Chapter 8 Cellular Reproduction Cells From Cells Guided Reading Activities

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1. Chapter 8 The Cellular Basis of Reproduction and Inheritance PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey © 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko
2. Figure 8.0_2 Chapter 8: Big Ideas Cell Division and Reproduction Meiosis and Crossing Over The Eukaryotic Cell Cycle and Mitosis Alterations of Chromosome Number and Structure
3. Figure 8.0_3
4. 8.1 Cell division plays many important roles in the lives of organisms  Organisms reproduce their own kind, a key characteristic of life.  Cell division – is reproduction at the cellular level, – requires the duplication of chromosomes, and – sorts new sets of chromosomes into the resulting pair of daughter cells. © 2012 Pearson Education, Inc.
5. 8.1  Cell division is used – for reproduction of single-celled organisms, – growth of multicellular organisms from a fertilized egg into an adult, – repair and replacement of cells, and – sperm and egg production. © 2012 Pearson Education, Inc.
6. 8.1  Living organisms reproduce by two methods. – Asexual reproduction – produces offspring that are identical to the original cell or organism and – involves inheritance of all genes from one parent. – Sexual reproduction – produces offspring that are similar to the parents, but show variations in traits and – involves inheritance of unique sets of genes from two parents. © 2012 Pearson Education, Inc.
7. Figure 8.1A
8. Figure 8.1B
9. Figure 8.1C
10. Figure 8.1D
11. 8.2 Prokaryotes reproduce by binary fission  Prokaryotes (bacteria and archaea) reproduce by binary fission ("dividing in half").  The chromosome of a prokaryote is – a singular circular DNA molecule – much smaller than those of eukaryotes. © 2012 Pearson Education, Inc.
12. 8.2 Prokaryotes reproduce by binary fission  Binary fission of a prokaryote occurs in three stages: 1. duplication of the chromosome and separation of the copies, 2. continued elongation of the cell and movement of the copies, and 3. division into two daughter cells. © 2012 Pearson Education, Inc.
13. Figure 8.2A_s1 Plasma membrane Prokaryotic chromosome Cell wall 1 Duplication of the chromosome and separation of the copies
14. Figure 8.2A_s2 Plasma membrane Prokaryotic chromosome Cell wall 1 Duplication of the chromosome and separation of the copies 2 Continued elongation of the cell and movement of the copies
15. Figure 8.2A_s3 Plasma membrane Prokaryotic chromosome Cell wall 1 2 3 Duplication of the chromosome and separation of the copies Continued elongation of the cell and movement of the copies Division into two daughter cells
16. 8.3 The large, complex chromosomes of eukaryotes duplicate with each cell division  Eukaryotic cells – are more complex and larger than prokaryotic cells, – have more genes, and – store most of their genes on multiple chromosomes within the nucleus. © 2012 Pearson Education, Inc.
17. 8.3  Eukaryotic chromosomes are composed of chromatin consisting of – one long DNA molecule and proteins  To prepare for division, the chromatin becomes highly compacted chromosomes © 2012 Pearson Education, Inc.
18. Figure 8.3A DNA in the form of condensed chromosomes DNA in the form of chromatin
19. 8.3  Before a eukaryotic cell begins to divide, it duplicates all of its chromosomes, resulting in – two copies called sister chromatids joined together by a narrowed "waist" called the centromere.  When a cell divides, the sister chromatids – separate from each other, now each is called a chromosome – Each chromosome (single chromatid) is distributed into separate daughter cells. © 2012 Pearson Education, Inc.
20. Figure 8.3B Chromosomes DNA molecules Sister chromatids Chromosome duplication Centromere Sister chromatids Chromosome distribution to the daughter cells
21. 8.4 The cell cycle multiplies cells  An ordered sequence of events that divide a cell  The cell cycle consists of two stages, characterized as follows: 1. Interphase: duplication of cell contents – G1—growth, increase in cytoplasm – S—duplication of chromosomes – G2—growth, preparation for division 1. Mitotic phase: division – Mitosis—division of the nucleus – Cytokinesis—division of cytoplasm © 2012 Pearson Education, Inc.
