Biology · Cell: The Unit of Life · NEET
Only three: the mitochondrion, the chloroplast (and other plastids), and the nucleus. Each of these is wrapped by two separate membranes, an outer one and an inner one. Every other organelle is different: lysosome, vacuole, Golgi cisterna and endoplasmic reticulum have a single membrane, while ribosomes and centrioles have no membrane at all. NEET often lists four organelles and asks which is single membrane bound, so remember the double-membrane list is short: mitochondrion, plastid, nucleus.
Yes. The mitochondrion has a single circular DNA molecule in its matrix, and the chloroplast has small double-stranded circular DNA in its stroma. Both also carry 70S ribosomes, so they can make some of their own proteins. This is why they can divide by fission and are called semi-autonomous organelles. The nucleus also has DNA, but that is the main chromosomal DNA of the cell, not the small circular type.
Yes. The nucleus is surrounded by a nuclear envelope made of two parallel membranes with a gap called the perinuclear space between them. The envelope has nuclear pores that let RNA and proteins pass both ways. So the nucleus counts as a double membrane bound structure. But be careful: unlike mitochondria and chloroplasts, the nucleus does not have small circular DNA; it holds the cell's chromosomes.
Lysosomes and vacuoles have a single membrane and contain NO DNA. Lysosomes hold hydrolytic (digesting) enzymes and vacuoles store water, sap and waste. NEET 2019 asked exactly this and the answer was lysosomes and vacuoles. Do not get tricked: mitochondria and chloroplasts DO have DNA, and the nucleus DOES have DNA, so any pair including them is wrong.
Chloroplast DNA is circular and double-stranded, and it sits in the stroma along with 70S ribosomes. NEET 2024 asked this directly and the correct answer was 'circular, double stranded'. Mitochondrial DNA is also a single circular DNA molecule. So for both semi-autonomous organelles, think circular DNA, not linear.
They are called semi-autonomous because they can make some of their own proteins and divide on their own, but not everything. They have their own circular DNA, their own 70S ribosomes, and they divide by fission. But they still depend on the nucleus for many proteins. 'Semi' means half or partly, so semi-autonomous means partly self-controlled.
Given below are two statements: Statement I: Mitochondria and chloroplasts are both double membrane bound organelles. Statement II: Inner membrane of Mitochondria is relatively less permeable, as compared to chloroplast. Choose the correct answer.
Which of the following pair of organelles does not contain DNA?
The DNA present in chloroplast is
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes. The nuclear envelope is made of two membranes with a perinuclear space between them and nuclear pores for transport. But its DNA is chromosomal, not the small circular DNA found in mitochondria and chloroplasts.
Lysosomes, vacuoles, Golgi apparatus and endoplasmic reticulum are single membrane bound. In NEET 2016, among mitochondria, chloroplast, lysosome and nucleus, the single membrane one was the lysosome.
Yes. NEET 2026 confirmed this: both mitochondria and plastids (chloroplasts) contain circular DNA. This is a key reason both are semi-autonomous organelles.
Ribosomes and centrioles (centrosome) have no membrane. Ribosomes are made of rRNA and protein and occur in both prokaryotic (70S) and eukaryotic (80S) cells.
The inner membrane folds inward to form cristae. These folds increase the surface area for the electron transport enzymes, which sit on the inner membrane, helping produce more ATP.
