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Reproduction
Asexual Reproduction
Asexual Reproduction
New organisms develop from cells of the parent – identical to parent
Asexual Reproduction
All cells arise from other cells by cell division
Mitosis
The exact duplication of the complete set of chromosomes
Separation of these chromosomes into two complete sets
Chromosome – contains hereditary information of an organism
Chromatid – one strand of a double-stranded chromosome
Centromere – structure which joins the two chromatids together
Chromatids
Centromere
Mitosis
Cytoplasmic division results in formation of two daughter cells
Each daughter cell contains exact number & type of chromosomes as parent cell
Mitosis – The Process
1) INTERPHASEReplication of each single-stranded
chromosome during the non-dividing period
Results in a double-stranded chromosome
Mitosis – The Process
2) PROPHASEDisintegration of the nuclear membraneSynthesis of a spindle apparatus to help
the division
Mitosis – The Process
3) METAPHASEAttachment of double-stranded
chromosomes to spindle apparatus at centromere
Mitosis – The Process
4) ANAPHASEReplication of each centromereResults in formation of two single-
stranded chromosomesChromosomes move along spindle
apparatus to opposite ends of the cell
Mitosis – The Process
5) TELOPHASENuclear membrane forms around each
set of chromosomesCell pinches in
Plant Mitosis vs Animal Mitosis
Similar process In animal cells:
– Centrioles form the spindle apparatus– Cytoplasmic division is a “pinching in”
of cell membraneIn plant cell, a cell plate is synthesized
Cancer
Group of diseases often characterized by uncontrolled cell division of certain abnormal cells
Asexual Reproduction
1) Binary fissionEqual division of cell of an ameba,
paramecium, bacteriumResult: Two equally sized organisms
Asexual Reproduction
2) BuddingUnicellular organisms (yeast) – similar
to binary fission except cytoplasm division is unequal
New cells stay together (colony) or may detach
Asexual Reproduction
Multicellular organisms (hydra) – Production of multicellular outgrowth from parent
Detach or form colony
Obelia colony
Asexual Reproduction
3) SporulationSpores – single, specialized cellsSurvive very well – withstand tough
conditions Released from parent &
develop into new individualsEx- bread mold
Asexual Reproduction
4) RegenerationDevelop of entire new organisms from
part of parentEx – starfish – develop from single armAlso refers to replacement of lost
structuresEx – lobster regenerates a lost claw
Asexual Reproduction
Invertebrate animals possess more undifferentiated cells than vertebrates
Means that invertebrates can regenerate easier than vertebrates
Asexual Reproduction
5) Vegetative propagationNew plants develop from roots, stems,
leaves of parent plant
Asexual Reproduction
Cuttings – GeraniumBulbs – OnionTubers – PotatoRunners – StrawberriesGrafting – Seedless Orange