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Gametophyte

 

 
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Gametophyte
 
 
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In plant
Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
s and algae
Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds....
 that undergo alternation of generations
Alternation of generations

The Alternation of phases describes the life cycle of plants, fungi and protists. A multicellular diploid phase alternates with a multicellular haploid phase....
, a gametophyte is the multicellular structure, or phase, that is haploid, containing a single set of chromosome
Chromosome

A chromosome is an organized structure of DNA and protein that is found in Cell . A chromosome is a single piece of DNA that contains many genes, regulatory sequence and other genetic sequence....
s:

The gametophyte produces male or female gamete
Gamete

A gamete is a Cell that fuses with another gamete during fertilization in organisms that sexual reproduction. In species which produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual which produces the larger type of gamete?called an ovum ?and a male produces th...
s (or both), by a process of cell division called mitosis
Mitosis

Mitosis is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei....
. The fusion of male and female gametes produces a diploid zygote
Zygote

A zygote is a cell that is the result of fertilization. That is, two ploidy cells—usually an ovum from a female and a sperm cell from a male—merge into a single ploidy cell called the zygote ....
 which develops by repeated mitotic cell divisions into a multicellular sporophyte
Sporophyte

All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or alga that has a double set of chromosomes....
. Because the sporophyte is the product of the fusion of two haploid gametes, its cells are diploid, containing two sets of chromosomes.






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In plant
Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
s and algae
Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds....
 that undergo alternation of generations
Alternation of generations

The Alternation of phases describes the life cycle of plants, fungi and protists. A multicellular diploid phase alternates with a multicellular haploid phase....
, a gametophyte is the multicellular structure, or phase, that is haploid, containing a single set of chromosome
Chromosome

A chromosome is an organized structure of DNA and protein that is found in Cell . A chromosome is a single piece of DNA that contains many genes, regulatory sequence and other genetic sequence....
s:

The gametophyte produces male or female gamete
Gamete

A gamete is a Cell that fuses with another gamete during fertilization in organisms that sexual reproduction. In species which produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual which produces the larger type of gamete?called an ovum ?and a male produces th...
s (or both), by a process of cell division called mitosis
Mitosis

Mitosis is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei....
. The fusion of male and female gametes produces a diploid zygote
Zygote

A zygote is a cell that is the result of fertilization. That is, two ploidy cells—usually an ovum from a female and a sperm cell from a male—merge into a single ploidy cell called the zygote ....
 which develops by repeated mitotic cell divisions into a multicellular sporophyte
Sporophyte

All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or alga that has a double set of chromosomes....
. Because the sporophyte is the product of the fusion of two haploid gametes, its cells are diploid, containing two sets of chromosomes. The mature sporophyte produces spore
Spore

In biology, a spore is a reproduction structure that is adapted for biological dispersal and surviving for extended periods of time in unfavorable conditions....
s by a process called meiosis
Meiosis

In biology or life science, meiosis is a process of reductional division in which the number of chromosomes per cell is halved. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores....
, sometimes referred to as "reduction division" because the chromosome pairs are separated once again to form single sets. The spores are therefore once again haploid and develop into a haploid gametophyte.

In mosses
Bryophyta

Bryophyta may refer to:*Mosses, a specific group of leafy bryophytes, now regarded as Division Bryophyta .*Bryophytes, a paraphyletic group of plants formerly regarded as a single division but now split into mosses , hornworts , and liverworts ....
, liverworts and hornworts (bryophytes), the gametophyte is the commonly known phase of the plant. An early developmental stage in the gametophyte of mosses (immediately following germination of the meiospore) is called the protonema
Protonema

A protonema is a thread-like chain of cells that forms the earliest stage of a bryophyte life cycle. When a moss or Marchantiophyta first grows from the spore, it grows as a protonema which develops into a leafy gametophore....
.

In most other land plants
Embryophyte

The embryophytes are the most familiar group of plants. They include trees, flowers, ferns, mosses, and various other green land plants. All are complex multicellular eukaryotes with specialized reproductive organs....
 the gametophyte is very small (as in fern
Fern

A fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta....
s and their relatives) or even reduced as in flowering plant
Flowering plant

The flowering plants or angiosperms are the most widespread group of Embryophytes. The flowering plants and the gymnosperms are the only extant groups of Spermatophyte....
s (angiosperms), where the female gametophyte (ovule) is known as a megagametophyte and the male gametophyte (pollen
Pollen

Pollen is a fine to coarse powder consisting of Gametophyte , which produce the male gametes of spermatophyta. A hard coat covering the pollen grain protects the sperm cells during the process of their movement between the stamens of the flower to the pistil of the next flower....
) is called a microgametophyte.

In some multicellular green algae
Green algae

The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic ....
, red algae
Red algae

The red algae are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000?6,000 species  of mostly multicellular, ocean algae, including many notable seaweeds....
, or brown algae
Brown algae

The Phaeophyceae or brown algae, is a large group of mostly Ocean multicellular algae, including many seaweeds of colder Northern Hemisphere waters....
 (Ulva is one example), the sporophytes and gametophytes are often isomorphic, but in some species the gametophyte may be reduced.

See also

  • Sporophyte
    Sporophyte

    All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or alga that has a double set of chromosomes....
  • Alternation of generations
    Alternation of generations

    The Alternation of phases describes the life cycle of plants, fungi and protists. A multicellular diploid phase alternates with a multicellular haploid phase....
  • Archegonium
    Archegonium

    An archegonium , from the ancient Greek ???? and ????? , is a multicellular structure or organ of the gametophyte phase of certain plants producing and containing the ovum or female gamete....
  • Antheridium
    Antheridium

    An antheridium is a haploid structure or organ producing and containing male gametes . It is present in the gametophyte phase of lower plants like mosses and ferns, and also in the primitive vascular Psilotophyta....