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Flashcards in L36 Deck (26):
1

Are bacteria haploid or diploid?

Haploid
X nucleus
X introns

2

What is the structure of the bacterial ribosome?

30S (w/ 16 rRNA)
50S

3

What are the 3 major bacterial genetic elements?

1. Chromosome
2. Plasmid = independently replicating
3. Transposon = integrates into plasmid or chromosome to replicate

4

What is the structure of transposons?

Start & end with inverted repeats
- allow for base pairing with the DNA it will integrate in with
tnpA = transposase gene
Ab resistant genes

5

What are insertion sequences?

Transposon - recongizable genetic patterns (i.e. no Ab resistance)

6

What is the action of transposons/insertion sequences?

Can inactivate target genes & cause genetic rearrangements

7

What is a bacteriophage?

Virus that infects bacteria
Can lyse & kill cells (lytic)
OR
Incorporate into bacterial DNA, replicate, then lyse cell (lysogenic)

8

What are pathogenicity islands?

DNA w/ virulence genes
@ "house keeping" part of the DNA
Nonpathogenic strains of bacteria can acquire PIs & gain properties responsible for disease

9

What are the 3 mechanisms of genetic exchange?

Transformation
Conjugation
Transduction

10

What is transformation?

Naked DNA from 1 cell taken up by another cell w/o participation of other bacteria/virus

11

What is conjugation?

Genetic transfer via cell-cell contact
Sexual mating

12

How does E.Coli accomplish conjugation?

F factor = fertility factor
- Encodes the sex pilus
Is an episome = capable of integrating into chromosome

13

What is high frequency recombination?

Once F factor is in the chromosome, can lead adjacent chromosomal regions out of donor cell and into recipient via single stand & replication

14

What is transduction?

Transfer of DNA between bacteria via VIRUSES

15

What are the 2 types of transduction?

Specialized = phage always integrates into specific site in host chromosome
Generalized = gene transfer in random manner

16

What is a regulon?

Multiple DNA operons linked together in a global regulatory network
Doesn't have to be a physical link

17

Where is the most important site of bacterial regulation of DNA replication?

Initiation of transcription

18

What is a 2 component regulatory system?

Sensory = sees changes in environment, transmits signal to regulator
Regulator = binds DNA and changes transcription via phosphorylation

19

What is quorum sensing?

How bacteria secrete low molecular weight compounds to signal other bacteria to turn on specific gene expression
Low [ ]s - no effect b/c diluted
High [ ]s - regulation of genetics in other bacterial

20

How does an autoinducer work?

Binds & actviates transcriptional regulator to turn on specific genes
Due to quorum sensing

21

What are simple ways that a bacteria can change the way its DNA is arranged to alter pathogen properties?

Duplication
Gene amplification
Deletion

22

What is phase variation?

Reversible switch on/off of expression phases to change a pathogen's properties
Genetic mechanism that can lead to antigenic variation

23

What is antigenic variation?

Expression of antigenically distinct but functionally conserved moieties within a population
To change a pathogen's properties
"Gene conversion"

24

Give an example/explain phase variation by gene inversion.

Salmonella
@ transcription
Alternate between H1 & H2 antigens
Controlled by recombinase that acts on inverted repeats to change orientation of genetic fragment

25

Give an example/explain slipped strand mispairng.

@ translation
Delete 1+ base pairs --> frame shits & premature stop codons
Reversible so silent genes can be expressed

26

What is an integron?

Incorporates promotor-less genes and converts them to functional genes