Campbell Biology In Focus - The Cell Cycle (PDF)

CAMPBELL BIOLOGY IN FOCUS URRY CAIN WASSERMAN MINORSKY REECE 9 The Cell Cycle Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge, Simon Fraser University © 2016 Pearson Education, Inc. SECOND...

CAMPBELL BIOLOGY IN FOCUS URRY CAIN WASSERMAN MINORSKY REECE 9 The Cell Cycle Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge, Simon Fraser University © 2016 Pearson Education, Inc. SECOND EDITION  Overview: The Key Roles of Cell Division ▪ The ability of organisms to produce more of their own kind best distinguishes living things from nonliving matter ▪ The continuity of life is based on the reproduction of cells, or cell division © 2016 Pearson Education, Inc.  Figure 9.1 How do Dividing Cells Distribute Chromosomes to Daughter Cells? © 2016 Pearson Education, Inc.  Overview: The Key Roles of Cell Division, Continued ▪ In unicellular organisms, division of one cell reproduces the entire organism ▪ Cell division enables multicellular eukaryotes to develop from a single cell and, once fully grown, to renew, repair, or replace cells as needed ▪ Cell division is an integral part of the cell cycle, the life of a cell from its formation to its own division © 2016 Pearson Education, Inc.  Figure 9.2 The Functions of Cell Division © 2016 Pearson Education, Inc.  Concept 9.1: Most cell division results in genetically identical daughter cells ▪ Most cell division results in the distribution of identical genetic material—DNA—to two daughter cells ▪ DNA is passed from one generation of cells to the next with remarkable fidelity © 2016 Pearson Education, Inc.  Cellular Organization of the Genetic Material ▪ All the DNA in a cell constitutes the cell’s genome ▪ A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells) ▪ DNA molecules in a cell are packaged into chromosomes © 2016 Pearson Education, Inc.  Figure 9.3 Eukaryotic Chromosomes © 2016 Pearson Education, Inc.  Cellular Organization of the Genetic Material, Continued ▪ Eukaryotic chromosomes consist of chromatin, a complex of DNA and protein ▪ Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus ▪ Somatic cells (nonreproductive cells) have two sets of chromosomes (diploid set of chromosomes) ▪ Gametes (sex cells; reproductive cells: sperm and eggs) have one set of chromosomes (haploid set of chromosomes) © 2016 Pearson Education, Inc.  Distribution of Chromosomes During Eukaryotic Cell Division ▪ In preparation for cell division, DNA is replicated and the chromosomes condense ▪ Each duplicated chromosome has two sister chromatids, joined identical copies of the original chromosome ▪ The centromere is where the two chromatids are most closely attached © 2016 Pearson Education, Inc.  Figure 9.4 A Highly Condensed, Duplicated Human Chromosome (SEM) © 2016 Pearson Education, Inc.  Distribution of Chromosomes During Eukaryotic Cell Division, Continued ▪ During cell division, the two sister chromatids of each duplicated chromosome separate and move into two nuclei ▪ Once separate, the chromatids are called chromosomes © 2016 Pearson Education, Inc.  Figure 9.5-s1 Chromosome Duplication and Distribution During Cell Division (Step 1) © 2016 Pearson Education, Inc.  Figure 9.5-s2 Chromosome Duplication and Distribution During Cell Division (Step 2) © 2016 Pearson Education, Inc.  Figure 9.5-s3 Chromosome Duplication and Distribution During Cell Division (Step 3) © 2016 Pearson Education, Inc.  Distribution of Chromosomes During Eukaryotic Cell Division, Continued-1 ▪ 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 ▪ Meiosis yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cell © 2016 Pearson Education, Inc.  Concept 9.2: The mitotic phase alternates with interphase in the cell cycle ▪ In 1882, the German anatomist Walther Flemming developed dyes to observe chromosomes during mitosis and cytokinesis © 2016 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 copying of chromosomes in preparation for cell division © 2016 Pearson Education, Inc.  Phases of the Cell Cycle, Continued ▪ Interphase (about 90% of the cell cycle) can be divided into subphases ▪ phase (“first gap”) ▪ S phase (“synthesis”) ▪ phase (“second gap”) ▪ The cell grows during all three phases, but chromosomes are duplicated only during the S phase ▪ Animation: How the Cell Cycle Works ▪ http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__ho w_the_cell_cycle_works.html © 2016 Pearson Education, Inc.  Figure 9.6 The Cell Cycle © 2016 Pearson Education, Inc.  Phases of the Cell Cycle, Continued-1 ▪ Mitosis is conventionally divided into five phases ▪ Prophase ▪ Prometaphase ▪ Metaphase ▪ Anaphase ▪ Telophase ▪ Cytokinesis overlaps the latter stages of mitosis ▪ Animation: Mitosis and Cytokinesis ▪ http://highered.mheducation.com/sites/0072495855/student_view0/chapt er2/animation__mitosis_and_cytokinesis.html © 2016 Pearson Education, Inc.  