Biological Molecules

• Most of our bodies are made up of water.
• We are also made up of proteins, fats, and carbohydrates. These substances are what our cells are made from.
• Chemical reactions are going on all the time. These reactions are called metabolism.
• Metabolic reactions can only take place if the chemicals reacting are dissolved in water.
• Water is an important solvent.
• If cells dry out, reactions stop and the organisms die.
• Plasma contains a lot of water so that substances like glucose can dissolve in it. When it is dissolved, it is transported around the body.
• Water is needed to dissolve enzymes and nutrients in the alimentary canal, so digestion can take place.
• Carbohydrates include starches and sugars and their molecules are made up of carbon, oxygen, and hydrogen.
• Simplest kinds of carbohydrates are simple sugars.
• Glucose is a simple sugar.
• Glucose is C6 H12 O6
• If two simple sugars join together, a larger molecule called a complex sugar is made.
• Two types of complex sugar are sucrose (what we put in hot drinks or breakfast cereal) and maltose (malt sugar).
• Complex sugars are chains of glucose.
• Animal cells contain glycogen.
• Carbohydrates are needed for energy.
• Energy from carbohydrates is released from respiration.
• The carbohydrate normally used in respiration is glucose.
• Glucose is the form of carbohydrate that is carried around the body through blood plasma.
• Human blood plasma contains dissolved glucose, that is being transported to all the cells. The cells use the glucose to release energy that they need to continue life.
• Plants use glucose in respiration to provide them with energy, however they do not carry glucose, they transport sucrose and change them to glucose when they need it.
• Plants store carbohydrates as starch.
• It is easy to change glucose into starch or starch into glucose.
• Plants store large quantities of starch in their seeds or tubers, we use this as food.
• Animals do not store starch, they store carbohydrates in the form of glycogen.
• Only small quantities of glycogen in stored in animals.
• Glycogen is mostly stored in cells in the liver and the muscles.
• Test for simple sugars: Add Benedict's solution and heat
• Blue Benedict's solution means that there is no reducing sugar present.
• Brick red, orange, yellow, and green solution means reducing sugars are present.
• Test for starch: Add iodine solution to sample, if starch is present it will turn blue, if there is no starch, it will remain orange-black.
• Fats give off more energy than carbohydrates.
• Most cells use carbohydrates first when they need energy, and only use fats when there are no carbohydrates available.
• Extra energy fats contain makes them useful for storing energy.
• In mammals, some cells (particularly the ones underneath the skin), become filled with fats and oils.
• Fat and oil underneath the skin are used to release energy when needed. it also helps keep heat inside the body (it insulates the body).
• Animals that live in cold places have lots of fat called blubber.
• Plants store their oil in seeds, such as peanut, coconut, and castor oil.
• Oils in plants provide a good store of energy for germination.