Cell Theory True or False Quiz

Cell Theory

• Modern Cell Theory developed by Schleiden and Schwann in 1938.
• Cells are the smallest unit of life and perform all necessary life processes (e.g., ATP and protein synthesis).
• Living cells arise from pre-existing living cells through processes like mitosis, meiosis, cytokinesis, and binary fission in prokaryotes.
• All living organisms consist of one or more cells, where all life-sustaining chemical reactions occur.

Mitochondria

• Mitochondria are rod-shaped or cylindrical with sizes ranging from 0.5-1.5 μm in diameter and 2.5-10 μm in length.
• Enclosed by a double membrane: smooth outer membrane is permeable to small solutes, while the inner membrane forms cristae to increase surface area for enzyme attachment.
• The intermembrane space is crucial for generating a proton gradient for the electron transport chain.
• The mitochondrial matrix contains circular mitochondrial DNA (mtDNA) and 70S ribosomes, allowing mitochondria to grow and divide independently.
• Mitochondria are the site of aerobic respiration and ATP synthesis.

Chloroplasts

• Chloroplasts are biconvex, lens-shaped organelles that move within cells via cytoplasmic streaming to optimize light absorption.
• Enclosed by a double membrane known as the chloroplast envelope, with a narrow intermembrane space.

Ribosome Synthesis in Eukaryotes

• Ribosomal RNA (rRNA) is transcribed in the nucleolus, and ribosomal proteins are produced in the nucleus.
• Proteins and rRNA combine in the nucleolus to form ribosomal subunits, which are assembled on mRNA during translation.

Centrioles

• Centrioles are found in animal cells and lower plant cells but absent in higher plant cells.
• Exist as pairs of perpendicular rod-like structures composed of microtubule triplets arranged in a ring.
• Organize spindle fibers during cell division.

Cytosol

• The cytosolic matrix is composed of 90% water, organic molecules, inorganic ions, and waste products.
• Functions include storage of vital chemicals and serving as the site for various metabolic pathways like glycolysis and translation.

Cytoskeleton

• A dynamic network of fibres providing structural support and facilitating cell movement.
• Comprises microtubules, intermediate fibers, and microfilaments, maintaining cell shape and anchoring organelles.

Plasma Membrane

• The plasma membrane is partially permeable, similar to eukaryotic membranes, and plays a role in cellular function.
• Mesosomes are infoldings found in some bacteria, aiding in the separation of DNA during binary fission and increasing surface area for enzymatic reactions.

Genetic Material in Bacteria

• Bacteria have a single circular double-stranded DNA chromosome located in the nucleoid region, associated with histone-like proteins.
• Transcriptionally active genes are found in loosely coiled regions, while inactive genes are in supercoiled regions.

Ribosomes

• Bacterial ribosomes are 70S, distinct from eukaryotic ribosomes, and crucial for protein synthesis.

Viral Structure

• The capsid is a protective protein coat surrounding the viral genome, composed of capsomeres.
• Some viruses are naked, containing only a genome and capsid.
• Enveloped viruses possess a membranous envelope derived from host cell membranes, incorporating viral and host proteins for cell recognition and attachment.
• Bacteriophages specifically infect bacteria.

Test your understanding of the key principles of cell theory with this True or False quiz. Determine whether statements about cells and their characteristics are accurate or not. Perfect for students studying biology or life sciences.