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Prokaryotic Cells

Prokaryotic cells have some features that are also found in eukaryotic cells. Prokaryotic cells may also contain plasmids, a capsule and one or more flagella.

Prokaryotes vs eukaryotes

Prokaryotes vs eukaryotes

  • Features common to these types of cells are:
    • A plasma membrane.
    • Cytoplasm.
    • DNA.
    • Ribosomes (ribosomes are 70S in prokaryotes).
  • So, the main difference in terms of organelles is that prokaryotes do NOT have any membrane-bound organelles (e.g. nucleus, mitochondria, Golgi apparatus etc.).
Features of prokaryotic cells

Features of prokaryotic cells

  • Key features of prokaryotic cells are:
    • 70S ribosomes.
    • Unicellular.
    • No membrane-bound organelles.
    • Typicall 1-5μm in diameter.
    • Peptidoglycan (PPG) cell wall.
    • No nucleus.
    • Circular DNA.
DNA in prokaryotes

DNA in prokaryotes

  • Prokaryotic DNA is found as a circular molecule in the cytoplasm.
  • Some prokaryotes have smaller loops of DNA called plasmids that are not part of the main circular DNA molecule.
  • Bacteria can exchange plasmids with other bacteria, sometimes receiving beneficial new genes that the recipient can add to their chromosomal DNA.
    • Antibiotic resistance is one trait that often spreads through a bacterial colony through plasmid exchange.
Capsule

Capsule

  • The capsule enables prokaryotic cells to attach to surfaces in its environment.
Flagella, pili and fimbriae

Flagella, pili and fimbriae

  • Some prokaryotes have flagella, pili, or fimbriae:
    • Flagella are tail-like and used for locomotion.
      • Some prokaryotes have none and others have more than one.
    • Pili are used to exchange genetic material during a type of reproduction called conjugation.
    • Fimbriae are used by bacteria to attach to a host cell.
Jump to other topics
1

Cell Structure

2

Biological Molecules

3

Enzymes

4

Cell Membranes & Transport

5

The Mitotic Cell Cycle

6

Nucleic Acids & Protein Synthesis

7

Transport in Plants

8

Transport in Mammals

9

Gas Exchange

10

Infectious Diseases

11

Immunity

12

Energy & Respiration (A2 Only)

13

Photosynthesis (A2 Only)

14

Homeostasis (A2 Only)

15

Control & Coordination (A2 Only)

16

Inherited Change (A2 Only)

17

Selection & Evolution (A2 Only)

18

Classification & Conservation (A2 Only)

19

Genetic Technology (A2 Only)

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