Cell: The Unit of Life for NEET UG
The cell is the smallest unit that can carry out all the processes of life. Learn how prokaryotic and eukaryotic cells differ and what each organelle does.
BiologyClass 1195 MCQs2 lessons15 flashcards3 memory tricks
Practise Cell: The Unit of Life free
What you'll learn
- Prokaryotic and eukaryotic cells
Compare prokaryotic and eukaryotic cells, and plant and animal cells. - Cell organelles and their functions
Match each organelle to its structure and function.
Memory tricks
ER is the road network; the nucleus is the control room with the DNA blueprints; the vacuole is the storage tank.
Prokaryotic ribosomes are 70S (50S + 30S); eukaryotic are 80S (60S + 40S). Svedberg units measure how fast particles settle, not their mass. Mitochondria and chloroplasts have 70S ribosomes.
Singer and Nicolson (1972): lipids and proteins move sideways within the bilayer. Flipping from one layer to the other is rare.
Try 3 NEET-style questions
Q1. Several ribosomes attached to a single mRNA, translating it at the same time, form a
- mesosome
- polysome (polyribosome)
- nucleosome
- lysosome
Show answer
Answer: (2) polysome (polyribosome)
Several ribosomes may attach to one mRNA to form a chain called a polyribosome or polysome. Each translates the mRNA into protein.
Q2. The bacterial flagellum is made of three parts:
- axoneme, basal body and centriole
- filament, hook and basal body
- shaft, pilus and fimbria
- head, neck and tail
Show answer
Answer: (2) filament, hook and basal body
A bacterial flagellum consists of a long filament, a hook and a basal body.
Q3. Lysosomes are membrane-bound vesicles formed by
- packaging in the Golgi apparatus
- budding from mitochondria
- division of the nucleolus
- fusion of ribosomes
Show answer
Answer: (1) packaging in the Golgi apparatus
Lysosomes form by packaging in the Golgi apparatus. They are rich in hydrolytic enzymes (lipases, proteases, carbohydrases) active at acidic pH.
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