Unit 4: Topic 3 - Signal Transduction Flashcards
What is the order of organization in biology?
The order of biology from least complex to most complex is: cells, tissues, organs, organ system.
In order for a group of cells to reach homeostasis after a disruption has occurred, what must it do with the other cells?
The cells must communicate with each other to regulate the movement of materials in and out of the cell, initate cell division and cell death and jumpstart the production of proteins and other materials within the cell
What changes in the environment can ellicit a celullar response?
Changes in temperature, pH, light and chemicals can cause a celullar response.
What are examples of cellular responses to stimulus?
A stimulus is a change that causes a response. These responses can happen within varying durations of time. For example, there are very quick responses that happen in less than a second. An example would be the opening of ion channels, which changes the membrane potentials seen in nerve systems, or the contraction of muscles. Some cellular responses may be a bit slower and take a few minutes to up to an hour to process such as cell locomotion, protein synthesis or changes in metabolic activity. Finally there are cell responses that can take hours to days to complete such as cell division. (where the cell would have to got through all the steps of mitosis to complete) or programmed cell death (apoptosis).
What are the steps to a signal transduction pathway?
Signal transduction pathways have 3 steps: 1) Signal reception 2) Signal Transduction and 3) Celullar response
What is signal reception?
Signal reception is when a chemical signal (ligand) binds to the receptor protein of the cell on the cell membrane. NOTE: This is a protein so the structure of the ligand directly impacts whether the ligand will bind with the receptor.
What is signal transduction?
Signal transduction is process where the message is received by the cell and processed in the cell before a response is made. This starts when the ligand changes the shape of the receptor protein after it binds to the receptor protein. This change causes the binding of more proteins along the pathway inside the cell. During this step the process of amplification occurs that increases the intensity of the cellular response by having the primary enzyme activate multiple secondary molecules which in turns activates even more molecules. This increases the speed of reaction because more product is being created with fewer stimuli.
What are the different types of receptors?
The 2 main types of receptors are internal receptors and cell surface receptors. Internal receptors do not need to activate other molecules and can instead pass straight through the cell membranes to activate a cellular response. This means that the ligands of a cell surface receptors must be hydrophobic (nonpolar). The other type is cell surface receptors that goes through the “normal” steps of signal transduction (reception, transduction and response). The internal receptors are faster than the cell surface receptors because they can pass straight into the nucleus membrane. This is why many proteins that need to be synthesized at a very fast pace are induced through internal receptors.
What are the different types of signalling?
Paracrine signaling, autocrine signaling, endocrine signaling, and signaling by direct contact.
What is paracrine signalling?
Paracrine signalling (or paracrine secretions) is when cells communicate over a relatively short distance by releasing small signalling molecules to be recepted by other cells. These signalling molecules, also called paracrine factors, act as a ligand and induce a targeted cell response. They usually enter the cell through diffusion but are sometimes receptor binding.
What is an example of paracrine signalling?
A common example given for paracrine signaling is during fetal development. This development involving the hedgehog proteins (the family of proteins that are involved in making sure the fetus’ body parts are ordered in the correct way). A cell that becomes a muscle cell sends out signaling molecules to the other cells nearby to make them into more muscles so that together they can become muscle tissue.
What is autocrine signaling?
Autocrine signaling is when the cell communicates and uses ligands to cause a cellular response within itself. These chemical signals that the cell releases are called autocrine agents, and they bind to autocrine receptors on the same cell they were released from. Once they bind, a signal transduction pathway occurs.
What is an example of autocrine signaling?
An example of autocrine signaling is in the immune system when the Helper T cell activates itself once the Antigen-presenting cell has bound to it.
What is endocrine signaling?
A cell targets a distant cell through the bloodstream. Similar to how our parathyroid signals the production of T3 and T4 in the thyroid gland.
What is signaling by direct contact?
Direct signaling transfers signals across gap junctions between neighboring cells.
