Sexual reproduction and Related Topics

Fungus

16 links

Any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms.

Fungal cell cycle showing Dikaryons typical of Higher Fungi

Omphalotus nidiformis, a bioluminescent mushroom

In 1729, Pier Antonio Micheli first published descriptions of fungi.

Mold growth covering a decaying peach. The frames were taken approximately 12 hours apart over a period of six days.

The 8-spore asci of Morchella elata, viewed with phase contrast microscopy

The bird's nest fungus Cyathus stercoreus

Prototaxites milwaukeensis (Penhallow, 1908)—a Middle Devonian fungus from Wisconsin

Arbuscular mycorrhiza seen under microscope. Flax root cortical cells containing paired arbuscules.

Diagram of an apothecium (the typical cup-like reproductive structure of Ascomycetes) showing sterile tissues as well as developing and mature asci.

The dark filaments are hyphae of the endophytic fungus Epichloë coenophiala in the intercellular spaces of tall fescue leaf sheath tissue

The lichen Lobaria pulmonaria, a symbiosis of fungal, algal, and cyanobacterial species

The plant pathogen Puccinia magellanicum (calafate rust) causes the defect known as witch's broom, seen here on a barberry shrub in Chile.

Gram stain of Candida albicans from a vaginal swab from a woman with candidiasis, showing hyphae, and chlamydospores, which are 2–4 µm in diameter.

Ergotamine, a major mycotoxin produced by Claviceps species, which if ingested can cause gangrene, convulsions, and hallucinations

Saccharomyces cerevisiae cells shown with DIC microscopy

The mold Penicillium rubens was the source of penicillin G.

A selection of edible mushrooms eaten in Asia

Stilton cheese veined with Penicillium roqueforti

Amanita phalloides accounts for the majority of fatal mushroom poisonings worldwide. It sometimes lacks the greenish color seen here.

Grasshoppers killed by Beauveria bassiana

The apothecium—a specialized structure important in sexual reproduction in the ascomycetes—is a cup-shaped fruit body that is often macroscopic and holds the hymenium, a layer of tissue containing the spore-bearing cells.

Meiosis

12 links

Meiosis Prophase I in mice. In Leptotene (L) the axial elements (stained by SYCP3) begin to form. In Zygotene (Z) the transverse elements (SYCP1) and central elements of the synaptonemal complex are partially installed (appearing as yellow as they overlap with SYCP3). In Pachytene (P) it's fully installed except on the sex chromosomes. In Diplotene (D) it disassembles revealing chiasmata. CREST marks the centromeres.

Schematic of the synaptonemal complex at different stages of prophase I and the chromosomes arranged as a linear array of loops.

Overview of chromatides' and chromosomes' distribution within the mitotic and meiotic cycle of a male human cell

Meiosis (, since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells.

Fertilisation

12 links

Fusion of gametes to give rise to a new individual organism or offspring and initiate its development.

In the Bryophyte land plants, fertilisation takes place within the archegonium. This moss has been genetically modified so that the unfertilised egg within the archegonium produces a blue colour.

Fertilisation in humans. The sperm and ovum unite through fertilisation, creating a zygote that (over the course of 8-9 days) implants in the uterine wall, where it resides for nine months.

Red-veined darters (Sympetrum fonscolombii) flying "in cop" (male ahead), enabling the male to prevent other males from mating. The eggs are fertilised as they are laid, one at a time.

The cycle of fertilisation and development of new individuals is called sexual reproduction.

A human spermatozoon penetrating a human ovum. The spermatozoon is approximately 100,000 times smaller in size than the human ovum.

Gamete

8 links

A gamete (, ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually.

Chromosome

8 links

Long DNA molecule with part or all of the genetic material of an organism.

Organization of DNA in a eukaryotic cell

The major structures in DNA compaction: DNA, the nucleosome, the 10 nm "beads-on-a-string" fibre, the 30 nm fibre and the metaphase chromosome.

Stages of early mitosis in a vertebrate cell with micrographs of chromatids

The 23 human chromosome territories during prometaphase in fibroblast cells

In Down syndrome, there are three copies of chromosome 21.

Chromosomal recombination during meiosis and subsequent sexual reproduction play a significant role in genetic diversity.

Production of new individuals along a leaf margin of the miracle leaf plant (Kalanchoe pinnata). The small plant in front is about 1 cm (0.4 in) tall. The concept of "individual" is obviously stretched by this asexual reproductive process.

Reproduction

7 links

Biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents.

Illustration of the twofold cost of sexual reproduction. If each organism were to contribute to the same number of offspring (two), (a) the population remains the same size each generation, where the (b) asexual population doubles in size each generation.

There are two forms of reproduction: asexual and sexual.

A haploid set that consists of a single complete set of chromosomes (equal to the monoploid set), as shown in the picture above, must belong to a diploid species. If a haploid set consists of two sets, it must be of a tetraploid (four sets) species.

Ploidy

10 links

Number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes.

Virtually all sexually reproducing organisms are made up of somatic cells that are diploid or greater, but ploidy level may vary widely between different organisms, between different tissues within the same organism, and at different stages in an organism's life cycle.

Life cycle of a mosquito. An adult female mosquito lays eggs which develop through several stages to adulthood. Reproduction completes and perpetuates the cycle.

Biological life cycle

6 links

Series of changes in form that an organism undergoes, returning to the starting state.

Life cycle of the apicomplexan, Babesia, Life cycle of the single-celled parasite Babesia, including the infection to humans

Transitions of form may involve growth, asexual reproduction, or sexual reproduction.

Egg cell

6 links

The process of fertilizing an ovum (Top to bottom)

Gene expression pattern determined by histochemical GUS assays in Physcomitrella patens. The Polycomb gene FIE is expressed (blue) in unfertilized egg cells of the moss Physcomitrella patens (right) and expression ceases after fertilization in the developing diploid sporophyte (left). In situ GUS staining of two female sex organs (archegonia) of a transgenic plant expressing a translational fusion of FIE-uidA under control of the native FIE promoter

The egg cell, or ovum (plural ova), is the female reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one).