Video: Animal Mitosis © 2016 Pearson Education, Inc.  Animation: Mitosis © 2016 Pearson Education, Inc.  Video: Nuclear Envelope © 2016 Pearson Education, Inc.  Figure 9.7-1 Exploring Mitosis in An Animal Cell (Part 1: G2 of Interphase Through Prometaphase) © 2016 Pearson Education, Inc.  Figure 9.7-2 Exploring Mitosis in An Animal Cell (Part 2: Metaphase Through Cytokinesis) © 2016 Pearson Education, Inc.  The Mitotic Spindle: A Closer Look ▪ The mitotic spindle is a structure made of microtubules and associated proteins ▪ It controls chromosome movement during mitosis ▪ In animal cells, assembly of spindle microtubules begins in the centrosome, a type of microtubule organizing center © 2016 Pearson Education, Inc.  The Mitotic Spindle: A Closer Look, Continued ▪ The centrosome replicates during interphase, forming two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase ▪ An aster (radial array of short microtubules) extends from each centrosome ▪ The spindle includes the centrosomes, the spindle microtubules, and the asters © 2016 Pearson Education, Inc.  The Mitotic Spindle: A Closer Look, Continued-1 ▪ During prometaphase, some spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes ▪ Kinetochores are protein complexes that assemble on sections of DNA at centromeres ▪ At metaphase, the centromeres of all the chromosomes are at the metaphase plate, an imaginary structure at the midway point between the spindle’s two poles © 2016 Pearson Education, Inc.  Video: Mitosis Spindle © 2016 Pearson Education, Inc.  Figure 9.8 The Mitotic Spindle at Metaphase © 2016 Pearson Education, Inc.  The Mitotic Spindle: A Closer Look, Continued-2 ▪ In anaphase, sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell ▪ The microtubules shorten by depolymerizing at their kinetochore ends ▪ Chromosomes are also “reeled in” by motor proteins at spindle poles, and microtubules depolymerize after they pass by the motor proteins © 2016 Pearson Education, Inc.  Figure 9.9 Inquiry: At Which End do Kinetochore Microtubules Shorten During Anaphase? Chromosome and Kinetochore https://www.youtube.com/watch?v=0JpOJ4F4984 © 2016 Pearson Education, Inc.  The Mitotic Spindle: A Closer Look, Continued-3 ▪ Nonkinetochore microtubules from opposite poles overlap and push against each other, elongating the cell ▪ At the end of anaphase, duplicate groups of chromosomes have arrived at opposite ends of the elongated parent cell ▪ Cytokinesis begins during anaphase or telophase, and the spindle eventually disassembles © 2016 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 © 2016 Pearson Education, Inc.  Animation: Cytokinesis © 2016 Pearson Education, Inc.  Video: Cytokinesis and Myosin © 2016 Pearson Education, Inc.  Figure 9.10 Cytokinesis in Animal and Plant Cells © 2016 Pearson Education, Inc.  Figure 9.11 Mitosis in a Plant Cell © 2016 Pearson Education, Inc.  Binary Fission in Bacteria ▪ Prokaryotes (bacteria and archaea) reproduce by a type of cell division called binary fission ▪ In E. coli, the single chromosome replicates, beginning at the origin of replication ▪ The two daughter chromosomes actively move apart while the cell elongates ▪ The plasma membrane pinches inward, dividing the cell into two ▪ Binary fission animation ▪ http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::500::5 00::/sites/dl/free/0073375225/594358/BinaryFission.swf::BinaryFission © 2016 Pearson Education, Inc.  Figure 9.12-s1 Bacterial Cell Division by Binary Fission (Step 1) © 2016 Pearson Education, Inc.  Figure 9.12-s2 Bacterial Cell Division by Binary Fission (Step 2) © 2016 Pearson Education, Inc.  Figure 9.12-s3 Bacterial Cell Division by Binary Fission (Step 3) © 2016 Pearson Education, Inc.  Figure 9.12-s4 Bacterial Cell Division by Binary Fission (Step 4) © 2016 Pearson Education, Inc.  The Evolution of Mitosis ▪ Since prokaryotes evolved before eukaryotes, mitosis probably evolved from binary fission ▪ Certain protists (dinoflagellates, diatoms, and some yeasts) exhibit types of cell division that seem intermediate between binary fission and mitosis © 2016 Pearson Education, Inc.  Figure 9.13 Mechanisms of Cell Division © 2016 Pearson Education, Inc.  Concept 9.3: The eukaryotic cell cycle is regulated by a molecular control system ▪ The frequency of cell division varies with the type of cell ▪ These differences result from regulation at the molecular level ▪ Cancer cells manage to escape the usual controls on the cell cycle © 2016 Pearson Education, Inc.  Evidence for Cytoplasmic Signals ▪ The cell cycle is driven by specific signaling molecules present in the cytoplasm ▪ Some evidence for this hypothesis comes from experiments with cultured mammalian cells ▪ Cells at different phases of the cell cycle were fused to form a single cell with two nuclei at different stages ▪ Cytoplasmic signals from one of the cells could cause the nucleus from the second cell to enter the “wrong” stage of the cell cycle © 2016 Pearson Education, Inc.  