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Mircobiology > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Describe three ways in which viruses are cultivated., and which are in vivo and in vitro.

A

In vivo: laboratory-bred animals and embryonic bird tissues.

In Vitro: cell or tissue culture methods

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2
Q

Discuss why antibiotics are not prescribed for a viral infection

A

Antibiotics designed to treat bacterial infections have no effect on viruses. It is difficult to find drugs that will affect viruses without damaging host cells

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3
Q

Distinguish between organic and inorganic nutrients

A

Inorganic: Not carbon and hydrogen. Found in the earth’s crust, bodies of water, and the atmosphere. Metals and thier salts.

Organic: Contain Carbon and hydrogen atoms usually the product of living things. Large polymers

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4
Q

List the nutrients that comprise 96% of the dry weight of a bacterial cell

A 
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorous
Sulfur
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5
Q

Define an photoautotroph

A

Energy source: Sunlight
Carbon Source: CO2
Ex: algae, plants

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6
Q

Define a chemoautotroph

A

Energy source: Organic compounds
Carbon Source: CO2
Ex: Methanogens

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7
Q

Define a photoheterotroph

A

Energy source: Sunlight
Carbon source: organic
Ex: “rock-eating” bacteria

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8
Q

Define a chemoheterotroph

A

Energy source: metabolic conversions of the nutrients from other organisms
Carbon source: organic
Ex: Protozoa, fungi, many bacteria, animals

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9
Q

Define saprobe

A

Free-living organisisms that feed on organic detritus from dead organisms. Decomposers of plant litter, animal matter, and dead microbes. recycle organic nutrients.

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10
Q

Define parasite

A

Derive nutrients from the cells and tissues of a living host

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11
Q

Define facultative parasite

A

able to change whether they grow inside of outside of a living host

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12
Q

Define obligate parasite

A

unable to grow outside of a living host

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13
Q

Distinguish between minimum, maximum, and optimal temp

A

Min temp: the lowest temp that permits microbes continues growth and metabolism; below this temp its activities stop.

Max: the highest temp at which growth & metabolism can proceed before proteins are denatured.

Opt: an intermediate between the min and the max that promotes the fastest rate of growth & metabolism

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14
Q

Why can psychrotroph and thermoduric organisims can be problematic in microbial food contamination

A

grow slowly in the cold but have an optimum temp of 15 and 30 degrees Celcius. S. aureus and L. monocytogenes are able to grow at refrigerator temps and cause food-borne illness

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15
Q

Describe the 4 different terms that describe a microbes growth under various oxygen conditions

A

Aerobes: can use gaseous oxygen
Facultative Anaerobes: do not require oxygen but use it when it’s present
Anaerobes: lack the metabolism enzymes systems for using O2 in respiration
Obligate anerobes: also lack the enzymes for processing toxic oxygen and die in it’s presence

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16
Q

Explain why microbes need to ‘detoxify’ oxygen

A

Oxygen can be highly reactive and bad for cells..

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17
Q

Define mutualism

A

Both members benefit

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18
Q

Define commensalism

A

One member benefits, other member isn’t harmed

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19
Q

Define parasitism

A

Parasite benefits; host is harmed

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20
Q

Define synergism

A

Members cooperate and share nutrients

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21
Q

Define antagonism

A

Some members are inhibited by others

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22
Q

Define a biofilm and the first 2 steps that lead to biofilm formation

A

Communities of microbes attached to a surface and each other.

1st: a “pioneer” colonizer intially attaches to a surface
2nd: other microbes then attach to those bacteria or a polymeric sugar or protein substance secreted by the microbial colonizers.

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23
Q

Identify binary fission and the 4 basic steps in the process

A

Central division of one cell into two.

  1. Parent cells enlarges
  2. Duplicates its chromosomes
  3. Starts to pull its cell envelope together to the center of the cell
  4. Cell wall eventually forms a complete central septum
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24
Q

Identify generation time/ doubling time in microbes

A

The time required for a complete fission cycle, from parent cell to 2 daughter cells

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25
Q

Identify a growth curve

A

a predictable pattern of a bacterial population in a closed system.

  1. Lag phase
  2. Exponential growth phase
  3. Stationary phase
  4. death phase
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26
Q

Which stage is most susceptible to treatment and why

A

Exponential growth

Actively growing cells are more vulnerable to conditions that disrupt cell metabolism and binary fission.

