45. CELL SURFACE STRUCTURES

Question 1

1. What are the 4 Cell Wall Functions of the Prokaryotic Cell?

Answer 1

1. Maintains the Cell Shape
2. Protects the Cell
3. Prevents the cell from bursting in a Hypotonic
   Environment
   (it preserves the Osmotic Pressure)
4. It plays a role in Cell Division

Question 2

2. What are Bacterial Cell walls made of?

Answer 2

• they contain Peptidoglycans

Question 3

3. What are Peptidoglycans?

Answer 3

• they are a network of polysaccharides and
  polypeptides

Question 4

4. What is the Archaea Cell Wall made of?

Answer 4

• it contains Polysaccharides and proteins
• it lacks Peptidoglycans
• it is not Pathogenic

Question 5

5. What does this image show?

Answer 5

• the Peptidoglycan Structure

Question 6

6. What is Gram Straining?

Answer 6

• it is a Straining Technique
• it is used to classify bacteria into 2 major categories
• these are based on the cell wall composition

Question 7

7. What substance is used for Gram Straining?

Answer 7

• a crystal violet dye

Question 8

8. What are the 2 major bacterial categories of Gram Straining?

Answer 8

1. Gram-positive Bacteria
2. Gram-negative Bacteria

Question 9

9. What are Gram-positive Bacteria?

Answer 9

• their cell walls consist mainly of Peptidoglycan
• they absorb the Crystal Violet
• they are a purple (violet) colour

Question 10

10. What is Gram-negative Bacteria?

Answer 10

• their cell walls consist of a small amount of
  Peptidoglycan
• their cell walls consist of a large amount of
  Lipopolysaccharides (LPS)
• they do not absorb the Crystal Violet
• they are pink in colour

Question 11

11. What does this image show?

Answer 11

• this is a Gram-Positive Bacterial Cell Wall

Question 12

12. What does this image show?

Answer 12

• this is a Gram-Negative Bacterial Cell Wall

Question 13

13. What does this image show?

Answer 13

• Gram- Positive Bacteria

Question 14

14. What does this image show?

Answer 14

• Gram-Negative Bacteria

Question 15

15. What is the composition of Gram-Positive Bacteria?

Answer 15

• it is composed of Peptidoglycans

Question 16

16. List 3 examples of Gram-positive Bacteria?

Answer 16

• Staphylococci
• Streptococci
• Micrococci

Question 17

17. What is the composition of Gram-negative Bacteria?

Answer 17

• it has a peptidoglycan
• it has an outer lipopolysaccharide (LPS) membrane
• it consists of a Periplasms

Question 18

18. What is a Periplasm?

Answer 18

• this is made of Peptidoglycan and Lipoproteins
• it is the space between the inner and the outer
  membrane

Question 19

19. What is the composition of the outer Lipopolysaccharide (LPS) membrane?

Answer 19

1. PHOSPHOLIPIDS
   - PE, PG, DPG
   - PE = Phosphatidylethanolamine
   - PG = Phosphatidylglycerol
   - DPG = Diphosphatidylglycerol
2. PROTEINS
   - glycoproteins
   - lipoproteins
3. LIPOPOLYSACCHARIDES (LPS)
   • lipids and sugars

Question 20

20. List 3 examples of Gram-Negative Bacteria?

Answer 20

1. Escherichia Coli
2. Shigella
3. Salmonella
   (food poisoning)

Question 21

21. What is the function of the Gram-Positive Bacterial Peptidoglycan Cell Wall?

Answer 21

• it is resistant to Physical stress
• it is sensitive to Lysozyme and Penicillin
• it is very rigid

Question 22

22. What is the function of the Gram-Negative Bacterial outer Lipopolysaccharide Layer?

Answer 22

• it is resistant to Lysozyme and Penicillin

Question 23

23. What do many antibiotics target ?

Answer 23

• they target the Peptidoglycan
• they damage the Bacterial cell walls

Question 24

24. Which type of Bacteria is more likely to be Antibiotic Resistant?

Answer 24

• Gram-negative Bacteria