Bacterial Genetics

Question 1

What does the majority of the bacterial genome encode?

Answer 1

Protein and tRNA

Question 2

What is interesting about the 16S rRNA of ribosomes in different bacterial strain?

Answer 2

Each bacterial strain has a different 16S rRNA sequence. However, the flanking sequences are the same in every bacteria and that is how is gets transcribed.

Question 3

What are extra-chromosomal units of the bacterial genome?

Answer 3

Plasmids and bacteriophages

Question 4

How do plasmids replicate?

Answer 4

Each has an independent origin of replication so it replicates independently of the chromosomal DNA

Question 5

How do bacteriophages contribute to extrachromosomal DNA?

Answer 5

These bacterial viruses carry a small number of genes that are NOT essential to the bacteria. The genetic material can be integrated to the chromosome of it can be extrachromosomal.

Question 6

Where are virulence factors encoded?

Answer 6

Plasmids, bacteriophage DNA, and Chromosomal DNA

Question 7

What are the different genotypes in bacterial genomes?

Answer 7

1- Biosynthetic genes
2- Catabloic Genes
3-Drug resistance genes

Question 8

What is an operon?

Answer 8

An operon is a single regulatory unit for genes of related function. Therefore, each individual gene DOES NOT have its own regulatory element.

Question 9

What is an ames test?

Answer 9

A test to see if an agent is carcinogenic to humans. If it is it will mutate bacteria

Question 10

What can cause mutations in bacterial genomes?

Answer 10

1- Spontaneous
2- Chemical modifying agents
3- Physical agents

Question 11

What are examples of physical agents that mutate bacterial genomes?

Answer 11

Xray and UV light

Question 12

What are examples of chemical modifying agents that mutate bacterial genomes?

Answer 12

Base modifying agents, base analogs, and intercalating agents

Question 13

What are three mechanisms of genetic exchange among bacteria?

Answer 13

1- Conjugation
2- Transformation
3- Transduction

Question 14

What is bacterial transformation?

Answer 14

One bacteria takes up bits of DNA from its environment (plasmid or chromosomal DNA)

Question 15

How is acquired DNA incorporated into a bacterial DNA genome?

Answer 15

Honologus recombiation

Question 16

What is conjugation?

Answer 16

Bacterial version of sex with the transfer of a F plasmid via a sex pilis

Question 17

What is significant about conjugation?

Answer 17

It is a major way that bacterial drug resistance is transferred to bacteria

Question 18

What is generalized transduction?

Answer 18

Lytic phage infects bacteria and causes lysis and release of DNA. Bacteriophages then take up this DNA and transmit it to another bacterial cell

Question 19

What is specialized transduction?

Answer 19

Lysogenic phages insert their own DNA into the bacterial genome and the when it is excised and repackaged there is exchange of DNA. The new phages go to infect other cells.

Question 20

What are transposons?

Answer 20

Segments of the genome that jump arund

Question 21

What do transposons encode?

Answer 21

1- transposase enzyme
2- prespressor gene
3- drug resistance gene?

Question 22

What are pathogenicity islands?

Answer 22

regions of bacterial chromosomes that may have several adjacent genes that contribute to pathogenesisof a disease

Question 23

How are operons regulated?

Answer 23

They are controlled via inducible expression and inducible repression.

Question 24

What is inducible expression?

Answer 24

The presence of a chemical can induce expression when bound to the operator region. lac operon example

Question 25

What is inducible repression?

Answer 25

The presence of the chemical (bound to the operator) inhibits expression

Question 26

What is a main transcriptional regulator in bacteria?

Answer 26

metabolic products and deficiencies typically directly regulate transcription

Question 27

Is there RNA splicing in bacteria?

Answer 27

No