Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MicroBio > Module 3 > Flashcards

Module 3 Flashcards

1
Q

Describe the prokaryotic process of prokaryotic process of binary fission

A

Look in text book.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What eukaryotic cellular process is most similar to prokaryotic binary fission

A

Mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In microbial growth what does “doubling time” mean?

A

The time it takes for the population to double through one round of binary fission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How are the number of cells in a culture and the generation number related?

A

Nn is the number of cells at any generation n, N0 is the initial number of cells, and n is the number of generations.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do you calculate the population size in a culture at a given time when you know the doubling time? (assuming no cell death)

A

2^n, where n is the number of generations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Lag phase

A
  • No increase in number of living bacterial cells.
  • Small number of cells (innoculum) added to culture medium
  • Cells gearing up for next phase of growth
  • Number of cells does not change
  • Cells grow larger
  • Cells are metabolically active, synthesizing proteins needed to grow within the medium
  • If any cells damaged or shocked, repair takes place here
  • Duration of lag phase determined by species, genetic make-up, composition of medium, size of original inoculum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Log phase

A
  • Exponential increase in number of living bacterial cells
  • Cells actively dividing by binary fission
  • Generation time under specific growth conditions genetically determined
  • Generation time referred to as intrinsic growth rate
  • Relationship between time and number of cells is not linear, but exponential, but growth curve plotted on semilogarithmic graph which gives appearance of linear relationship.
    -Waste products accumulate, nutrients used up, depletion of oxygen limit aerobic cell growth, which stall population growth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Stationary phase

A
  • Plateau in number of living bacterial cells; rate of cell division and death roughly equal
  • Population of living cells relatively stagnant
  • Culture density and stationary culture constant
  • Cultures carrying capacity or maximum culture density depends on the types of microorganisms and specific conditions of culutre
    -carrying capacity is constant for a given organism grown under the same conditions.
  • Cells switch to survival mode of metabolism
  • Growth slows so does synthesis of peptidoglycans, proteins, nucleic acids, less susceptible to antibiotics that disrupt these processes.
    -In bacteria capable of producing endospores, many cells undergo sporulation during the stationary phase.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Death phase

A
  • Exponential decrease in number of living bacterial cells
  • Culture medium accumulates toxic waste and nutrients are exhausted, cells die in greater and greater numbers.
  • Number of dying cells exceeds number of dividing cells
  • Cells lyse and release nutrients into medium allowing surviving cells to maintain viability and form endospores.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why is the standard growth curve observed only in closed cultures (i.e.
nothing is added or removed after inoculation)? How is a chemostat
different?

A

Bacteria will grow in a predictable pattern in closed cultures (growth curve). A chemostat is used to maintain a continuous culture in which nutrients are supplied at a steady rate. Bacterial suspension is removed at the same rate as nutrients flow in to maintain an optimal growth environment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the difference between direct and indirect methods of quantifying growth

A
  • Direct cell count refers to counting the cells in a liquid culture or colonies on a plate. Ex. Direct microscope cell count
  • Indirect cell counts are an indirect detection of cell density and are commonly used to estimate and compare cell densities in a culture. Ex. Turbidity (cloudiness) of a sample of bacteria in a liquid suspension using spectrophometer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a biofilm?

A

Complex and dynamic ecosystems that form on a variety of environmental surfaces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the same in all environments where biofilms occur?

A

Regardless of the environment where they occur, biofilms are not random collections of microorganisms; rather, they are highly structured communities that provide a selective advantage to their constituent microorganisms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Explain in simple terms how a biofilm forms on a surface

A
  1. Reversible attachment of planktonic cells
  2. First colonizers become irreversible attached.
  3. Growth and cell division
  4. Production of EPS and formation of water channels
  5. Attachment of secondary colonizers and dispersion of microbes to new sites.
    - Involves the attachment of planktonic cells to a substrate, where they become sessile (attached to a surface).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Obligate anaerode

A

Are killed by oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

aerotolerant

A

Indifferent to the presence of oxygen, do not use oxygen because they have fermentative metabolism, but are not harmed by oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

microaerophile

A

Require minimum level of oxygen for growth (1-10%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

facultative anaerobe

A

Thrive in the presence of oxygen, but also grow in its absence by relying on fermentation or anaerobic respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

obligate aerobe

A

Cannot grow without an abundant supply of oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Explain the different between optimum oxygen concentration and minimum/maximum permissive oxygen concentrations

A

Optimum oxygen concentration is the ideal concentration of oxygen for a particular microorganism. The minimum permissive oxygen concentration is the lowest concentration of oxygen that allows for growth. The maximum permissive oxygen concentration is the highest tolerated concentration of oxygen.