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27
Q

Which stage is most likely to spread

A

A person actively shedding bacteria in the early and middle stages of infection is more likely to spread

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28
Q

Identify metabolism

A

Pertains to all chemical reactions and physical workings of the cell

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29
Q

Define catabolism

A

Breaks the bonds of larger molecules into smaller molecules. releases energy

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30
Q

Define anabolism

A

A building and bond-making process that forms larger macromolecules from smaller ones. Requires energy input

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31
Q

Describe why catabolism and anabolism are linked

A

Energy is never gained or lost by the cell, just transferred

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32
Q

Describe an enzyme

A

Simply types of proteins. Comprise amino acids like any proteins but can break and form chemical bonds. Biological catalysts.
Increase the rate of chemical reactions

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33
Q

Describe an active site

A

The lock to an enzyme

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34
Q

Describe a cofactor

A

Non-protein molecules attached to an enzyme required for enzyme activity

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35
Q

Describe a coenzyme

A

organic molecules (often modified vitamins)

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36
Q

Describe a holoenzyme

A

Enzyme plus cofactor

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37
Q

Describe what it means to state an enzyme as a catalyst

A

They’re able to lower the energy barrier needed to create a reaction

38
Q

Define ‘enzyme specificty’

A

An enzyme is specific; it recognizes one and only one complementary shaped substrate

39
Q

Why is a denatured enzyme bad for a reaction

A

Because it can no longer function

40
Q

Explain the difference between a constitutive enzyme and regulated enzymes

A

Constitutive enzymes: are central to life and so are generally always around. Must be produced at a constant rate all the time.

Regulated: Some enzymes only need to present when they are needed. They are produced and destroyed at specific times

41
Q

Explain the difference between competitive and noncompetitive inhibition

A

Competitive Inhibition: molecular “mimic” occupies the active site, preventing actual substrate from binding.

Noncompetitive: Enzymes have 2 binding sites: the active site and a regulatory site. Molecules bind to the regulatory site, which reduces activity.

42
Q

Explain the difference between a repressed and induced enzyme gene

A

Enzyme repression: Genetic apparatus responsible for replacing enzymes is automatically turned ‘off’

Enzyme induction: Enzymes appear (are induced- gene is turned on) only when suitable substrates are present

43
Q

Identify the metabolic pathway

A

The forming and breaking of cells to create chemical reactions within the body

44
Q

Identify oxidation

A

the loss of electrons

45
Q

Identify reduction

A

the gain of electrons

46
Q

Identify redox

A

Reactions that are common in the cell and are indispensable to the required energy transformations

47
Q

Identify carrier electrons in redox reactions

A

Oxidoreductase: enzymes that remove electrons from one substrate and add them to another

48
Q

Name the chemical where energy from redox reactions is stored and released

A

ADP

49
Q

Identify the 3 main catabolic pathways

A
  1. Aerobic Respiration
  2. Anaerobic Respiration
  3. Fermentation
50
Q

Aerobic Respiration Stages

A
  1. Glycolysis: breaks down Glucose. Uses 2 ATP. Yields 4 ATP 2 NADH
  2. The Krebs Cycle: Uses acetyl CoA. Yields 6 NADH 2 FAHD2 and 2 ATP
  3. ETC: Uses 8 NADH and 2 FADH2. Yields 32 to 34 ATP
51
Q

Anaerobic Respiration

A

The same as Aerobic excepts uses an inorganic final electron acceptor produces 2 to 36 ATP

52
Q

Fermentation

A

Glycolysis same as Aerobic uses organic final electron acceptor. Produces 2 ATP

53
Q

Describe Oxidative Phosphorylation

A

the coupling of ATP synthesis to electron transport

54
Q

Describe what the respiratory chain is

A

A chain of special redox reactions. Embedded in the inner membrane of the mitochondria. Receives electrons from reduced carries generated and passes them in a sequential and orderly fashion from one redox molecule to the next

55
Q

How many ATP are produced in total andper NADH/FADH molecule?

A

NADH gives 3

FADH2 gives 2

56
Q

Name the final electron acceptor

A

Oxygen

57
Q

Describe how the anaerobic respiration differs from aerobic in terms of final electron acceptors, ATP production, and name at least two different types of electron acceptors

A

It differs in that it doesn’t use oxygen as a final electron acceptor. So anaerobic respiration can produce less ATP, anywhere from 2 to 36 versus 36-38. It can use Nitrate and Sulfate as a final electron acceptor

58
Q

List three products of fermentation

A

Alcoholic beverages: ethanol and CO2
Organic acids: lactic and acetic acid
Solvents: acetone & butanol

59
Q

Name two molecules that can be used in glycolysis besides glucose

A

Carbohydrates and fats

60
Q

Describe what amphibolism means and how it contributes to the overall efficiency of the cell

A

The ability of a system to integrate catabolic and anabolic pathways to improve cell efficiency

61
Q

Define genome

A

The sum total of genetice material of an organism

62
Q

Identify where the genome is located and what it is composed of (DNA or RNA) in bacteria, eukaryotes and viruses

A

In chromosomes
It’s composed of DNA
Viruses can be DNA or RNA

63
Q

Contrast the composition, shape, ploidy, and number of chromosomes in eukaryotes,bacteria, and viruses

A

Eukaryotes: DNA wound around histone proteins, all covered in protein. DNA covered in chromatin protein. Located in the nucleus, diploid or haploid, linear species, 3 dozens/species
Bacteria: DNA condensed into a packet by means of “histone-like proteins”, otherwise naked DNA. 1-3 circular chromosomes, always haploid,
Viruses: Don’t have chromosomes

