Prokaryotic Cells Class 11 Notes (NCERT + Structure + Diagram + MCQ + NEET PYQ)

Introduction to Prokaryotic Cells

Prokaryotic cells are those that lack a well-defined nucleus and membrane-bound organelles. They are generally smaller and multiply more rapidly than eukaryotic cells. This topic is important for Class 11 Biology and NEET exams.

Examples

Bacteria, Cyanobacteria (Blue-green algae), Mycoplasma and PPLO.

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Shapes of Bacteria

Bacillus (Rod-shaped)

Coccus (Spherical)

Vibrio (Comma-shaped)

Spirillum (Spiral)

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Key Characteristics of Prokaryotic Cells

• Genetic Material: Naked DNA without nuclear membrane.
• Plasmids: Small circular DNA providing antibiotic resistance.
• Cell Wall: Present in most, except Mycoplasma.

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Cell Envelope

Glycocalyx

Outermost layer; may be slime layer or capsule.

Cell Wall

Provides shape and protection.

Plasma Membrane

Selectively permeable layer controlling entry and exit.

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Special Structures

Mesosomes

Help in respiration and DNA replication.

Flagella

Help in movement.

Pili and Fimbriae

Help in attachment (not motility).

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Ribosomes and Inclusion Bodies

• Ribosomes: 70S type (50S + 30S).
• Polysomes: Multiple ribosomes on mRNA.
• Inclusion Bodies: Storage materials.

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Gram Staining

• Gram Positive: Purple color.
• Gram Negative: Pink/red color.

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NEET MCQs on Prokaryotic Cells

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Top NEET MCQs on Prokaryotic Cells

Q1. Which of the following is an exception to the presence of a cell wall in prokaryotes?
A) Bacteria
B) Cyanobacteria
C) Mycoplasma
D) PPLO
Answer: C

Q2. The structure involved in respiration and cell wall formation is:
A) Ribosome
B) Mesosome
C) Plasmid
D) Nucleoid
Answer: B

Q3. Prokaryotic ribosomes are of which type?
A) 80S
B) 70S
C) 60S
D) 50S
Answer: B

Q4. Circular DNA present outside the genomic DNA is called:
A) Nucleoid
B) Inclusion body
C) Plasmid
D) Mesosome
Answer: C

Q5. Which structure helps in bacterial motility?
A) Pili
B) Fimbriae
C) Flagella
D) Capsule
Answer: C

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Previous Year Questions (PYQ)

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Previous Year Questions (PYQ) - NEET

Q1. Which of the following is an exception to the presence of cell wall in prokaryotes?
A) Bacteria
B) Blue-green algae
C) Mycoplasma
D) PPLO
Answer: C

Q2. Prokaryotic ribosomes are:
A) 80S
B) 70S
C) 60S
D) 50S
Answer: B

Q3. Mesosomes are associated with:
A) Respiration
B) Protein synthesis
C) Storage
D) Digestion
Answer: A

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