Ecology4

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Published on February 28, 2014

Author: vannessangel24

Source: slideshare.net

ECOLOGY By: MARIA KRISIA FAE DELOS REYES DE ASIS, BSN-RN

PHOTOSYNTHESIS -process by which green plants and certain other organisms use the energy of light to convert carbon dioxide and water into the simple sugar glucose -provides the basic energy source for virtually all organisms -occurs in green plants, seaweeds, algae, and certain bacteria

PHOTOSYNTHESIS -Plants use much of this glucose, a carbohydrate, as an energy source to build leaves, flowers, fruits, and seeds -They also convert glucose to cellulose, the structural material used in their cell walls -Most plants produce more glucose than they use, however, and they store it in the form of starch and other carbohydrates in roots, stems, and leaves

PHOTOSYNTHESIS -humans and other animals depend on glucose as an energy source, but they are unable to produce it on their own and must rely ultimately on the glucose produced by plants -the oxygen humans and other animals breathe is the oxygen released during photosynthesis

PHOTOSYNTHESIS -The pigment chlorophyll is responsible for the green color of plants as well as their ability to photosynthesize -In common terrestrial plants photosynthesis is usually carried out in the leaves, although it can also occur in the stem or other parts of the plant

WHERE PHOTOSYNTHESIS OCCURS? -Plant photosynthesis occurs in leaves and green stems within specialized cell structures called chloroplasts -One plant leaf is composed of tens of thousands of cells, and each cell contains 40 to 50 chloroplasts

WHERE PHOTOSYNTHESIS OCCURS? -The chloroplast, an oval-shaped structure, is divided by membranes into numerous diskshaped compartments called thylakoids -A stack of thylakoids is called a granum or grana which lie suspended in a fluid known as stroma

WHERE PHOTOSYNTHESIS OCCURS? -Embedded in the membranes of the thylakoids are hundreds of molecules of chlorophyll, a light-trapping pigment required for photosynthesis -REMEMBER THE CARBON CYCLE. 

HOW PHOTOSYNTHESIS OCCURS? -It is divided into two stages: a. LIGHT DEPENDENT REACTION - the chloroplast traps light energy and converts it into chemical energy contained in nicotinamide adenine dinucleotide phosphate (NADPH) and adenosine triphosphate (ATP), used in the second stage of photosynthesis

HOW PHOTOSYNTHESIS OCCURS? - Light energy causes the electrons in chlorophyll and other light-trapping pigments to boost up and out of their orbit - Certain red and blue wavelengths are most effective. They have the right amount of energy to energize chlorophyll electrons and boost them out of their orbits to a higher energy level

HOW PHOTOSYNTHESIS OCCURS? - Other pigments, called accessory pigments, enhance the light-absorption capacity of the leaf by capturing a broader spectrum of blue and red wavelengths, along with yellow and orange wavelengths - None of the photosynthetic pigments absorb green light; as a result, green wavelengths are reflected, which is why plants appear green

HOW PHOTOSYNTHESIS OCCURS? - The electrons are then passed down a chain of carrier molecules, called an electron transport chain - The electrons are passed from one carrier molecule to another in a downhill direction because electrons release energy as they move down the chain

HOW PHOTOSYNTHESIS OCCURS? - At the end of the electron transport chain lies the molecule nicotine adenine dinucleotide (NADP+) - Using the energy released by the flow of electrons, two electrons from the electron transport chain combine with a hydrogen ion and NADP+ to form NADPH

HOW PHOTOSYNTHESIS OCCURS? - the electrons are then transferred and passed through a different electron transport chain - As they pass along the cascade of electron carrier molecules, the electrons give up some of their energy to fuel the production of ATP, formed by the addition of one phosphorus atom to adenosine diphosphate (ADP)

HOW PHOTOSYNTHESIS OCCURS? - electrons are replenished by the water that has been absorbed by the plant roots and transported to the chloroplasts in the leaves - The movement of electrons and the action of an enzyme split the water into oxygen, hydrogen ions, and electrons

HOW PHOTOSYNTHESIS OCCURS? - Some of the hydrogen ions may be used to produce NADPH at the end of the electron transport chain, and the oxygen from the water diffuses out of the chloroplast and is released into the atmosphere through pores in the leaf

HOW PHOTOSYNTHESIS OCCURS? - The transfer of electrons in a step-by-step fashion releases energy and heat slowly, thus protecting the chloroplast and cell from a harmful temperature increase - It also provides time for the plant to form NADPH and ATP

HOW PHOTOSYNTHESIS OCCURS? b. LIGHT INDEPENDENT REACTION - The chemical energy required for the light-independent reaction is supplied by the ATP and NADPH molecules produced in the lightdependent reaction - is cyclic, that is, it begins with a molecule that must be regenerated at the end of the reaction in order for the process to continue

HOW PHOTOSYNTHESIS OCCURS? - Termed the Calvin cycle after the American chemist Melvin Calvin who discovered it - use the electrons and hydrogen ions associated with NADPH and the phosphorus associated with ATP to produce glucose

HOW PHOTOSYNTHESIS OCCURS? - These reactions occur in the stroma, the fluid in the chloroplast surrounding the thylakoids, and each step is controlled by a different enzyme - requires the presence of carbon dioxide molecules, which enter the plant through pores in the leaf, diffuse through the cell to the chloroplast, and disperse in the stroma

