Ragged Boy on 05 Nov at 5: I got this idea after watching Dr.
Animal Cell Plant Cell In plant cells, if a plant cell is placed in distilled water, water molecules will move from the distilled water to the cell, the cell swells up and becomes turgid but it will never burst because plant cells are surrounded by cell walls, which are made of cellulose and is elastic, it will stretch but never break, the cell becomes turgid.
If we place a plant cell in a concentrated salt solution whith low water potential, water will move from the cell to the solution causing the cell to become plasmolysed as in the diagram.
Active transport occurs in cells, it is basically the movement of molecules or ions from a region of their low concentration to a region of their high concentration against the concentration gradient using energy of respiration. Active transport occurs in living, active cells only because it needs energy, these cells usually have a structure called mitochondria which respires producing energy to be used in active transport.
Active transport happens in roots to absorb mineral salts from the soil. It also occurs in the digestive system of mammals. Molecules are taken into the cell by protein carriers within the cell membrane.
Enzymes Enzymes are proteins that function as a biological catalyst. They are proteins in nature. Hydrogen peroxide H2O2 is a substance that decomposes into Water H2O and Oxygen O2 if it is left in room temperature for a period of time.
This reaction could a long time, but it could be sped up if we add a catalyst. Each catalyst can catalyse a specific substance and nothing but it.
The catalyst for Hydrogen peroxide is called Manganese4 oxide. If it is added we will get water and oxygen gas in a very short time, and the manganese4 oxide could be obtained again as it was, it remains unchanged.
How Do Enzymes Work? Enzymes work the same way as catalysts do, they can work with only one substrate and they can be used more than once. Enzymes have a structure that is called active site.
Only one substance can fit into the active site to be digested, and it is the only substrate that this particular enzyme works with. The figure above shows the function of enzymes: The substrate enters the active site of the enzyme.
The reaction takes place. The substrate exits the enzyme as two simpler products. You can also think of the way enzymes work as a key and a lock, the key is the substrate and the lock is the enzyme.
The key should be exactly the right shape to fit in the lock, so does the substrate to fit in the active site of the enzyme.
The key could only open only one lock, and the lock could be unlocked by only that key. Enzymes are two types, Builders and Breakers. Builder enzymes do the opposite of breaker enzymes. Breakers break large molecules into smaller simpler ones, builders combine smaller ones to make large molecules.
Breaker enzymes are used in the digestive system to break down large insoluble molecules into simpler soluble ones to be used by the body. They are also present in cells that respire to break down sugars and oxygen into carbon dioxide, water and energy. Builder enzymes are present in plants to be used in photosynthesis, the opposite of respiration, in photosynthesis, oxygen and water are combined together to form carbon dioxide and sugars.
Naming enzymes depends on the substrate they work on. The sucrase enzyme works on sucrose. The maltase enzyme works on maltose. Enzymes are reusable and are only affected by the change in temperature and pH. Each enzyme has an optimum temperature, this is the temperature at which the enzyme is most active, below this temperature the activity of the enzyme decreases until it becomes inactive at low temperatures, above this optimum temperature the enzyme becomes denatured and can no longer work.
As the temperature increases, the enzyme and substrate gain more kinetic energy and move faster colliding more, the enzyme becomes more active and the reaction takes place. The enzymes become denatured when the shape of their active site changes as a result of high temperature, thus the substrate cannot fit into the active site and the enzyme is useless.
Each enzyme has its own optimum temperature, enzymes in humans have optimum temperatures of around 40 degrees. Plants have enzymes with optimum temperature of about 25 degrees.
As in temperature, enzymes have an optimum pH. The scale runs from 1 to Each enzyme has an optimum pH, if this pH changes, the shape of the active site of the enzyme is changed, thus the substrate will not be able to fit in it, and the enzyme becomes useless.Heroes and Villains - A little light reading.
Here you will find a brief history of technology. Initially inspired by the development of batteries, it covers technology in general and includes some interesting little known, or long forgotten, facts as well as a few myths about the development of technology, the science behind it, the context in which it occurred and the deeds of the many.
PHOTOCHEMISTRY Theoretical Concepts and Reaction Mechanisms Yuri V.
Il'ichev Cordis Corporation, a Johnson and Johnson Company P.O. Box , . Exposing the climate geoengineering cover-up.
Though the official ozone layer “recovery” lie is still being propagated, some sources are acknowledging reality as the truth becomes ever more difficult to hide.. Much more geoengineering / ozone destruction supporting data is listed below.
The magnification was × Calculate the real size of the cell. Use the equation: Give your answer in micrometres. View and Download Heinz Walz PAM handbook online. Portable Chlorophyll Fluorometer. PAM Measuring Instruments pdf manual download.
The magnification was × Calculate the real size of the cell. Use the equation: Give your answer in micrometres.