Microbiology - Bacteria

Question 1

When were microscopes discovered?

Answer 1

1600’s, until then scientists did not know about cells

Question 2

Gram positive appear…

Answer 2

Purple (stain with crystal violet dye)

Question 3

Gram negative appear…

Answer 3

Pink (stain with safranin dye)

Question 4

What is taxonomy?

Answer 4

Study of naming and classifying organisms. Five kingdom system developed by Robert Whittaker

Question 5

Eukaryotes vs Prokaryotes

Answer 5

Eukaryotes:
-have a nucleus
-no cell wall
Prokaryotes:
-no nucleus
-cell wall

Question 6

How is taxonomy divided?

Answer 6

• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Question 7

Bacteria cell morphology

Answer 7

• Cocci (round and spherical)
• Bacilla (rod-shaped)
• Spirilla (curved or spiral)

Question 8

Bacteria cell structures

Answer 8

• Capsule
• Cell wall
• Outer membrane (gram -)
• Cytoplasmic membrane
• Cytoplasm
• Flagella
• Pilli/fimbriae
• Nucleoid
• Ribosomes

Question 9

Why do antibiotics not attack our regular cells?

Answer 9

Detect the cell wall made of peptidoglycan and penetrate (create holes) in it. Results in killing of some good bacteria as well :(

Question 10

Why are gram negative bacteria so much harder to kill?

Answer 10

They have an outer membrane as well

Question 11

What is the gram staining procedure?

Answer 11

Stain the bacteria first with crystal violet, it will turn purple immediately. Then, rinse it with water and apply iodine solution, which will decrease solubility of violet stain. If it retains the purple, it is gram positive, if discolouration happens, stain it with safranin as it is likely gram negative, and this will cause it to turn pink

Question 12

How do antimicrobial agents work?

Answer 12

Interfere with nutrient intake and metabolism of cell by acting on cytoplasmic membrane

Question 13

How do bacteria grow and reproduce?

Answer 13

Growth: increase in cell number or multiplication

Reproduce through binary fission (each cell divides into 2 daughter cells)

Question 14

What are the 5 major conditions/growth requirements for bacteria?

Answer 14

• Temperature
• pH
• Nutrients
• Oxygen
• Water

Question 15

What is a thermophile?

Answer 15

Bacterias that love heat (above 56 Celsius)

Question 16

What are mesophiles?

Answer 16

Bacteria that grow best at body temperature (37 celsius)

Question 17

What are psychophiles?

Answer 17

Bacteria that love the cold (0-15 celsius, grow best at 7)

Question 18

What are obligate aerobes?

Answer 18

Bacteria that require high oxygen (20%)

Question 19

What are microaerophiles?

Answer 19

Bacteria that can only tolerate a little oxygen (2-10%)

Question 20

What are obligate anaerobes?

Answer 20

Bacteria that can only grow in the absence of oxygen

Question 21

What are facultative anaerobes?

Answer 21

Bacteria that can grow with or without oxygen but prefer without

Question 22

Which type of bacteria are most commonly found in the oral cavity?

Answer 22

99% of oral bacteria are oligtate anaerobes or facultative anaerobes

Question 23

What do all bacteria require in order to grow?

Answer 23

Water

Question 24

How do we control growth of bacteria?

Answer 24

-preventing multiplication of microbe
or
-killing/destruction of microbe

Question 25

What are bacteriostatic agents?

Answer 25

• Do not kill mature cells, stop growth

- Allow the body’s natural immune system to kill the remaining microbes

Question 26

What are bactericidal agents?

Answer 26

Kill bacteria

Question 27

How do we grow/culture bacteria in a lab?

Answer 27

• Using liquid broth

- Semi-solid agar

Question 28

What is the kingdom associated to bacterias?

Answer 28

Monera