Bacteria Lab

Background:

Bacteria are the oldest organisms on the planet, and are very diverse. Bacteria are composed of many parts. The cell wall of bacteria helps protect the cell and gives it its shape. Eubacteria cell walls are made of peptidoglycan, while archeabactiera have a different material. The cell membrane regulates materials, while the outer membrane can help protect the bacterium against some antibiotics, yet the membrane is only there in Gram-negative cells. The cytoplasm contains many organelles, along with the DNA. The chromosomes contain the genetic information of the bacterium. Plasmids inside of bacteria contain an extra ring of genetic information. The capsule of a bacterium allows the cell to attach to other cells, and can also help protect it. The endospore if a structure produced by some Gram-positive bacteria that aids in protecting them against harsh environments, temperatures, chemicals, and radiation. The pili of a bacterium cell allow the cell to attach to other surfaces, and the flagellum found in some bacteria allows cells to move.

Bacteria are classified in many ways. Yet, because bacteria don't often vary in size or shape, it can be harder to classify them. They have been grouped by their structure, physiology, composition, and reaction to stains. Most bacteria are one of three shapes. The shapes are bacilli, which is rod-shaped, cocci, which are sphere-shaped, and spirilla, which are spiral shaped. Bacteria can appear in clusters, which we give the prefix "staphylo", or chains, which we give the prefix "strepto". A bacterium's reaction to Gram Stains allows it to be organized as well. Gram-positive bacteria will appear purple after a Gram stain test, due to a thicker layer of peptidoglycan in their cell wall. Gram-negative bacteria will appear pink instead.

Bacteria reproduce using the process of binary fission. Binary fission is the asexual cell division of prokaryotic cells, such as bacteria, that produces identical offspring. The bacterium's chromosomes will copy itself, and then the cell will grow to about twice its original size. Once a cell wall forms between the two, the cells will split, creating two identical cells. Bacteria can produce identical cells through binary fission, but also have three ways to recombine their genetic information.

Objective: The objective of this lab to create a better understanding of bacteria and bacteria growth through the physical growing of bacteria from different environments, conditions, and locations.

Materials:

Cotton swab Agar Petri dish

Incubator Tape Water

Procedure:

1. Collect a sample of bacteria from a location using a damp to wet cotton