Bacteria

Prokaryotic! Bacteria are the ONLY prokaryotes on Earth! Eukaryotic Can be Both Prokaryotic! Bacteria are the ONLY prokaryotes on Earth!

Remember! All Life Prokaryotic Bacteria Eukaryotic Fungi Protists Plants Animals

Prokaryotic vs. Eukaryotic Cells Small & simple NO NUCLEUS No membrane-bound organelles Larger & more complex Contain a nucleus Contain membrane-bound organelles

Unicellular! Bacteria are composed of a single cell! Multicellular Can be Both Unicellular! Bacteria are composed of a single cell!

In what kingdoms can we find bacteria? Protista Fungi Monera None of the above Bacteria can be found in the kingdoms Archaebacteria & Eubacteria!

Kingdom Archae-bacteria All Life on Earth Kingdom Eubacteria Kingdom Animalia Kingdom Plantae Kingdom Fungi Kingdom Protista Kingdom Archae-bacteria

Archaebacteria vs. Eubacteria Cell walls NOT made of peptidoglycan Live in extreme environments Cell walls made of peptidoglycan Identified using gram staining Prokaryotic Unicellular

Structures of Bacterial Cells Plasma Membrane: selectively permeable for exchange of nutrients and waste Cytoplasm: fluid inside of the cell Cell Wall

Structures of Bacterial Cells DNA: free in the cytoplasm, but clustered in a “nucleoid region” Flagella Ribosomes

Structures of Bacterial Cells Pili: small protein extensions used to anchor themselves OR to help exchange DNA with other bacteria

So how do we classify all these bacteria? There are thousands of identified species of bacteria, but scientists have estimated that there are millions waiting to be discovered! So how do we classify all these bacteria? Bacteria are classified according to: Shape Cell Wall Metabolism

What are some differences between the 2 types of bacteria shown here? Shape! Bacteria come in 3 shapes: Round Rod Corkscrew

Classification by Shape Coccus (cocci, pl.): round, can be found in clumps or lines Baccillus (baccillis, pl.): rod shaped Spirillum (spirilli, pl.): corkscrew (spiral) shaped

Spirillum Coccus Bacillus

Classification by Cell Wall Eubacteria can be identified by the thickness of their cell wall. Gram Staining determines how thick the cell wall is. Gram + Bacteria: stains purple, have a thick cell wall Gram - Bacteria: stains pink, have a thin cell wall Gram Positive (+) Gram Negative (-)

Gram + Gram + Gram – Both Neither Bacillus anthracis

Gram - Gram + Gram – Both Neither Spirillum volutans

Gram + and Gram - Gram + Gram – Both Neither Staphylococcus aureus & Escherichia coli

A scientist uses gram staining on a colony of bacteria that she collected from a volcanic vent. What will her results be? Gram + Gram – Both Neither Neither! The bacteria collected was archaebacteria. Gram staining will be ineffective, because archaebacteria do not have peptidoglycan in their cell walls. Gram staining can only be used to identify eubacteria!

Classification By Metabolism Classified by how they obtain energy Can be heterotrophic – obtains food from another source Can be autotrophic – makes own food Chemoautotrophs: make own food with inorganic molecules Photoautotrophs: use photosynthesis

Where can we find bacteria? What do you think the dirtiest part of the classroom is? Your group will swab a location of your choice & see if bacteria are present. We will check the growth in a few days.

Directions to Prepare the Petri Dish Pre-Lab Questions Write your group’s info on the bottom (initials of all of the members, & class period) Agree on a location to test. Come to me for a sterile Q-tip. Rub 1 side of the Q-tip on the location, then lightly rub the same side onto the agar. Draw your dish on your handout. Replace the lid & tape it shut. Place it on the tray.