Lesson 5.3: Bacterial Genetics

Microbial Genetics

is the study of how microorganisms, including bacteria, inherit

information, evolve, and express genetic information

Bacterial Chromosome (genophore or

nucleoid)

carries genetic information

carried from past generations

Bacterial Plasmid

small extra-

chromosomal DNA contain some

genes such as antibiotic resistance

obtained through recombination

Pilus

–important for bacterial gene

transfers

Fertility plasmid

Resistantance plasmids

Virulence plasmid

Metabolism plasmids

What are the types of bacterial plasmids?

Fertility plasmids (F factor)

initiates

bacterial conjugation

Resistance plasmids (R Factors)

genes that code for antibiotic resistance or poisons

Virulence plasmid

turns the bacteria into a

pathogen

Metabolism plasmids

enables digestion of

unusual substances like petroleum.

Antibiotic resistance

is a conditions in which bacteria continue to grow in the presence of antibiotics.

Transformation

is a process of horizontal gene transfer

by which some bacteria take up foreign genetic material

(naked DNA) from the environment.

Conjugation

–the transfer of genetic material between bacterial

cells by direct cell-to-cell contact or by a bridge-like connection (sex

pilus) between two cells. The transfer of DNA (depends upon the

presence of plasmid). The genetic information transferred is often

beneficial to the recipient.

Transduction

–the process by which foreign DNA is transferred

from one bacterium to another by a virus or viral vector (eg.

bacteriophage)

Genomic plasticity

Viruses evolve rapidly. A prime sample is influenza.

Antigenic drift

Accumulations of small point mutations over time. Reason for annual flu shots

Antigenic shift

Sudden major change due to reassortment. Occurs when two different viral strain coinfect the same cell and swap genomic segment.

Micronucleus

The germline nucleus (diploid). Used for reproduction.

Macronucleus

The somatic nucleus (polyploid). Control cell function.

Heterokaryosis

Fusions of hyphae leads to genetically different nuclei sharing the same cytoplasm.

Karyogamy

Rare fusions of two haploid nuclei to form a diploid nucleus.

Haploidization

Random loss of chromosomes restore the haploid state, creating new genetic combinations.

RNA interference (RNAi)

A biological process where rna molecules inhibit gene expressions or translation.

Mechanism

Double-stranded rna is chopped by an enzyme (dicer) into small fragments, which guide the destructions of matching mRNA.