Describe the structure of the following with the help of labelled diagrams.
(i) Nucleus
(ii) Centrosome
(i) Nucleus
Nucleus controls all the cellular activities of the cell. It is spherical in shape. It is composed of the following structures:
Nuclear membrane: It is a double membrane separating the contents of the nucleus from the cytoplasm. The narrow space between the two membranes is called the perinuclear space. Nuclear membrane has tiny holes called nuclear pores. These holes allow specific substances to be transferred into a nucleus and out from it.
Nucleoplasm/Nuclear matrix: It is a homogenous granular fluid present inside the nucleus. It contains the nucleolus and chromatin. Nucleolus is a spherical structure that is not bound by any membrane. It is rich in protein and RNA molecules, and is the site for ribosome formation. Chromatin is an entangled mass of thread-like structures. It contains DNA and some basic proteins called histones.
(ii) Centrosome
Centrosome consists of two cylindrical structures called centrioles. Centrioles lie perpendicular to each other. Each has a cartwheel-like organisation.
A centriole is made up of microtubule triplets that are evenly spaced in a ring. The adjacent triplets are linked together. There is a proteinaceous hub in the central part of a centriole. The hub is connected to the triplets via radial spokes. These centrioles help in organising the spindle fibres and astral rays during cell division. They form the basal body of cilia and flagella as well.
NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:
This question is important because it tests key concepts from the NCERT syllabus and is frequently asked in CBSE exams.
This question is based on core NCERT concepts explained in the chapter and should be revised thoroughly before exams.
Students often lose marks by skipping steps, writing incomplete explanations, or misunderstanding keywords used in the question.
(i) Nucleus
Nucleus controls all the cellular activities of the cell. It is spherical in shape. It is composed of the following structures:
Nuclear membrane: It is a double membrane separating the contents of the n...
Step-by-step explanation:
• (i) Nucleus
•
• Nucleus controls all the cellular activities of the cell
• It is spherical in shape
• It is composed of the following structures:
Stay updated with our latest educational content and study tips
Pay upfront, or pay off less and over time? The truth depends on four factors most consumers will never compare at the same time: the interest rate on the house loan, the interest rate on the savings account, the rate of home price appreciation, and the cost of renting the home until you actually buy … Read more
Read More
Thirty is when the question starts to get raised and you’re able to do something because you know you have the experience—you know you have the responsibility. Here are some ways to consider the choice based on a realistic assessment without idealizing either aspect. Restlessness is one of those things that appears in your early … Read more
Read More
It’s not about starting over if you took a break to care for children, take care of yourself, be healthy or for any other reason. This is a realistic strategy for the recovery of skills, selection of the right job, and overcoming the resume problem. One year, three years or 10 years of a career … Read more
Read More
There’s no need to score 95% or achieve a JEE/NEET rank. You don’t need to score 95% or rank in JEE/NEET to build a solid career. A candid and pragmatic guide to the routes that actually work for students who have an average mark and what to do when faced with the options. If … Read more
Read More
Student Discussion
ADD NEW COMMENT