Unit 3 - Reproductive Strategies

se-xual reproduction

The production of gametes by meiosis followed by fertilization between two parental gametes to produce genetically distinct offspring

gametes

A gamete is a reproductive cell, or sex cell, a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Female gametes are called ova or egg cells, and male gametes are called sperm.

asexual reproduction

Produces genetically identical offspring, it does not involve the fusion of gametes or a change in the number of chromosomes.

binary fission

Many prokaryotes (ie., bacteria) use a process called binary fission to replicate DNA and create two daughter cells. Due to the fact that these cells have no nucleus and there’s only one chromosome, the process is much simpler than mitosis.

conjugation

Some bacteria can reproduce through a process called conjugation. Genetic material can be transferred between non-genetically identical bacterial cells through a bridging structure called a pilus (plur. - pili). This creates cells with new genetic combinations and thereby provides a chance that some cells may be better adapted to a changing environment.

pilus (plur. - pili)

A hair-like structure on bacterial cells that facilitates the transfer of genetic material during conjugation. It connects two cells, allowing DNA exchange and forming genetic diversity.

Budding

Budding is a form of asexual reproduction in which a complete but miniature version of the parent grows out from the parent’s body.

Vegetative reproduction

Vegetative reproduction can occur in any type of shoot or root, resulting in a new plant that’s genetically identical to the parent plant. Examples of this would be suckers in elms & roses, tubers in potatoes & runners in strawberry plants.

Fragmentation

Fragmentation involves the creation of a new organism from a portion of a parent. Gardeners rely on fragmentation to propagate new plants from cuttings. Other organisms that use this technique include molds, lichens, flatworms, some annelids, echinoderms & coral.

Parthenogenesis

Parthenogenesis is a form of asexual reproduction in which an unfertilized egg develops into an adult. It occurs naturally in many plants and some invertebrate species such as scorpions and honeybees.

Spores

Spores are structures that contain genetic material and cytoplasm surrounded by a protective sheath or wall. Organisms that utilize them (ie., plants, algae, fungi & protozoa) are able to disperse their offspring long distances. They are usually haploid and unicellular.

alternation of generations

Some organisms produce spores by meiosis, resulting in alternation of generations. Some animals’ life cycles alternate between an asexual and a sexual reproducing phase.

sporophyte

1. The diploid generation is called the sporophyte, which produces one or more haploid spores which develop without fertilization.

gametophyte

1. Each haploid spore grows into a plant body called the gametophyte, which produces male and female gametes. These fuse at fertilization and develop into the sporophyte, completing the cycle.

polyp

A polyp is a cylindrical, sessile form of certain cnidarians characterized by a mouth surrounded by tentacles. It typically attaches to a substrate and can reproduce asexually or develop into a medusa in some life cycles.

medusa

A medusa is a free-swimming, umbrella-shaped form of certain cnidarians, characterized by tentacles that hang down from the margin. It reproduces sexually, releasing gametes into the water to produce new offspring.

cnidaria

Most of the members in the phylum Cnidaria (ie., jellyfish, sea anemones and corals) alternate reproductive phases. Their life cycles are characterized by two distinct adult forms: a non-motile polyp and a free-swimming medusa.

what organisms use budding as a reproductive strategy?

Brewer’s yeast (Saccharomyces cerevisiae) and members of the phylum Cnidaria called hydras are examples of organisms that undergo this process. Many plant species use a form of asexual reproduction similar to budding.

how do honey bees reproduce?

pathogenesis

how does the new mexico whiptail lizard reproduce?

parthogenesis

spermatogonia

diploid cell in the seminiferous tubules

spermatocytes

spermatogonia) in the seminiferous tubules, which divides mitotically to produce two diploid primary spermatocytes

secondary spermatocytes

primary spermatocyte then undergoes meiosis I to produce two haploid secondary spermatocytes

spermatids

The haploid secondary spermatocytes undergo meiosis II to produce four haploid spermatids. Each spermatid begins to grow a tail and a mitochondrion-filled midpiece, while the chromatin is tightly packaged into an acrosome at the head.

spermatozoa

Maturation removes excess cellular material, turning spermatids into inactive, sterile spermatozoa that are transported via peristalsis to the epididymis. The spermatozoa gain motility in the epididymis, but do not use that ability until they are ejaculated into the vagina.

Oogenesis

The process of egg cell development in females, resulting in the formation of an ovum.

oogonia

The early, diploid germ cells in the ovaries that develop into oocytes during oogenesis.

primary oocytes

The diploid cells in the ovaries that develop into eggs during oogenesis.

oocytogenesis

process of developing oogonia via the transformation of primordial follicles into primary oocytes, a process called oocytogenesis. Oocytogenesis is complete either before or shortly after birth in humans. During the menstrual cycle

secondary oocyte

Enters meiosis II, but is frozen in metaphase II until fertilization occurs. During ovulation, the egg matures further and is released from the ovarian follicles into the oviduct. If it is fertilized by sperm, it finishes meiosis II and becomes an ootid.

first polar body

A small cell produced during oocyte meiosis that typically degenerates.

fertilization

The process where a sperm cell merges with an egg cell, resulting in the formation of a zygote. This marks the beginning of development in sexually reproducing organisms.

secondary polar bodies

Cells produced during the meiotic division of oocytes that do not develop into eggs, occurring during oogenesis.

zygote

diploid cell formed when sperm and egg nuclei fuse, rapidly grows into new organism

spermatogenesis

The process by which male gametes, or sperm, are produced in the male reproductive system through meiosis and cell differentiation.