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Minne Life Cycles and Adaptations of Marine organisms > Life cycles Rhodophyta > Flashcards

Life cycles Rhodophyta Flashcards

1
Q

How do Rhodophyta cells reproduce?

A
  • Asexually
  • Some species sexually (isomorphic or heteromorphic diplohaplontic life cycle)
  • Rhodophyta have a haplontic life cycle (most of the time haploid)
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2
Q

What characterizes an isomorphic or heteromorphic diplohaplontic life cycle in Rhodophyta?

A

In this life cycle, Rhodophyta alternates between diploid and haploid phases, where the diploid (2n) and haploid (n) phases may look similar (isomorphic) or different (heteromorphic).

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3
Q

What type of fusion characterizes sexual reproduction in Rhodophyta?

A

Oogamous fusion, where a large non-motile egg is fertilized by a small motile sperm.

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4
Q

What distinguishes the reproductive cells of Rhodophyta from other algae groups?

A

Rhodophyta reproductive cells, including male gametes, are non-flagellate spherical protoplasts.

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5
Q

What are the three phases involved in the complex life cycle of many Rhodophyta species? (triphasic or trigenetic)

A
  • The three phases are gametophyte, carposporophyte, and tetrasporophyte.
  • Gametophyte and tetrasporophyte are independent organisms, while the carposporophyte is implanted on the female gametophyte.
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6
Q

Gametophyte in Rhodophyta

A
  • haploid
  • produces non-flagellate gametes (reproduction by oogamy)
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7
Q

Carposporophyte in Rhodophyta

A
  • diploid
  • develops from the zygote on the female gametophyte
  • produces diploid spores, carpospores
  • The differences between the various groups of Florideophyceae are based on the differences in the formation of the carposporophyte
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8
Q

Tetrasporophyte

A
  • diploid
  • formed by the development of carpospores.
  • Through meiosis it forms haploid spores, called tetraspores, which give rise to the gametophyte
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9
Q
A
  • Polysiphonia species
  • show the typical triphasic life cycle
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10
Q

What structures does the male gametophyte of Polysiphonia spp. produce?

A

The male gametophyte produces spermatangia, that form spermatia ( = male gametangia) on special fertile branches called trichoblasts.

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11
Q

Where do spermatangia develop in Polysiphonia spp.?

A
  • They produce spermatia (non-flagellate gametes transported passively by water)
  • And develop on fertile “side shoots” of the male gametophyte.

On middle picture:
1 = spermatangia
2 = spermatia

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12
Q

What structures does the female gametophyte of Polysiphonia spp. produce?

A

The female gametophyte produces carpogonial branches, with terminal cells called carpogonia, which act as female gametangia.

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13
Q

Describe the structure of a carpogonium in Polysiphonia spp.

A

A carpogonium consists of a swollen basal portion with a flask shape containing the female nucleus, along with a long sticky extension called a trichogyne, which captures spermatia.

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14
Q

Post-Fertilization Events: After a spermatium attaches itself to the trichogyne of the carpogonium in Polysiphonia spp., several events occur:

A
  • Spermatium-Trichogyne Fusion
  • Nucleus Migration
  • Nuclei Fusion
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15
Q

What occurs after a spermatium attaches to the trichogyne in Polysiphonia spp.?

A

After attachment, the spermatium wall merges with the trichogyne wall

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16
Q

Describe the process of nucleus migration in Polysiphonia spp. after spermatium attachment.

A

the male nucleus from the spermatium migrates into the trichogyne and then into the carpogonium.

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17
Q

What is the process of nuclei fusion in Polysiphonia spp. after fertilization?

A

Inside the carpogonium, the male nucleus from the spermatium fuses with the female nucleus of the carpogonium, resulting in the formation of a zygote.

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18
Q

What initiates the carposporophyte generation in Polysiphonia spp. after fertilization?

A
  • After fertilization, the carpogonium transfers the diploid zygote nucleus to an auxiliary cell
  • marking the initiation of the carposporophyte generation
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19
Q

What structures are formed from the auxiliary cell in Polysiphonia spp. after fertilization?

A
  • The auxiliary cell gives rise to a carposporophyte.
  • Carposporophyte produces carpospores, as well as other protrusions that connect to secondary auxiliary cells
  • This leads to the formation of additional carposporophytes and protrusions
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20
Q

What is the carposporophyte or gonimocarp in Polysiphonia spp.?

A

The carposporophyte or gonimocarp is a compact system of diploid branched filaments called gonimoblasts, consisting of diploid cells originating from the zygotic nucleus.

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21
Q

What surrounds the gonimocarp in Polysiphonia spp.?

A
  • The gonimocarp in Polysiphonia spp. is surrounded by a tissue called the pericarp,
  • providing protection and support to the developing structure.
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22
Q

What is the cystocarp in the life cycle of Polysiphonia spp.?

A
  • The cystocarp is the mature reproductive structure formed by the combination of the gonimocarp (carposporophyte) and the surrounding pericarp tissue
  • It contains the developing carpospores.
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23
Q

What marks the beginning of gonimoblast development in Polysiphonia spp.?

