What is spontaneous generation?
It is a theory that says that living organisms can come from non-living organisms (Abiogenesis). However, this theory has been falsified by Louis Pasteur in 1864. Living organism can only come from living organisms (Biogenesis).
Microbial control Method
Disinfection: The destruction or removal of vegetative pathogens but not bacterial endospores. Usually used only on inanimate object
Sterilization: The complete removal or destruction of viable microorganisms. Usually used only on inanimate object
Antisepsis: Chemicals applied to the body surfaces to destroy or inhabit vegetative pathogens
Chemotherapy: Chemicals used internally to kill or inhabit growth of microorganisms with host tissues.
| Organelle | Function |
| Plasma membrane | Selectively permeable barrier, mechanical boundary of cell, nutrients and waster transport, location of many metabolic processes (respiration, photosynthesis), detection of environment cues for chemotaxis |
| Gas vacuole | Buoyancy for floating in aquatic environment |
| Ribosome | Protein synthesis |
| Inclusion bodies | Storage of carbon, phosphates, and other substances |
| Nucleoid | Location of genetic materials (DNA) |
| Periplasmic space | Contains hydrolytic enzyme and binding proteins for nutrients processing and uptake |
| Cell wall | Give prokaryotic shape and protection from osmotic stress |
| Capsules and slime layers | Resistance to phagocytosis, adherence to surfaces |
| Fimbriae and Pili | Attachment to surfaces , bacterial mating |
| Flagella | Movement |
| Survival under harsh environment conditions |
*Chemotaxis – Bacterial does not move around aimlessly, but are attracted to nutrient (sugar, amino acid), and repelled by many harmful substance. Environment cues – temperature (thermo taxis), light (photo taxis), oxygen (aero taxis), etc .. Movement toward chemical attraction and away from repellents is known as chemotaxis.
Function of Eukaryotic Structure
| Organelle | Function |
| Plasma membrane | Selectively permeable barrier with transport system, mechanical boundary of cell, mediates cell-cell interactions and adhesion to surfaces, secretion |
| Cytoplasmic matrix | Environment for other organelles, location of many metabolic processes |
| Ribosome | Protein synthesis |
| Endoplasmic Reticulum | Transport of materials, protein and lipid synthesis |
| Microfilament, intermediate filament, microtubules | Cell structure and movements, formation of cytoskeleton |
| Golgi apparatus | Packing and secretion of materials for various purpose, lysosomes formation |
| Cell wall and Pellicle | Strengthen and give shape to cell |
| Lysosomes | Intracellular digestion |
| Mitochondria | Energy production through use of the tricarboxylic acid cycle, electron transport chain, oxidative phosphorylation, and other pathways |
| Flagella and cilia | Cell Movement |
| Chloroplasts | Photosynthesis – trapping light energy and formation of carbohydrates from CO2 and water |
| Nucleus | Repository for genetic information, control center for cell |
| Nucleolus | Ribosomal RNA synthesis, ribosome contrustion |
| Vacuole | Temporary storage and transport, digestion (food vacuole), water balance (contractile vacuole) |
Bacterial Endospores
Endospores act as a defense mechanism to help bacteria to survive in harsh environment conditions
Endospores are metabolically inactive, like a seed that is able to wait for the environment to again become favourable. Once environmental conditions improve, the endospore then germinates back into a living, vegetative cell that can grow and thrive.
Vegetative bacteria are those bacteria or microorganisms that can grow and reproduce in place where many nutrients are available. The actively growing bacteria in these conditions are referred to as "vegetative cells".
Some bacterial survive adverse environment conditions by forming endospores, dormant structure resistant to heat, desiccation, and many chemicals.
**The spores are surrounded by a thin, delicate covering called exosporium. A spore coat lies beneath the exosporium, is composed of several protein layers, and may be fairly thick. It is impermeable to many toxic molecules and is responsible for the spore resistance to chemicals. The coat also is thought to contain enzyme that are involved in germination.