General Biology I Reviewer PDF

REVIEWER IN GENERAL BIOLOGY I THE ROLE OF ATP Living cells accomplish this by using the compound adenosine triphosphate (ATP) which known as the “energy currency” of the cell due to its versatility to fill any energy need of the cell. It functions similarly to a rechargeable battery. Life process...

REVIEWER IN GENERAL BIOLOGY I THE ROLE OF ATP Living cells accomplish this by using the compound adenosine triphosphate (ATP) which known as the “energy currency” of the cell due to its versatility to fill any energy need of the cell. It functions similarly to a rechargeable battery. Life processes require a constant supply of energy. Cells use energy that is stored in the bonds of certain organic molecules. Adenosine triphosphate (ATP) is a molecule that transfers energy from the breakdown of food molecules to cell processes. Adenine Base - chemical formula of C5H5N5 A six membered nitrogen ring and a five membered nitrogen ring Ribose- pentose sugar molecule Phosphate group - 3 serially bonded ATP: Structure Adenosine triphosphate (ATP) is the most important biological molecule that supplies energy to the cell. A molecule of ATP is composed of three parts bonded together by “high energy” 1.A nitrogenous base ( adenine ) 2. A sugar ribose 3. Three phosphate groups (triphosphate) CELLULAR RESPIRATION the process by which organisms combine oxygen with foodstuff molecules, diverting the chemical energy in these substances into life sustaining activities and discarding, as waste products, carbon dioxide and water. Where does ATP come from? - ATP comes indirectly from the food that we eat. Molecules of carbohydrates (glucose) and lipids are broken down through the process of cellular respiration to produce ATP. ATP ADP Cycle The energy stored in ATP is released when a phosphate group is removed from the molecule by an enzyme called ATPase. ATP has three phosphate groups, but the bond holding the third phosphate groups is easily broken. When the phosphate is removed, ATP becomes ADP adenosinedi phosphate. A phosphate is released into the cytoplasm and energy Is released. ADP is a lower energy molecule than ATP, but can be converted to ATP by the addition of a phosphate group. ATP → ADP + phosphate + energy available for cell processes. Steps in the ADP ATP Cycle To supply cells with energy, a “high energy” bond in ATP is broken. ADP is formed and a phosphate is released back into the cytoplasm. ATP = ADP + phosphate + energy As the cell requires more energy, ADP becomes ATP when a free phosphate attaches to the ADP molecule. Then energy needed to create an ATP molecule is much less than the amount of energy produced when the bond is broken. ADP + phosphate + energy = ATP ADP is continually converted to ATP by the addition of a phosphate during the process of cellular respiration. ATP carries much more energy than ADP. As the cell requires more energy, it uses energy from the breakdown of food molecules to attach a free phosphate group to an ADP molecule in order to make ATP. ADP+ phosphate + energy from breakdown of food molecules→ ATP When is ATP used? ATP is consumed in the cell by energy requiring processes and can be generated by energy releasing processes. In this way ATP transfers energy between separate biochemical reactions in the cell. ATP is the main energy source for the majority of cellular functions. This includes the production of organic molecules, including DNA and, and proteins. ATP also plays a critical role in the transport of organic molecules across cell membranes, for example during exocytosis and endocytosis. COUPLED REACTION PROCESSES Energy production within a cell involves many coordinated chemical pathways. Most of these pathways are combinations of oxidation and reduction in a compound. TYPES OF REACTIONS: Exergonic (energy yielding) - an exergonic reactions releases energy. An example of exergonic reaction is cellular respiration. Produces ATP Endergonic (energy requiring) reactions – Endergonic reactions require an input of energy. An example of endergonic reaction in the living system is photosynthesis. THE IMPORTANCE OF CHLOROPHYLL AND OTHER PIGMENTS LIGHT White light is a mixture of all colors, in roughly equal proportions. White objects look white because they reflect back all the visible wavelengths of light that shine on them so the light still looks white to us. Colored objects, on the other hand, reflect back only some of the wavelengths; the rest they absorb. The electromagnetic spectrum describes all of the kinds of light, including those the human eye cannot see. In fact, most of the light in the universe is invisible to our eyes. Light, as it encounters an object, is either reflected, transmitted, or absorbed. It is detected as various colors by the human eye. The color that is not absorbed by pigments of objects is transmitted or reflected and that is the color of the object that we see PIGMENTS- are substances that absorb visible light. Different pigments absorb light of different wavelengths. Pigments are the means by which plants capture sun’s energy to be used in photosynthesis. However, since each pigment absorbs only a narrow range of wavelength, there is usually a need to produce several kinds of pigments of different colors to capture more of sun’s energy. Chlorophyll refers to a pigment responsible for the green color in plants. Chloroplasts are organelles within a plant cell, acting as the site for photosynthesis. Pigment necessary for photosynthesis. Chlorophyll is the greenish pigment found in the thylakoid membrane inside the chloroplast of a plant cell. Chlorophyll absorbs blue and red light while it transmits and reflects green light. This is why leaves appear green. Why are there different colors of leaves? Different color of leaves is due to the different types of pigments present in the leaves. There are three kinds of primary pigments in the plant leaves. They are: Chlorophyll - for Green Color Carotenoids - Yellow Orange Color and Anthocyanins - Red or Purple Color