Bacterial Structure and Function

• Bacteria have extreme flexibility and also rapid growth, reproduction and possess great age
• Most bacteria are heterotrophic, absorbing nutrients from the environment
• Some bacteria are photosynthetic, using light for energy or chemosynthetic, using inorganic chemicals for energy
• Some bacterial are useful and aid in digestion
• Bacteria form bases of food webs in an environment
• Bacteria are often associated with causing disease in humans and animals

Bacterial Structure

• Biochemical processes occur in the inner membrane of prokaryotes, which for eukaryotes these normally occur in a chloroplast or mitochondria
• Circular bacterial DNA is in the cytoplasm, and this DNA is called the nucleoid
• Scattered within the inner membrane, there are small loops of DNA known as plasmids
• Some bacteria have flagella, but the structure of that flagella is different to that found in eukaryotes
• The ribosomes of bacterial cells have different sized subunits than those of eukaryotes
• Ribosomes are where proteins are assembled

Bacterial Cellular Shapes

• Rod shaped cells are called bacilli
• Sphere shaped cells are called coccoid
• Spiral shaped cells are called spirilla

Microbe Colony Morphology

• Colony shape can be circular, rhizoid, irregular, or filamentous
• Colony edge can be entire, undulate, lobate, filamentous, or curled
• Colony surface can be smooth, glistening, rough, wrinkled, or dry powdery
• Colony elevation can be flat, raised, convex, pulvinate, or umbonate
• Colony morphology is used to identify the microbial life that has been found and cultured

Reproduction

• Prokaryotic cell division occurs via binary fission
• A single DNA molecule replicates
• Each copy attaches to a different part of the cell membrane
• The cell begins to pull apart
• Cytokinesis creates two cells of identical genetic composition

Experiment

• The purpose is to identify various colonies and investigate species diversity by isolating, culturing, and analyzing bacterial colonies
• Environments that these colonies likely inhabit include air, pond water, raw chicken, washed and unwashed hands, keyboards, and soil samples
• Bacteria can generally thrive anywhere on the planet, therefore all the tested environments should grow bacterial species
• Use the streak plate method to isolate colonies from chicken, soil, pond and keyboard samples
• Leave agar plate open for air sample
• Gently press washed and unwashed hands onto agar plate
• Cultures should be wrapped in Parafilm and incubated for 48 hours at 22°C
• Examine the morphology for each type of colony

Bacteria exhibit flexibility, rapid growth, and diverse metabolic strategies including heterotrophic, photosynthetic, and chemosynthetic processes. Bacterial DNA is circular and resides in the nucleoid, with additional plasmids scattered. These organisms play crucial roles in food webs and can be both beneficial and disease-causing.