Microbial Genetics - Bacterial Variation

Question 1

Genome

Answer 1

All chromosomes (DNA or RNA single or double stranded circle) PLUS extrachromosomal elements (plasmids)

Question 2

Genotype

Answer 2

All genes present in an organism

Question 3

Phenotype

Answer 3

all physical characteristics

Question 4

Replicon

Answer 4

DNA or RNA molecule that controls its own replications

Question 5

Extra Chromosomal Elements

Answer 5

replicons in a cell, excluding host cell DNA

Question 6

Genome chromosome

Answer 6

DNA or RNA single or double stranded circle encoding housekeeping genes (ALL bacteria possess this)

Question 7

Plasmids

Answer 7

usually double-stranded, circular DNA, replicon, encoding for ancillary genes (some bacteria possess this)

Question 8

Plasmid replication

Answer 8

replicon, utilize host bacterial DNA replication machinery, control own copy number

Question 9

Plasmid host

Answer 9

RANGE: some only in G(+) some in G(-), others only in 1 genus

Question 10

Conjugative plasmid

Answer 10

encode for a mechanism to transfer a copy of itself (donor cell) from the cell it’s in to a cell lacking (recipient cell)

Question 11

Resistance plasmid

Answer 11

possesses antibiotic resistance determinants

Question 12

Housekeeping genes are

Answer 12

required for viability and found on chromosomes of the genome

Question 13

Bacteriophage

Answer 13

virus replicons (DNA or RNA) that infect bacteria cells

Question 14

prophage

Answer 14

bacteriophage in a latent stage, can be in the form of a plasmid or integrated into cell’s chromosome, and may encode genes that change the cell’s phenotype

Question 15

Recombination

Answer 15

exchange of recipient DNA with donor DNA, breaking and joining of replicon DNA to form a hybrid

Question 16

Homologous recombination

Answer 16

when donor DNA is integrated into the chromosome and recipient DNA is degraded - RecA DEPENDENT, must share significant homology

Question 17

Site-specific (non-homologous) Recombination

Answer 17

insertion of DNA to sequence specific locations - RecA INDEPENDENT, must have identical sequence (insertion sequence or transposons)

Question 18

Horizontal Gene Transfer

Answer 18

genetic elements carried on tRNA from donor to recipient

Question 19

Why do microorganisms have a large genome but express fewer genes (small phenotype)

Answer 19

having a large genome gives them the ability to response to radically different environments, energy conservation

Question 20

How do bacteria change their phenotype

Answer 20

regulatory proteins that control gene expression, signal transduction via sensory kinases, quorum sensing, antigenic variation

Question 21

Phenotypic variation

Answer 21

change in expression pattern of genes, but does not involve genome variation

Question 22

Genotypic variation

Answer 22

genome alteration (addition of new genetic information)

Question 23

Name the 2 types of Genotypic variation

Answer 23

internally by mutations, externally by horizontal gene transfer

Question 24

Horizontal gene transfer (3 types)

Answer 24

transformation, conjugation, transduction

Question 25

Mutations create new genes, while HGT

Answer 25

transfers pre-existing genes, but does not create new genes

Question 26

Transformation

Answer 26

DNA fragments released by autolysis is accumulated and incorporated into the recipient DNA

Question 27

Transduction

Answer 27

phages carrying DNA from a donor host and infecting/transferring DNA to a recipient

Question 28

Conjugation

Answer 28

donor cell plasmid encodes for a mechanism to transfer a copy of itself to the recipient cell which lacks the plasmid