21
Q

Describe why cells require defenses against reactive oxygen species and provide example of oxygen stress defense enzymes

A

Most organisms could not survive the powerful oxidative properties of reactive oxygen species (ROS), highly unstable ions and molecules derived from partial reduction of oxygen that can damage virtually any macromolecule or structure with which they come in contact. 3 main enzymes break down toxic byproducts: superoxide dismutase, peroxidase, and catalase

22
Q

What is the pH range for neutrophile?

A

Grow optimally at a pH one or two pH units of pH7

23
Q

What is the pH range for acidophile

A

Grow optimally at pH less than 5.55

24
Q

What is the pH range for alkaliphile?

A

Grow best at pH between 8.0 and 10.5

25
Q

What are some of the effects we might expect on proteins and membranes at extremes of pH?

A

Moderate changes in pH modify the ionization of amino-acid functional groups and disrupt hydrogen bonding, which, in turn, promotes changes in the folding of the molecule promoting denaturation and destroying activity.

26
Q

Distinguish between optimum growth pH and minimum/maximum growth pH

A

The optimum growth pH is the most favorable pH for the growth of an organism. The lowest pH value that an organism can tolerate is called the minimum growth pH. The highest pH is the maximum growth pH.

27
Q

Psychrophiles

A
  • Can grow at 0 and below
  • Optimum growth temperature close to 15
  • Do not survive above 20
28
Q

Psychrotrophs

A
  • High of 25 to 4
29
Q

Mesophiles

A
  • Optimal growth at room temps (20) to 45
30
Q

Thermophiles

A
  • Grow at optimum of 50 to max of 80
31
Q

Hyperthermophiles

A
  • grow at ranges from 80 to 110 with some extreme examples above 121
32
Q

Physiological adaptions in Extreme heat? Provide one example of a hyperthermophile and the
environment where it was discovered

A
  • Ratio of saturated to polyunsaturated lipids increases to limit the fluidity of the cell membranes
  • DNA sequences show a higher proportion of guanine-cytosione nitrogenous bases
  • Additional secondary structures, ionic and covalent bonds, as well as the replacement of key amino acids to stabilize folding, contribute to the resistance of proteins to denaturation.
33
Q

Physiological adaptations Extreme cold? Provide one example of a psychrophile and the
environment where it was discovered

A
  • Rich in hydrophobic residues
  • Increase flexibility
  • Lower number of secondary stabilizing bonds
34
Q

Describe the physical/chemical environment of Halophile

A

Require high salt concentrations for growth
- salt loving

35
Q

Describe the physical/chemical environment of Barohphile

A

Require high atmospheric pressure for growth

36
Q

Are photosynthetic organisms “extremeohiles”?

A

Some are because they live in extreme harsh environments such as hotsprings and hypersaline bays.

37
Q

Defined growth media

A

When the complete chemical composition of a medium is known

38
Q

Selective growth media

A

Media that inhibit the growth of unwanted microorganisms and support the growth of the organism of interest by supplying nutrients and reducing competition

39
Q

Enriched growth media

A

Contains growth factors, vitamins, and other essential nutrients to promote the growth of fastidious organisms, organisms that cannot make certain nutrients and require them to be added to the medium.

40
Q

Differential growth media

A

Make it easy to distinguish colonies of different bacteria by a change in color of the colonies or the color of the medium.

41
Q

how did experiments with single-celled Acetabularia contribute to our
understanding of genetics and expression of genetic information?

A

Established that the genetic information in a eukaryotic cell is housed within the nucleus

42
Q

How did Griffith’s experiments demonstrate the process of transformation?

A

Griffith concluded that something had passed from the heat-killed S strain into the live R strain and “transformed” it into the pathogenic S strain; he called this the “transforming principle.”

43
Q

What is transformation?

A

A process in which external DNA is taken up by a cell, thereby changing its characteristics

44
Q

How did Hershey and Chase’s experiments demonstrate that DNA, and not
protein, is the genetic material for cells?

A

In the tube with the protein labeled, the radioactivity remained only in the supernatant. In the tube with the DNA labeled, the radioactivity was detected only in the bacterial cells. Hershey and Chase concluded that it was the phage DNA that was injected into the cell that carried the information to produce more phage particles, thus proving that DNA, not proteins, was the source of the genetic material.

45
Q

Describe the chemical composition and structure of nucleotides and DNA

A
46
Q

Distinguish between the structures of the bases found in DNA in terms of hydrogen bonding and number of ring structures

A
47
Q

Distinguish between the structures of the bases found in RNA in terms of hydrogen bonding and number of ring structures

A
48
Q

Explain how duplex (double-stranded) DNA is stabilized by chemical interactions and how those interactions can be disrupted

A

MicroBio (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions