Dr. Malik| The life cycle of algae and the alternation of generation in algae

 

The life cycle of algae and the alternation of generation in algae

Firstly, we will discuss the alternation of generation:

Simply it is the existence of two different stages in the life cycle of any organism. These stages are the sporophyte stage and the gametophyte stage. In algae, the main body is gametophyte.

Now, what is meant by the main body of Algae?

The simple meaning of this sentence is main or long-time algae live as gametophytes in nature or haploid in nature or the thallus of algae produces gametes.

This gametophyte alga forms a sporophyte stage during its life cycle and the conversion of gametophyte to sporophyte or sporophyte to gametophyte is called alternation of generation.

In the case of algae, the zygote acts as a sporophyte because meiosis directly occurs in the zygote, and no other structures are formed.

Alternation of generation in algae:

• We have the gametophyte stage and sporophyte stage
• Gametophyte is haploid and sporophyte is diploid in nature
• The gametophyte produces gametes after mitosis while sporophyte produces spores after meiosis
• Zygote act as a sporophyte.

 

 The life cycle of algae:

• Usually, Algae produce two types of gamete, one is small and motile, which is called a male gamete, while the other is large but non-motile and is called a female gamete.
• Both male and female gamete is haploid and produced by mitosis.
• Both gametes fuse and form a zygote, which is diploid.
• The zygote acts as a sporophyte because meiosis directly occurs in the zygote.
• Zygotes undergo meiosis and form four cells that are called spores.
• These spores then undergo mitosis to form a new thallus of algae that is haploid.

Points to be remembered:

1. The main body of algae is gametophyte.
2. The Gametophyte stage is always haploid.
3. Mitosis occurs at gametophytes while meiosis takes place at sporophytes.
4. Zygote act as a sporophyte.
5. The sporophyte is always diploid.
6. One zygote produces four spores (in the case of algae).
7. Every single spore can form a new thallus.
8. Spores undergo mitosis to form a new thallus.