Chlorophyta And Rhodophyta Flashcards
(95 cards)
Zygotes meiosis
Organisms are haploid
Zygote is the only diploid structure (short lived so not alternation of generations)
No alteration of generations
Dominant gametophye
Unicellular gametophyte
Fungi, some algae
Gametic meiosis
Zygotes continue to divide mitotically-> multicellular adult sporophyte
Delayed meiosis (no alteration of generations: only one multicellular generation)
Gametes are the only haploid cells
Most animals, green and brown algae
No gametophyte
Dominant multicellular sporophyte
Sporic meiosis (isomorphic)
Alteration of generations (two multicellular generations)
Same size in multicellular stages
Isomorphic alternation of generations (many algae)
One generation may be more dominant than other
Sporic meiosis (heterotrophic)
Alternation of generations
Many plants
One generation is clearly the dominant and larger generations and the other is of lesser importance or size
Two distinct events occur during fertilization
Plasmotomy: fusion of gamete Protoplast=single cell with two haploid nuclei
Karyogamy=fusion of two nuclei
In fungi, may persist with two haploid nuclei, without kayogamy
This is known as …..
Dikayotic
Phylum Chlorophyta is predominantly a _____ phylum (habitat)
Freshwater
Chlorophyta means
Green algae
Phylum Chlorophyta includes five morphological types with orders
- Motile, unicellular and colonial (Volvocales)
- Non-motile, unicellular and colonial (Chlorellales)
- Filamentous (Oedongoniales)
4.Membranous (Ulvales)
5.Siphonous (Caulerpales)
Class Chlorophyceae
Order Vilvocales
Characteristics
-motility
-lifestyle
-organelles
-only order with motile, vegetative cells
-either colonial or unicellular
-individual cells usually have 2 flagella
-flagella are apical and equal
-definite cell walls, eyespots, one or more pyrenoid bodies, and cup shaped chloroplasts
Class Chlorophyceae
Order Vilvocales
Reproduction
Unicellular membranes reproduce asexually by zoospores or binary fission
Colonial species are coenoboic and resource by daughter colony formation
Almost all species demonstrate isogamous sexual reproduction with the dominant generation being haploid
Volvocales and Ubiquitous are most often found where
Shallow, freshwater areas such as puddles, ditches and ponds
Particularly those with high organic content
Class Chlorophyceae
Order Volvocales
vacuoles
Do not have large central vacuoles, but have one or more osmoregulation contradict vacuoles
Chlamydomonas sp.
Taxonomy
Class Chlorophyceae
Order Volvocales
How do Chlamydomonas reproduce
Asexually by either cell division within the parent cell or the formation of zoospores
Sexual reproduction in Chlamydomonas is ________ (entire cell becomes a gamete)
Holocarpic
Two individuals of different strains of the same species fuse to form a non flagellate zygote (isogamous)
The zygote divided meiotically to form four haploid flagellated meiospores
The meiospres enlarge to the size of the vegetative adults
Pyrenoid
Center of starch formation inside chloroplast
Gonium sp
Taxonomy
Class Chlorophyceae
Order Volvocales
Gonium sp.
Lifestyle and reproduction
Individuals form flattened colonies of 4-32 cells
Individuals in their genus are coenboic: each colony has the same number of cells. Coordinated movement. Dead cells within a colony are not replaced. Reproduce by forming daughter colonies
Volvox sp
Taxonomy
Class Chlorophyceae
Order Volvocales
Volvox lifestyle and asexual reproduction
Form daughter colonies to reproduce asexually. Several cells in the parent colony differentiate into reproductive cells called gonidia. Gonidia divide and form miniatures of the parent colony within the hollow parental sphere. Daughter colonies are released through the rupture of the parent colony.
Volvox sexual reproduction
Gonidia either become eggs or Sperm packets aka reproduction is oogamous
The species may be monoecious or dioecious. The sperm packets are released and swim as units to receptive colonies. Following fertilization, the zygote develops a spiny outer wall. Finally, the zygote divides meiotically to produce a single motile zoospore. This cell swims for a short period then divided to form a small colony
How do volvox move
Coorinated movement of flagella in colonies
How many cells can be in a volvox colony
Around 50,000