6, 19-12, 19-14 C DNA
replication requires an RNA primer Fig. 19-11 C
DNA ligases join fragments of single-stranded
DNA C Replication of DNA at the end of
chromosomes requires additional steps Fig. 19-15,
19-16 B Cells have two main DNA repair
mechanisms Fig. 19-17 C Excision systems remove
one strand of damaged DNA and replace it Fig.
19-18 C Recombination systems repair
large-scale DNA damage
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A Mitosis Separates Replicated Chromosomes B
Mitosis is divided into stages Fig. 19-20 B
Prophase prepares the cell for division Fig.
19-20. 19-25 B Chromosomes attach to the
mitotic spindle during prometaphase C
Kinetochores attach chromosomes to the mitotic
spindle Fig. 19-22 B Arrival of the chromosomes
at the spindle equator signals the beginning of
metaphase Fig. 19-26 B Separation of chromatids
at the metaphase plate occurs during anaphase C
The onset of anaphase requires dissolving the
connections between sister chromatids condensins
and cohesins C Anaphase is subdivided into two
phases, anaphase A and anaphase B Fig. 19-24,
19-27 B Telophase begins to reverse the
structural rearrangements that occurred in
prophase B Cytokinesis completes mitosis by
partitioning the cytoplasm to form two new
daughter cells Fig. 19-28 C Fragmentation of
nonnuclear organelles ensures their equal
distribution in the daughter cells
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Macromolecular Transport into and out of the
Nucleus
Figure 18-29
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PYROPHOSPHATE
Figure 19-7
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Arrangement of Proteins at the Replication Fork
Figure 19-14
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The Extension of Telomeres by Telomerase
Figure 19-16c
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Figure 19-25
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Figure 19-24
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Figure 19-25 Microtubule Polarity in the Mitotic
Spindle
Figure 19-27a Mitotic Motors
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Quiz Time!
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Research article

• Rationale
• Cancer cells have extra copies of some
  advantageous genes, and these are in
  extrachromosomal structures called double minutes
  (pronounced my-noots)
• Getting rid of double minutes will make cancer
  cells more sensitive to chemotherapy drugs by
  reducing the number of advantageous
  genes/proteins
• http//en.wikipedia.org/wiki/Double_minute

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Research strategy

• Create a human colon cancer cell line that has
  easy-to-identify genes that are present in double
  minutes
• Introduce three pieces of foreign DNA
• a piece of bacterial DNA encoding multiple copies
  of a gene operator (lacO, a regulatory sequence)
  this sequence will end up in the double minutes
• a bacterial gene encoding a protein that binds to
  lacO (lacR), fused to Green Fluorescent Protein
  (easy to see with fluorescence microscope)
• a piece of DNA containing sequences necessary to
  create double minutes
• The cells form lacO-containing double minutes
  that are bound by GFP-tagged lacR protein

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Research strategy

• Add hydroxurea to cells HU removes double
  minutes by introducing double-stranded breaks in
  DNA
• Look for evidence of double stranded breaks by
  immunofluorescence microscopy use a primary
  antibody that binds to the phosphorylated form of
  a histone (histone H2AX)
• DATA Green fluorescence shows presence of double
  minutes, phospho-H2AX (red), and position of all
  DNA (blue)

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Exercise form groups

• Translate the title
• Write out the hypothesis
• Identify three premises look in Figures 1, 2,
  and 3
• Write out one logical argument containing at
  least two of your premises
• Does this argument support or disprove their
  hypothesis?