08_Lecture_Presentation_PC_Hongmin

Chapter 8Cellular Reproduction: Cells from Cells

PowerPoint® Lectures forCampbell Essential Biology, Fifth Edition, and Campbell Essential Biology with Physiology, Fourth Edition– Eric J. Simon, Jean L. Dickey, and Jane B. Reece

Lectures by Edward J. Zalisko

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The Cellular Basis of Reproduction and Inheritance Lecture Outline:1. Connections between cell division and reproduction 2. The eukaryotic cell cycle and mitosis

3. Meiosis and crossing over4. Alterations of chromosome number and structure

Biology and Society: Virgin Birth of a Dragon In 2002, zookeepers at the Chester Zoo were surprised to discover that their Komodo Dragon laid eggs.– The female dragon had not been in the company of a male.

– The eggs developed without fertilization, in a process called parthenogenesis.– DNA analysis confirmed that her offspring had genes only from her.

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Biology and Society: Virgin Birth of a Dragon A second European Komodo dragon is now known to have reproduced– asexually, via parthenogenesis, and– sexually.

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Figure 8.0

Types of Cell Reproduction Asexual reproduction:– Offspring are exactly identical to parents

Sexual reproduction:– Offspring are unique‘blending’ of parents– No two offspring have the same genetic material (except twins)

Cell Theory All organisms made of one or more cells The cell is the fundamental unit of life

“Where a cell exists, there must be a preexisting cell.” Rudolf Virchow (1858)

The Key Roles of Cell Division Each new cell is a result of cell division The continuity of life is based on the reproduction of cells, or cell division Single celled organisms:

– Reproduce the whole organism Multicellular organisms

– Development from a fertilized cell– Growth

– Repair– Regeneration

Figure 8.1b

FUNCTIONS OF CELL DIVISIONAsexual Reproduction

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Division of an amoeba

Regeneration of a sea star

Growth of a clipping

Figure 8.1a

FUNCTIONS OF CELL DIVISIONCell Replacement Growth via Cell Division

Human kidney cell

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Early human embryo

Colorized SEM

BuddingParent

Bud

Hydra

Regeneration of Lobster

WHAT CELL REPRODUCTION ACCOMPLISHES In asexual reproduction, the lone parent and its offspring have identical genes.

Mitosis is the type of cell division responsible for– asexual reproduction and– growth and maintenance of multicellular organisms.

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WHAT CELL REPRODUCTION ACCOMPLISHES Sexual reproduction requires fertilization of an egg by a sperm using a special type of cell division called meiosis. Thus, sexually reproducing organisms use– meiosis for reproduction and– mitosis for growth and maintenance.

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THE CELL CYCLE AND MITOSIS In a eukaryotic cell,– most genes are located on chromosomes in the cell nucleu

s and– a few genes are found in DNA in mitochondria and chloroplasts.

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Eukaryotic Chromosomes Each eukaryotic chromosome contains one very long DNA molecule, typically bearing thousands of genes. The number of chromosomes in a eukaryotic cell depends on the species.

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Figure 8.2

SpeciesIndian muntjac deer Koala Opossum Giraffe Mouse

Number of chromosomes in body cells6 16 22 30 40 46 54 60 78 102

HumanDuck-billed platypus

BuffaloDog

Red viscacha rat

Eukaryotic Chromosomes Chromosomes are– made of chromatin, fibers composed of roughly equal amounts of DNA and protein molecules and– not visible in a cell until cell division occurs.

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Figure 8.3

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Chromosomes

Eukaryotic Chromosomes The DNA in a cell is packed into an elaborate, multilevel system of coiling and folding.

Histones are proteins used to package DNA in eukaryotes. Nucleosomes consist of DNA wound around histone molecules.

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Animation: DNA PackingRight click slide/ select“Play”© 2013 Pearson Education, Inc.

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