Problem 153 - Objective Biology for NEET

Question

The outer membrane of nucleus remains continuous with which cell organelle (a) ER (b) Golgi body (c) Lysosome (d) All of these

Step-by-Step Solution

Answer

The correct answer is (a) ER - the outer membrane of the nucleus remains continuous with the Endoplasmic Reticulum.

Step 1: Understand the Question

The question is asking about the structure of eukaryotic cells and trying to identify the organelle which is continuous with the outer membrane of the nucleus. Options are provided, which are different organelles present in a cell.

Step 2: Analyze Given Options

Let's go through the given options: ER (Endoplasmic Reticulum), Golgi body, Lysosome, and 'All of these'. Recall that the Endoplasmic Reticulum is a network of membranous tubules within the cytoplasm that is involved in protein and lipid synthesis. The Golgi apparatus is involved in the transport of lipids around the cell, and the creation of lysosomes. Lysosomes are involved in digestion and waste removal.

Step 3: Identify the Correct Option

The membrane of the cell nucleus is directly connected to one type of organelle. This organelle is the Endoplasmic Reticulum (ER). The ER and nuclear membrane are continuous to allow for communication and transfer of materials between the nucleus and cytoplasm.

Step 4: Reject other options

While the Golgi apparatus and lysosomes are important organelles in a cell, the outer membrane of the nucleus is not continuous with them. So, the options 'Golgi body', 'Lysosome' and 'all of these' should be rejected and are incorrect.

Key Concepts

Cell Organelles

In the world of biology, understanding cell organelles helps unravel the mysteries of life at the cellular level. Cell organelles are the specialized structures within eukaryotic cells that perform distinct processes necessary for its survival and function. Each organelle has a unique role, akin to the various parts of a factory working together to produce a product.

Some key organelles include:

• Nucleus: The control center of the cell, housing the cell's DNA and coordinating activities like growth and reproduction.
• Mitochondria: Often referred to as the powerhouses of the cell, they generate ATP which is used as an energy source.
• Ribosomes: These tiny particles are the sites of protein synthesis.
• Lysosomes: Function as the digestive system of the cell, breaking down unwanted materials.
• Golgi apparatus: Acts like a post office, modifying, sorting, and packaging proteins and lipids for delivery.

Understanding how these organelles interact helps in grasping the overall function and the complex nature of eukaryotic cells.

Endoplasmic Reticulum

The Endoplasmic Reticulum (ER) is a crucial cell organelle, present in eukaryotic cells. It is part of the extensive membranous network designed for synthesis, storage, and transport within the cell. Broadly, the ER comes in two types: the Rough ER and the Smooth ER.

Rough ER:

• Studded with ribosomes on its surface, giving it a 'rough' appearance.
• Primary site for protein synthesis, where ribosomes build proteins that may be secreted from the cell.

Smooth ER:

• Lacks ribosomes, hence, appears 'smooth'.
• Involved in lipid synthesis, detoxification of chemicals, and calcium storage.

The ER is closely associated with the nuclear membrane, forming a continuous network that allows for the transfer of materials between the nucleus and cytoplasm, providing the interplay essential for cellular function.

Nuclear Membrane

The nuclear membrane, also known as the nuclear envelope, is the protective barrier of the cell's nucleus. This double-layered structure surrounds the nucleus, maintaining the security of the cell's genetic material, DNA.

Some important features include:

• Double-Membrane Structure: Composed of two lipid bilayers, ensuring double protection for genetic information.
• Nuclear Pores: Embedded in the membrane are these large complexes allowing controlled movement of substances in and out of the nucleus.
• Connection to the ER: The outer nuclear membrane is continuous with the endoplasmic reticulum, facilitating the exchange of materials, which is critical for processes like protein synthesis and transport.

With its role as the gatekeeper of genetic material, the nuclear membrane not only protects DNA but also regulates essential activities needed for cell life and replication.