BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 8 The Cellular Basis of Reproduction and Inheritance Modules 8.1 – 8.3

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Parents Daughter Cell Division Reproduction Inheritance Cell Cycle Life cycle

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Parents Daughter Cell Division Cell Cycle Mitosis Meiosis Reproduction Inheritance Sexual Asexual

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Some organisms make exact copies of themselves, asexual reproduction 8.1 Like begets like, more or less

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings All cells come from cells Cellular reproduction is called cell division –Cell division allows an embryo to develop into an adult –It also ensures the continuity of life from one generation to the next 8.2 Cells arise only from preexisting cells

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Prokaryotic cells divide asexually –These cells possess a single chromosome, containing genes –The chromosome is replicated –The cell then divides into two cells, a process called binary fission 8.3 Prokaryotes reproduce by binary fission Figure 8.3B Prokaryotic chromosomes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.3A Binary fission of a prokaryotic cell Prokaryotic chromosome Plasma membrane Cell wall Duplication of chromosome and separation of copies Continued growth of the cell and movement of copies Division into two cells

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A eukaryotic cell has many more genes than a prokaryotic cell –The genes are grouped into multiple chromosomes, found in the nucleus –The chromosomes of this plant cell are stained dark purple 8.4 The large, complex chromosomes of eukaryotes duplicate with each cell division THE EUKARYOTIC CELL CYCLE AND MITOSIS Figure 8.4A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings When the cell divides, the sister chromatids separate –Two daughter cells are produced –Each has a complete and identical set of chromosomes Centromere Sister chromatids Figure 8.4C Chromosome duplication Chromosome distribution to daughter cells

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The cell cycle consists of two major phases: –Interphase, where chromosomes duplicate and cell parts are made –The mitotic phase, when cell division occurs 8.5 The cell cycle multiplies cells Figure 8.5

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Eukaryotic cell division consists of two stages: –Mitosis –Cytokinesis 8.6 Cell division is a continuum of dynamic changes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings INTERPHASEPROPHASE Centrosomes (with centriole pairs) Chromatin NucleolusNuclear envelope Plasma membrane Early mitotic spindle Centrosome Centromere Chromosome, consisting of two sister chromatids Fragments of nuclear envelope Spindle microtubules Figure 8.6

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings METAPHASETELOPHASE AND CYTOKINESIS Metaphase plate SpindleDaughter chromosomes Cleavage furrow Nucleolus forming Nuclear envelope forming ANAPHASE Figure 8.6 (continued)

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In animals, cytokinesis occurs by cleavage –This process pinches the cell apart 8.7 Cytokinesis differs for plant and animal cells Figure 8.7A Cleavage furrow Contracting ring of microfilaments Daughter cells

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In plants, a membranous cell plate splits the cell in two Vesicles containing cell wall material Cell plate forming Figure 8.7B Cell plateDaughter cells Wall of parent cell Daughter nucleus Cell wallNew cell wall

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Proteins within the cell control the cell cycle –Signals affecting critical checkpoints determine whether the cell will go through a complete cycle and divide 8.9 Growth factors signal the cell cycle control system G 1 checkpoint M checkpoint G 2 checkpoint Control system Figure 8.9A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cancer cells have abnormal cell cycles –They divide excessively and can form abnormal masses called tumors Radiation and chemotherapy are effective as cancer treatments because they interfere with cell division 8.10 Connection: Growing out of control, cancer cells produce malignant tumors

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Malignant tumors can invade other tissues and may kill the organism Tumor Figure 8.10 Glandular tissue 123 A tumor grows from a single cancer cell. Cancer cells invade neighboring tissue. Lymph vessels Cancer cells spread through lymph and blood vessels to other parts of the body. Metastasis

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Let’s Recapitulate (Recap) what is mitosis: Mitosis is nuclear division plus cytokinesis, and produces two identical daughter cells

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Images: 1.plant root tip (meristem)

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Images: 2 different phases in mitosis

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Images: 2 different phases in mitosis

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Images: 2 different phases in mitosis

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Parents Daughter Cell Division Cell Cycle Mitosis Meiosis Reproduction Inheritance Sexual Asexual

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Somatic cells of each species contain a specific number of chromosomes –Human cells have 46, making up 23 pairs of homologous chromosomes MEIOSIS AND CROSSING OVER 8.12 Chromosomes are matched in homologous pairs Chromosomes Centromere Sister chromatids Figure 8.12

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The human life cycle Figure 8.13 MEIOSISFERTILIZATION Haploid gametes (n = 23) Egg cell Sperm cell Diploid zygote (2n = 46) Multicellular diploid adults (2n = 46) Mitosis and development

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.14, part 1 MEIOSIS I : Homologous chromosomes separate INTERPHASEPROPHASE I METAPHASE I ANAPHASE I Centrosomes (with centriole pairs) Nuclear envelope Chromatin Sites of crossing over Spindle Sister chromatids Tetrad Spindle attached to homologous chromosomes Metaphase plate Centromere Sister chromatids remain attached Homologous chromosomes separate

