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BIO 233 > Bacterial and Viral Genetics > Flashcards

Bacterial and Viral Genetics Flashcards

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1
Q
  • Central Dogma
  • Transcription
    • RNA Polymerase
    • Reads DNA to make RNA
  • Translation
    • Ribosomes
    • mRNA read to make proteins
A

Protein Synthesis

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2
Q

Regulation of Protein Synthesis

What are the components for transcriptional regulation?

A

Transcriptional Regulation

  1. Sigma factors
  2. Promoters
  3. Operon
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3
Q

Regulation of Protein Synthesis

What is the factor for translational regulation?

A

Translational Regulation

  1. Ribosome binding site
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4
Q
  • Protein that directs RNA polymerases to transcribe a particular gene(s)
  • Several different sigma factors in a bacterial cell
  • Each sigma factor recognizes specific sequences called promoters
  • Regulate which genes transcribed
A

Regulation of Transcription Via

Sigma Factor

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5
Q
  • DNA sequence recognized by sigma factor/RNA polymerase to begin transcription
  • Different promoter sequences for difference genes
A

Regulation of Transcription Via

Promoters

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6
Q
A

Regulation of Transcription

  1. Sigma Factors
    1. Recognizes promoters and regulates what genes will be transcribed
  2. Promoter
    1. Different promoters for different genes
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7
Q
  • Genes that are expressed at all time
  • About 75% of genes in bacterium
A

Constitutive Genes

(Part of transcription regulation)

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8
Q
  • Genes that are turned on and off as the cell’s needs change
A

Facultative genes

(Part of transcription regulation)

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9
Q

Reads DNA to RNA

A

Transcription

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10
Q

Reads RNA to proteins

A

Translation

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11
Q
  • A set of genes controlled by a common promoter
A

Operon

  • Part of transcription regulation
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12
Q
  • A set of genes controlled by a common promoter
  • Genes usually related by a common metabolic pathway
  • Transcribed as a single unit, one mRNA transcript for the entire set of genes
  • Each gene is then translated separately
A

Operon

  • Part of the regulation of transcription
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13
Q
A

Operon

  • Part of the regulation of transcription
  • A set of genes controled by a commmon promoter
  • Genes usually are related by a common metabolic pathway
  • Transscribed as a single unit, one mRNA transcript for entire set of genes
  • Each gene is then translated separately
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14
Q

Types of operation regulation(s)

A

Operon Regulation

  1. Inducible operons
  2. Repressible operons
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15
Q
  • Operon off by default
  • Must be turned on (induced)
  • Activated by molecules called inducers
    • Ex: Lactose operon
A

Inducible Operon

  • Example of operon regulation
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16
Q

Lactose operons are an example of what type of regulations?

A

Inducible operons

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17
Q
  • In absense of lactose, operon is off
  • Regulatory gene codes for active repressor proetin that binds to operator region of operon
  • When operator is blocked, RNA polymerase cannot transcribe DNA
A

Lactose Operon = Inducible Operon

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18
Q
A

Lactose Operon

  • In absence of lactoose, operon is off
  • Regulartory gene codes for active repressor protein than binds to operator region of operon
  • When operator is blocked, RNA polymerase cannot transcribe the DNA
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19
Q
A

Lactose Operon

  • When lactose is present, a small percentage of lactose molecules spontaneously convert to allolactose in solution
  • Allolactose binds to active repressor protein, prevents binding of repressor to operator
  • When operator is not blocked, RNA polymerase can transcribe DNA
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20
Q
  • Operon on by default
  • Must be turned off
  • Deactivated by molecules called co-repressors
    • Ex: Tryptophan operon
A

Represssible Operon

Part of operon regulation

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21
Q
  • Repressible operon
  • When levels of tryptophan in the cell are low, the operon is turned on by default
  • The regulatory protein is inactive under these conditions and cannot bind to operator
A

Tryptophan Operon

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22
Q
A

Tryptophan Operon

  • Part of repressible operon
  • On by default, but can be turned off (repressed)
  • When levels of tryptophan in the cell are low, the operon is turned on by default
  • The regulatory protein is inactive under these conditions and cannot bind to operator
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23
Q
  • If protein synthesis ceases, the amount of tryptophan within the cell increases
  • Excess tryptophan (the co-repressor) binds to inactive repressor, activating it
  • Active repressor now binds to operator, repressing the transcription of the trp operon
A

Tryptophan Operon

  • Repressible operon
24
Q
A

Tryptophan Operon

  • If protein synthesis ceases, the amount of tryptophan within the cell increases
  • Excess tryptophan (the co-repressor) binds to inactive repressor, activating it
  • Active repressor now binds to operator, repressing the transcription of the trp operon
25
Q
  • Change in the nucleotide sequence of a gene
  • Types
    • Spontaneous
    • Induced
  • Effect is dependent upon its type
  • Many bacteria have mechanisms that aid in its repair
A

Mutations

26
Q

The two types of mutations

A
  1. Spontaneous
  2. Induced
27
Q
  • Due to unrepaired mistaked by replication enzymes
  • 1 in 250,000 to 1 in 250,000,000 bases replicated
A

