Chapter 3: Cell Structure and Function

Question 1

List and describe the four sequential steps that lead to an infectious disease

Answer 1

• Entry/ introduction- into the body or tissues of the host
• Attachment- attach to the tissues of the host (and they attach firmly)
• Colonization (contamination)- accomplished by defeating phagocytosis (white blood cells) and other defenses of the immune system.
• Disease- caused generally by destroying the body cells, tissues, or organs. (this is when you know you are sick)

Question 2

Describe what virulent factors are.

Answer 2

• Parts, components, or secretions of microorganisms that allow them to progress towards and establish an infectious disease.

Question 3

Describe what a capsule is and their function

Answer 3

Capsule- Main function is to protect bacteria from being phagocytized; prevents recognition of bacteria by the phagocytes due to chemical composition. Highly organized layers composed of polysaccharides that are firmly attached to the cell.

Question 4

Describe what a slime layer is and what they’re function is

Answer 4

a loose of water- soluble glycocalyx that is viscous (sticky), providing one means by which bacteria can attach to surfaces. Unorganized layers of polysaccharides that can be easily removed from the cell.

Question 5

function of flagella

Answer 5

• Flagella (propellers)- function is to confer motility. Used to propel organisms in liquid environment at a speed of 60 body lengths per second. ( moves away from white blood cells which makes them virulent factors)

Question 6

Function for fimbriae

Answer 6

Fimbriae- they are sticky, bristle- like projections sprouting off some bacterial cells. Bacteria use Fimbriae for attachment; because they attach, they are virulence factors

Question 7

Function of pili

Answer 7

Pili- are tubular structures composed of pilin. They are present only in gram negative bacteria. They function mainly in the transfer of DNA from one bacterium to another through a process of DNA transferred called Conjugation.

Question 8

Give the main function of the bacterial cell wall.

Answer 8

Cell walls give bacteria their characteristics shape and provide strong structural support keeping them from bursting or collapsing by osmotic pressure.

Question 9

List the three cellular shapes that bacteria can have.

Answer 9

• Cocci: spheres, oval shape, kidney, or coffee bean-shaped- Cocci cell arrangement include: diplococci (2 cells, acorns like), streptococcal (chain) staphylococcal (clusters)
• Bacillus: they are cylinder- or rod-shaped bacteria
• Spiral: vibrio, spirillum, and spiroquete

Question 10

Give the main differences between the two types of bacterial cell walls. Which
component of the cell wall is responsible for the way in which the two types of cell
walls stain during the gram stain procedure?

Answer 10

• Gram- positive: thick later of peptidoglycan (thicker the layer, the more it retains the crystal layer); contain teichoic acids but lack an outer membrane
• Gram- Negative: thin layer of peptidoglycan; have an outer membrane; the lipid (lipid A) is a component of the outer membrane that is toxic and is referred to as an endotoxin.

Question 11

Explain the importance of lipid A as a virulent factor.

Answer 11

• Lipid A/ endotoxin
• Gram- negative bacteria has lipid A which are endotoxin—it is a component of the outer membrane that is toxic and prevents it from phagocytized.
• The release of lipid A can cause inflammation, fever, vasodilation, blood clotting and shock.

Question 12

List the functions of the cytoplasmic membrane. Is the cytoplasmic membrane a virulent factor? Why or why not?

Answer 12

• It regulates transport in and out of the cell—nutrients in and wastes are out
• Secretion of metabolic product
• It’s the site for energy reaction (cellular or anaerobic respiration) where ATP is produced

It is NOT a virulent factor. It does not allow bacteria to carry any of the 4 steps

Question 13

Bacteria Chromosome

Answer 13

most bacteria have a single circular chromosome. It contains the hereditary (genetic) information of the bacteria

Question 14

Plasmid

Answer 14

non-essential circular pieces of DNA. Many plasmid are associated with a resistance to antibiotics; they are transferred through the pili during conjugation. These are what is being transferred through the pili.

Question 15

Ribosomes

Answer 15

site of protein synthesis

Question 16

Endospores

Answer 16

an extremely resistance stage. They are dormant (asleep)` bodies produces by gram positive bacteria in the genera Bacillus and clostridium. They are dehydrated, have a very thick cell wall, and are extremely hard to destroy
 bacteria have endospores. Once the bacteria dies (because they can’t live in harsh conditions), these endospores can stay alive In harsh conditions. And once there aren’t hard conditions, they become bacteria cells again.

Question 17

Define normal (resident) flora. What would lead to normal flora causing a disease

Answer 17

• The organism that lives in the skin and mucous membranes without causing harm to the host—supposed to be there
• It shouldn’t gain access to sterile areas of the body—places without this bacteria
• Normal flora would cause a disease when it goes somewhere in the body where it shouldn’t be.

Question 18

Describe what infectious dose is and relate it to pathogenicity.

Answer 18

• Minimum number of organisms required to establish an infection.
• The less the organisms are, the more pathogenic it is

Question 19

Describe what antiphagocytic factors are and describe the role of the capsule, the “M” protein, waxes (Mycolic acids), and leukocidins as antiphagocytic factors.

Answer 19

• Antiphagocytic factors are components or secretions that allow bacteria to inhibit or survive the process of phagocytosis.
• Role: prevent it from being phagocytized and being recognized by the immune system
• Capsules- prevents them from being recognized by the immune system (white blood cells)
• M Protein (waxes): their role is like an armor prevent it from being phagocytized—does get phagocytized. M proteins cannot be dissolved
• Leukocidins- they kill white blood cells.

Question 20

List the two bacterial enzymes discussed in class as examples of virulent factors and describe the effects that they have in the body of the host.

Answer 20

• Collagenase: digest collagen—destroys tissues
• Hyaluronidase: digests hyaluronic acid—destroy tissues
• Both are spreading factors

Question 21

Explain the difference in which bacteria produce and release endotoxins, as opposed to way in which they produce and release exotoxins.

Answer 21

Endotoxins are lipid A- lives in gram negative bacteria—endotoxins are release when the bacteria dies.

Exotoxins- produced by both gram negative and gram positive. It has to be alive to produce. Actively being released. When it dies nothing happens as opposed to endotoxins.

Question 22

List examples of the symptoms caused by endotoxins.

Answer 22

• Fever, inflammation, blood clotting, septic shock, vasodilation

Question 23

List the three categories or types of exotoxins discussed in class and give their main effects on cells. What is septic shock? What is its connection with Multiple Organ Dysfunction (MOD)? What toxins (mentioned in class) cause it?

Answer 23

• Enterotoxins: affects cell lining of the Gi Tract causing diarrhea (food poising)
• Neurotoxins: Interfere with normal nerve impulses (Botulism, Tetanus)
• Cytotoxins: toxins that kills cells
   Hemolysins: Destroy red blood cells
   Leukocidins: kill white blood cells
   Shiga Toxins: kill epithelial cells lining the L.I
• Septic shock: occurs as bacterial toxins cause serve hypotension, which then leads to, or occurs along with, multiple organ dysfunction (MOD) caused by endotoxin