FSc Biology Notes: Mitochondria Structure, Function & Origin

Introduction

Mitochondria (singular: mitochondrion) are rod-shaped organelles.

Known as the powerhouses (or power generators) of the cell.

Present in almost all eukaryotic cells (plants, animals, fungi, protists).

Visible under a light microscope due to their relatively large size.

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Structure

Double Membrane Bound organelle:

Outer Membrane – Smooth, acts like a sieve, allows small molecules to pass.

Inner Membrane – Highly folded into cristae, increasing surface area for reactions.

Intermembrane Space – Narrow space between the two membranes.

Matrix – Inner fluid-filled space, contains enzymes, mitochondrial DNA, and ribosomes.

Cristae – Infoldings of inner membrane.

F1 Particles (ATP Synthase Enzymes): Present on cristae; help in ATP formation.

Electron Carrier Complexes: Located on the inner membrane for electron transport chain (ETC).

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Genetic Material

Mitochondria have their own circular DNA (similar to prokaryotes).

Contain all types of RNA and 70S ribosomes.

Can replicate independently of the cell’s nucleus.

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Functions

Cellular Respiration

Main site of aerobic respiration.

Break down of glucose and oxygen to produce ATP (adenosine triphosphate).

ATP Production

ATP is the energy currency of the cell.

Powers all metabolic activities.

Krebs Cycle Enzymes

Found in the matrix; catalyze important reactions.

Electron Transport Chain (ETC)

Located in the inner membrane; helps in ATP synthesis.

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Number of Mitochondria in Cells

Varies with the cell’s energy demand.

Can range from one to thousands per cell.

Examples: muscle cells, liver cells, and sperm cells have more mitochondria due to high energy needs.

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Origin (Endosymbiotic Theory)

Scientists believe mitochondria originated from free-living prokaryotes.

Millions of years ago, smaller prokaryotes were engulfed by larger ones.

Instead of being digested, a symbiotic relationship was formed:

Larger cell provided nutrients.

Smaller prokaryote provided ATP.

Over time, they evolved into present-day mitochondria.

 

Focus Keywords

# FSc Biology Notes
# Mitochondria structure and function
# Mitochondria notes for FSc
# Powerhouse of the cell
# ATP production in mitochondria
# Endosymbiotic theory mitochondria
# Cellular respiration mitochondria

# Mitochondria in eukaryotic cells