22. Figure 8.4 INT ERPH ASE G1 (first gap) O MIT M ito si s si s kine o Cyt TIC A PH SE S (DNA synthesis) M G2 (second gap)
23. 8.5 Cell division is a continuum of dynamic changes  Mitosis progresses through a series of stages: – prophase, – prometaphase, – metaphase, – anaphase, and – telophase.  Cytokinesis often overlaps telophase. © 2012 Pearson Education, Inc.
24. 8.5 Cell division is a continuum of dynamic changes  A mitotic spindle (spindle fibers) is – required to divide the chromosomes, and composed of microtubules – produced by centrosomes – contain a pair of centrioles in animal cells. © 2012 Pearson Education, Inc.
25. 8.5 Cell division is a continuum of dynamic changes  Interphase – The cytoplasmic contents double, – two centrosomes form, – chromosomes duplicate in the nucleus during the S phase, and – nucleoli, sites of ribosome assembly, are visible. © 2012 Pearson Education, Inc.
26. Figure 8.5_left MITOSIS INTERPHASE Prophase Centrosomes (with centriole pairs) Centrioles Nuclear envelope Chromatin Early mitotic spindle Prometaphase Centrosome Fragments of the nuclear envelope Kinetochore Plasma membrane Centromere Chromosome, consisting of two sister chromatids Spindle microtubules
27. 8.5 Cell division is a continuum of dynamic changes  Prophase – In the cytoplasm microtubules begin to emerge from centrosomes, forming the spindle. – In the nucleus – chromosomes coil and become compact and – nucleoli disappear. © 2012 Pearson Education, Inc.
28. Figure 8.5_left MITOSIS INTERPHASE Prophase Centrosomes (with centriole pairs) Centrioles Nuclear envelope Chromatin Early mitotic spindle Prometaphase Centrosome Fragments of the nuclear envelope Kinetochore Plasma membrane Centromere Chromosome, consisting of two sister chromatids Spindle microtubules
29. 8.5 Cell division is a continuum of dynamic changes  Prometaphase – Spindle microtubules reach chromosomes, where they – attach at kinetochores on the centromeres of sister chromatids and – move chromosomes to the center of the cell through associated protein "motors." – Other microtubules meet those from the opposite poles. – The nuclear envelope disappears. © 2012 Pearson Education, Inc.
30. Figure 8.5_left MITOSIS INTERPHASE Prophase Centrosomes (with centriole pairs) Centrioles Nuclear envelope Chromatin Early mitotic spindle Prometaphase Centrosome Fragments of the nuclear envelope Kinetochore Plasma membrane Centromere Chromosome, consisting of two sister chromatids Spindle microtubules
31. 8.5  Metaphase – The mitotic spindle is fully formed. – Chromosomes align at the cell equator. – Kinetochores (protein structure at centromere) of sister chromatids are facing the opposite poles of the spindle. © 2012 Pearson Education, Inc.
32. Figure 8.5_right MITOSIS Anaphase Metaphase Metaphase plate Mitotic spindle Daughter chromosomes Telophase and Cytokinesis Cleavage furrow Nuclear envelope forming
33. 8.5  Anaphase – Sister chromatids separate at the centromeres. – Daughter chromosomes are moved to opposite poles of the cell – The cell elongates due to lengthening of microtubules. © 2012 Pearson Education, Inc.
34. Figure 8.5_right MITOSIS Anaphase Metaphase Metaphase plate Mitotic spindle Daughter chromosomes Telophase and Cytokinesis Cleavage furrow Nuclear envelope forming
35. 8.5  Telophase – The cell continues to elongate. – The nuclear envelope forms around chromosomes at each pole, establishing daughter nuclei. – Chromatin uncoils and nucleoli reappear. – The spindle disappears. © 2012 Pearson Education, Inc.