Spontaneous mutations

28
Q
  • Chemical or physical agents that increase mutation rate
    • Mutagens
A

Induced mutations

29
Q
  • UV light
  • Causes thymine dimers
  • Presence of dimers causes DNA molecule to be misshappen, interferes with DNA function
  • Useful for microbial control
A

Physical Mutagens

30
Q
A

Physical Mutagens

  • UV light
  • Causes thymine dimers
  • Presence of dimers causes the DNA molecule to be misshapen, interferes with DNA function
  • Useful for microbial control
31
Q
  • Bacteria that uses seveal mechanisms/ enzymes to “fix” different types mutations
A

Mutation Repair

32
Q

Type of mutation repair that uses the enzyme photolysase

A

Light Repair

33
Q

Explain Light Repair

A
  • Type of mutation repair
  • Uses the enzyme photolyase that uses energy from visible light
  • Breaks down the covalent bonds in the thymine dimer
34
Q
A

Thymine Dimer Repair by Photolyase

35
Q
  • Type of bacterial genetics
  • Transfer of DNA between cells
  • Donor contributes part of genome to recipient
  • Consists of three types
A

Horizontal Gene Transfer

36
Q

Name the three types of horizontal gene transfer for bacteria

A
  1. Transformation
  2. Bacterial conjugation
  3. Transduction
37
Q
  • Type of bacterial horizontal gene transfer
  • The ability of some bacterial cells to take in DNA from the environment
A

Transformation

38
Q

Types of transformation

A
  1. Competency (competent)
  2. Artificial competency
39
Q

Explain Competency (competent)

A

Type of transformation (horizontal bacterial gene transfer)

Property of cells tht can naturally take in DNA from the environment

40
Q

Explain artificial competency

A

Type of transformation (bacterial horizontal gene transfer)

Bacterial cells can be induced in cells using techniques in the lab

41
Q
A

Transformation

The ability of some bacterial acells to take in DNA from the environement

42
Q
A

Artifical competency (type of transformation)

43
Q
  • Gene transfer mediated by bacteriophage
    • Infect host cell
    • Newly packaged viruses contain host DNA instead of viral DNA
  • Consists of two types
A

Transduction

44
Q

The type types of transduction are:

A
  1. Generalized
  2. Specialized
45
Q
  • Type of bacterial horizontal gene transfer that consists of:
    • Lytic phage
    • Random DNA fragment from host bacterial cell is carried by phage to recipient bacterial cell
A

Generalized Transduction

46
Q
A

Generalized Transduction

  • Lytic phage
  • Random DNA fragment from host bacterial cell is carried by phage to recipient bacterial cell
47
Q

Type of transduction which consists of:

  • Lysogenic phage
  • Specific host DNA sequences are carried by phage from donor to recipient bacterial cell
  • Genes that code for certain bacterial toxins (cholera toxin)
A

Speciaized Transduction

48
Q
  • “Bacterial sex”
  • Some bacteria contain a specific plasmid called F plasmid (F+ cells)
  • The F plasmid contains genes that allow the F+ cell to make a sex pilus
  • F+ cell contacts F- cell
  • Copy of F plasmid is transferred to the F- cell
  • Recipient cell then becomes a F+ cell
A

Conjugation

49
Q
A

Conjugation

  • “Bacterial sex”
    • Some bacteria contain a specific plasmid called F plasmid (F+ cells)
    • The F plasmid contains genes that allow the F+ cell to make a sex pilus
    • F+ cell contacts F- cell
    • Copy of F plasmid is transferred to the F- cell
    • Recipient cell then becomes a F+ cell
50
Q

What does microbial genetics consists of in terms of viral genetics?

A

Viral Genetics

  1. Mutation rate
  2. Antigenic drift
  3. Antigenic shift
51
Q
  • Viruses have a mutation rate much faster than bacterial and cellular organisms
  • Viral enzymes are prone to mistakes
  • In bacteriophage, 2 per genome replicated
  • In influenza, 1 per genome replicated
A

Virus Mutation Rate

52
Q
  • Spontaneous mutations during replication
  • Leads to minor changes in glycoproteins
  • Alters recognition of virus by immune system
  • Leads to slight increase in number of seasonal flu cases
A

Antigenic Drift

(Viral genetics)

53
Q
  • Genomoe of influenza made up of 8 different segments
  • On rare occasions, two or more separate strains will infect a single host cell
  • When this occurs, genome segments from different strains will combine in new ways during assembly
A

Antigenic Shift

(Viral Genetics)

54
Q
  • In influenza, leads to major changes in antigenic properties
  • Associated with major outbreaks
  • On average, occurs about every 10 years
  • 2009 H1N1 genes from pig, human, and bird influenza strains
A

Antigenic Shift of Viral Genetics

55
Q
A

Antigenic Shift

  • In influenza, leads to major changes in antigenic properties
  • Two or more separate strains will infect a single host cell
  • When this occurs, genome segments from different strains will combine in new ways during assembly

BIO 233 (13 decks)

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