Question

Which of the following organelles contains no DNA? a. nucleus b. Golgi body c. mitochondrion d. chloroplast

Short answer

Golgi body contains no DNA.

Step-by-step solution

Identify Organelles Known to Contain DNA

The nucleus is the primary organelle containing the cell's genetic material, DNA, in the form of chromosomes. Both mitochondria and chloroplasts are organelles that contain their own DNA, which is inherited maternally in mitochondria and also found in chloroplasts in plants and algae.

Evaluate the Golgi Body

The Golgi body, or Golgi apparatus, is responsible for modifying, sorting, and packaging proteins for secretion. Unlike the nucleus, mitochondria, and chloroplasts, the Golgi body does not contain its own DNA. It functions primarily in protein modification and transport.

Conclusion

Based on the information above, the nucleus, mitochondria, and chloroplasts all contain DNA. The Golgi body does not. Hence, the correct answer to the question of which organelle contains no DNA is the Golgi body.

Key concepts

Nucleus

The nucleus is often referred to as the "command center" of the cell. It houses the cell's genetic material, in the form of DNA, which is organized into chromosomes. The DNA within the nucleus contains the instructions necessary for the cell's structure and functions. These instructions are used to make proteins that the cell needs to operate and to carry out processes essential for life.
The nucleus also regulates gene expression, controlling which genes are turned on or off in response to the cell's needs. It's enveloped by a double membrane called the nuclear envelope, which has pores allowing passage of molecules in and out.

• Contains most of the cell's genetic material
• Regulates gene expression
• Surrounded by a nuclear envelope

Mitochondria

Mitochondria are known as the "powerhouses" of the cell. They are responsible for producing energy through a process called cellular respiration. This process converts oxygen and nutrients into adenosine triphosphate (ATP), the energy currency of the cell.
Uniquely, mitochondria possess their own DNA, known as mitochondrial DNA (mtDNA), which is inherited exclusively from the mother. This DNA contains genes critical for mitochondrial function.
Mitochondria have a double membrane; their inner membrane folds to form structures known as cristae, which increase the surface area for cellular respiration.

• Produce ATP through cellular respiration
• Contain their own DNA
• Have an inner folded membrane creating cristae

Chloroplasts

Chloroplasts are key organelles found in plant cells and some algae. They enable plants to perform photosynthesis, a process that converts sunlight, carbon dioxide, and water into glucose and oxygen. This conversion not only fuels plant cells but also adds oxygen to the atmosphere.
Chloroplasts contain a green pigment called chlorophyll, which captures sunlight. Additionally, like mitochondria, chloroplasts have their own DNA and share a similar double membrane structure with intricate inner compartments.
They play a crucial role in energy transformation and are vital for life on Earth as they influence the Earth's atmospheric composition.

• Site of photosynthesis, converting solar energy to chemical energy
• Contains chlorophyll and its own DNA
• Contributes to Earth's oxygen supply

Golgi Apparatus

The Golgi apparatus, also known as the Golgi body, is an organelle that functions like a cellular post office. It modifies, sorts, and packages proteins and lipids for use within the cell or for export outside the cell. Proteins made in the rough endoplasmic reticulum are transported to the Golgi apparatus, where they undergo further processing.
Unlike the nucleus, mitochondria, and chloroplasts, the Golgi apparatus does not contain DNA. Instead, it relies on signals from these other organelles to function efficiently. Its cisternae, which are flattened stacked pouches, allow it to effectively package and ship materials.

• Modifies and packages proteins and lipids
• Does not contain its own DNA
• Consists of a series of flattened membranous sacs