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Microbiology > Unit 2 videos 6-7 > Flashcards

Unit 2 videos 6-7 Flashcards

1
Q

What is Microbial growth?

A

Increase in the number of cells.

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2
Q

What are the chemical and energy requirements for growth?

A

Carbon, energy, and electrons

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3
Q

Organisms classified into two groups based on the source of carbon?

A
  • Autotrophs (inorganic) ex carbon dioxide
  • Heterotrophs (organic) ex Lipids, carbs, proteins
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4
Q

Organisms are classified into two groups based on the source of energy.

A
  • Chemotrophs (chemical)
  • Phototrophs (light)
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5
Q

What is an autotroph?

A

Make their organic carbon molecules from inorganic start materials using a process called Carbon fixation.

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6
Q

What is a heterotroph?

A

They cannot fix carbon; They require an external source of organic carbon to live and grow.

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7
Q

What are phototrophs?

A

Harvest energy from light to make ATP.

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8
Q

What are chemotrophs?

A

Harvest energy from chemical bonds of their nutrients to make ATP.

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9
Q

What are humans’ energy sources?

A

Chemohetrotrophs

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10
Q

What are pathogens’ energy sources?

A

Chemohetrotrophs

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11
Q

An organism that utilizes an inorganic source of carbon as its sole source is called?

A

Autotroph

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12
Q

What is the classification And type of cellular respiration if the final electron acceptor is oxygen?

A

Classification - obligate aerobes

Type of cellular respiration - aerobic respiration.

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13
Q

What is the classification And type of cellular respiration if the final electron acceptor is Nitrate, carbonate, or sulfate?

A

Classification - Obligate anaerobes

Type of cellular respiration - Anaerobic respiration

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14
Q

What is the classification And type of cellular respiration if the final electron acceptor is an organic compound?

A

Classification- Facultative Anaerobes

Type of cellular respiration - aerobic respiration and fermentation.

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15
Q

Oxygen is essential for?

A

Obligate aerobes

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16
Q

Oxygen is deadly for?

A

Obligate anaerobes

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17
Q

What are the four forms of toxic oxygen?

A
  • Singlet oxygen
  • Superoxide radicals
  • peroxide anion
  • Hydroxyl radical
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18
Q

What three enzymes detoxify oxygen?

A
  • Superoxide dismutase
  • catalase
  • peroxidase
    (only in obligate aerobe and facultative aerobe)
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19
Q

What is the goal of detoxifying enzymes?

A

Turn into water.

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20
Q

Physical requirements for growth?

A
  • Temperature
  • PH
  • Physical effect of water
  • Association and biofilms
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21
Q

Low temperature.

A

Decreases enzymatic reaction.

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22
Q

Increased temperature.

A
  • Speeds up enzymatic reactions.
  • Can increase the growth rate
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23
Q

High temperatures.

A

Denature proteins (kills cells)

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24
Q

Three temperature growth.

A

Maximum temperature - Highest temperature That supports growth

Minimum temp. - the lowest temperature that supports

Optimal temperature - temperature where cell growth is highest

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25
Q

Psychrophiles temperature range.

A

Thrive between -20 C to 10 C

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26
Q

Psychrotrophs temperature range.

A

Grow at 0 - 30 C
associated with food born illness

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27
Q

Mesophiles temperature range.

A

Grow at 10 - 50 C
Humans and pathogens

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28
Q

Thermophiles Temperature range.

A

Grow around 40-75 C
Associated with compost piles and hot springs

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29
Q

Extreme thermophiles temperature range.

A

Grow around 65 to 120 C

30
Q

Neutrophiles

A

Grow best in a narrow range around neutral PH; make up the majority of organisms

31
Q

Acidophiles

A

Grows best in acidic habitats

32
Q

Alkalinophiles

A

Live in alkaline soil and water.

33
Q

osmotic pressure

A

Pressure exerted on a semipermeable membrane by a solution containing salutes that cannot move free across the membrane

34
Q

Use for osmotic pressure in life?

A

Preserve food

35
Q

Halophiles

A

Prefer high concentrations of salt

36
Q

Obligate Halophiles

A

Grow optimally in solutions of 25% NaCl ( high osmatic pressure)

37
Q

Faculative Halophiles

A

They are resistant to salt, though they do not reside in high-salt environments ( S. aureus)

38
Q

Hydrostatic pressure

A

Water exerts pressure in proportion to its depth.

39
Q

Barophiles

A

Live under extreme pressure.

40
Q

What is binary fission?

A
  • Occurs in most prokaryotic cells
  • Involves diving a single cell into two
  • Asexual process
41
Q

Steps in binary fission.

A
  1. Replication of genetic material
  2. Cell elongation
  3. Cells form a new cytoplasmic membrane and wall across the midline (septum created)
  4. Splitting apart of new daughter cells (identical)
42
Q

Which step will make the two daughter cells identical to each other?

