Aadya Isai

1.Binary Fission

Definition

Binary fission is a type of asexual reproduction in which one parent cell divides to produce two genetically identical daughter cells. It is the main method of reproduction in bacteria.

How Binary Fission Occurs

Step 1: The DNA is copied.

Before the cell divides, it makes an exact copy of its DNA. This ensures that each daughter cell receives a complete set of genetic information.

Step 2: The cell grows larger.

The cell enlarges by producing more cytoplasm, cell membrane, cell wall, and other cellular components. This provides enough material for the two daughter cells after division.

Step 3: The DNA copies move to opposite ends of the cell.

As the cell grows, the two DNA copies separate and move to opposite ends of the cell. This ensures that each daughter cell will receive one complete copy of the DNA.

Step 4: The cell divides.

The cell membrane constricts inward while a new cell wall forms between the two DNA copies. This gradually separates the cell into two.

Step 5: Two daughter cells are formed.

Each daughter cell has:

• One complete copy of the DNA.

• Its own cell membrane and cell wall.

• A share of the cytoplasm and cellular components needed to function.

The daughter cells are genetically identical to the parent cell (except for rare mutations). They are called clones.

Budding:

Definition

Budding is a type of asexual reproduction in which a new organism develops from a small outgrowth, called a bud, on the parent organism. As the bud grows, it eventually detaches and becomes a genetically identical organism called a clone.

Budding is common in yeast and hydra.

How Budding Occurs

Step 1: A bud forms.

A small outgrowth, called a bud, forms on the parent organism. Cells in this region divide by mitosis, producing genetically identical cells that form the growing bud.

Step 2: The bud grows.

The bud increases in size as more cells are produced by mitosis. As it grows, it develops the structures needed to survive independently.

Step 3: The bud remains attached.

The bud remains attached to the parent while it continues to grow and develop. During this time, it remains connected to the parent and receives the materials needed for growth until it is able to survive independently.

Step 4: The bud detaches.

Once the bud is fully developed, it separates from the parent and lives as an independent organism. Because it was produced by mitosis, it has the same genetic information as the parent and is therefore a clone.

Spore Formation:

Definition:

Spore formation is a type of asexual reproduction in which an organism produces tiny reproductive cells called spores. Each spore can develop into a new organism when it lands in suitable environmental conditions.

Spore formation is common in fungi, such as bread mould, and in some plants, such as ferns and mosses.

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What is a Spore?

A spore is a tiny, single reproductive cell.

Unlike a seed:

* A spore consists of only one cell.

* It does not contain a food store.

* In asexual reproduction, it can develop into a new organism without fertilization.

Because spores are extremely small and light, they can be dispersed over long distances by wind, water, or animals.

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How Spore Formation Occurs

Step 1: Spores are produced.

The parent organism produces large numbers of spores inside special structures called sporangia (spore cases).

The spores are produced by mitosis, so they are genetically identical to the parent (except for rare mutations).

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Step 2: Spores are released.

When the spores are mature, the sporangium breaks open and releases them into the environment.

Producing large numbers of spores increases the chance that some will land in suitable places to grow.

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Step 3: Spores are dispersed.

The spores are carried away by:

* Wind

* Water

* Animals

This helps the organism spread to new areas and reduces competition with the parent.

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Step 4: Spores germinate.

If a spore lands in a suitable environment with enough water, oxygen (if required), a suitable temperature, and the nutrients needed for growth, it germinates.

The spore then divides by mitosis and develops into a new organism genetically identical to the parent (except for rare mutations).