Introduction to bacteria 1 & 2 April 16th, 2014

Introduction to Bacteria (3) Biology 11 Mr. McCallum

Exit slip (previous class) Number of bacterial cells in/around us Communication between bacteria – Multi-lingual “chemical words” Bacteria do good things for our bodies (digestion, educating immune system, etc.) Bacteria wait to attack – need numbers Complexity – not solitary Vibrio fischeri – bioluminescence Adaptation of squid – relationship? Scope of medical application Impede signalling/communication enzymes Enhance current functioning of good bacteria WE DO NOT KNOW IT ALL – SO MUCH MORE TO DISCOVER Students are the engine of modern research

Reproduction (Binary fission) Cell division (but not technically Mitosis… why??) Doubles in size, replicates DNA, divides in half Producing clones/identical copies Example of exponential population growth Asexual reproduction

Binary Fission VS. MITOSIS

Reproduction (Binary Fission) BOTH start with one cell and result with two genetically identical cells Binary Fission: Prokaryotic organisms only. Single stranded RNA/DNA. Does not include “steps” of mitosis (does not involve centromeres, kinetochores, sister chromatids, spindle fibres, etc.) Mitosis: Eukaryotic organisms only. Does not occur in single celled organisms – rather in somatic cells or multicellular organisms

reproduction (Conjugation) Simple sexual reproduction – uncommon Way to introduce genetic variety Exchanging of genetic material Hollow bridge forms

Reproduction (Conjugation)

Reproduction (Spore formation) Some species can form an endospore in unfavourable conditions Dormant phase Heat resistant Hard to destroy

Reproduction (Spore formation)

Benefits of bacteria Benefits outweigh harmful effects Essential for decomposition and recycling matter into nutrients for living things Three examples of beneficial bacteria: Intestinal bacteria help us digest and synthesize vitamins! Streptococci and lactobacilli are responsible for dairy production (cheese, buttermilk, and yogurt)! Streptomyces are a source of antibiotics!

Harmful effects of bacteria Best known for causing disease Tuberculosis, diphtheria, typhoid fever, bubonic plague (black death), and E. coli Impact of bacterial infection Sheer number = burden on host Destroy cells and tissues Produce poisons (toxins)

Bacterial resistance to antibiotics There are more than 2500 naturally occurring antibiotics Over the last 50 years, bacteria have slowly developed resistance to common antibiotics Resistance develops from variations/mutations within a bacterial population Weakest bacteria die out, those with variations/mutations can reproduce  pass on this resistance Their plasmids contain R (resistance) factors  have special genes that code for enzymes that inactivate specific drugs Have R factors always existed, or have they evolved with the introduction of antibiotics?