CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry Cain Wasserman Minorsky Jackson Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 9 The Cell Cycle

© 2014 Pearson Education, Inc. Figure 9.1

© 2014 Pearson Education, Inc. Figure 9.2 (a) Reproduction 100  m (c) Tissue renewal (b) Growth and development 200  m 20  m

Cellular Organization of the Genetic Material  prokaryotic genome - a single looped DNA molecule (common in cells) or a number of DNA molecules (common in cells)  eukaryotic genome -DNA molecules packaged into chromosomes © 2014 Pearson Education, Inc.

Figure 9.3 Eukaryotic chromosomes 20  m

 Eukaryotic chromosomes consist of chromatin, (complex of DNA and protein)  Every species has a characteristic number of chromosomes in each nucleus  Somatic cells (nonreproductive cells) have two sets of chromosomes  Gametes (reproductive cells: sperm and eggs) have one set of chromosomes © 2014 Pearson Education, Inc.

Distribution of Chromosomes During Eukaryotic Cell Division  preparation for cell division… 1- DNA replicated 2 - chromosomes condense  Each duplicated chromosome has two sister chromatids, identical copies joined at the centromere © 2014 Pearson Education, Inc.

Figure 9.4 Centromere 0.5  m Sister chromatids

© 2014 Pearson Education, Inc. a One chromosome (unduplicated) b One chromosome (duplicated) one chromatid two sister chromatids one chromatid Fig. 9-3a, p.142 Stepped Art Chromosome

 During cell division, sister chromatids separate and move to separate poles  Once separate, the chromatids are called chromosomes © 2014 Pearson Education, Inc.

Figure Centromere Chromosomal DNA molecules Chromosomes Chromosome arm 1

© 2014 Pearson Education, Inc. Figure Centromere Sister chromatids Chromosomal DNA molecules Chromosomes Chromosome arm Chromosome duplication 1 2

© 2014 Pearson Education, Inc. Figure Centromere Sister chromatids Separation of sister chromatids Chromosomal DNA molecules Chromosomes Chromosome arm Chromosome duplication 1 3 2

 Eukaryotic cell division consists of  Mitosis, the division of the genetic material in the nucleus  Cytokinesis, the division of the cytoplasm  Gametes are produced by a variation of cell division called …  …Meiosis © 2014 Pearson Education, Inc.

Phases of the Cell Cycle  The cell cycle consists of  Mitotic (M) phase, including mitosis and cytokinesis  Interphase, including cell growth and replication in preparation for cell division © 2014 Pearson Education, Inc.

 Interphase (about 90% of the cell cycle) can be divided into subphases  G 1 phase (“first gap”)  S phase (“synthesis”)  G 2 phase (“second gap”)  cell grows during all three phases  Chromosomes duplicated during S phase © 2014 Pearson Education, Inc.

Figure 9.6 Cytokinesis Mitosis S (DNA synthesis) G1G1 G2G2

 Mitosis is conventionally divided into five phases  Prophase  Prometaphase  Metaphase  Anaphase  Telophase  Cytokinesis overlaps the latter stages of mitosis © 2014 Pearson Education, Inc.

Video: Animal Mitosis Video: Microtubules Mitosis Animation: Mitosis Video: Microtubules Anaphase Video: Nuclear Envelope

© 2014 Pearson Education, Inc. Figure 9.7a Centrosomes (with centriole pairs) G 2 of InterphaseProphasePrometaphase Chromosomes (duplicated, uncondensed) Early mitotic spindle Centromere Aster Fragments of nuclear envelope Nonkinetochore microtubules Kinetochore microtubule Kinetochore Nucleolus Plasma membrane Two sister chromatids of one chromosome Nuclear envelope 10  m

© 2014 Pearson Education, Inc. Figure 9.7b Metaphase Anaphase Telophase and Cytokinesis Cleavage furrow Nucleolus forming Nuclear envelope forming Spindle Centrosome at one spindle pole Daughter chromosomes 10  m Metaphase plate

© 2014 Pearson Education, Inc. Figure 9.7c Centrosomes (with centriole pairs) G 2 of InterphaseProphase Chromosomes (duplicated, uncondensed) Early mitotic spindle Centromere Aster Nucleolus Plasma membrane Two sister chromatids of one chromosome Nuclear envelope