Figure 9.14 Inquiry: Do Molecular Signals in the Cytoplasm Regulate the Cell Cycle? © 2016 Pearson Education, Inc.  Checkpoints of the Cell Cycle Control System ▪ The sequential events of the cell cycle are directed by a distinct cell cycle control system, which is similar to a timing device of a washing machine ▪ The cell cycle control system is regulated by both internal and external controls ▪ The clock has specific checkpoints where the cell cycle stops until a go-ahead signal is received ▪ Animation: Control of the Cell Cycle ▪ http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__control_of_the_cell_cycle.html © 2016 Pearson Education, Inc.  Figure 9.15 Mechanical Analogy for the Cell Cycle Control System © 2016 Pearson Education, Inc.  Checkpoints of the Cell Cycle Control System, Continued ▪ For many cells, the checkpoint seems to be the most important ▪ If a cell receives a go-ahead signal at the checkpoint, it will usually complete the S, , and M phases and divide ▪ If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a nondividing state called the phase Most cells of the human body are actually in G0 phase, i.e. mature nerve cells and muscle cells never divide. © 2016 Pearson Education, Inc.  Figure 9.16 Two Important Checkpoints © 2016 Pearson Education, Inc.  Checkpoints of the Cell Cycle Control System, Continued-1 ▪ The cell cycle is regulated by a set of regulatory proteins and protein complexes including kinases and proteins called cyclins © 2016 Pearson Education, Inc.  Checkpoints of the Cell Cycle Control System, Continued-2 ▪ An example of an internal signal occurs at the M phase checkpoint ▪ In this case, anaphase does not begin if any kinetochores remain unattached to spindle microtubules ▪ Attachment of all of the kinetochores activates a regulatory complex, which then activates the enzyme separase ▪ Separase allows sister chromatids to separate, triggering the onset of anaphase © 2016 Pearson Education, Inc.  Checkpoints of the Cell Cycle Control System, Continued-3 ▪ Some external signals are growth factors, proteins released by certain cells that stimulate other cells to divide ▪ For example, platelet-derived growth factor (PDGF) stimulates the division of human fibroblast cells in culture © 2016 Pearson Education, Inc.  Figure 9.17-s1 The Effect of Platelet-Derived Growth Factor (PDGF) on Cell Division (Step 1) © 2016 Pearson Education, Inc.  Figure 9.17-s2 The Effect of Platelet-Derived Growth Factor (PDGF) on Cell Division (Step 2) © 2016 Pearson Education, Inc.  Figure 9.17-s3 The Effect of Platelet-Derived Growth Factor (PDGF) on Cell Division (Step 3) © 2016 Pearson Education, Inc.  Figure 9.17-s4 The Effect of Platelet-Derived Growth Factor (PDGF) on Cell Division (Step 4) © 2016 Pearson Education, Inc.  Checkpoints of the Cell Cycle Control System, Continued-4 ▪ Another example of external signals is density-dependent inhibition, in which crowded cells stop dividing ▪ Most animal cells also exhibit anchorage dependence, in which they must be attached to a substratum in order to divide ▪ Cancer cells exhibit neither density-dependent inhibition nor anchorage dependence © 2016 Pearson Education, Inc.  Figure 9.18 Density-Dependent Inhibition and Anchorage Dependence of Cell Division © 2016 Pearson Education, Inc.  Loss of Cell Cycle Controls in Cancer Cells ▪ Cancer cells do not respond to signals that normally regulate the cell cycle ▪ Cancer cells do not need growth factors to grow and divide ▪ They may make their own growth factor ▪ They may convey a growth factor’s signal without the presence of the growth factor ▪ They may have an abnormal cell cycle control system © 2016 Pearson Education, Inc. Loss of Cell Cycle Controls in Cancer Cells, Continued ▪ A normal cell is converted to a cancerous cell by a process called transformation ▪ If abnormal cells remain only at the original site, the lump is called a benign tumor ▪ Malignant tumors invade surrounding tissues and undergo metastasis, exporting cancer cells to other parts of the body, where they may form additional tumors © 2016 Pearson Education, Inc.  Figure 9.19 The Growth and Metastasis of a Malignant Breast Tumor © 2016 Pearson Education, Inc.  Loss of Cell Cycle Controls in Cancer Cells, Continued-1 ▪ Recent advances in understanding the cell cycle and cell cycle signaling have led to advances in cancer treatment ▪ Medical treatments for cancer are becoming more “personalized” to an individual patient’s tumor ▪ Cancer and Cell Cycle animations ▪ https://science.education.nih.gov/supplements/webv ersions/CellBiology/activities/activity2_animations.ht ml © 2016 Pearson Education, Inc.  The Eukaryotic Cell Cycle and Cancer from BioInteractive ▪ http://www.hhmi.org/biointeractive/eukaryotic-cell-cy cle-and-cancer © 2016 Pearson Education, Inc.