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24 Dec 2025

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Prokaryotic Cells & Viruses Notes for AQA A-Level Biology

Kovu 🍁🫶

@kovuisalive

Ever wondered what makes bacteria so different from your own... Show more

Prokaryotic Cells
organelles
↳> cytoplasm has no membrane-bound organelles. It
has nbosomes which are smaller than those in a
eukaryotic cel

Prokaryotic Cells and Viral Structure

Prokaryotic cells are fundamentally different from the cells in your body - they're like stripped-down versions without many of the fancy compartments you'd find in human cells. The cytoplasm contains no membrane-bound organelles, just smaller ribosomes floating about doing their protein-making job.

The plasma membrane acts as the cell's bouncer, controlling what gets in and out through its mix of lipids and proteins. Surrounding this is the cell wall made of glycoprotein murein, which keeps the cell's shape intact and provides crucial support.

Instead of a proper nucleus, prokaryotic DNA just floats freely in the cytoplasm as one long, coiled circular strand - no histone proteins attached. Plasmids are brilliant little extras: small DNA loops that carry handy genes like antibiotic resistance and can be shared between cells like trading cards.

Some prokaryotes have a flagellum - essentially a biological propeller that spins to help them swim around. Others sport a capsule made of slime that acts like armour against immune system attacks.

Quick Tip: Remember that prokaryotes lack a nucleus - the name literally means "before nucleus"!

Binary Fission and Viruses

Binary fission is how prokaryotes reproduce - it's much simpler than the complex cell division you'll learn about in eukaryotes. The circular DNA and plasmids copy themselves first, then the cell grows larger and splits the genetic material to opposite ends before dividing completely into two daughter cells.

Viruses are in a league of their own - they're not even technically alive! They're basically genetic material (DNA or RNA) wrapped in a protein coat called a capsid, with attachment proteins sticking out like keys looking for the right lock.

Viruses are masters of deception. They use their attachment proteins to bind to specific receptor proteins on host cells - this is why some viruses only infect certain cell types. Once attached, they inject their genetic material and essentially turn the host cell into a virus-making factory.

Exam Focus: Understanding how viruses target specific cells through protein recognition is crucial for explaining why different viruses cause different diseases.

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Prokaryotic Cells & Viruses Notes for AQA A-Level Biology

Kovu 🍁🫶

@kovuisalive

Ever wondered what makes bacteria so different from your own cells, or how viruses manage to hijack our bodies? Understanding prokaryotic cells and viruses is crucial for grasping how life works at its most basic level - and it's essential... Show more

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Prokaryotic Cells and Viral Structure

Quick Tip: Remember that prokaryotes lack a nucleus - the name literally means "before nucleus"!

Binary Fission and Viruses

Exam Focus: Understanding how viruses target specific cells through protein recognition is crucial for explaining why different viruses cause different diseases.