bacterial mutations and horizontal gene transfer

how do restiances of certain things develop

mutations and horizontal gene transfer

inactivating enzymes

efflux pumps

decreased uptake

drug target alteration

mechanism sof antibiotic resistance

inactivating enzymes

uses enzyme to block antibiotic from working

efflux pumps

pumps the antibiotic back out the cell once it enters

decreased uptake

prevent antibiotic from entering the cell wall or plasma membrane

drug target alteration

changes the antibiotic structure so it cant bind to its target

microbial replication

fast

mutations

a permanent change in the DNA sequence

what causes mutations

Errors in DNA replication

Exposure to mutagens

spontaneous mutation

error in DNA replication

regeneration time for prokaryotes compared to eukaryotes

prokaryotes mutate faster than eukaryotes

base substitution

a single incorrect nucleotide replacing the initial nucleotide

frameshift mutation

a deletion on insertion of nucleotides

silent base substitution mutation

no AA change

missense base substitution mutation

AA change

nonsense base substitution mutation

results in stop codon

mutagens

environmental agents that brings about mutation…

physical

chemical

biological

physical mutagen ex.

radiation

chemical mutagen ex.

cigs

biological mutagen ex.

viruses

radiation mutagen

exposure to short waves of lights leading to DNA damage

IONIZING RADIATION DNA double strand breaks

NON IONIZING RADIATION thymine dimers

chemical mutagens

intertwine DNA to cause changes or mismatch during DNA synthesis

What type of mutation is in the mutant DNA strand

below compared to the typical DNA strand?

• Typical DNA: 3’-AATTACATGCCCACT-5’

• Mutant DNA: 3’-AATTACATCCCCACT-5

notice 3’ to 5’

convertion to mRNA

5’ to 3’

convert to AA

=nonsense

Methicillin (antibiotic) typically binds to bacterial protein called PBP to kill the bacteria. S. aureus can make a variation of this bacterial protein called PBP2a (mecA gene) that prevents binding of methicillin. What method of antibiotic resistance is this

drug target alteration

The bacteria NDM-CRE secretes an enzyme called NDM that disrupts the structure of almost all antibiotics making them non-functional. What method of antibiotic resistance is this?

inactivating enzymes

vertical gene transfer

replication such as binary fission of passing DNA from parent to offspring

horizontal gene transfer

movement of genes between cells without replication

homologous replication

2 pieces of DNA swap places if sequence is similar

horizontal replication (conjugation)

DNA is transferred from one bacterium donor (F+) to a recipient cell (F-) with the use of a sex pili to transfer plasmids

horizontal replication (transduction)

transfer DNA from donor cell to recipient with a specific bacteriophage

generalized: random

specialized: specific

horizontal replication (transformation)

taking in naked dna