A

Step 1. Replication of genetic material

43
Q

What is binary fission?
A - the exchange of DNA between two cells
B - a way some organisms create energy
C- The fusion of two cells to create a new larger cell
D - A process in which a cell grows and divides to produce to daughter cells

A

D - A process in which a cell grows and dividends to produce daughter cells.

44
Q

What is generation time?

A
  • The time that is required for one cell to divide into two cells.
  • Times can be from 15 min to 24 hrs
  • depends on species and conditions
45
Q

Calculation for generation time

A

Generation time in minutes/ number of generations

46
Q

What is the type of growth called?

A

Exponential growth is always doubling. (2^n)

47
Q

Formula determines cell diving over time.

A

(initial number of cells) x ( 2^ number of generations)

48
Q

Four phases of the population curve

A

Lag phase - intense activity preparing for population growth. But no increase in population

Log phase - exponential increase in population

Stationary phase - Period of equilibrium; microbial deaths balance the production of new cells

Death phase - the population is decreasing at a logarithmic rate

49
Q

What is chemostat?

A

Device used to maintain a continuous culture in which nutrients are supplied at a steady rate.

Goal - sustain microbial growth in the log phase

50
Q

What is the name of genes that are expressed at all times?

A

Constitutive genes

51
Q

What are facultative genes?

A

Are made selectively, when a cell encounters a specific environmental change or has a specific job to do

52
Q

What is pre-transcriptional gene regulation?

A

Allows cells to control gene expression by regulating how much mRNA is made

Example - Operons

53
Q

What is post-transcriptional gene regulation?

A

Allows cells to control gene expression by regulating how often mRNA is translated into protein.

54
Q

What are operons?

A

A collection of genes controlled by a shared regulatory system.

55
Q

Do operons make catabolic reactions or anabolic reactions?

56
Q

What are the four parts of an operon?

A
  1. Promoter - the site where RNA Polymerase binds to start transcription.
  2. Genes - 2 or more that encode proteins that work together toward a shared task
  3. Repressor - that blocks transcription
  4. Operator - part of the operon that the repressor binds to to block transcription.
57
Q

What does the regulatory gene do?

A

Codify the repossessor

58
Q

Inducible operons

A
  • Involved in catabolic reactions
  • Off by default
  • Certain conditions activate (induce) transcription
59
Q

Repressible operons

A
  • involved in anabolic reactions
  • On by default
  • Actively transcribe until turned off (repressed)
60
Q

Lactose operon with glucose present and lactose absent.

A
  • Operon would be off (no transcription)
  • repressor would be active to maintain operon off
61
Q

Lactose operon with the presence of lactose and the absence of glucose.

A
  • inactivate repressor
  • operon will be on
62
Q

Repressor operon

A
  • usually on
  • anabolic operons
  • are transcribed continually until the repressor
  • For example, tryptophan operon
63
Q

Tryptophan is an example of a Repressor operon.

A

When tryptophan is low/absent, the operon on the repressor is inactive.

When tryptophan is high/present, the operon is off, and the repressor is active.

Co-repressor; excess of end product through feedback inhibition

64
Q

What kind of gene sequence is typically active and produces proteins but can be shut down?

A

A repressible operon

65
Q

What is vertical gene transfer?

A

Occurs when cell pass their genetic information to the next generation as a result of sexual or asexual

66
Q

What horizontal gene transfer?

A

Passes genetic information between cells by an independent process. (without cell division)
- passing of genes within the same generation
- Donor cell contributes part of the genome to the recipient cell

67
Q

What is transformation?

A
  • Recipient cell takes up all DNA in the environment
  • Must be competent
  • The donor cell is a dead cell that left behind naked DNA
  • naked DNA is DNA no longer enclosed in a cell
68
Q

What is transduction?

A
  • The donor cell is infected by bacteriophage
  • Goes through the lytic cycle
  • The donor cell will release a transducing phage that will infect the recipient cell
  • The bacteriophage Injects DNA in the host
  • recipient cell incorporates new DNA in chromosome through recombination.
  • Donor killed
  • recipient lives
69
Q

Process of Conjunction

A
  1. Donor cell attaches to recipient cell with sex pili
  2. Pilus may draw cells together
  3. One strand of F plasmid DNA transfers to the recipient
  4. The recipient synthesizes a complementary strand with pilus, and the donor synthesis a complementary strand, restoring its complete plasmid

Donor gives f + through sex pilus to recipient cell turning from f - to F +

70
Q

Hfr Conjugation

A
  1. F plasmid integrates into the chromosome by recombination
  2. cells join via sex pilus
  3. A portion of the plasmid partially moves into the recipient cell, trailing a strand of donor DNA.
  4. conjugation ends with pieces of f plasmid and donor DNA in the recipient cell. Cells synthesize complementary DNA strands
  5. Donor cells and recipient DNA recombine. Making a recombinant f -

( gains part of f plasmid and part of donor DNA)

71
Q
A

just in case

Microbiology (23 decks)

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