Discovering the Bacterial Cell Advanced Biotechnology (c)(5)(b)

The Importance of Bacteria  Bacteria are extremely important in the biosphere  Food Production  Examples?  Nutrient Cycling  Such as nitrogen fixation in soil  Genetic engineering  Bacterial cells transformed  Agrobacterium-mediated recombination

"Nitrogen Cycle.“ Nitrogen Fixation Cycle

Bacterial Cells  Bacterial is a large domain of prokaryotic microorganisms  Prokaryote: single-celled organisms lacking a membrane bound nucleus  Microorganism : microscopic living organisms, either single celled or multicellular  Even though bacteria are relatively simple, they boast a well-developed cellular structure responsible for their many unique functions  Organelle: subunit within a cell with a specific function.

Cell Morphology  Bacterial cells have different shapes. Some examples:  Coccus – spheres  Bacillus – round-ended cylinders  Spiral – twisting  Filamentous – very long thin rods, many times longer than wide

Coccus

Bacillus

Spiral _jejuni.jpg Book/cantlivewithoutum/spirals.jpg

Filamentous q9p215SPAgg/T8J2T0v1ZeI/AAAAAAAAAGA/5Jxjf_pj0hQ/s1600/40X_S oilIsolate_1.JPG

Bacterial Cell Structures

 Pili and fimbriae are interchangeable  Pili : hair-like appendage found on the surface of many bacterial.  Used for attachment to surfaces, and gene transfer Pili / Fimbriae

 Flagellum: leash-like appendage protruding from the body.  Primary role is movement.  Also used as a sensory organelle. Flagellum content/uploads/2012/09/bacteria1.jpg

The ribosome is a complex molecular machine serving as the primary site of protein biosynthesis. Ribosomes Functional protein Export polypeptide to cytoplasm Link together amino acids collected from cytoplasm by tRNA Translate mRNA

Ribosomes

 Plasmids are small DNA molecules within a cell that is separate from chromosomal DNA. This makes it extrachromosomal DNA.  Plasmids carry genes benefitting survival of the cell. They carry extra information  Artificial plasmids are used as vectors in molecular cloning.  Drives the replication of recombinant DNA sequences in host organisms Plasmid

 Cytoplasm comprises the gel-like substance within the cell membrane and all organelles. All contents of the cell are contained in the cytoplasm. Cytoplasm

 The cell envelope contains the:  Capsule  Cell Wall  Plasma membrane Cell Envelope

 The capsule is the outer envelope of the bacterial cell. The capsule is well-organized and not easily washed off. Help prevent water loss  The capsule can be the cause of diseases, but also can play a role in the development of vaccines Capsule

 The cell wall of bacterial cells is a distinctive structure compared to plant and animal cells.  Cell wall made of peptidoglycan.  The cell wall has two types:  gram-positive and gram-negative.  Determined through reaction of cell walls to Gram stain.  Peptidoglycan levels play an important role in this. Cell Wall

 The plasma membrane is composed of a phospholipid bilayer. Acts as a permeability barrier, and location for the transport of molecules into the cell.  The phospholipid bilayer is a layer of two lipid layers that form a barrier around cells. It is found in almost all living organisms. Plasma Membrane

 The nucleoid contains all/most of the genetic material. It is NOT a nucleus because it is not surrounded by a nuclear membrane.  Approx. 60% DNA with small amounts of RNA and protein (later is generally mRNA and transcription factors) Nucleoid

 Why are bacterial cells important?  They perform activities essential for our every day survival: nutrient cycling, food production, microbial flora in our gut, etc.  What is a Prokaryote?  single-celled organisms lacking a membrane bound nucleus  What is an organelle?  subunit within a cell with a specific function. Summary

 Describe the following structures and their importance:  Pili / Frimbraie  Flagellum  Ribosomes  Plasmid  Cytoplasm  Cell envelope:  Cell wall  Peptidoglycan  Plasma membrane  Capsule  Nucleoid Summary: Organelles

Developed for the Texas Education Agency Educational Excellence for AFNR project under contract with the Department of Agricultural Leadership, Education & Communications, Texas A&M University © Texas Education Agency, 2014 Authors: Ian Sprouse, Kirk C. Edney PhD