© 2014 Pearson Education, Inc. Figure 9.7d Prometaphase Fragments of nuclear envelope Nonkinetochore microtubules Kinetochore microtubule Kinetochore Spindle Centrosome at one spindle pole Metaphase plate Metaphase

© 2014 Pearson Education, Inc. Figure 9.7e Anaphase Telophase and Cytokinesis Cleavage furrow Nucleolus forming Nuclear envelope forming Daughter chromosomes

© 2014 Pearson Education, Inc. Figure 9.7f G 2 of Interphase 10  m

© 2014 Pearson Education, Inc. Figure 9.7g Prophase 10  m

© 2014 Pearson Education, Inc. Figure 9.7h Prometaphase 10  m

© 2014 Pearson Education, Inc. Figure 9.7i 10  m Metaphase

© 2014 Pearson Education, Inc. Figure 9.7j Anaphase 10  m

© 2014 Pearson Education, Inc. Figure 9.7k Telophase and Cytokinesis 10  m

The Mitotic Spindle: A Closer Look  mitotic spindle (microtubules and proteins) controls chromosome movement during mitosis  In animal cells, assembly of spindle begins in the centrosome © 2014 Pearson Education, Inc.

 centrosome replicates during interphase  Centrosomes migrate to opposite poles  An aster (radial array of short microtubules) extends from each centrosome  spindle includes centrosomes, microtubules, and the asters © 2014 Pearson Education, Inc.

Kinetochore forms at centromere during nuclear division Kinetochore - a docking site for microtubules Fig. 9-3a, p.142 Stepped Art Chromosome

 spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes  Kinetochores - a docking site for microtubules © 2014 Pearson Education, Inc.

Figure 9.8 Metaphase plate (imaginary) Chromosomes Aster Kinetochore microtubules Kineto- chores Sister chromatids 1  m Centrosome Overlapping nonkinetochore microtubules Centrosome Microtubules 0.5  m

© 2014 Pearson Education, Inc. Figure 9.8a Chromosomes 1  m Centrosome Microtubules

 sister chromatids separate and move toward opposite ends of the cell  The microtubules shorten by depolymerizing at their kinetochore ends  Chromosomes also “reeled in” by motor proteins at spindle poles © 2014 Pearson Education, Inc.

Figure 9.9a Kinetochore Experiment Spindle pole Mark

© 2014 Pearson Education, Inc. Figure 9.9b Results Kinetochore Conclusion Tubulin subunits Chromosome Motor protein Chromosome movement Microtubule

 Cytokinesis begins during anaphase or telophase and the spindle eventually disassembles © 2014 Pearson Education, Inc.

Cytokinesis: A Closer Look  In animal cells, cytokinesis occurs by a process known as cleavage, forming a cleavage furrow  In plant cells, a cell plate forms during cytokinesis © 2014 Pearson Education, Inc. Animation: Cytokinesis Video: Cytokinesis and Myosin

© 2014 Pearson Education, Inc. Figure 9.10 (a) Cleavage of an animal cell (SEM) New cell wall Contractile ring of microfilaments Cleavage furrow Daughter cells Cell plate Wall of parent cell Vesicles forming cell plate 100  m 1  m (b) Cell plate formation in a plant cell (TEM)

© 2014 Pearson Education, Inc. Figure  m Nucleus Telophase Nucleolus Chromosomes condensing Chromosomes Prometaphase Cell plate Prophase AnaphaseMetaphase

© 2014 Pearson Education, Inc. Figure 9.11a 10  m Nucleus Nucleolus Chromosomes condensing Prophase 1

© 2014 Pearson Education, Inc. Figure 9.11b 10  m 2 Prometaphase Chromosomes

© 2014 Pearson Education, Inc. Figure 9.11c 10  m 3 Metaphase

© 2014 Pearson Education, Inc. Figure 9.11d 10  m 4 Anaphase

© 2014 Pearson Education, Inc. Figure 9.11e 10  m 5 Telophase Cell plate

Binary Fission in Bacteria  Prokaryotes reproduce by binary fission  single chromosome replicates, beginning at the origin of replication  2 daughter chromosomes actively move apart while the cell elongates  The plasma membrane pinches inward, dividing the cell into two © 2014 Pearson Education, Inc.

Figure Origin of replication Two copies of origin Bacterial chromosome Plasma membrane Cell wall E. coli cell Chromosome replication begins.

