Question

Where are the ribosomes found in prokaryotic cells? (a) Cytoplasm (b) Mitochondria (c) Chloroplast (d) All of these

Short answer

(a) Cytoplasm

Step-by-step solution

Understanding Prokaryotic Cells

Prokaryotic cells are characterized by lack of a nucleus and membrane-bound organelles such as mitochondria and chloroplasts. These cells include bacteria and archaea.

Identifying the Location of Ribosomes

Ribosomes, the protein factories of the cell, are not confined within any organelle. Therefore, in prokaryotic cells, ribosomes are located in the cytoplasm, where they synthesize proteins directly into the cellular environment.

Answer Determination

Out of given options: Cytoplasm, Mitochondria, Chloroplast, and All of these, the only valid option is the Cytoplasm. Hence, the correct answer is (a) Cytoplasm.

Key concepts

Ribosomes

Ribosomes are tiny, yet essential, structures found in both prokaryotic and eukaryotic cells. They are often referred to as the "protein factories" of the cell. This is because they play a crucial role in interpreting genetic messages from the cell's DNA to synthesize proteins.

In prokaryotic cells, ribosomes are smaller in size (70S) compared to those in eukaryotic cells (80S). Despite this size difference, they perform the same function. They read mRNA sequences in the cytoplasm and translate them into polypeptides, which later fold into functional proteins. It's important to note that, unlike eukaryotic ribosomes that can attach to the endoplasmic reticulum, prokaryotic ribosomes are free-floating in the cytoplasm.

Cytoplasm

The cytoplasm of a prokaryotic cell is a gel-like, transparent material that fills the interior of the cell. It serves as the site where all cellular processes occur, including the critical process of protein synthesis.

In prokaryotic cells, the cytoplasm holds all of the cell's components, since these cells do not have membrane-bound organelles like mitochondria or chloroplasts. Instead, everything happens in this bustling center of activity. The ribosomes suspended in the cytoplasm engage in protein synthesis, utilizing the cell's genetic instructions. Additionally, the cytoplasm houses the genetic material of the cell in an area called the nucleoid.

Protein Synthesis

Protein synthesis is a fundamental biological process that creates proteins, essential molecules for cell structure and function. In prokaryotic cells, this process takes place entirely in the cytoplasm, due to the absence of a nucleus.

The process begins with transcription, where a segment of DNA is transcribed into messenger RNA (mRNA). This mRNA carries the code for protein synthesis from the DNA to the ribosomes in the cytoplasm. The ribosomes then decode this information in a process called translation, linking together amino acids in the correct order to form a polypeptide chain. This chain eventually folds into a functional protein. The efficiency of protein synthesis in prokaryotic cells is high due to the proximity of DNA and ribosomes, ensuring quick communication and response.