Lecture 2: Intro

Question 1

How do we classify bacteria?

Answer 1

1. Morphology
2. Biochemical Reactions
3. Serology
4. Nucleic Acid Profiles

Question 2

Spherical organisms

Answer 2

Cocci

Question 3

Rod-shaped organisms

Answer 3

Rod or Bacillus

Question 4

Organisms in chains

Answer 4

Strep

Question 5

Organisms in clusters

Answer 5

Staph

Question 6

Club-shaped organisms

Answer 6

Diptherioid

Question 7

Are Gram stains good for cytology?

Answer 7

NO, good for identifying Gram +/- bacteria and presence/absence of other cells, not what type

Question 8

What color are G+ bacteria?

Answer 8

PURPLE

Question 9

What color are G - bacteria?

Answer 9

RED

Question 10

What color are mycobacteria?

Answer 10

clear/white

Question 11

Why is the capsule/slime layer important?

Answer 11

Anti-phagocytic! Also, helps adherence and longevity in environment

Question 12

Are capsules antigenically diverse?

Answer 12

YES, hard to mount Humoral Immune response

Question 13

How is the Cell Wall important?

Answer 13

20% of dry weight of bacteria

Helps determine what kind of bacteria (ie: Gram Stain)

Question 14

Describe Gram Staining Method:

Answer 14

1. Fixation with heat
2. stain with crystal violet - enters organisms cell wall
3. Rinse
4. Iodine mordant - binds CV and makes larger complex
5. Rinse
6. De-colorize w/ 95% ethanol - dehydrates G+ cell wall, trapping I-CV complex OR washes awayI-CV complex and cell wall of G-
7. Counter stain w/ Safranin stain - G- bacteria uptake and stain Red/Pink

Question 15

What is the order of efficacy of detergents against bacteria?

Answer 15

Efficacy greatest for G+ > G- > AF (acid fast)

Question 16

List characteristics of G+ Bacteria and how different from others.

Answer 16

• Thicker cell wall of peptidoglycan
• peptidoglycan dessicates upon declorization (ethanol)
• more resistant to MECHANICAL damage
• Peptidoglycan is target of antimicrobials and LYSOZYME

Question 17

List characteristics of G- Bacteria and how different from others.

Answer 17

• LPS is MAJOR Virulence Factor!!
• They have Porins
• less peptidoglycan
• more resistant to DETERGENTS

Question 18

List characteristics of Acid Fast Bacteria and how different from others.

Answer 18

• Cell envelope contains: MYCOLIC ACID, glycolipids and polypeptides
• difficult to stain (won’t take up stain)
• intense cell envelope allows them to survive well in the environment
• cell envelope allows INTRACELLULAR survival (difficult to kill, can often result in chronicity)
• antibiotics target this CELLULAR ENVELOPE

Question 19

What are FLAGELLA important for?

Answer 19

Motility

Question 20

What are FIMBRIAE/PILI important for?

Answer 20

Adherence

Question 21

What are SPORES important for?

Answer 21

Long Term Survival and Physical Resistance

Question 22

What are BIOFILMS important for?

Answer 22

Allows Bacteria to attach to each other

• aiding in colonization
• avoid phagocytosis
• avoid antibiotics
• allows “quorom sensing” – bacteria act as a single organism

Question 23

What is clonal expansion?

Answer 23

On an agar plate, a SINGLE COLONY is the clonal expansion of a SINGLE BACTERIUM

• SMALL colonies = slow growing
• LARGE colonies = fast growing

Question 24

In general, is an organism that divides more rapidly more virulent than the alternative?

Answer 24

NO.

Question 25

What is the optimal pH for bacterial growth?

Answer 25

Neutral to alkaline

Question 26

What is the optimal tonicity (osmotic balance) for bacterial growth?

Answer 26

Isotonic to hypOtonic

Question 27

What is the optimal Temperature for bacterial growth?

Answer 27

Our body temperature = 98.6˚F - most can grow 68-113˚F - Listeria grow in COLD temperatures (39˚F)

Question 28

What kind of environment do strict/obligate aerobes require?

Answer 28

Oxygen present

Question 29

What kind of environment do strict/obligate anaerobes require?

Answer 29

NO oxygen

Question 30

What kind of environment to Facultative Anaerobes (FA) require?

Answer 30

Can grow with or without oxygen

Question 31

What kind of environment do microaerophiles require?

Answer 31

Require Reduced Oxygen (

Question 32

Where in your body are anaerobic conditions?

Answer 32

ORAL CAVITY and INTESTINES: - Mucus, Facultative Anaerobes, Anaerobes, Healthy Tissue Also, areas of NECROSIS

Question 33

Identify the Genetic Elements of bacteria.

Answer 33

Bacterial Genome (haploid, circular chromosome, double stranded DNA) Plasmid (Small circular DNA, autonomous replication) Bacteriophage (Virus that infect bacteria and insert DNA)

Question 34

What Genetic Element(s) of bacteria may encode virulence, toxins, or antibacterial resistance?

Answer 34

PLASMIDs and BacterioPHAGES

Question 35

With respect to genotypic variation of bacteria, what is a MUTATION?

Answer 35

Change in chromosomal DNA

Question 36

With respect to genotypic variation of bacteria, what is a RECOMBINATION?

Answer 36

Exchange of DNA between bacteria

Question 37

With respect to genotypic variation of bacteria, what is a TRANSPOSITION?

Answer 37

Relocation of PARTS of DNA in the genome mediated by transposable elements

Question 38

With respect to RECOMBINATION, what is TRANSDUCTION?

Answer 38

Phage-mediated transfer

Question 39

With respect to RECOMBINATION, what is CONJUGATION?

Answer 39

Plasmid mediated transfer

Question 40

With respect to RECOMBINATION, what is TRANSFORMATION?

Answer 40

Uptake of naked segment of DNA

Question 41

What is mostly responsible for genetic variation of bacteria?

Answer 41

Recombination via CONJUGATION

Question 42

What antimicorbials target the peptioglycan in the cell wall of bacteria?

Answer 42

Beta-Lactams