A Level Biology: Prokaryote Structure and Division (binary fission)

A: Cytoplasm. Contains all the enzymes needed for all metabolic reactions, (since there are no cellular organelles prokaryotes).


B: Ribosomes. The smaller (70S) type (sites of protein synthesis).


C: Nucleoid / circular DNA. The region of the cytoplasm that contains DNA. It is not surrounded by a nuclear membrane. Prokaryotic DNA is always circular and NOT associated with any proteins which form chromatin.


D: Plasmid. Small circles of DNA, used to exchange DNA between bacterial cells, and very useful for genetic engineering.

E: Cell membrane. Phospholipid bilayer - Composed of phospholipids and proteins, (just like eukaryotic cell membranes.)


F: Cell Wall. Made of murein, which is a glycoprotein (i.e. a protein/carbohydrate complex, also called peptidoglycan). There are two kinds of cell wall, which can be distinguished by a Gram stain: Gram positive bacteria have a thick cell wall and stain purple, while Gram negative bacteria have a thin cell wall with an outer lipid layer and stain pink.

G: Capsule (or Slime Layer). A thick polysaccharide layer outside of the cell wall, like the glycocalyx of eukaryotes. Function: for sticking cells together, as a food reserve, as protection against desiccation and chemicals, and as protection against phagocytosis.

H: Flagellum. A rigid rotating helical-shaped tail used for motility (propulsion/movement). The flagella "motor" is embedded in the cell membrane and is driven by a Hydrogen ion gradient across the membrane. Clockwise rotation drives the cell forwards, while anticlockwise rotation causes a chaotic spin. The Flagella is the only known example of a rotating "motor" in nature!

A Level Biology: The Structure and Function a Prokaryotic cell (Bacterial cells structure and function)


Check Where this Lesson fits into your Exam Specification!

00:00 Learning Outcomes

00:26 Prokaryotes (bacteria)

01:02 ALL bacteria have...

01:40 Bacteria are Diverse

02:19 Some Bacteria have additional features

02:52 Structure -- Function of bacterial (prokaryotic) cell Features.

A Level Biology: The Structure and function of Prokaryotes Revision Notes with Knowledge Check Questions and Answers PDF
The Structure and Function of Prokaryotes Revision Notes Poster A3 PDF

A Level Biology: - Prokaryotic Cell Division: 

Bacteria Divide by Binary Fission.


Check Where this Lesson fits into your Exam Specification!

A-Level Biology Lesson “Prokaryotic cell division: Bacterial cells divide by binary fission."

00:00 Intro Screen

00:16 Learning Outcomes

00:43 - Introduction - All cells "reproduce"

01:17 Binary Fission - the division of a prokaryote

01:39 Binary Fission - Step 1.

02:00 Binary Fission - Step 2.

02:17 Binary Fission - Step 3.

02:36 Binary Fission - Step 4.

Prokaryotic cell division - Bacteria divide by binary fission Revision Notes Poster A3 PDF for A Level Biology
Check Your Exam Specification

AQA Specification Reference: - Structure of prokaryotic cells and of viruses. Prokaryotic cells are much smaller than eukaryotic cells. They also differ from eukaryotic cells in having: cytoplasm that lacks membrane-bound organelles, smaller ribosomes, no nucleus; instead they have a single circular DNA molecule that is free in the cytoplasm and is not associated with proteins, a cell wall that contains murein, a glycoprotein. In addition, many prokaryotic cells have: one or more plasmids, a capsule surrounding the cell, one or more flagella.  All cells arise from other cells. Binary fission in prokaryotic cells involves: Replication of the circular DNA and of plasmids. Division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids.


CIE Specification Reference: - 1. Cell structure. Outline key structural features of typical prokaryotic cells as seen in a typical bacterium (including: unicellular, 1–5μm diameter, peptidoglycan cell walls, lack of membrane-bound organelles, naked circular DNA, 70S ribosomes)


Edexcel (Biology A – Salters-Nuffield) Specification Reference: - Topic 3: Voice of the Genome. 3.4 Know the ultrastructure of prokaryotic cells, including cell wall, capsule, plasmid, flagellum, pili, ribosomes, mesosomes and circular DNA.


Edexcel (Biology B) Specification Reference: - Topic 2: Cells, Viruses and Reproduction of Living Things. 2.1 Eukaryotic and prokaryotic cell structure and function. iii) Know the ultrastructure of prokaryotic cells and the structure of organelles, including: nucleoid, plasmids, 70S ribosomes and cell wall. Topic 6: Microbiology and Pathogens as basic introduction to bacterial cell division, before moving on to the different phases of a bacterial growth curve.


OCR (Biology A) Specification Reference: - 2.1 Foundations in biology. 2.1.1 Cell structure. The similarities and differences in the structure and ultrastructure of prokaryotic and eukaryotic cells.


OCR (Biology B) Specification Reference: - Module 2: Cells, chemicals for life, transport and gas exchange. 2.1.1 Cells and microscopy: h (i) the ultrastructure of prokaryotic cell, as revealed by an electron microscope. to include: Circular DNA, plasmids, mesosome, pili and flagella in prokaryotic 


WJEC Specification Reference: - Core Concepts. 2. Cell structure and organisation, (b) the structure of prokaryotic cells. Basic understanding of how bacterial cells divide, applied to growth conditions. covered in section 4. Microbiology.

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