microbio chapter 6

Question 1

oxygen requirements

Answer 1

-anerobic
-aerobic

Question 2

Aerobic

Answer 2

• utilize oxygen as terminal electron acceptor
• 1 glucose in = 38 ATP made
• utilize cellular respiration

Question 3

What enzyme is present in aerobic bacteria

Answer 3

• catalase is present to break down H2O2
• hydrogen peroxide can be made accidentally because oxygen is the terminal electron acceptor
• bacteria can do this 10k times/sec to prevent toxication

Question 4

micro-aerobic

Answer 4

• 2-10% O2
• utilize aerobic respiration
• common in ocean water and our intestines

Question 5

facultative anaerobes

Answer 5

• can live without oxygen
• don’t need krebs cycle
• but if oxygen is present, they will switch to oxygen use as terminal electron acceptor

Question 6

anaerobic

Answer 6

• non oxygen as terminal electron acceptor
• usually a sulfur salt as terminal electron acceptor
• 1 glucose in = 2-38 ATP made

Question 7

strict anaerobes

Answer 7

• oxygen is toxic
• if exposed they die

Question 8

pschotrophs/pschrophile

Answer 8

• 0-20 degrees Celsius
• their enzymes fall apart at temps higher than 20 degrees C
• in nature live in snow fields, ice, and cold water
• do not causes disease in humans

Question 9

mesophiles

Answer 9

• 15-45 degrees C
• causes disease in humans because our temp falls in range
• humane pathogens

Question 10

thermophiles

Answer 10

• 40-80 degrees C
• can grow best above 45 degrees C
• found in compost piles and hot springs

Question 11

extreme thermophiles

Answer 11

• 70 degrees and above
• grow best above 80 degrees C
• tend to be archaea
• stabilize their proteins by extra H and covalent bonds between aa
• do not causes disease in humans

Question 12

pH requirements

Answer 12

• acidophiles <7
• basophiles >7

Question 13

phases of microbial growth

Answer 13

1. lag phase
2. log or exponential growth phase
3. stationary phase
4. death phase

Question 14

lag phase

Answer 14

• bacteria are sensing the environment and ‘turning’ on
• genes are needed to take advantage of the environment
• cells do not reproduce immediately, they are actively synthesizing proteins/enzymes to utilize nutrients in media
• organisms appear dormant but are not

Question 15

log phase/exponential growth phase

Answer 15

• bacteria utilize media surroundings to grow and reproduce
• bacteria cells utilize binary fission to reproduce
• 1 cell becomes 2, 2 become 4, 4 become 8…

Question 16

stationary phase

Answer 16

• cells run out of nutrients and become surrounded by their wastes
• rate of reproduction decreases
• eventually number of dying cells = number of cells reproduced
• population is constant

Question 17

death phase

Answer 17

• lack of nutrients and accumulation of waste
• cells die faster than they reproduce
• some cells remain alive and continue to metabolize/reproduce

Question 18

biofilms

Answer 18

• primary residence of microorganisms in nature
• 99% of bacteria utilize biofilms
• account for 2/3 of infections bacteria in humans

Question 19

examples of biofilms causing diseases

Answer 19

• gum disease
• lung infection
• cystic fibrosis: body lacks enzymes that make mucous thinner so mucous cannot drain and bacterial colonies continue to grow

Question 20

antibiotics with biofilms

Answer 20

• bacteria cells that encounter antibiotics first will communicate with other bacteria cells in biofilm to upregulate genes for antibiotic resistance
• serves as a head start for other bacteria cells to protect themselves
• communicate through chemical signals

Question 21

teeth and biofilms

Answer 21

• bacteria in biofilms digest nutrients and release acid on teeth
• this can decay teeth and cause cavities

Question 22

sepsis

Answer 22

• bacteria all over body
• can lead to biofilm production
• increases mortality rate if biofilms form in lungs, heart, arteries….

Question 23

mechanisms of resistance in biofilms

Answer 23

• increase cell density and physical exclusion of antibiotics
• bacteria cells can undergo individual physiological changes to increase antibiotic resistance

Question 24

biofilm development

Answer 24

1. attachment
2. multiplication
3. exodus
4. quorum sensing
5. new cells and water channels
6. escapers and new biofilms

Question 25

attachment

Answer 25

bacteria cells settle on a surface and attach

Question 26

multiplication

Answer 26

• cells begin matrix production and secrete quorum sensing molecules
• cells begin to multiply

Question 27

exodus

Answer 27

• colony purposely gets rid of some bacteria that may take a longer time to grow
• matrix adheres cells to one another and to their substrates
• microenvironments are formed within biofilm
• water channels are formed between groups of cells

Question 28

quorum sensing

Answer 28

• microbes secrete molecules that act to communicate number and types of cells among members of the biofilm
• cells have receptors to bind with molecules
• if not enough molecules bind to bacteria cells, bacteria decide not to make enzymes otherwise it’s a waste of energy
• if enough chemical signals are present, they can make enzymes

Question 29

new cell arrival

Answer 29

• new cells can arrive to be part of biofilm
• there can be different bacteria cells in one biofilm
• biofilms attach to surfaces
• members assume different roles in different areas in biofilm

Question 30

microbes escape

Answer 30

• some bacteria cells can escape from biofilm and form new biofilms on different surfaces

Question 30

antimicrobial resistance

Answer 30

because biofilms can have many different bacteria cells it makes it harder for antimicrobial drugs to be effective