LG 5.5 - Bacterial Cells

Question 1

(1) What are the minimum requirements of a bacterial cell?

Answer 1

• DNA (in nucleoid)
• Ribosomes
• Cytoplasm
• Cytoplasmic membrane to house everything.

Question 2

(2) Bacterial cell membrane is called what? What is it composed of? Why is it so important?

Answer 2

• Plasma membrane
• Phospholipid bilayer, proteins
• Functional equivalent of most of the organelles of the eukaryotic cell:
  Site of DNA synthesis.
  Site of cell wall polymer synthesis.
  Site of membrane lipid synthesis.
  Contains entire electron transport system.
  Passive, active transport.
  Secretion.

Question 3

(2) How does the peptidoglycan differ in Gr + vs. Gr - bacterium?

Answer 3

• Larger in Gr +

Question 4

(2) Which type of bacteria are more resistant to certain antibiotics? What structural component do they have that assists in this?

Answer 4

• Gr -

- Their outer membrane assists in this greatly.

Question 5

(3) Can Gr + bacteria cause septic shock? Due to what?

Answer 5

• Yes, due to peptidoglycan etc.

Question 6

(3) How does simple staining work? Examples?

Answer 6

• Bacteria are negatively charged, stains have a positive charge so its attracted to the bacterial cell.
• Crystal violet, methylene blue, malachite green, safranin.

Question 7

(3) What will a gram stain tell you about a bacteria? When is a gram stain a good idea?

Answer 7

• Gram reaction, morphology, arrangement.
• Most reproducible on young, growing bacteria.
• Can but used on MOST but NOT all bacteria.

Question 8

(4) What is Staphylococcus epidermidis and Escherichia coli? Gram and arrangement?

Answer 8

• Staphylococcus epidermidis = Gr +, clusters

- Escherichia coli = Gr -, bassilus