| Talk about syngamy. | Syngamy is the process of fusion of two gametes (of different sexes, male and female) to produce a diploid zygote which later becomes the new individual. Syngamy can be divided into two sequential stages: plasmogamy (fusion of the cytoplasm of two parent cells) and karyogamy (fusion of two haploid nuclei to produce a diploid cell). Usually, plasmogamy is immediately followed by karyogamy. In some systems of reproduction, karyogamy is delayed; the two haploid parental nuclei cohabit without fusing the cell (dikaryotic cell (n+n) or a dikaryon) that results from plasmogamy. |
| What does isogamy mean? | The fusion of gametes of similar morphology (same size and form) but of different mating types, most commonly noted as male and female gametes or as "+" and "−" strains e.g. Chlamydomonas. |
| What does anisogamy mean? | AKA heterogamy
The fusion of two different gametes (different sizes and/or forms). The female gamete is larger than the male gamete.
e.g. Ulva. |
| What does planogamy mean? | The fusion of two motile gametes (planogametes, zoogametes). Planogamy can be isogamous or anisogamous.
e.g. Chlamydomonas (Isogamous planogamy)
Ulva (Anisogamous planogamy) |
| What does Aplanogamy mean? | The fusion of two non-motile gametes (aplanogametes). e.g. Red algae.
AKA heterogamy. |
| What does oogamy mean? | Fertilization by the fusion of a large, non-motile, female gamete (macrogametes) with a small, motile, male gamete (microgametes) e.g. Fucus. |
| Talk about the somatogamy type of sexual reproduction | Somatic cells of two haploid filaments of opposite mating types (+ and -) come in contact and fuse (without the fusion of nuclei) involving only plasmogamy. Karyogamy is delayed and is separated from plasmogamy by a dikaryotic phase (n+n). e.g. Basidiomycota. |
| Talk about the conjugation type of sexual reproduction related to fertilization mode. | Conjugation (Cystogamy) is a process by which a donor cell (- mating type) makes a temporary contact with a recipient cell (+ mating type) through a conjugation tube (e.g. Spirogyra) or a protuberance (e.g. Mucor) to transfer and fuse its content and its genetic material directly from the donor into the recipient cell. |
| Talk about trichogamy | Trichogamy is a mode of fertilization that occurs when a male, non-motile spermatium (carried by water currents) collides with a hair-like extension of the female gametangia, the trichogyne. The spermatium and the trichogyne fuse their cytoplasms then the nucleus of the spermatium migrates through the trichogyne and fuse with the egg nucleus. e.g. Red algae |
| Talk about sphenogamy. | Siphonogamy is a process of gametes fusion in which non motile sperms are transferred and conducted to the egg (non motile) via a tube. e.g. Angiosperms |
| Talk in general about the life cycle. | A life cycle represents the series of changes that an organism undergoes as it passes from the beginning of a given developmental stage to the inception of that same developmental stage in a subsequent generation.
The life cycle of every sexually reproducing group of organisms has a characteristic pattern. Alternation of meiosis and fertilization is common to all sexually reproducing organisms; however, the timing of these two events in the life cycle varies among species. When fertilization is followed by mitosis, a diploid sporophyte is produced. When meiosis is followed by mitosis, a haploid gametophyte is produced. |
| Talk in general about monobiontic cycle | AKA monogenic
It describes a life cycle in which there is only a single independent generation (monogenetic). |
| Talk about haplotonic monobiontic cycle | when it encompasses a single generation of organisms whose cells are haploid (absence of a sporophytic phase). In this case, meiosis occurs immediately after fertilization and the formation of the zygote. The produced haploid cells undergo mitosis and produce a multicellular haploid organism, the gametophyte. In the whole cycle, zygotes are the only diploid cell; mitosis occurs only in the haploid phase. The individuals or cells that result from the mitosis are called haplonts; e.g.: some fungi and some green algae - e.g. |
| Talk about diplobiontic monogenic cycle | when the cycle encompasses a single generation of organisms whose cells are diploid. Organisms produce sex cells that are haploid, and each of these gametes must combine with another gamete in order to obtain the double set of chromosomes necessary to grow into a complete organism, the sporophyte. Meiosis occurs only during the formation of gametes and the gametes undergo no further cell division (by mitosis) until fertilization occurs. In the whole cycle, gametes are the only haploid cells. The diploid multicellular individual is a diplont; this is the case of some brown algae, e.g. Fucus. |
| Talk about digenic cycle | AKA haplodiplotonic
In some protists and some fungi as well as in plants, the life cycle is, by contrast, multigenerational, characterized by an alternation of generations - it includes both a multicellular sporophyte (diploid generation) and a multicellular gametophyte (haploid generation).
Life cycles that present two phases are called digenetic (also known as diplobiontic, diplohaplontic, haplodiplontic, or dibiontic):
A diploid (2n) sporophyte produce through meiosis, haploid (n) cells, called spores. The germination of a haploid spore undergoes mitosis and grows into a gametophyte (gamete-producing organism). The gametophyte reaches maturity and produces haploid (n) gametes by mitosis, which following fertilization, grow into a zygotic sporophyte (spore-producing organism). |
| Talk about triplobiontic cycle | In most red algae (e.g. Rhodophytes), the life cycle includes three phases. Such multigenerational cycles are said to be “trigenetic” because they produce three successive generations : the gametophyte (haploid), the carposporophyte (diploid) and the tetrasporophyte (diploid). |
