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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
Identify a growth curve
a predictable pattern of a bacterial population in a closed system. 1. Lag phase 2. Exponential growth phase 3. Stationary phase 4. death phase
26
Which stage is most susceptible to treatment and why
Exponential growth | Actively growing cells are more vulnerable to conditions that disrupt cell metabolism and binary fission.
27
Which stage is most likely to spread
A person actively shedding bacteria in the early and middle stages of infection is more likely to spread
28
Identify metabolism
Pertains to all chemical reactions and physical workings of the cell
29
Define catabolism
Breaks the bonds of larger molecules into smaller molecules. releases energy
30
Define anabolism
A building and bond-making process that forms larger macromolecules from smaller ones. Requires energy input
31
Describe why catabolism and anabolism are linked
Energy is never gained or lost by the cell, just transferred
32
Describe an enzyme
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
33
Describe an active site
The lock to an enzyme
34
Describe a cofactor
Non-protein molecules attached to an enzyme required for enzyme activity
35
Describe a coenzyme
organic molecules (often modified vitamins)
36
Describe a holoenzyme
Enzyme plus cofactor
37
Describe what it means to state an enzyme as a catalyst
They're able to lower the energy barrier needed to create a reaction
38
Define 'enzyme specificty'
An enzyme is specific; it recognizes one and only one complementary shaped substrate
39
Why is a denatured enzyme bad for a reaction
Because it can no longer function
40
Explain the difference between a constitutive enzyme and regulated enzymes
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
Explain the difference between competitive and noncompetitive inhibition
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
Explain the difference between a repressed and induced enzyme gene
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
Identify the metabolic pathway
The forming and breaking of cells to create chemical reactions within the body
44
Identify oxidation
the loss of electrons
45
Identify reduction
the gain of electrons
46
Identify redox
Reactions that are common in the cell and are indispensable to the required energy transformations
47
Identify carrier electrons in redox reactions
Oxidoreductase: enzymes that remove electrons from one substrate and add them to another
48
Name the chemical where energy from redox reactions is stored and released
ADP
49
Identify the 3 main catabolic pathways
1. Aerobic Respiration 2. Anaerobic Respiration 3. Fermentation
50
Aerobic Respiration Stages
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
Anaerobic Respiration
The same as Aerobic excepts uses an inorganic final electron acceptor produces 2 to 36 ATP
52
Fermentation
Glycolysis same as Aerobic uses organic final electron acceptor. Produces 2 ATP
53
Describe Oxidative Phosphorylation
the coupling of ATP synthesis to electron transport
54
Describe what the respiratory chain is
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
How many ATP are produced in total and per NADH/FADH molecule?
NADH gives 3 | FADH2 gives 2
56
Name the final electron acceptor
Oxygen
57
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
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
List three products of fermentation
Alcoholic beverages: ethanol and CO2 Organic acids: lactic and acetic acid Solvents: acetone & butanol
59
Name two molecules that can be used in glycolysis besides glucose
Carbohydrates and fats
60
Describe what amphibolism means and how it contributes to the overall efficiency of the cell
The ability of a system to integrate catabolic and anabolic pathways to improve cell efficiency
61
Define genome
The sum total of genetice material of an organism
62
Identify where the genome is located and what it is composed of (DNA or RNA) in bacteria, eukaryotes and viruses
In chromosomes It's composed of DNA Viruses can be DNA or RNA
63
Contrast the composition, shape, ploidy, and number of chromosomes in eukaryotes, bacteria, and viruses
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
List the two different types of coding genes
Protein-coding genes & RNA genes
65
Contrast gene number and density in eukaryotes, bacteria, and viruses
``` Eukaryotes: 5-100 thousand Large genomes Bacteria: 1-10 thousand Medium genomes Virus: 5-500 ```
66
Identify phenotype versus genotype
Genotype: the sum of all genotypes; an organisms distinctive genetic makeup Phenotype: the expression of certain traits
67
Describe all nucleotides, which are purines/pyrimidines
(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
How is complementary double strands of DNA are constructed
Replication proceeds in both directions from each starting point
69
Describe the flow of information in the cell and the central dogma
Replication then transcription and translation
70
List the three steps of transcription
Initiation Elongation Termination
71
Contrast initiation complexity in eukaryotes and bacteria
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
Describe the differences in gene organization and processing between eukaryotes and bacteria
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
Describe the differences in ribosomes between eukaryotes and bacteria
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
Explain what a polyribosome is and why the lack of cellular compartments in bacteria allows for near simultaneous transcription and translation
Many ribosomes on a single transcript are added as the transcript is made. So many proteins can code at one time
75
Identify an operon
Protein genes that can be turned on and off as a unit
76
Contrast gene induction versus repression
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
Describe how the lac operon is controlled
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
Identify steps in the three processes of genetic exchange: conjugation
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
Compare, contrast, describe, identify steps in the three processes of genetic exchange: transformation
A chromosome released by a lysed cell breaks into fragments small enough to be accepted by a recipient cell
80
, identify steps in the three processes of genetic exchange: Generalized transduction
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
identify F factor
Fertility factor
82
Contrast F factor versus Hfr conjugation
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
Describe what competent bacterial cells are with respect to transformation
Competent: cells that are capable of accepting genetic material
84
Distinguish between generalized and specialized transduction
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
Describe what a transposable element is and how it acts on the genome
"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
Define missense mutation
Any change in the code that leads to the placement of a different amino acid
87
Define silent mutation
Alters a base, but does not change the amino acid, and has no effect
88
Define nonsense mutation
Changes a normal mutation into a stop codon
89
Define back-mutation
When a gene that has undergone a mutation reverses back to its original base composition
90
Define frameshift mutation
One or more bases are inserted or deleted Changes the reading frame of the mRNA Nearly always results in a nonfunctional protein
91
Define SNP
Single nucleotide polymorphism (SNP) only a single base is altered

Mircobiology (3 decks)

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