Bacterial and Viral Genetics Flashcards
1
Q
- Central Dogma
- Transcription
- RNA Polymerase
- Reads DNA to make RNA
- Translation
- Ribosomes
- mRNA read to make proteins
A
Protein Synthesis
2
Q
Regulation of Protein Synthesis
What are the components for transcriptional regulation?
A
Transcriptional Regulation
- Sigma factors
- Promoters
- Operon
3
Q
Regulation of Protein Synthesis
What is the factor for translational regulation?
A
Translational Regulation
- Ribosome binding site
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
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
6
Q
A
Regulation of Transcription
- Sigma Factors
- Recognizes promoters and regulates what genes will be transcribed
- Promoter
- Different promoters for different genes
7
Q
- Genes that are expressed at all time
- About 75% of genes in bacterium
A
Constitutive Genes
(Part of transcription regulation)
8
Q
- Genes that are turned on and off as the cell’s needs change
A
Facultative genes
(Part of transcription regulation)
9
Q
Reads DNA to RNA
A
Transcription
10
Q
Reads RNA to proteins
A
Translation
11
Q
- A set of genes controlled by a common promoter
A
Operon
- Part of transcription regulation
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
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
14
Q
Types of operation regulation(s)
A
Operon Regulation
- Inducible operons
- Repressible operons
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
16
Q
Lactose operons are an example of what type of regulations?
A
Inducible operons
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
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
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
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
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
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
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
* 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
Mutations
26
The two types of mutations
1. Spontaneous
2. Induced
27
* Due to unrepaired mistaked by replication enzymes
* 1 in 250,000 to 1 in 250,000,000 bases replicated
Spontaneous mutations
28
* Chemical or physical agents that increase mutation rate
* Mutagens
Induced mutations
29
* UV light
* Causes thymine dimers
* Presence of dimers causes DNA molecule to be misshappen, interferes with DNA function
* Useful for microbial control
Physical Mutagens
30
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
* Bacteria that uses seveal mechanisms/ enzymes to "fix" different types mutations
Mutation Repair
32
Type of mutation repair that uses the enzyme photolysase
Light Repair
33
Explain Light Repair
* Type of mutation repair
* Uses the enzyme photolyase that uses energy from visible light
* Breaks down the covalent bonds in the thymine dimer
34
Thymine Dimer Repair by Photolyase
35
* Type of bacterial genetics
* Transfer of DNA between cells
* Donor contributes part of genome to recipient
* Consists of three types
Horizontal Gene Transfer
36
Name the three types of horizontal gene transfer for bacteria
1. Transformation
2. Bacterial conjugation
3. Transduction
37
* Type of bacterial horizontal gene transfer
* The ability of some bacterial cells to take in DNA from the environment
Transformation
38
Types of transformation
1. Competency (competent)
2. Artificial competency
39
Explain Competency (competent)
Type of transformation (horizontal bacterial gene transfer)
Property of cells tht can naturally take in DNA from the environment
40
Explain artificial competency
Type of transformation (bacterial horizontal gene transfer)
Bacterial cells can be induced in cells using techniques in the lab
41
Transformation
The ability of some bacterial acells to take in DNA from the environement
42
Artifical competency (type of transformation)
43
* Gene transfer mediated by bacteriophage
* Infect host cell
* Newly packaged viruses contain host DNA instead of viral DNA
* Consists of two types
Transduction
44
The type types of transduction are:
1. Generalized
2. Specialized
45
* 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
Generalized Transduction
46
Generalized Transduction
* Lytic phage
* Random DNA fragment from host bacterial cell is carried by phage to recipient bacterial cell
47
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)
Speciaized Transduction
48
* "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
Conjugation
49
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
What does microbial genetics consists of in terms of viral genetics?
Viral Genetics
1. Mutation rate
2. Antigenic drift
3. Antigenic shift
51
* 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
Virus Mutation Rate
52
* 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
Antigenic Drift
| (Viral genetics)
53
* 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
Antigenic Shift
| (Viral Genetics)
54
* 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
Antigenic Shift of Viral Genetics
55
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