36. Figure 8.5_right MITOSIS Anaphase Metaphase Metaphase plate Mitotic spindle Daughter chromosomes Telophase and Cytokinesis Cleavage furrow Nuclear envelope forming
37. 8.6 Cytokinesis differs for plant and animal cells  During cytokinesis, the cytoplasm is divided into separate cells.  In animal cells, cytokinesis occurs as 1. a cleavage furrow forms from a contracting ring of microfilaments, interacting with myosin, and 2. the cleavage furrow deepens to separate the contents into two cells. © 2012 Pearson Education, Inc.
38. Figure 8.6A Cytokinesis Cleavage furrow Contracting ring of microfilaments Daughter cells Cleavage furrow Animation: Cytokinesis
39. 8.6  In plant cells, cytokinesis occurs as 1. a cell plate forms in the middle, from vesicles containing cell wall material, 2. the cell plate grows outward to reach the edges, dividing the contents into two cells, 3. each cell now possesses a plasma membrane and cell wall. © 2012 Pearson Education, Inc.
40. Figure 8.6B New cell wall Cytokinesis Cell wall of the parent cell Cell wall Plasma membrane Daughter nucleus Cell plate forming Vesicles containing cell wall material Cell plate Daughter cells
41. Figure 8.10A
42. 8.11 Chromosomes are matched in homologous pairs  In humans, somatic cells have – 23 pairs of homologous chromosomes – one chromosome of each pair from each parent.  The human sex chromosomes X and Y differ in size and genetic composition.  The other 22 pairs of chromosomes are autosomes with the same size and genetic composition. © 2012 Pearson Education, Inc.
43. 8.11  Homologous chromosomes are matched in – length, – centromere position, and – gene locations.  A locus (plural, loci) is the position of a gene.  Different versions of a gene may be found at the same locus on maternal and paternal chromosomes. © 2012 Pearson Education, Inc.
44. Figure 8.11 Pair of homologous chromosomes Locus Centromere Sister chromatids One duplicated chromosome
45. 8.12 Gametes have a single set of chromosomes  Humans and many animals and plants are diploid, with body cells that have – two sets of chromosomes, – one from each parent. © 2012 Pearson Education, Inc.
46. 8.12  Meiosis is a process that converts diploid nuclei to haploid nuclei. – Diploid cells have two homologous sets of chromosomes. – Haploid cells have one set of chromosomes. – Meiosis occurs in the sex organs, producing gametes —sperm and eggs.  Fertilization is the union of sperm and egg.  The zygote has a diploid chromosome number, one set from each parent. © 2012 Pearson Education, Inc.
47. Figure 8.12A Haploid gametes (n = 23) n Egg cell n Sperm cell Meiosis Ovary Fertilization Testis Diploid zygote (2n = 46) 2n Key Multicellular diploid adults (2n = 46) Mitosis Haploid stage (n) Diploid stage (2n)
48. Figure 8.12B INTERPHASE MEIOSIS I MEIOSIS II Sister chromatids 2 1 A pair of homologous chromosomes in a diploid parent cell A pair of duplicated homologous chromosomes 3
49. 8.13 Meiosis reduces the chromosome number from diploid to haploid  Meiosis I – Prophase I – events occurring in the nucleus. – Chromosomes coil and become compact. – Homologous chromosomes come together as pairs – Each pair, with four chromatids, is called a tetrad. – Nonsister chromatids exchange genetic material by crossing over. © 2012 Pearson Education, Inc.
50. Figure 8.13_1 MEIOSIS I INTERPHASE: Chromosomes duplicate Centrosomes (with centriole pairs) Prophase I Sites of crossing over Centrioles Spindle Tetrad Nuclear envelope Chromatin Sister chromatids Fragments of the nuclear envelope
51. 8.13  Meiosis I – Metaphase I – Tetrads align at the cell equator.  Meiosis I – Anaphase I – Homologous pairs separate and move toward opposite poles of the cell. © 2012 Pearson Education, Inc.
