1. PROKARYOTIC
CELLS
Topic 2.2
IB Biology
Miss Werba

2. TOPIC 2 - CELLS 2.1 CELL THEORY 2.2 2.5 CELL DIVISION
PROKARYOTIC CELLS
2.3
EUKARYOTIC CELLS
2.4
MEMBRANES
2.5 CELL DIVISION
J WERBA – IB BIOLOGY 2

3. THINGS TO COVER Ultrastructure of a prokaryotic cell
Functions of cell structures
Structures identifiable under an EM
Binary fission
J WERBA – IB BIOLOGY 3

4. PROKARYOTIC CELLS What differences can you see?
2.2
PROKARYOTIC CELLS What differences can you see?
J WERBA – IB BIOLOGY 4

5. PROKARYOTIC CELLS Prokaryotic cells were the first to evolve
2.2
PROKARYOTIC CELLS
Prokaryotic cells were the first to evolve
Perform all functions of life
Remember: MRS C GREN
They have no nucleus
They have no membrane-bound organelles
J WERBA – IB BIOLOGY 5

6. BINARY FISSION Command term = STATE
2.2.4
BINARY FISSION Command term = STATE
Prokaryotic cells divide by binary fission
Basically, one cell splits into two!
DNA replicates and attaches to cell membrane
Cell growth pulls DNA loops apart (cytokinesis)
Cell wall growth between loops separates cell into two.
J WERBA – IB BIOLOGY 6

7. PROKARYOTIC CELLS E. coli
2.2.3
PROKARYOTIC CELLS E. coli
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8. PROKARYOTIC CELLS E. coli
2.2.1
PROKARYOTIC CELLS E. coli
ribosome (70S)
cell membrane
cell wall
slime capsule
flagellum
cytoplasm
plasmid
nucleoid region (DNA)
pili
J WERBA – IB BIOLOGY 8

9. PROKARYOTIC CELLS E. coli
2.2.1
PROKARYOTIC CELLS E. coli
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10. PROKARYOTIC CELLS Cell wall Cell membrane Cytoplasm Nucleoid Plasmid
2.2.2
PROKARYOTIC CELLS
Cell wall
A rigid outer layer that maintains shape and protects the cell from damage or bursting if internal pressure is high
Cell membrane
Semi-permeable barrier that controls the entry and exit of substances
Cytoplasm
Fluid component which contains enzymes needed for cell metabolism
Nucleoid
Region of the cytoplasm which contains the DNA
Plasmid
Additional DNA molecule that can exist and replicate independently - it can be transmitted between bacterial species
Ribosome
Protein synthesis (prokaryotic ribosomes smaller than eukaryotic - 70S)
J WERBA – IB BIOLOGY 10

11. PROKARYOTIC CELLS Slime Capsule Flagella (sing. flagellum )
2.2.2
PROKARYOTIC CELLS
Slime Capsule
Protects against desiccation (drying out) and phagocytosis
Flagella (sing. flagellum )
Long, slender projection which spins like a propeller, enabling movement
Pili (sing. pilus)
Hair-like extensions which can serve for attachment or communication.
Attachment pili: Shorter in length, allow adhesion to other bacteria or surfaces
Communication pili: Longer in length, allow for the exchange of plasmids
J WERBA – IB BIOLOGY 11

12. QUESTION 1 The diagram below shows a bacterium.
What structure does the part labelled X identify?

13. QUESTION 1 - answer
X = Nucleoid

14. QUESTION 2
Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9 marks)

15. What does the ‘OUTLINE’ command term ask for?
QUESTION 2
Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9 marks)
Step 1: Command term
What does the ‘OUTLINE’ command term ask for?

16. QUESTION 2 Give a brief account or summary.
Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9 marks)
Give a brief account or summary.
May or may not involved a diagram.

17. What vocab words would be relevant?
QUESTION 2
Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9 marks)
Step 2: Relevant words
What vocab words would be relevant?

18. Capsule Cell membrane Cell wall Cytoplasm
QUESTION 2
Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9 marks)
Capsule Cell membrane Cell wall Cytoplasm
Flagella Naked DNA
Nucleoid Pili
Plasmids Ribosomes

19. Can you put some order to your ideas?
QUESTION 2
Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9 marks)
Step 3: Order ideas
Can you put some order to your ideas?

20. QUESTION 2
Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9 marks)
Might be good to make a little flowchart or for this question, work from the outside in or vice versa

21. Step 4: Check the mark allocation
QUESTION 2
Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9 marks)
Step 4: Check the mark allocation
Do you have enough to get all the marks?

22. QUESTION 2 9 marks = 9 separate statements
Escherichia coli is a unicellular organism, so each cell must carry out all of the processes required for life. Outline the functions of each of the structures in the cells of Escherichia coli.
(9 marks)
9 marks = 9 separate statements
There were at least 10 words on the list!

23. QUESTION 2 - answer
cell wall protects the cell from damage; cell wall prevents the cell from bursting;
plasma membrane pumps substances/carries out active transport; plasma membrane controls entry and exit of substances;
cytoplasm contains enzymes that carry out metabolism;
pili are used to connect bacterial cells/can pull bacteria closer together;
flagella used for locomotion/movement of the bacterial cell;
ribosomes synthesize proteins;
(naked) DNA of main chromosome is located in the nucleoid (region); nucleoid initiates reproduction/binary fission; (naked) DNA/chromosome/nucleoid controls/determines cell structure/function;
plasmids confer (luxury) functions such as disease resistance/antibiotic resistance/other;
capsule protects cell/promotes adherence;
If the answer includes any eukaryotic structures, award [8 max].