Essential Characteristics and Components of Living Beings
Defined Functions of Living Beings
- Nutrition: Exchange of matter and energy with the outside
- Reproduction: Leaving offspring, keeping the species
- Engaging: Layers respond to stimuli
Bioelements
All living things have a restricted group of parent chemical elements (C, H, N, P, S) that have special properties to build molecules of living beings. They constitute 98% of its weight.
Children (Ca, K, Mg, Cl, I, Cu, Zn) – some do not reach 0.1% and receive the name “trace” due to their low proportion (Fe), but
Read MoreEnzyme Activity and Regulation: A Comprehensive Look
Enzymes: Biological Catalysts
Enzymes are usually proteins that specifically catalyze certain biochemical reactions by binding to the molecule or metabolite that is going to transform, the substrate. There are also ribonucleoprotein enzymes called ribozymes. The region of the enzyme where the substrate fits is the active site. The bond between enzyme and substrate involves a steric recognition, i.e., related to the shape and size of the substrate itself, which binds specifically. Therefore, the variety
Read MoreNickel: Properties, Reactions, Health and Environmental Impacts
Nickel: Properties, Reactions, Health, and Environmental Impacts
Chemical Properties of Nickel
Nickel (Ni), atomic number 28, is a hard, silvery-white, ductile, and malleable metal. Its atomic mass is 58.71. Nickel is primarily used in stainless steel and other corrosion-resistant alloys. It is also used in currencies as a silver substitute. Finely divided nickel serves as a catalyst for hydrogenation.
Chemical Reactions of Nickel
- Sodium Hydroxide (NaOH) Solutions: Forms a green nickel oxide precipitate,
Microorganism Cultivation and Isolation Techniques
Nutritive Agar for Undemanding Microorganisms
Peptone Water
Liquid culture medium for prior non-selective isolation of bacteria. Incubation: Approximately 18 hours at 37ºC.
Blood Agar, 6.8 pH
Isolation, cultivation, and identification of various bacteria.
Potato Dextrose Agar
Cultivation, isolation, and determination of the number of yeast and mold organisms. Incubation: Up to 5 days at room temperature.
Sabouraud Agar
Clear culture medium recommended for the cultivation of dermatophytes and the sensitivity
Read MoreNerve Signals, Muscle Control, and Synaptic Function
Nerve Membrane Potential and Nerve Transmission
General
All nerve signals are transmitted by nerve fibers, either in the brain, spinal cord, or peripheral nerves. These long nerve fibers are called axons. The axon is a tubular structure bounded by a cell membrane and filled with a liquid called axoplasm. Within the membrane of all nerve fibers, an electrical potential of about -90 millivolts exists. This is known as the membrane potential, generated by ionic concentration differences across the cell
Read MoreBacterial Structure, Types, and Functions
Bacteria are very simple organisms, classified as prokaryotes. Based on their shape, they can be categorized as:
- Rod-shaped bacilli
- Spherical cocci
- Spiral spirilla
- Comma-shaped vibrios
Bacterial Structure
Capsule
The capsule is a mucus layer that surrounds the bacterial wall, present only in some bacteria.
Function:
- Makes it difficult for antibodies and phagocytic cells of the host to recognize and destroy the bacteria.
- Facilitates the formation of colonies.
- Participates in exchange processes involving water,