Microbes: Harmful and Beneficial Roles

• Microbes impact human, animal, and plant health, as well as food production and environmental cleanup

Harmful Uses of Microbes

• Microbes cause diseases that include influenza, tuberculosis, rabies, and blight
• Streptococcus causes strep throat
• E. coli leads to food poisoning

Beneficial Uses of Microbes

• Play a critical role in food production through fermentation
• Yeast in bread and Lactobacillus in yogurt are examples
• Useful in environmental cleanup via bioremediation by degrading oil spills

3 Domains and Their Characteristics

• The three domains include Archaea, Bacteria, and Eukarya

Archaea

• Extremophiles thrive in extreme conditions such as high salinity and temperature
• They have unique adaptations, including special enzymes and membrane lipids

Bacteria

• Exhibit diverse shapes, including cocci, bacilli, and spirilla
• They have cell walls made of peptidoglycan, a polymer of sugars and amino acids

Eukarya

• Kingdoms include Animals, Plants, Fungi, and Protists
• Eukaryotic cells have membrane-bound organelles and a true nucleus
• Prokaryotic cells lack these structures

Properties of Viruses

• Viruses are acellular and cannot exist independently
• They consist of genetic material (DNA or RNA) surrounded by a protein coat called a capsid
• Considered obligate intracellular parasites because they can only replicate within a host cell

Spontaneous Generation vs. Biogenesis

• Spontaneous Generation says that life arises from non-living matter
• Biogenesis says that living organisms arise from pre-existing life

Contributions and Experiments

• Redi's experiment demonstrated that maggots arise from eggs laid by flies, not spontaneously from meat
• Spallanzani showed that sealed flasks of broth remained free of microorganisms, disproving spontaneous generation from broth
• Pasteur's swan-neck flask experiment demonstrated that boiling broth in a flask prevents microbial growth, disproving spontaneous generation

Historical Contributions

• Jenner developed the first smallpox vaccine by inoculating individuals with cowpox
• Fleming discovered penicillin from Penicillium notatum, opening the field of antibiotics
• Lister pioneered antiseptic techniques in surgery, significantly reducing infections
• Ehrlich introduced the concept of "magic bullets" in medicine, leading to the discovery of Salvarsan, a treatment for syphilis

Vaccines and Antibiotics

• Vaccines induce immunity against pathogens by stimulating an immune response
• Examples of vaccines include those for measles and influenza
• Antibiotics kill or inhibit the growth of bacteria
• Common antibiotics include penicillin and amoxicillin, often targeting bacterial cell wall synthesis or protein synthesis

Normal Flora

• Normal flora (microbiota) refers to the community of microorganisms residing in areas like the gut, skin, and respiratory tract
• They play essential roles in host defense, nutrient metabolism, and immune system development
• Disruption of normal flora can lead to infections, digestive issues, and weakened immunity

Total Magnification

• Total magnification is calculated by multiplying the magnification power of the eyepiece (ocular lens) by the magnification power of the objective lens

Resolution and Refraction

• Resolution is the ability to distinguish two close points as separate
• Refraction is the bending of light as it passes through different media

Types of Microscopes

• Compound Microscope: Useful for viewing thin sections with limited resolution
• Dark Field Microscope: Allows observation of live specimens but can be difficult to set up
• Phase Contrast Microscope: Enhances contrast in transparent specimens, and can produce halos
• Fluorescence Microscope: Used for studying cellular components tagged with fluorescent dyes but is complex and can have photobleaching
• Electron Microscope: Provides high resolution and magnification, but it's expensive and requires sample preparation

Wavelength and Resolution

• Shorter wavelengths provide higher resolution compared to longer wavelengths
• This is because resolution is inversely related to wavelength

Smear/Acidic/Basic Dyes

• A smear involves spreading a sample thinly on a slide to observe microbes under a microscope
• Basic dyes are positively charged and bind to negatively charged components of cells
• Acidic dyes are negatively charged and stain the background for negative staining

Staining

• Staining refers to the application of dyes to improve visibility of cells under a microscope
• Simple staining uses a single dye to color all cells uniformly
• Differential staining distinguishes between types of bacteria based on their cell wall properties (e.g., Gram staining)

Background Staining

• Refers to unwanted staining of the slide or surrounding area, and can obscure the sample
• Can be minimized by adjusting the staining technique, using proper dilution of dyes, or using a clean slide

Cell Structures and Functions of Organelles

• Fimbriae: Are hair-like structures aiding in attachment and are found in prokaryotes
• Pili: Involved in DNA transfer and are found in bacteria
• Ribosomes: Are protein synthesis sites in both prokaryotes (70S) and eukaryotes (80S)
• Golgi Apparatus: Modifies and packages proteins in eukaryotes
• Mitochondria: Is the powerhouse of the cell in eukaryotes and is involved in ATP production
• Lysosomes: Contain digestive enzymes in eukaryotes
• Cell Wall: Provides structure and is composed of peptidoglycan in bacteria and cellulose in plants
• Plasma Membrane: Controls substance entry/exit in both types of cells

Simple Diffusion/Facilitated Diffusion/Active Transport

• Simple Diffusion: Is the movement of molecules across a membrane down the concentration gradient without energy
• Facilitated Diffusion: Is the transport of molecules via specific protein channels or carriers without energy, down the gradient
• Active Transport: Is the movement of substances against the concentration gradient using ATP via protein pumps