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• Cell-to-cell communication is essential for multicellular organisms, such as nerve cells must communicate with muscle cells for muscle contraction to occur.
• Chemical signals can pass from the cytosol of one cell to another through junctions known as Gap Junctions & Plasmodesmata.
• Benign and malignant tumors can be compared based on their characteristics.
• There are various ways to treat cancer.
• Immune cells interact by cell-cell contact.
• Local regulators, also known as messenger molecules, travel only short distances and include hormones used in long-distance signaling.
• Hormones bind to receptor proteins in the cytoplasm, acting as a transcription factor by binding to a gene and turning it on.
• Hydrophobic hormones diffuse across the membrane and bind to intracellular receptors.
• Protein hormones are hydrophilic, so they bind to receptors found on the cell surface.
• Signal transduction pathway is a series of steps linking a chemical signal molecule to a particular cellular response.
• Signal transduction pathways can be initiated by direct contact or chemical signaling (local or long distance).
• Humans have two sexes: females, who are XX, and males, who are XY.
• The sex-determining region Y (SRY) gene is ordinarily found on the Y-chromosome in placental and marsupial mammals.
• The SRY gene encodes a protein (transcription factor) that is involved in activating genes that leads to the development of male gonads (testes) and prevents the development of female reproductive features (uterus and fallopian tubes).
• Lack of the SRY gene leads to the formation of a female.
• A chromosome is a threadlike, gene-carrying structure found in the nucleus.
• Each eukaryotic chromosome is made of chromatin.
• During interphase, the DNA is found in the loose Chromatin state so the genes can be accessed easily.
• During prophase of mitosis, the chromatin coils and folds tightly into condensed chromosomes, so the sister chromatids can be separated easily during mitosis.
• A duplicated chromosome consists of 2 sister chromatids that are connected at the centromere and contain identical copies of original DNA.
• Signal transduction stages include Reception, Transduction, and Response.
• Reception in signal transduction is the binding between a signal molecule (ligand) and a receptor, which is highly specific.
• Ligands bind to receptor proteins found in the plasma membrane, causing the intracellular domain of the receptor to change shape, allowing the receptor to interact with molecules relaying the message to the interior of the cell.
• There are three main types of membrane receptors: G protein-coupled receptors, Receptor tyrosine kinases, and Ligand-gated ion channel receptors.
• A G protein-coupled receptor is a plasma membrane receptor that works with the help of a G protein.
• Hormone (ligand) binds to G-protein coupled receptor.
• Receptor changes shape.
• G-proteins bind to receptor becoming active.
• Cells can communicate with each other through two main ways: signal transduction pathways and local signaling.
• Hydrophilic and hydrophobic hormones interact differently with the target cell.
• A ligand is a substance that binds to a receptor, causing the receptor's shape to change and initiating transduction of the signal.
• A second messenger is a substance that transduces the signal from the receptor to the target cell.
• The three steps of a signal transduction pathway are: receptor binding, signal transduction, and second messenger activation.
• Insulin signal transduction pathway is an example of a signal transduction pathway.
• Quorum sensing is a process where bacteria communicate with each other, count their own numbers and coordinate their behavior when their numbers reach a certain threshold.
• Behaviors of bacteria include formation of biofilm, bioluminescence, and release of toxins (virulence).
• Quorum sensing involves the release of chemical signaling molecules into the environment by a species of bacteria, which bind to receptors on the same species of bacteria when the population density rises to a specific threshold.
• The signal molecules cause the receptor protein’s shape to change, which initiates transduction of the signal.
• The signal turns on the genes that code for the molecules involved in light generation.
• The endocrine system is an internal system of chemical communication involving endocrine glands that release hormones.