Organismal Biology: Asexual Reproduction

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Organismal Biology - Reproduction and Development

• Reproduction is a biological process where organisms produce another of their kind and is vital for species perpetuation and survival (heredity).
• Reproduction is the basis for speciation
• There are two types of reproduction: asexual and sexual.

Asexual Reproduction

• Asexual reproduction doesn't require fertilization (union of gametes).
• Asexual reproduction is not necessary to have two parents to produce offspring

Budding

• Budding forms a "bud" on the body of a parent organism, which separates to create a smaller individual.
• The offspring develops from an "outgrowth" of the parent and later detaches.
• Budding is common among hydra, corals, sponges, and larvae.

Fragmentation

• A cut body part regenerates and becomes its own separate organism.
• The offspring develops from the detached body part of a parent organism.
• Fragmentation examples: starfish, planaria, lichens, molds, and sea stars.

Regeneration

• Regeneration is the regrowth of a cut or injured body part, not becoming its separate organism.
• Regeneration falls under fragmentation
• Starfish and lizards are examples of regeneration

Binary Fission

• Meiosis is when parent organisms split into two "daughter" organisms.
• Binary fission is typically observed among prokaryotes.
• Bacteria and archaea are examples of binary fission

Vegetative Reproduction

• A plant part is used to reproduce another plant.
• Vegetative reproduction doesn't use seeds.

Plant Vegetative Reproduction

• Strawberry uses stolons, extensions of the stem.
• Tubers (potatoes)
• Kataka-taka plant
• Mango

Spore Formation

• Spore formation involves the production of spores, which are specialized asexual reproductive cells.
• Spores are dispersed into the air where they germinate and create a new plant under favorable conditions.
• Ferns and molds are examples of spore formation

Parthenogenesis

• Parthenogenesis is the process where females can produce offspring without fertilization.
• Examples: komodo dragon, bonnethead shark, water flea, Bynoe's gecko, Warramaba Virgo grasshopper, and mulga trees.

Sexual Reproduction

• Sexual reproduction involves the union of gametes (egg and sperm).
• Through fertilization, a haploid egg (ovum) unites with a haploid sperm to become a diploid zygote (46 chromosomes in 23 pairs), which eventually becomes an embryo.

Reproduction in Plants

• Flowering plants reproduce sexually through pollination.
• The flower male sex organs are the STAMEN (consisting of the ANTHER, which contains pollen).
• The flower female sex organs are the PISTIL (consisting of the STIGMA where the pollen must go for reproduction).

Process of Reproduction

• Pollen proceeds from the anther to the stigma.
• Pollen travels through the style.
• Pollen then fertilizes the ovules.

Self-Pollination

• Self-pollination occurs within the same flower.
• Self-pollination pertains to hermaphrodites

Hermaphrodites

• Hermaphrodites contain both male and female flowers.
• Tapeworms and earthworms are hermaphrodites

Cross-Pollination

• Cross-pollination occurs between two different flowers of the same species.
• Cross-pollination involves pollinators (bees, humans).

Reproduction in Animals

• External fertilization occurs outside the body of an organism.
• Frogs release sperm and eggs into water, where fertilization takes place.
• Clownfish lay eggs on a flat rock surface close to their host anemone and males swim over the eggs to fertilize them.
• Internal fertilization occurs inside the body of an organism characterized by sperm fertilizing the egg within the female body.

Development

• Development is the process involving the formation of gametes, zygote, and subsequent stages in one's lifespan, terminated by death.

Growth

• Growth is the stage of development characterized by an increase in size of an individual.

Plant life cycle

• Most plants undergo alternation of generations, where they exhibit sexual and asexual life cycles.

• Gametophyte (n): is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes.

  • It is the sexual phase in the life cycle of plants and algae

• Sporophyte (2n): is the diploid multicellular stage in the life cycle of a plant or algae.

  • It develops from the zygote produced when a haploid egg cell is fertilized by a haploid sperm.

Animal life cycle

• Diploid (2N) adults produce haploid (N) gametes (sperm and egg) through meiosis, which halves the chromosome number.
• Fertilization restores the diploid number, forming a zygote that grows into a multicellular organism through mitosis.
• Mammals: the development of the embryo takes place inside the female body (leading to live births).