Plant hormones are specialized chemical substances produced by plants. They are the main internal factors controlling growth and development. Hormones are produced in one part of a plant and transported to others, where they are effective in very small amounts. Depending on the target tissue, a given hormone may have different effects.
Plant hormones play an integral role in controlling the growth and development of plants. A plant hormone is generally described as an organic compound synthesized in one part of the plant and translocated to another part, where in low concentrations elicits a physiological response.
There are five generally recognized classes of plant hormones; some of the classes are represented by only one compound, others by several different compounds. They are all organic compounds, they may resemble molecules which turn up elsewhere in plant structure or function, but they are not directly involved as nutrients or metabolites.
Hormone Source Action
Auxins apical meristem (only moves down), embryo of seed, young leaves • Control of cell elongation
• apical dominance (prevents lateral buds)
• prevents abscission
• continued growth of fruit
• cell division in vascular and cork cambium
--formation of lateral roots from pericycle
--formation of adventitious roots from cuttings
Gibberellins Roots and young leaves • Cell (stem) elongation (works in stems and leaves, but not roots)
• breaking seed/bud dormancy
• stimulating fruit set
Cytokinins roots, embryos, fruits actively growing • Promote cell division
--signal axillary/lateral bud growth
--prevent leaf abscission
• chloroplast development
• breaking dormancy in some seeds
• enhance flowering
• promote fruit development
Abscissic Acid ...
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...ascade ultimately resulting in modification of enzyme activity, altered metabolic processes, and different phenotypes.
One thing plant hormones specifically control is gene expression. The exact mechanisms by which hormones regulate gene expression are poorly understood. Gene expression is part of a large amplification process. This process involves repeated transcription of DNA resulting in many copies of mRNA (1st amplification step); mRNA is processed and enters the cytoplasm where it is translated many times by ribosomes into a gene product such as an enzyme (2nd amplification step); enzymes are modified to become functional and capable of high catalytic activity even at low concentrations. They catalyze the production of many copies of an important cellular product (3rd amplification step).
It is likely that gene regulation is affected by certain enzymes after initial hormone binding. Genes may be altered by secondary and tertiary messengers of a cellular cascade as well. Hormones may indirectly control gene expression through these enzymes and messengers at a number of control sites such as transcription, mRNA processing, mRNA stability, translation, and post-translation
The Effect of Light on the Organic Plant Elodea Aim: To calculate the rate of photosynthesis from the number of oxygen bubbles produced by the plant. Photosynthesis: The process by which green plants use the sun's energy to build up carbohydrate reserves. Plants make their own organic food such as starch. Plants need Carbon dioxide, water, light and chlorophyll in order to make food; and starch and oxygen are produced. Carbon dioxide and water are the raw materials of photosynthesis.
The endocrine system is very dynamic and has ties to most, if not all of the other major systems of the body. It is responsible for production of hormones and the regulation of them as well. These hormones act as chemical messengers within the body. Through several differing mechanisms, they are able to trigger very specific responses in target cells or organs. This is what enables the endocrine system to guide growth, development, reproduction, and behavior, among many others as well.
...e involved in the plants carbohydrate metabolism. This response causes the plant’s cell walls to be rearranged and strengthened. THis would increase the plants resistance to infection and the uptake of harmful chemicals.
Gene expression is the ability of a gene to produce a biologically active protein. This process is regulated by the cells of an organism, it is very important to the survival of organisms at all levels. This is much more complex in eukaryotes than in prokaryotes. A major difference is the presence in eukaryotes of a nuclear membrane, which prevents the simultaneous transcription and translation that occurs in prokaryotes. Initiation of protein transcription is started by RNA polymerase. The activity of RNA polymerase is regulated by interaction with regulatory proteins; these proteins can act both positively, as activators, and negatively as repressors. An example of gene regulation in cells is the activity of the trp operon. The trp operon encodes the genes for the synthesis of tryptophan. This type of gene, like the lac operon, is regulated by a repressor that binds to the operator sequences. The activity of the trp repressor is enhanced when it binds tryptophan; in this capacity, tryptophan is known as a corepressor. Since the activity of the trp repressor is enhanced in the presence of tryptophan, the rate of expression of the trp operon is graded in response to the level of tryptophan in the cell. Another example of gene regulation in cells is gene amplification. This is a Technique by which selected DNA from a single cell can be duplicated indefinitely until there is a sufficient amount to analyse by conventional genetic techniques.
Behavior is defined as the way in which one acts or conducts oneself, especially toward others. Behavior is controlled by a system of the body called the endocrine system. The endocrine system is made of glands whose secretions pass directly into the bloodstream or lymph system. This system is responsible for growth, mood, tissue function, metabolism, sexual function and reproductive processes. The endocrine system affects almost every organ and cell in the body. Hormones and glands make up this system. As with any system, diseases can occur that are dangerous to the body.
My group, fertilizer group 3, is testing the variables of plant color and number of leaves. Fertilizer can affect that drastically! Those two variables are basically what determine a healthy plant. Fertilizer can help to boost the minerals in the soil and give the plant what it needs to survive and be healthy.
