Living Environment Asexual Reproduction

How do cells make new cells? What happens when you cut a worm in half? Why do you think you can grow new skin over a cut on you hand but you can’t grow new fingers?

What is Asexual Reproduction Only one parent is involved. Offspring are genetically identical to their parents. All cells that come from a single cell are genetically identical to it and to each other They are all clones.

Mitosis The exact duplication of the nucleus of a cell so as to form two identical nuclei during cell division.

Types of Asexual Reproduction How many ways can you do mitosis? Binary Fission Budding Regeneration Sporulation Vegetative Propagation Parthenogenesis

Binary Fission Binary fission is used by most prokaryotes for asexual reproduction. This process replicates the original, or mother, cell, to produce two identical daughter cells.

Binary Fission Simplest form of asexual reproduction. Parent organism divides into two approximately equal parts. Each daughter cell becomes a new individual.

Binary Fission Binary fission offspring genetically identical to the parent cell. Bacterial DNA has a relatively high mutation rate. This rapid rate of genetic change resistance to antibiotics exploit invasion into a wide range of environments. Organisms that reproduce through binary fission generally grow exponentially. E coli cells are able to divide every 20 minutes under optimum conditions.            

Binary Fission Occurs prokaryotes Occurs in one-celled organisms such as the amoeba and paramecium.

Budding The parent organism divides into two unequal parts The new organism is created as a smaller out growth or bud on the outside of the parent The division of cytoplasm is unequal so one of the daughter cells is larger than the other.

Budding The daughter cells can separate or remain attached. Buds may break off and live independently or remain attached and form a colony. Occurs in hydra and yeast.

They were Best Buds

Regeneration (don’t try this at home) Refers to the replacement or re-growth of lost or damaged body parts

Regeneration All organisms, including humans have the ability to regenerate something in the body, but the process is much more developed in lower organisms such as plants, invertebrates, and amphibians.

Sporulation Spores are produced in large numbers by mitosis and meiosis. spores are small specialized cells that contain a nucleus and cytoplasm surrounded by a thick outside wall.

Can I have some spore? Spores are found in Mosses Molds Yeast Ferns Bacteria Mosses Molds Yeast Ferns Mushrooms and some protozoans

Can I have some spore ? Spores are surrounded by a tough coat to help them survive harsh environmental conditions. Some spores can live for years until the right conditions are available for them to become a new organism

Vegetative Propagation . Occurs only in plants (vegetative). New plants develop from the roots, stems, or leaves of the parent plant.

Vegetative Propagation - Bulbs . Short underground stem surrounded by thick leaves. Contain stored food. As the plant grows it produces new bulbs which will grow into new plants. Tulips, onions, and lilies.

Vegetative Propagation - Corms . Similar to bulbs but do not contain leaves, just underground stems Water chestnuts

Vegetative Propagation - Tuber Enlarged part of an underground stem that contains stored food. Potatoes, dahlias, are tubers. “Eyes” = tiny buds that can form a new potato plant.

Vegetative Propagation - Runner Also called a stolen Horizontal stem above the ground with buds. If a bud touches the ground it will form roots and stems and start a new plant. Strawberries, beans

Vegetative Propagation - Rhizome Horizontal stem that grows underground. Thick and contains stored food. Upper portion form nodes which will form buds which will form new plants. Lower portion forms roots. Ferns, cattails, and water lilies.

Parthenogenesis Derived from Greek term meaning “virgin birth” Usually found in lower vertebrates and invertebrate species Female produces offspring without fertilization

Parthenogenesis Selection advantage Able to reproduce when lacking mate Usually species that are capable of parthenogenesis go back to reproducing sexually Method of parthenogenesis determines whether or not offspring are clones of the mother In some species, egg cells do not undergo meiosis – clones! In others, two haploid eggs fuse

Parthenogenesis Here’s Flora http://www.nbcnews.com/id/16298548/ns/technology_and_science-science/t/virgin-dragon-give-birth-holiday-season/

Parthenogenesis LONDON, England (Reuters) -- Flora, a pregnant Komodo dragon living in a British zoo, is expecting eight babies in what scientists said on Wednesday could be a Christmas virgin birth. Flora has never mated, or even mixed, with a male dragon, and fertilized all the eggs herself, a process culminating in parthenogenesis, or virgin birth. Other lizards do this, but scientists only recently found that Komodo dragons do too. Parthenogenesis has occurred in other lizard species, but Buley and his team said this was the first time it has been shown in Komodo dragons -- the world's largest lizards.

Parthenogenesis Parthenogenesis in wild Komodo dragons could be adaptive, given that viable offspring are always male and that sexual reproduction can resume, albeit between related individuals, in a colony founded by a single unfertilized female. Fewer than 4,000 Komodo dragons remain in the wild, of which perhaps fewer than 1,000 are mature females

Parthenogenesis A parthenogenetically activated human egg 15 hours after activation.

Parthenogenesis While human eggs sometimes activate on their own, they never go on to complete embryonic development. Here, a four-cell human egg.

THE END (or beginning)

References http://www.huffingtonpost.com/2012/12/27/virgin-birth-in-animals-parthenogenesis_n_2372246.html http://www.findingdulcinea.com/features/science/environment/Parthenogenesis--When-Animals-Reproduce-Without-a-Mate.html http://www.nbcnews.com/id/16298548/ns/technology_and_science-science/t/virgin-dragon-give-birth-holiday-season/