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