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BIO153 > Lecture 8: Bacterial growth and metabolism > Flashcards

Lecture 8: Bacterial growth and metabolism Flashcards

(43 cards)

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1
Q

how does bacteria replicate?

A

binary fission: a fundamental form of asexual reproduction where a single cell divides into two genetically identical daughter cells

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2
Q

how do bacteria populations grow?

A

Bacterial population grows exponentially

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3
Q

what does the large numbers of bacterial populations mean for natural selection?

A
  • More cell division means more DNA
    replication
  • More DNA replication means more chance for DNA to mutate
  • Members of population may have mutations advantageous to environment
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4
Q

Explain antibiotic resistance

A
  1. Some members of population mutated into antibiotic resistance strains by chance (red cells)
  2. Antibiotic resistant strains survive
    antibiotics (natural selection)
  3. Survivors grow back into a population of antibiotic resistant bacteria
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5
Q

requirements of life/growth?

A
  1. Needs energy
  2. Needs carbon source
  3. (among many other elements like nitrogen)
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6
Q

Photoautotrophs make __ from __

A

organic molecules (such as glucose)
sunlight, water and CO2

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7
Q

Chemoheterotrophs use

A

organic molecules to extract energy and as a carbon source

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8
Q

Glycolysis

A

the process from which energy is extracted from glucose

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9
Q

Glucose has how many carbons?

A

6 carbon sugar

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10
Q

Glycolysis generates

A
  • 2 pyruvate (3-carbon sugar)
  • 4 ATP
  • 4 electrons (e-) + 4 protons (H+)
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11
Q

What is the net gain per glucose

A

Net 2 ATP gain per glucose

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12
Q

Of 4 ATP produced after splitting 1 glucose:

A
  • 2 gets used to split another glucose
  • 2 gets used for other jobs in the cell
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13
Q

NAD +

A

an organic molecule which can
bind to electrons

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14
Q

chemical reaction for NADH

A

(NAD^+) + (H^+) + 2 e- = NADH

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15
Q

Every time glucose gets split…

A

NAD + is used to accept electrons

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16
Q

what is the problem regarding NAD+

A

Limited number in cell

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17
Q

Can not do __ once NAD + gets
depleted

A

glycolysis

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18
Q

What is fermentation used to do?

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A
  • Use pyruvate to regenerate NAD+
  • Pyruvate is the other product produced by
    glycolysis
19
Q

chemical reaction showing regeneration of NAD+

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A

Pyruvate + NADH = (NAD^+) + fermented products

20
Q

Pyruvate gets turned into fermentation
products in the process such as

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A

acids, alcohols etc

21
Q

Fermentation happens

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A

anaerobically

22
Q

is Fermentation efficient?

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A

Fermentation is not efficient
* Pyruvate is a 3-carbon molecule
which has more energy stored
* Fermentation does not use this extra
energy since it uses pyruvate to
regenerate NAD+

23
Q

Krebs cycle extracts energy which is left
inside pyruvate. What does one pyruvate become?

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A

One pyruvate eventually becomes 3 CO 2

24
Q

Krebs cycle makes more ___

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A

NADH (and other electron carriers) + ATP

25
NADH gives electrons to
ETC, this regenerates NAD+
26
Energy is produced as
electrons pass through ETC, used to make ATP * At the end of ETC, electrons are put onto O2, the terminal electron acceptor
27
Aerobic respiration extracts the maximum amount of energy from glucose, producing up to
38 ATP per glucose
28
What part does O2 play?
* O2 is a very powerful electron acceptor * Using O 2 as the terminal electron acceptor allows electrons to pass through ETC at maximum efficiency, extracting maximum energy * Aerobic organisms (like human) are dependent on O2 to produce energy
29
Anaerobic Respiration
* Respiration can be done using molecules other than O 2 as terminal electron acceptors * NO 3- (nitrate) * SO 42- (sulphate) * Non-O 2 electron acceptors are not as effective as O 2 to drive electrons through ETC
30
Order the following processes based on how much total energy is produced: aerobic respiration, anaerobic respiration, fermentation
Fermentation < Anaerobic < Aerobic
31
Obligate aerobes
Oxygen required for survival
32
Facultative anaerobes
* Can use oxygen when available * Can survive by anaerobic respiration and/or fermentation if necessary
33
Obligate anaerobes
* Can not survive when oxygen is present * Oxygen is extremely reactive and is poisonous for organisms who does not have protective measures
34
Mycobacterium tuberculosis
* Obligate aerobe * Respiratory pathogen
35
E. coli
* Facultative aerobe * Gut microbe/pathogen
36
____ is consumed using ___ during aerobic exercise
Glucose O2
37
We ferment pyruvate into ___ to produce more energy anaerobically
lactic acid * Accumulation of Lactic acid Lactic is said to be correlated with muscle fatigue, although this theory is sill being debated
38
yogurt fermentation process
* Must be done anaerobically * Lactobacillus bulgaricus and Streptococcus thermophilus are put into milk * Both Gram positive lactose-fermenting bacteria * Lactose fermented to lactic acid * Acidifies the product, thickening the solution * In addition, L. bulgaricus and S. thermophilus performs other other metabolic activities * All of this contributes to the taste and texture of yogurt
39
how is the growth of organisms like E coli stopped during yogurt fermentation?
Acidification of yogurt (+ high incubation temperature) suppresses growth of other bacteria such as E. coli
40
ethanol/alcohol fermentation
* Yeast (Saccharomyces cerevisiae), a unicellular eukaryote (Fungi) * Used for many food processes, including production of alcohol from various sources of starch * Type of starch contributes to the type of alcoholic beverage produced * Alcohol production begins to inhibit yeast growth after a while
41
Cyanobacteria: producing glucose
* Gram negative photoautotrophic bacteria * Only clade of bacteria capable of photoautotrophy * Use sunlight to produce organic molecules like glucose from CO 2 * Carbon fixation: Chemical energy generated by sunlight gets stored in glucose CO2 + H 2O + sunlight = glucose + O2
42
Some cyanobacteria are also capable of
nitrogen fixation: convert atmospheric N 2 to ammonia (NH3) * Nitrogen is essential for making DNA, proteins, etc. * Most organisms can not use N2 as their nitrogen source and depend on ammonia produced by nitrogen fixers
43
how does cyanobacteria do nitrogen fixation while producing O2 as a product
* Some cells in cyanobacteria filament terminally differentiate to heterocysts: cells specialized for nitrogen fixation * Heterocysts can not survive on its own * Can not photosynthesize and depends on neighboring vegetative cells to provide glucose etc. * Heterocysts form barrier to block O2 entry, allowing nitrogen fixation inside their cell * Heterocysts provide fixed nitrogen to neighboring cells

BIO153 (18 decks)

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