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.14, part 2 MEIOSIS II : Sister chromatids separate TELOPHASE I AND CYTOKINESIS PROPHASE II METAPHASE II ANAPHASE II Cleavage furrow Sister chromatids separate TELOPHASE II AND CYTOKINESIS Haploid daughter cells forming

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.15 MITOSISMEIOSIS PARENT CELL (before chromosome replication) Site of crossing over MEIOSIS I PROPHASE I Tetrad formed by synapsis of homologous chromosomes PROPHASE Duplicated chromosome (two sister chromatids) METAPHASE Chromosome replication 2n = 4 ANAPHASE TELOPHASE Chromosomes align at the metaphase plate Tetrads align at the metaphase plate METAPHASE I ANAPHASE I TELOPHASE I Sister chromatids separate during anaphase Homologous chromosomes separate during anaphase I ; sister chromatids remain together No further chromosomal replication; sister chromatids separate during anaphase II 2n2n2n2n Daughter cells of mitosis Daughter cells of meiosis II MEIOSIS II Daughter cells of meiosis I Haploid n = 2 nnnn

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.16 POSSIBILITY 1POSSIBILITY 2 Two equally probable arrangements of chromosomes at metaphase I Metaphase II Gametes Combination 1Combination 2Combination 3Combination 4 Meiosis produces genetic variations : Independent orientation of chromosomes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.17A, B Coat-color genesEye-color genes BrownBlack CE ce WhitePink CE ce CE ce Tetrad in parent cell (homologous pair of duplicated chromosomes) Chromosomes of the four gametes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.18A Tetrad Chaisma Centromere Crossing over during prophase I of meiosis

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings How crossing over leads to genetic recombination Figure 8.18B Tetrad (homologous pair of chromosomes in synapsis) Breakage of homologous chromatids Joining of homologous chromatids Chiasma Separation of homologous chromosomes at anaphase I Separation of chromatids at anaphase II and completion of meiosis Parental type of chromosome Recombinant chromosome Parental type of chromosome Gametes of four genetic types Coat-color genes Eye-color genes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings To study human chromosomes microscopically, researchers stain and display them as a karyotype –A karyotype usually shows 22 pairs of autosomes and one pair of sex chromosomes ALTERATIONS OF CHROMOSOME NUMBER AND STRUCTURE 8.19 A karyotype is a photographic inventory of an individual’s chromosomes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Preparation of a karyotype Figure 8.19 Blood culture 1 Centrifuge Packed red And white blood cells Fluid 2 Hypotonic solution 3 Fixative White Blood cells Stain 45 Centromere Sister chromatids Pair of homologous chromosomes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings This karyotype shows three number 21 chromosomes An extra copy of chromosome 21 causes Down syndrome 8.20 Connection: An extra copy of chromosome 21 causes Down syndrome Figure 8.20A, B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The chance of having a Down syndrome child goes up with maternal age Figure 8.20C

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Abnormal chromosome count is a result of nondisjunction –Either homologous pairs fail to separate during meiosis I 8.21 Accidents during meiosis can alter chromosome number Figure 8.21A Nondisjunction in meiosis I Normal meiosis II Gametes n + 1 n – 1 Number of chromosomes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –Or sister chromatids fail to separate during meiosis II Figure 8.21B Normal meiosis I Nondisjunction in meiosis II Gametes n + 1n – 1nn Number of chromosomes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Fertilization after nondisjunction in the mother results in a zygote with an extra chromosome Figure 8.21C Egg cell Sperm cell n + 1 n (normal) Zygote 2n + 1

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Nondisjunction can also produce gametes with extra or missing sex chromosomes –Unusual numbers of sex chromosomes upset the genetic balance less than an unusual number of autosomes 8.22 Connection: Abnormal numbers of sex chromosomes do not usually affect survival

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Table 8.22

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A man with Klinefelter syndrome has an extra X chromosome Figure 8.22A Poor beard growth Under- developed testes Breast development

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A woman with Turner syndrome lacks an X chromosome Figure 8.22B Characteristic facial features Web of skin Constriction of aorta Poor breast development Under- developed ovaries

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Chromosome breakage can lead to rearrangements that can produce genetic disorders or cancer –Four types of rearrangement are deletion, duplication, inversion, and translocation 8.23 Connection: Alterations of chromosome structure can cause birth defects and cancer

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.23A, B Deletion Duplication Inversion Homologous chromosomes Reciprocal translocation Nonhomologous chromosomes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Chromosomal changes in a somatic cell can cause cancer Figure 8.23C Chromosome 9 –A chromosomal translocation in the bone marrow is associated with chronic myelogenous leukemia Chromosome 22 Reciprocal translocation “Philadelphia chromosome” Activated cancer-causing gene

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Parents Daughter Cell Division Cell Cycle Mitosis Meiosis Reproduction Inheritance Sexual Asexual