64
Q

List the two different types of coding genes

A

Protein-coding genes & RNA genes

65
Q

Contrast gene number and density in eukaryotes, bacteria, and viruses

A 
Eukaryotes: 5-100 thousand
Large genomes
Bacteria: 1-10 thousand
Medium genomes
Virus: 5-500
66
Q

Identify phenotype versus genotype

A

Genotype: the sum of all genotypes; an organisms distinctive genetic makeup
Phenotype: the expression of certain traits

67
Q

Describe all nucleotides, which are purines/pyrimidines

A

(A)denine pairs with (T)hymine (G)uanine pairs with (C)ytosine

A and G are purines
T and C are pyrimidines

Double stranded DNA is complementary

68
Q

How is complementary double strands of DNA are constructed

A

Replication proceeds in both directions from each starting point

69
Q

Describe the flow of information in the cell and the central dogma

A

Replication then transcription and translation

70
Q

List the three steps of transcription

A

Initiation
Elongation
Termination

71
Q

Contrast initiation complexity in eukaryotes and bacteria

A
  1. Eukaryotes chromosomes must be exposed
  2. The second added complexity is that the ‘promoter’ sequence alone is often insufficient to initiate, and distant ‘enhancer’ regions of DNA must also be activated by proteins for transcription in addition to those present at the promoter site

Bacteria chromosomes are already exposed are easier to initiate

72
Q

Describe the differences in gene organization and processing betweeneukaryotes and bacteria

A

Bacterial genomes are more compact, and related genes with respect to function can be placed on a single transcript, later separated as different protein genes following translation.

Eukaryotic genes contain introns and exons that must be spliced prior to translation

73
Q

Describe the differences in ribosomes betweeneukaryotes and bacteria

A

Ribosomes in bacteria, mitochondria, and chloroplasts are 70S size, made up of 50S and 30S subunits

Eukaryotic ribosomes are 80S, made up of 60S and 40S subunits

74
Q

Explain what a polyribosome is and why the lack of cellular compartments in bacteria allows for near simultaneous transcription and translation

A

Many ribosomes on a single transcript are added as the transcript is made.

So many proteins can code at one time

75
Q

Identify an operon

A

Protein genes that can be turned on and off as a unit

76
Q

Contrast gene induction versus repression

A

Catabolic operons:
Induced by the substrate of the enzyme(s) for which the structural genes code
Only produce the enzyme when the substrate is present

Repressible operons:
Anabolic enzymes
Turned off by the product synthesized by the enzyme

77
Q

Describe how the lac operon is controlled

A

Regulator: composed of the gene that codes for a protein capable of repressing the operon (a repressor)
Control locus:
Promoter: recognized by RNA polymerase
Operator: on/off switch

78
Q

Identify steps in the three processes of genetic exchange: conjugation

A

Conjugation is a conservative process in which the donor bacterium retains (“conserves”) a copy of the genetic material being transferred
So no bacteria loose or trade DNA, one bacteria makes a copy that will be given to the donor

79
Q

Compare, contrast, describe, identify steps in the three processes of genetic exchange: transformation

A

A chromosome released by a lysed cell breaks into fragments small enough to be accepted by a recipient cell

80
Q

, identify steps in the three processes of genetic exchange: Generalized transduction

A

Bacteriophage serves as a carrier from a donor cell to a recipient cell
Random fragments of disintegrating host DNA are taken up by the bacteriophage
Virtually any gene from the bacterium can be transmitted

81
Q

identify F factor

A

Fertility factor

82
Q

Contrast F factor versus Hfr conjugation

A

Plasmid becomes integrated into the F+ donor chromosome
Some chromosomal genes get transferred to the recipient
Plasmid genes may or may not be transferred

83
Q

Describe what competent bacterial cells are with respect to transformation

A

Competent: cells that are capable of accepting genetic material

84
Q

Distinguish between generalized and specialized transduction

A

In generalized transduction, the bacteriophages can pick up any portion of the host’s genome. In contrast, with specialized transduction, the bacteriophages pick up only specific portions of the host’s DNA

85
Q

Describe what a transposable element is and how it acts on the genome

A

“Jumping genes”

Transposable elements capable of shifting from one part of the genome to another
Can be transferred from a chromosome to a plasmid, or vice versa; or from one cell to another in bacteria and some eukaryotes
Some replicate themselves before jumping to the next location and some simply move

86
Q

Define missense mutation

A

Any change in the code that leads to the placement of a different amino acid

87
Q

Define silent mutation

A

Alters a base, but does notchange the amino acid, and has no effect

88
Q

Define nonsense mutation

A

Changes a normal mutation into a stop codon

89
Q

Define back-mutation

A

When a gene that has undergonea mutation reverses back to its original basecomposition

90
Q

Define frameshift mutation

A

One or more bases are inserted or deleted
Changes the reading frame of the mRNA
Nearly always results in a nonfunctional protein

91
Q

Define SNP

A

Single nucleotide polymorphism (SNP) only a single base is altered

Mircobiology (3 decks)

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