52. Figure 8.13_2 MEIOSIS I Metaphase I Spindle microtubules attached to a kinetochore Centromere (with a kinetochore) Anaphase I Sister chromatids remain attached Metaphase plate Homologous chromosomes separate
53. Figure 8.13_left MEIOSIS I: Homologous chromosomes separate INTERPHASE: Chromosomes duplicate Centrosomes (with centriole pairs) Prophase I Metaphase I Sites of crossing over Spindle microtubules attached to a kinetochore Centrioles Anaphase I Sister chromatids remain attached Spindle Tetrad Nuclear envelope Chromatin Sister chromatids Fragments of the nuclear envelope Centromere (with a kinetochore) Metaphase plate Homologous chromosomes separate
54. 8.13  Meiosis I – Telophase I – Duplicated chromosomes have reached the poles. – A nuclear envelope re-forms around chromosomes in some species. – Each nucleus has the haploid number of chromosomes. © 2012 Pearson Education, Inc.
55. Figure 8.13_3 Telophase I and Cytokinesis Cleavage furrow
56. 8.13  Meiosis II follows meiosis I without chromosome duplication.  Each of the two haploid products enters meiosis II.  Meiosis II – Prophase II – Chromosomes coil and become compact (if uncoiled after telophase I). – Nuclear envelope, if re-formed, breaks up again. © 2012 Pearson Education, Inc.
57. Figure 8.13_right MEIOSIS II: Sister chromatids separate Telophase I and Cytokinesis Prophase II Metaphase II Anaphase II Telophase II and Cytokinesis Cleavage furrow Sister chromatids separate Haploid daughter cells forming
58. 8.13  Meiosis II – Metaphase II – Duplicated chromosomes align at the cell equator.  Meiosis II – Anaphase II – Sister chromatids separate and – chromosomes move toward opposite poles. © 2012 Pearson Education, Inc.
59. 8.13 Meiosis reduces the chromosome number from diploid to haploid  Meiosis II – Telophase II – Chromosomes have reached the poles of the cell. – A nuclear envelope forms around each set of chromosomes. – With cytokinesis, four haploid cells are produced. © 2012 Pearson Education, Inc.
60. 8.14 Mitosis and meiosis have important similarities and differences  Mitosis and meiosis both – begin with diploid parent cells that – have chromosomes duplicated during the previous interphase.  However the end products differ. – Mitosis produces two genetically identical diploid somatic daughter cells. – Meiosis produces four genetically unique haploid gametes. © 2012 Pearson Education, Inc.
61. Figure 8.14 MEIOSIS I MITOSIS Parent cell (before chromosome duplication) Prophase Duplicated chromosome (two sister chromatids) Chromosome duplication Site of crossing over Prophase I Tetrad formed by synapsis of homologous chromosomes Chromosome duplication 2n = 4 Metaphase I Metaphase Chromosomes align at the metaphase plate Tetrads (homologous pairs) align at the metaphase plate Anaphase Telophase Anaphase I Telophase I Homologous chromosomes separate during anaphase I; sister chromatids remain together Sister chromatids separate during anaphase Daughter cells of meiosis I MEIOSIS II 2n 2n Daughter cells of mitosis No further chromosomal duplication; sister chromatids separate during anaphase II n n n n Daughter cells of meiosis II Haploid n= 2
62. 8.15 Independent orientation of chromosomes in meiosis and random fertilization lead to varied offspring  Genetic variation in gametes results from – independent orientation at metaphase I – Each pair of chromosomes independently aligns at the cell equator. – random fertilization – Combination of a unique sperm with a unique egg © 2012 Pearson Education, Inc.
63. Figure 8.15_s1 Possibility A Possibility B Two equally probable arrangements of chromosomes at metaphase I
64. Figure 8.15_s2 Possibility A Possibility B Two equally probable arrangements of chromosomes at metaphase I Metaphase II
65. Figure 8.15_s3 Possibility A Possibility B Two equally probable arrangements of chromosomes at metaphase I Metaphase II Gametes Combination 1 Combination 2 Combination 3 Combination 4
66. 8.17 Crossing over further increases genetic variability  Genetic recombination is the production of new combinations of genes due to crossing over.  Crossing over is an exchange of corresponding segments between separate (nonsister) chromatids on homologous chromosomes. – Nonsister chromatids join at a chiasma (plural, chiasmata), the site of attachment and crossing over. – Corresponding amounts of genetic material are exchanged between maternal and paternal (nonsister) chromatids. Animation: Crossing Over © 2012 Pearson Education, Inc.
67. Figure 8.17A Chiasma Tetrad
68. 8.18 A karyotype is a photographic inventory of an individual's chromosomes  A karyotype is an ordered display of magnified images of an individual's chromosomes arranged in pairs.  Karyotypes – are often produced from dividing cells arrested at metaphase of mitosis and – allow for the observation of – homologous chromosome pairs, – chromosome number, and – chromosome structure. © 2012 Pearson Education, Inc.
69. Figure 8.18_s5 Centromere Sister chromatids Pair of homologous chromosomes 5 Sex chromosomes
70. 8.20 Accidents during meiosis can alter chromosome number  Nondisjunction is the failure of chromosomes or chromatids to separate normally during meiosis. This can happen during – meiosis I, if both members of a homologous pair go to one pole or – meiosis II if both sister chromatids go to one pole.  Fertilization after nondisjunction yields zygotes with altered numbers of chromosomes. © 2012 Pearson Education, Inc.
71. Figure 8.20A_s1 MEIOSIS I Nondisjunction
72. Figure 8.20A_s2 MEIOSIS I Nondisjunction MEIOSIS II Normal meiosis II
73. Figure 8.20A_s3 MEIOSIS I Nondisjunction MEIOSIS II Normal meiosis II Gametes Number of chromosomes n+ 1 n+ 1 n− 1 Abnormal gametes n−1
74. Figure 8.20B_s1 MEIOSIS I Normal meiosis I
75. Figure 8.20B_s2 MEIOSIS I Normal meiosis I MEIOSIS II Nondisjunction
76. Figure 8.20B_s3 MEIOSIS I Normal meiosis I MEIOSIS II Nondisjunction n+ 1 n−1 Abnormal gametes n n Normal gametes
77. Table 8.21
78. 8.23 CONNECTION: Alterations of chromosome structure can cause birth defects and cancer  These rearrangements may include – a deletion, the loss of a chromosome segment, – a duplication, the repeat of a chromosome segment, – an inversion, the reversal of a chromosome segment, or – a translocation, the attachment of a segment to a nonhomologous chromosome that can be reciprocal. © 2012 Pearson Education, Inc.
79. Figure 8.23A Deletion Inversion Duplication Reciprocal translocation Homologous chromosomes Nonhomologous chromosomes
80. You should now be able to 1. Compare the parent-offspring relationship in asexual and sexual reproduction. 2. Explain why cell division is essential for prokaryotic and eukaryotic life. 3. Explain how daughter prokaryotic chromosomes are separated from each other during binary fission. 4. Compare the structure of prokaryotic and eukaryotic chromosomes. 5. Describe the stages of the cell cycle. 6. List the phases of mitosis and describe the events characteristic of each phase. 7. Compare cytokinesis in animal and plant cells. 8. Describe the functions of mitosis. © 2012 Pearson Education, Inc.
81. You should now be able to 9. Explain how chromosomes are paired. 10. Distinguish between somatic cells and gametes and between diploid cells and haploid cells. 11. Explain why sexual reproduction requires meiosis. 12. List the phases of meiosis I and meiosis II and describe the events characteristic of each phase. 13. Compare mitosis and meiosis noting similarities and differences. 14. Explain how genetic variation is produced in sexually reproducing organisms. 15. Explain how and why karyotyping is performed. 16. Define nondisjunction, explain how it can occur, and describe what can result. © 2012 Pearson Education, Inc.