A

Gonimoblast initials (GI) are formed, as seen in picture 2 and 3, indicating the start of gonimoblast development.

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24
Q

What are the early stages of post-fertilization development in Polysiphonia spp. characterized by?

A

The early stages involve the presence of the auxiliary cell and the supporting cell. (1st picture)

25
Q

What occurs when gonimoblasts progress in their development in Polysiphonia spp.?

A
  • As gonimoblasts progress in their development, they eventually form the carposporophyte phase
  • This phase represents the mature reproductive structure responsible for producing carpospores.
26
Q

What is the function of the carposporophyte or gonimocarp in Polysiphonia spp.?

A

The carposporophyte or gonimocarp ensures the production of many diploid carpospores, which are released into the water.

27
Q

What role do gonimoblasts play in the life cycle of Polysiphonia spp.?

A

Gonimoblasts function as carposporangia within the carposporophyte or gonimocarp, producing and releasing the diploid carpospores into the water

28
Q

What do the diploid carpospores give rise to in the life cycle of Polysiphonia spp.?

A

The diploid carpospores give rise to diploid tetrasporophytes, the next phase in the life cycle.

28
Q

When is the life cycle of Polysiphonia spp. completed?

A

The life cycle is completed when the tetraspores, released into the water from the tetrasporophyte, grow into new haploid gametophytes.

29
Q

How do tetrasporophytes in Polysiphonia spp. produce haploid spores?

A

Tetrasporophytes bear tetrasporangia, within which each undergoes meiosis to produce four haploid spores, called tetraspores.

30
Q
A

Diploid tetrasporophytes

31
Q
A

Haploid tetraspores

32
Q

What is the difference between a gametophyta and a tetrasporophyte?

A

Gametophyte and tetrasporophyte are morphologically identical, but one is haploid and the other is diploid.

33
Q
A

In the tetrasporophyte you can see the tetraspores

34
Q

Life cycle of Polysiphonia Flexicaulis

A
35
Q

Life cycle of the genus Polyshiponia

A
36
Q

Scheme of the triphasic life cycle of Florideophyceae

A
37
Q
A

Fertile trichoblasts with spermatangia

38
Q
A

Fertile trichoblasts with spermatangia

39
Q
A

Female gametophyte with carposporophyte

40
Q
A

Female gametophyte with carposporophyte

41
Q
A

Tetrasporophyte with tetrasporangia

42
Q
A

Tetrasporophyte with tetrasporangia (cruciate tetrasporangia)

43
Q

Life cycle of Antithamnion sp.

A
44
Q
A

Gametophyte (1) vs Tetrasporophyte (2)

45
Q

Why do many Rhodophytes exhibit a triphasic life cycle?

A

Many Rhodophytes have evolved a triphasic life cycle to compensate for the low frequency of fertilization, primarily due to the presence of non-flagellate male gametes.

46
Q

How do some trigenetic life cycles deviate from the proposed basic scheme?

A
  • Some trigenetic life cycles show variations, including morphological differences between gametophytes and the tetrasporophyte.
  • These differences can be significant enough to initially attribute the two life phases to two different species.
47
Q

What is the life cycle called when gametophyte and sporophyte are completely different?

A
  • The life cycle is a heteromorphic trigenetic life cycle
  • E.g. for the genus Nemalion
48
Q

The Reproductive life cycle of Porphyra sp.is a Haplodiplontic Heteromorphic Life Cycle, what does this mean?

A

It involves a life cycle where both haploid and diploid phases are multicellular and morphologically distinct.

49
Q

What are the two phases involved in the reproductive life cycle of Porphyra sp.?

A

The two phases are:
- the leaf-like macrothallus (haploid phase)

  • the filamentous microthallus, also known as the Conchocelis phase (diploid phase).
50
Q

The leaf-like macrothallus produces four different kinds of reproductive structures in undifferentiated cells:

A
  • Monospores
  • Spermatia
  • Undifferentiated cells of the blade
  • Carpospores
51
Q

Monospores

A
  • produced to carry out an asexual reproduction of the leaf.
  • They produce other haploid thalli
52
Q

Spermatia

A
  • liberated after the spermatangium divides into many (64 or 128) male gametes
  • They are involved in the fertilization with Undifferentiated cells of the blade
53
Q

Undifferentiated cells of the blade

A

representing the female gametangia or carpogonia

54
Q

Carpospores

A
  • Arise from repeated divisions of fertilized carpogonial cells, giving rise to a system of branched filaments, representing the microscopic Conchocelis phase.
  • These filaments are able to live into the calcareus shells of molluscs or barnacles
55
Q

How does the Conchocelis phase of Porphyra sp. reproduce?

A

The Conchocelis phase can reproduce by means of:

  • monospores (2n) asexually
  • or through the formation of conchospores (n) via meiosis

which give rise to new haploid macrothalli.

56
Q

What are some characteristics of the Bangioideae subfamily regarding their reproductive structures?

A
  • Bangioideae lack distinct carpogones
  • Do not possess the carposporophyte stage
  • Have undifferentiated tetrasporangia
57
Q

Scheme of reproductive cycle of Porphyra

A

Minne Life Cycles and Adaptations of Marine organisms (23 decks)

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