Answer:

Introduction:
Cell organelles are specialized structures within a cell that perform specific functions. These organelles can be categorized into two types: membrane-bound organelles and non-membrane-bound organelles. Each organelle has a specific role in the overall functioning of the cell. One of the important characteristics of a cell organelle is whether it possesses its own genetic material encoding proteins. In this question, we are asked to identify the cell organelle that does NOT possess its own genetic material encoding proteins.

Explanation:
To answer this question, let's discuss each option and determine whether the organelle possesses its own genetic material encoding proteins or not.

a) Ribosome:
Ribosomes are small structures composed of RNA and proteins. They are responsible for protein synthesis within the cell. Ribosomes do not possess their own genetic material encoding proteins. Instead, they use the genetic information encoded in the DNA of the nucleus to synthesize proteins.

b) Nucleus:
The nucleus is the control center of the cell and contains the cell's genetic material, DNA. The DNA within the nucleus encodes proteins through a process called transcription and translation.

c) Mitochondria:
Mitochondria are often referred to as the "powerhouses" of the cell because they generate energy in the form of ATP through a process called cellular respiration. Mitochondria possess their own genetic material in the form of circular DNA, which encodes some of the proteins necessary for their functioning.

d) Chloroplast:
Chloroplasts are found in plant cells and are responsible for photosynthesis, the process by which plants convert sunlight into energy. Like mitochondria, chloroplasts also possess their own genetic material in the form of circular DNA, which encodes proteins involved in photosynthesis.

Conclusion:
Out of the given options, the organelle that does NOT possess its own genetic material encoding proteins is the ribosome. Ribosomes use the genetic information encoded in the DNA of the nucleus to synthesize proteins.