Plant hormones are certain chemicals present in plants that control plant growth and development by affecting the division, differentiation, and elongation of cells. (Campbell, 2008) Each hormone has multiple effects depending on its site of action, its concentrations, and the developing stage of the plant. (Campbell, 2008) Auxin is a plant hormone that is synthesized within the apical meristems and young leaves of a growing plant. Auxin stimulates stem elongation when it is present is low concentrations. It promotes the formations of lateral and adventitious roots, regulates development of fruit, enhances apical dominance, functions in gravitropism and phototropism, promotes vascular differentiation, and retards leaf abscission. Gibberellic acid is one of several plant hormones that govern a plant’s growth. Gibberellins allow for stem elongation in plants. Plants without enough of this hormone tend to grow short or stunted. This chemical is high in the element potassium, which is one the main components of plant fertilizer and very important for plant growth on its own. The...
Today people are using pesticides and hormones in many of the items that we use each day and it’s affecting our society in various ways. Pesticides are used in many different ways including: keeping insects away from plants, controlling weeds, and controlling the spread of diseases to plants. Hormones make animals grow faster and/or produce leaner meat for food. Although some people believe that pesticides and hormones should be used to help crops and livestock, they can be very harmful to others as well as the environment.
Each plant species has a unique pattern of resource allocation that is genetically determined but not fixed. Plants can adjust there allocation pattern when they experience different environments and the presence of other species. Phenotypic plasticity goes hand in hand with resource allocation as well. When a plant has to adjust itʻs resource allocation, sometimes it uses itʻs resources to help the plant grow different characteristic so that the plant can have a greater chance of living in the environment. For example, if a plant from an environment that does not experience wind on the regular basis enters a new environment that has a lot of wind the plant may change itʻs resource allocation and spend more of itʻs resources growing deeper
Endocrine Hormones Are Involved In the Homeostasis of Blood Pressure Human body is probably as scientific as it could get with a whole network of controls and balances well in place. We have the nervous systems and immune systems and these systems are there to stay and more importantly they evolve and change with the passage of time. They keep upgrading themselves and this what keeps the man up to par with everything else and the change as and when they do come about. The hormone is like a messenger or a communicator in the case of out body. Once released, it carries the message through and forth and it travels through the main blood stream until it reaches and finds a cell with a receptor that it fits. This has to be a perfect fit and that is why it is sale that it must attach itself to the molecule like a key made for a certain lock. Then, like a key in a lock, the molecule attaches to the receptor and sends a signal inside the cell, which is relayed from here onwards. It is the content of the message which implies as to whether produce, release, take in or reduce the supply of p...
...for yield, harvestability and disease resistance. Three primary components of the genetic package inserted into corn; protein genes, promoters, and genetic markers. Protein genes, Bt genes modified for improved expression in corn, produce Cry proteins. Initial Bt hybrids in the United States and Canada includes one of three Cry proteins, Cry1Ab, Cry1Ac or Cry9C. Future hybrids may produce other Cry proteins, or proteins from other sources. A promoter controls where and how much of the Cry protein a plant produces. Some promoters limit protein production to specific parts of the plant (for example, leaves, green tissue and pollen) whereas others produce protein throughout the plant. The presence of a genetic marker allows seed companies to identify successful transformations. Current examples of markers include genes for herbicide resistance or antibiotic resistance.
Plants are grown under controlled and sterile conditions which reduce the risk of being exposed to pests, pathogens and diseases.
Asexual propagation is the process through which reproduction without passage through the seed cycle occurs. The advantages of asexual propagation are that it preserves genetic makeup, propagates seedless plants, disease control, rapid production, the plants are identical, cheaper, faster and easier reducing or avoiding juvenility. The disadvantages of asexual propagation are that it increases disease and insect susceptibility, plants are bulky, and the mother plants could become contaminated. The goal of this experiment was to determine the development of adventitious roots and shoots, and observe these plants over a period of five weeks. Due to auxin being produced in the tip, tip cuttings should root faster than any other cuttings. Auxin is a plant hormone that is responsible for cell elongation and enlargement, root formation, and growth. There are two forms of auxins; phototropism, which is produced in the tip and moves downward on the side away from the light and gravitropism, which is where plant roots grow downward and plant shoots grow upward.(Plant Auxin 201...
The endocrine system is contained glands that pass on and discharge hormones, made substances made in the body that control the progression of cells or organs. These hormones encourage the body's change, assimilation (the physical and compound approaches of the body), and sexual development and purpose of restriction. The hormones are transmitted into the circulatory system and may influence maybe a couple or three organs all through the body.
Plant nutrition is area of plant biology that is of the utmost importance for the proliferation of plants. Without proper nutrition, plants would simply cease to exist unless drastic alterations were made. There are certain elements that are required for the plant to grow and reproduce; these elements are known as essential elements. There are three requirements of an essential element: the element must be required for the completion of the plant’s life cycle, the element must not be replaceable by another element in whole, and finally the element must be direction involved in the metabolism of the plant. Chemical compounds that are involved in proper nutrition have been designated as nutrients, and further classified as macronutrients and micronutrients. Macronutrients are needed for growth, metabolism, and many other functions, but are designated as “macro” because they are required in larger amounts. Macronutrients include carbohydrates, proteins, and fat molecules. Micronutrients have a much wider function that depends on the exact micronutrient. Micronutrients are designated as so because they are needed in much smaller amounts when compared to macronutrients. Examples of micronutrients include vitamins and minerals.