SH4: Bacterial taxonomy, genomics and genetics Flashcards Preview

BS1040: Microbiology and Cell Biology > SH4: Bacterial taxonomy, genomics and genetics > Flashcards

Flashcards in SH4: Bacterial taxonomy, genomics and genetics Deck (32)
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1

What is taxonomy?

The science of classification. It is concerned with nomenclature and identification, and organising groups of organisms, defining the relationships between them.

2

What is taxonomy?

The science of classification. It is concerned with nomenclature and identification, and organising groups of organisms, defining the relationships between them.

3

Name a bacterium and virus that cause diarrhoea.

shigella dysenteriae/ E.coli

4

A lower level than species is subspecies which show members of the same species differ in certain ways. Name these ways.

• Biological characteristics (biotypes or biovars)
• Expression of surface antigens (serotypes or serovars)
• Virulence -pathogenic or not (virotypes)
• Strains, pure cultures of mutants, isolates and variants

5

How do they determine subspecies of organisms in hospitals?

The phenetic approach, which is looking at characteristics such as cell size, gram stain, shape

6

How to scientists classify organisms into subspecies?

The phylogenetic approach, which is looking at evolutionary relationships

7

What is the issue with the phenetic approach of classification?

Convergent evolution- a biological property can arise by more than one route meaning have evolved in different ways.

8

What is numerical taxonomy

A way to quantitatively analyse variation within organisms and come up with relationships. Technique removes subjectivity, implying that not all features were equally as important for example gram stain is more important than cell shape.

9

What are some chemical and molecular markers used in phenetic taxonomy?

• Cell wall composition – crosslinking in peptidoglycan
• Membrane lipid structure
• Proteins
• Nucleic acid composition
• Base pairs - looking at the percentage of G-C pairs
• Hybridisation – if DNA from different organisms mix easily, they are closely related

10

What is genomics?

The branch of molecular biology concerned with the structure, function, evolution, and mapping of genomes based upon the sequence analysis.

11

Using genomics, what can be told about a micro-organism by looking at its genome?

• Transcriptosome- can look at cells and see what RNA’s are being made, what genes are being expressed and when, how much and in response to stimulus
• Proteome- what proteins are being expressed, when, how much, in response to what stimulus
• Metabolic potential
• glycome (sugars)
• interactome- interactions between proteins and macromolecules

12

Bacteria have plasmids. What are these?

Heterogeneous group of dsDNA molecules, separate from the chromosomes, encoding for additional features.

13

What are the 2 types of virus specific bacteria?

1. Virulent/ lytic cycle - infects cell, grows, cell burst, virus infects other cells
2. Temperate – inserts itself into the genome of the bacteria cell, living harmlessly

14

What are transposable elements (jumping genes)?

DNA that replicate themselves and are able to move within and between DNA molecules.

15

What are insertion sequences?

Sequences that can ‘jump’ into a gene and inactivate it

16

What are complex transposons?

Larger versions of insertion sequences that include more genetic information, like genes such as antibiotic resistance.

17

What are some mechanisms of genetic exchange in bacteria?

• Transformation- uptake of DNA of dead cell released into the environment, fragments in the soil. This fragmented DNA is sampled by living bacteria and proteins of the surface of the bacteria take up the DNA from the dead species and recombine it with its own genome
• Transduction- a phage dependent process, where the phage carries the bacterial DNA from one infected cell to another
• Conjugation- plasmid dependent DNA transfer between bacteria. ‘conjugate’ plasmids initiate cell to cell contact; the DNA is transferred by rolling circle replication. (F+ plasmid induces the formation of a membrane protrusion called the ‘sex pilus’ off of the membrane of the bacterial cell to another. Either plasmid moves to the other cell, or the desired gene in the DNA is copied and moves across.)

18

Name a bacterium and virus that cause diarrhoea.

shigella dysenteriae/ E.coli

19

A lower level than species is subspecies which show members of the same species differ in certain ways. Name these ways.

• Biological characteristics (biotypes or biovars)
• Expression of surface antigens (serotypes or serovars)
• Virulence -pathogenic or not (virotypes)
• Strains, pure cultures of mutants, isolates and variants

20

How do they determine subspecies of organisms in hospitals?

The phenetic approach, which is looking at characteristics such as cell size, gram stain, shape

21

How to scientists classify organisms into subspecies?

The phylogenetic approach, which is looking at evolutionary relationships

22

What is the issue with the phenetic approach of classification?

Convergent evolution- a biological property can arise by more than one route meaning have evolved in different ways.

23

What is numerical taxonomy

A way to quantitatively analyse variation within organisms and come up with relationships. Technique removes subjectivity, implying that not all features were equally as important for example gram stain is more important than cell shape.

24

What are some chemical and molecular markers used in phenetic taxonomy?

• Cell wall composition – crosslinking in peptidoglycan
• Membrane lipid structure
• Proteins
• Nucleic acid composition
• Base pairs - looking at the percentage of G-C pairs
• Hybridisation – if DNA from different organisms mix easily, they are closely related

25

What is genomics?

The branch of molecular biology concerned with the structure, function, evolution, and mapping of genomes based upon the sequence analysis.

26

Using genomics, what can be told about a micro-organism by looking at its genome?

• Transcriptosome- can look at cells and see what RNA’s are being made, what genes are being expressed and when, how much and in response to stimulus
• Proteome- what proteins are being expressed, when, how much, in response to what stimulus
• Metabolic potential
• glycome (sugars)
• interactome- interactions between proteins and macromolecules

27

Bacteria have plasmids. What are these?

Heterogeneous group of dsDNA molecules, separate from the chromosomes, encoding for additional features.

28

What are the 2 types of virus specific bacteria?

1. Virulent/ lytic cycle - infects cell, grows, cell burst, virus infects other cells
2. Temperate – inserts itself into the genome of the bacteria cell, living harmlessly

29

What are transposable elements (jumping genes)?

DNA that replicate themselves and are able to move within and between DNA molecules.

30

What are insertion sequences?

Sequences that can ‘jump’ into a gene and inactivate it