© 2014 Pearson Education, Inc. Figure Origin of replication Two copies of origin Bacterial chromosome Plasma membrane Cell wall E. coli cell Origin Chromosome replication begins. 2 One copy of the origin is now at each end of the cell.

© 2014 Pearson Education, Inc. Figure Origin of replication Two copies of origin Bacterial chromosome Plasma membrane Cell wall E. coli cell Origin Chromosome replication begins. 2 3 One copy of the origin is now at each end of the cell. Replication finishes.

© 2014 Pearson Education, Inc. Figure Origin of replication Two copies of origin Bacterial chromosome Plasma membrane Cell wall E. coli cell Origin Chromosome replication begins One copy of the origin is now at each end of the cell. Replication finishes. Two daughter cells result.

© 2014 Pearson Education, Inc. Figure 9.13 Chromosomes Intact nuclear envelope Microtubules Kinetochore microtubule Intact nuclear envelope (a) Dinoflagellates (b) Diatoms and some yeasts

Concept 9.3: The eukaryotic cell cycle is regulated by a molecular control system  frequency of division varies with type of cell  Cancer cells escape the controls on cell cycle © 2014 Pearson Education, Inc.

Checkpoints of the Cell Cycle Control System  The cell cycle control system regulated by internal and external controls with specific checkpoints where the cell cycle stops until a go-ahead signal is received © 2014 Pearson Education, Inc.

Figure 9.15 M checkpoint S M G1G1 G2G2 G 1 checkpoint G 2 checkpoint Control system

 G 1 checkpoint seems to be the most important  If a cell passes G 1 checkpoint, it will usually complete the S, G 2, and M phases and divide  If not it will exit the cycle, switching into a nondividing state called the G 0 phase © 2014 Pearson Education, Inc.

Figure 9.16a G1G1 G 1 checkpoint Without go-ahead signal, cell enters G 0. G0G0 With go-ahead signal, cell continues cell cycle. (a) G 1 checkpoint G1G1

© 2014 Pearson Education, Inc. Figure 9.16b M checkpoint M G1G1 G2G2 Prometaphase Without full chromosome attachment, stop signal is received. (b) M checkpoint M G1G1 G2G2 G 2 checkpoint Metaphase Anaphase With full chromosome attachment, go-ahead signal is received.

 The cell cycle regulated by a set of regulatory protein complexes including kinases and proteins called cyclins © 2014 Pearson Education, Inc.

Loss of Cell Cycle Controls in Cancer Cells  Cancer cells do not respond to signals © 2014 Pearson Education, Inc.

 A normal cell is converted to a cancerous cell by a process called transformation  Cancer cells not eliminated by immune system form tumors  If abnormal cells remain only at the original site, the lump is called a benign tumor  Malignant tumors invade surrounding tissues and can metastasize (move to other parts of the body) © 2014 Pearson Education, Inc.

Figure 9.19c Breast cancer cell (colorized SEM) 5  m

© 2014 Pearson Education, Inc. Figure 9.UN02 S G1G1 G2G2 Mitosis Telophase and Cytokinesis MITOTIC (M) PHASE Anaphase Metaphase Prometaphase Prophase

© 2014 Pearson Education, Inc. Figure 9.UN03

© 2014 Pearson Education, Inc. Mitosis lab Onion Root Tip & Whitefish Blastula

© 2014 Pearson Education, Inc. Mitosis lab Onion Root Tip & Whitefish Blastula Determine and display the % of their time spent in Mitosis.

© 2014 Pearson Education, Inc. Mitosis lab Onion Root Tip & Whitefish Blastula Determine and display the % of their time spent in Mitosis. Today - Write Hypothesis and “Methods” section Get approval and turn in.

© 2014 Pearson Education, Inc. Mitosis lab Onion Root Tip & Whitefish Blastula Determine and display the % of their time spent in Mitosis. Today - Write Hypothesis and “Methods” section Get approval and turn in. Wednesday - Do procedure in class

© 2014 Pearson Education, Inc. Mitosis lab Onion Root Tip & Whitefish Blastula Determine and display the % of their time spent in Mitosis. Today - Write Hypothesis and “Methods” section Get approval and turn in. Wednesday - Do procedure in class Friday – Turn in report (1 per group) including Methods, Data, and just your display of the % times as your conclusion