Bacteria Notes

Basic Definition Bacteria Bacteria: Prokaryotic Organisms – Pro: Primitive or “prior to” – Karyon: Nucleus or “kernel” – Single-celled organisms without a nucleus – Has circular DNA – Often has “plasmid” DNA that helps codes for genes to increase fitness (ex. Antibiotic resistance) – Bacteria can be measured in micrometers m or Pro karyo

What are the two groups of bacteria? 1.Bacteria Cell walls with peptidoglycan 2.Archaebacteria Cell walls lack peptidoglycan Adapted to extreme environments:  Extremely hot and cold, salty, without oxygen, etc. peptidoglycan Made up of types of peptide and sugar bonds

What are the basic shapes of bacteria? – Rod-shaped (Bacilli) Bacillus anthracis (Anthrax), Yersinia pestis (Bubonic plague) – Comma-shaped (Vibrios) Vibrio cholerae – Spherical (Cocci) Streptococcus, Staphylococcus – Spiral (Spirilla) Treponema pallidum (Syphillis)

Bacterial Staining Gram-positive: Retains the crystals of violet dye in the peptidoglycan of the cell wall. Only has an inner layer of plasma membrane Infection by this type can be treated by antibiotics such as penicillin, which attacks the peptidoglycan of the cell wall.

Gram-negative: Will not pick up much the violet dye because the cell wall is covered by an additional outer membrane, and instead appears pink. Infection by this type must be treated by a broad- spectrum antibiotic such as ciprofloxacin that enters bacteria and disrupts protein synthesis Bacterial Staining Peptidoglycan Outer membrane Inner membrane

What is a plasmid? Plasmids are circles of DNA that can replicate separately from the main bacterial DNA. Plasmids may carry genes that allow bacteria to survive exposure to antibiotics.

Bacterial Growth and Reproduction Binary Fission: (video) Binary Fission -Asexual division -DNA replicates and cytoplasm divides -Creates two genetically identical cells from one parent cell Conjugation: (2 video) Conjugationvideo -Not true sexual reproduction -Sex pilus extends between bacteria -Plasmid DNA is transferred from one bacterium to another to introduce genetic diversity Spore Formation: -Occurs when growth conditions are unfavorable -An endospore is a “spore” with a thick internal wall of membrane that encloses and protects its DNA

Summary to Bacteria Notes Answer 2 questions 1. Explain two different ways antibiotics work in treating bacterial infections. Use your knowledge of bacterial cell walls to defend your answer. 2. Which would be better at introducing genetic diversity in a bacterial population: binary fission or conjugation? Explain.