In a diagram of the nucleus, which structure is represented by the two layers highlighted in yellow?

• A. Endoplasmic reticulum
• B. Nucleolus
• C. Chromatin
• D. Nuclear envelope

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the structure of the nucleus. The nucleus is a membrane-bound organelle found in eukaryotic cells that houses genetic material (DNA). It is surrounded by a double membrane called the nuclear envelope.
2. Step 2: Learn about the nuclear envelope. The nuclear envelope consists of two lipid bilayer membranes: an inner membrane and an outer membrane. These membranes are separated by a space called the perinuclear space.
3. Step 3: Differentiate the nuclear envelope from other structures in the nucleus. The nucleolus is a dense region within the nucleus responsible for ribosome synthesis, chromatin refers to the DNA-protein complex that makes up chromosomes, and the endoplasmic reticulum is a separate organelle involved in protein and lipid synthesis.
4. Step 4: Recognize that the nuclear envelope is highlighted in yellow in diagrams to emphasize its double-layered structure. This feature distinguishes it from other single-layered or non-membranous structures within the nucleus.
5. Step 5: Conclude that the correct answer is the nuclear envelope, as it is the structure represented by the two layers highlighted in yellow in the diagram of the nucleus.