Lab Manual: Binary Fission in Amoeba and Budding in Yeast | Lab Manuals for Class 10 PDF Download

Objective

Materials Required
Permanent slides showing binary fission in Amoeba and budding in yeast, charts of binary fission and budding and a compound microscope.

Theory/Principle

Process of reproduction is of two types as shown in Fig. 1.
Asexual reproduction is the method of reproduction involving only one parent and there is no gamete formation. It is the process of rapid multiplication in which the new organisms or offsprings produced are identical copies of the parent organism. These identical offsprings are thus also referred to as clones. Binary fission and budding are forms of asexual reproduction commonly occurring in lower organisms like bacteria, Paramecium, Euglena, yeast, etc.

Binary Fission
The type of asexual reproduction, in which the parent cell divides itself into two identical daughter cells by amitosis. The division of nucleus is called amitosis due to fact that the stages of a typical mitotic division are not observed in these cells. After division, the two daughter cells grow into adult ceils, e.g. Amoeba.

Budding
The type of asexual reproduction where the parent cell produces daughter cells by developing a small bud-like outgrowth. On maturation, it breaks off from the parent body by developing a separating wall between the bud and parent cell like in Hydra. If detachment does not occur, it leads to the formation of a long chain, e.g. yeast.

Procedure

• Take the permanent slides and mark them as slide 1 for Amoeba and slide 2 for yeast. Take slide 1 of Amoeba showing binary fission mode of asexual reproduction.
• Focus the slide under low power of compound microscope.
• Observe the slide carefully and record your observations.
• Without removing the slide from the stage of compound microscope, the magnification or focus of the objective lens is changed from low to high.
• Observe carefully and note the stages occurring during binary fission.

  Similarly, repeat the above steps (1 to 5) for slide 2 and observe the stages occurring during asexual reproduction by budding in yeast.

• Draw well labelled diagram of different stages of binary fission in Amoeba and budding in yeast.

• Compare the features with established characteristics of both types of asexual reproduction in the given organism.

Observations
1. Binary Fission in Amoeba

• Amoeba reproduces by binary fission method where division of the parent cell and its components occur by stretching.
• The nucleus of parent cell grows and divides into two daughter nuclei (karyokinesis) by amitosis.
• Division of nucleus is followed by cytoplasmic division (cytokinesis).
• At the end of the process, two identical daughter cells are formed (see Fig, 2) and identity of the parent organism is lost.
  

2. Budding in Yeast

• The given slide shows the budding method of asexual reproduction in yeast.
• Yeast ceils are large in size, spherical or oval in shape.
• Budding is the method, in which a bulb-like projection called as buds are formed on the parent body.
• First nucleus divides by stretching followed by division of cytoplasm.
• Nucleus divides by mitosis and forms two daughter nuclei.
• One of the two daughter nuclei moves into the enlarging bud forming a daughter cell (Fig. 3).
  

Result
Slide 1 (Amoeba)
The binary fission method of asexual reproduction in Amoeba is observed.
Slide 2 (Yeast)

The budding method of asexual reproduction in yeast is observed.

Precautions

• Slides should be handled carefully.
• Clean the stage of microscope before and after the use.
• Do not tilt the microscope and hold it vertically.
• Slide should be firmly clipped on the stage.
• Focus the slides properly.
• First observe under low power of objective and than change to high power lens for better and detailed study.
• Keep microscope in box carefully when not in use.