Bacteria I & II

Question 1

Differences between Eukaryots and Prokaryots:
- DNA
- Membranous organelles
- Ribosomes
- Envelope
- Flagella and Cilia

Answer 1

-Ver Cuadro del libro

Question 2

Draw a bacteria and put the different parts

Answer 2

Ver libro

Question 3

Types of forms of bacteria

Answer 3

Coccus, Bacillum, Vibrio, Cocobacillus, Spirillum and Spirochetes.

Question 4

How can coccus be divided.

Answer 4

Coccus, Diplococcus, Streptococcus and Staphylococcus.

Question 5

Difference between gram positives and gram negatives in membrane structure.
How each is colorated.

Answer 5

Gram positives (blue): thick peptidoglycan wall, ONE membrane.
Gram negatives (red): Thin peptidoglycan wall and two membranes, a inner membrane and a outer membrane.
Colored with crystal violet and safranin.

Question 6

Functions of peptidoglycan bacteria wall

Answer 6

Rigid support, maintains the shape of bacteria and withstands low osmotic pressure (prevents bursting).

Question 7

How can we destroy the bacterial wall?

Answer 7

With antibacterial drugs (beta-lactans; penicillin) and lysozyme (in tears, saliva…)

Question 8

Of what is the peptidoglycan wall made?

Answer 8

N-acetylglucosamine and N-acetylmuramic acid. Stabilized by 4 Aa polypeptide chain and in the case of GRAM POSITIVES by pentaglycine cross-linking.

Question 9

What are some of the ‘strange things’ that we can find in the peptodoglycan wall?

Answer 9

• D-aminoacids (usually not found in nature, protection against peptidases).
• Meso-Diaminopimelic acid (DAP) ONLY FOUND IN GRAM NEGATIVES.

Question 10

What are the unique components of Gram-positive and Gram-negative?

Answer 10

Gram-positive: Teichoic acid and Lipoteichoic acid.
Gram-negative: Lipolisaccharides.

Question 11

Structure and function of Teichoic and Lipoteichoic Acids.

Answer 11

Composed of Glycerol Phosphate and Ribitol Phosphate. Negatively charged.
Maintain the structure of the cell envelope, binding to the host tissue and providing defense against antibiotics and host defenses.

Question 12

Structure of Lipolysacharides

Answer 12

• Lipid A: (endotoxin, septic shock, death) 2 glucosamines, phosphate group (negatively charged), and fatty acids. (Conserved upon bacteria).
• Core polysaccharide: has an inner core and outer core.
• O-antigen (major surface antigen): long chain polysaccharide, linear or branched, high variability, immunogenic.

Question 13

Which is the major surface antigen?

Answer 13

O-Antigen

Question 14

Function of Lipolisacharides

Answer 14

• Amphypatic, creates a permeability barrier.
• Stabilizes membrane.
• Protects bacteria from host defenses.
• Involved in Biofilm formation.

Question 15

What are the two bacteria which are exceptions of Gram bacteria?

Answer 15

Mycobacteria and Mycoplasma.

Question 16

Structure of Mycobacteria.

Answer 16

Unique cell wall, waxy, hydrophobic, rich in lipids (60%).
Mycolic acid (wax, f.a) bound to peptidoglycans via arabinogalactan polysaccharide.
Fatty acids such as lipoarabinomannan and other glycolipids.
Impenetrable by water and antibiotics.

Question 17

Characteristics of Mycoplasma

Answer 17

• No cell wall.
• Resistant to Beta-Lactans (penicilllin).
• Pleomorphic (can adopt many shapes9
• Plasma membrane stabilized by sterols.
• Smallest bacterium with smallest genome.
• Fried-egg.

Question 18

What are the functions of capsules?

Answer 18

• Attachment to surfaces.
• Protect from desiccation.
• Protect from phagocytosis.
• Protect from viruses and detergents,
• Involved in the creation of biofilms.

Question 18

What’s the difference between Smoth LPS and rough LPS?

Answer 18

Smooth LPS: has the O-antigen and the Core polysaccharide. More pathogenic.
Rough LPS: lacks the O-antigen and has a truncated core polysacharide. Less pathogenic.

Question 18

Of what are capsules made?

Answer 18

Polysaccharides or Proteins