Photosynthesis and Chemosynthesis: Energy Conversion in Organisms
Light Phase (Photochemical)
Photosynthetic pigments are associated with membrane proteins, constituting photosystems. By absorbing a photon, the pigment is ionized (oxidized). The pigment acts as an electron donor to a molecule called an electron acceptor. Then, a series of electron acceptors are reduced and successively oxidized, forming a transport chain. During this process, energy is released, which is harnessed by ATP synthases to produce ATP via the chemiosmotic hypothesis (proton accumulation
Read MoreUnderstanding Genetics, Human Genome, and Neurons
Nature Genetics
Genetics is the science that studies the mechanisms of heredity, as the traits passed from parent to child. The basic units of heredity are the genes that allow the continuity of species and determine that each individual has some distinctive features, unique and unrepeatable.
Each cell in the body contains 23 pairs of chromosomes, structures that are composed of DNA and determine your genotype or genetic inheritance. There are 22 pairs of chromosomes, not related to sex, and another
Read MorePlant Epidermis: Deposits, Cells, and Trichome Secretion
Plant Epidermis: Deposits, Cells, and Secretion Mechanisms
Cuticular and Epidermal Deposits
In epidermal cells, various salt deposits manifest as crystals. These deposits are located both on the cuticle surface and permeating it, even within the cell wall itself. Many plants exhibit significant mineralization of the cell wall, with silica joining other salt deposits. These salts distribute evenly between cellulose and cutin. Calcium carbonate mineralization appears coarser than silica, with a granular
Darwin, Lamarck, and Neo-Darwinism: Evolution Theories
Darwin’s Theory of Evolution
Darwin’s theory posits that populations evolve over time through a process of natural selection. Key points include:
- Organisms produce more offspring than can survive.
- Despite overpopulation, population sizes generally remain constant.
- This leads to a struggle for resources (food, space).
- Individuals within a species vary in their traits (some are more “fit”).
- The fittest individuals are more likely to survive and reproduce.
Conclusions of Darwin’s Theory
- Individuals with traits
Plant Hormone Mechanisms: Auxins, Amylases, Ethylene
Rhizobium-Legume Symbiosis: Infection Process
- Union of *Rhizobium* to a radical emergent hair by chemotaxis.
- The hair grows curved, and bacteria grow inside.
- Degradation of the cell wall allows infection.
- The infection cord reaches the base of the hair.
- *Rhizobium* is freed in the apoplast and initiates the formation of a new cord.
- The infection branches and releases vesicles into the cytosol. Nodule differentiation occurs.
Auxin Action Mechanism: Cell Elongation and Growth
Auxins induce cell growth and
Read MoreNervous Impulse Transmission: Synapse and Invertebrates
Nervous Impulse Transmission
From Neuron to Neuron: Synapse
Neurons are independent; they are not in physical contact with each other (synaptic cleft). The synapse is the process of functional communication between two neurons.
- Presynaptic Area: This is the axon of the neuron from which the information arrives.
- Postsynaptic Area: This is the specialized part of another neuron to which the information is directed.
- Synaptic Cleft: This is the space separating the two areas.
The transmission of nerve impulses
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