HOW PHOTOSYNTHESIS OCCURS? - begins in the stroma when these carbon dioxide molecules link to sugar molecules called ribulose bisphosphate (RuBP) in a process known as carbon fixation - With the help of an enzyme, six molecules of carbon dioxide bond to six molecules of RuBP to create six new molecules

HOW PHOTOSYNTHESIS OCCURS? - Several intermediate steps, which require ATP, NADPH, and additional enzymes, rearrange the position of the carbon, hydrogen, and oxygen atoms in these six molecules - when the reactions are complete, one new molecule of glucose has been constructed and five molecules of RuBP have been reconstructed

HOW PHOTOSYNTHESIS OCCURS? - This process occurs repeatedly in each chloroplast as long as carbon dioxide, ATP, and NADPH are available - The thousands of glucose molecules produced in this reaction are processed by the plant to produce energy in the process known as aerobic respiration, used as structural materials, or stored

PHOTOSYNTHESIS VARIATIONS - On hot days, they partially close the pores in their leaves to prevent the escape of water. With the pores only slightly open, adequate amounts of carbon dioxide cannot enter the leaf, and the Calvin cycle comes to a halt

PHOTOSYNTHESIS VARIATIONS - To get around this problem, certain hot-weather plants have developed a way to keep carbon dioxide flowing to the stroma without capturing it directly from the air - They open their pores slightly, take in carbon dioxide, and transport it deep within the leaves

PHOTOSYNTHESIS VARIATIONS - Here they stockpile it in a chemical form that releases the carbon dioxide slowly and steadily into the Calvin cycle - With this system, these plants can continue photosynthesis on hot days, even with their pores almost completely closed

PHOTOSYNTHESIS VARIATIONS - Bacteria lack chloroplasts, and instead use structures called chromatophores or membranes formed by numerous foldings of the plasma membrane or cytoplasm - The chromatophores house thylakoids similar to plant thylakoids, which in some bacteria contain chlorophyll

PHOTOSYNTHESIS VARIATIONS - Bacteria lack chloroplasts, and instead use structures called chromatophores or membranes formed by numerous foldings of the plasma membrane or cytoplasm - The chromatophores house thylakoids similar to plant thylakoids, which in some bacteria contain chlorophyll

Cactus Many cacti, such as the prickly pear cactus shown here, carry out photosynthesis in enlarged stems rather than leaves. The stems also serve to store water, essential for photosynthesis.

CELLULAR RESPIRATION - process in which cells produce the energy they need to survive - cells use oxygen to break down the sugar glucose and store its energy in molecules of adenosine triphosphate (ATP) - critical for the survival of most organisms because the energy in glucose cannot be used by cells until it is stored in ATP

CELLULAR RESPIRATION - occurs within a cell constantly, day and night, and if it ceases, the cell—and ultimately the organism—dies - Two critical ingredients required for cellular respiration are glucose and oxygen - cells must have a steady supply of glucose so that ATP production is continuous

CELLULAR RESPIRATION - Cellular respiration sometimes is referred to as aerobic respiration, meaning that it occurs in the presence of oxygen - transfers about 40 percent of the energy of glucose to ATP - The rest of the energy is released as heat, which warmblooded organisms use to maintain body temperature, and cold-blooded organisms release to the atmosphere

CELLULAR RESPIRATION - The process of cellular respiration occurs in four stages: glycolysis; the transition stage; the Krebs cycle, also known as the citric acid cycle; and the electron transport chain. Each stage accomplishes different tasks

GLYCOLYSIS - the first stage of cellular respiration wherein glucose is the primary fuel - glucose is broken down with the help of enzymes and other molecules found in the cytoplasm - Enzymes first attach two phosphate groups to glucose to make it more reactive (A phosphate group is a cluster of one phosphorus and four oxygen atoms)

GLYCOLYSIS - The addition of the two phosphate groups prepares glucose for the action of another enzyme - This enzyme splits glucose in half to produce two threecarbon molecules, each with one phosphate group attached - In the next step, an enzyme removes one hydrogen atom and two electrons from each threecarbon molecule

GLYCOLYSIS - Both hydrogen atoms are modified to hydrogen ions, positively charged particles - A hydrogen ion and two electrons from each threecarbon molecule are transferred as a unit to a large molecule called nicotinamide adenine dinucleotide (NAD+) to form two molecules of NADH

GLYCOLYSIS - The hydrogen ions and electrons stored in each molecule of NADH are used to make ATP in later stages of cellular respiration - In the final steps of glycolysis, two hydrogen atoms are removed from each threecarbon compound - These hydrogen atoms bond to free-floating oxygen atoms in the cytoplasm to form water

GLYCOLYSIS - This step prepares the two three-carbon compounds for action by the next enzyme in the pathway - This enzyme removes the phosphate group from each three-carbon compound - Each phosphate group then bonds to a single molecule of adenosine diphosphate (ADP)

GLYCOLYSIS - ADP is composed of three carbon-based rings and a tail of two phosphate groups. The addition of the third phosphate group to the tail forms ATP - In this step, two new ATP molecules are produced - When cells require energy, another enzyme breaks off the third phosphate group, releasing energy that powers the cell

GLYCOLYSIS - The removal of the third phosphate from ATP converts ATP back to ADP, which is used again in cellular respiration to make more ATP - When the two three-carbon compounds are separated from the phosphate groups, the three-carbon compounds are converted to two molecules of pyruvate, each composed of three carbon, three oxygen, and three hydrogen atoms

TRANSITION STAGE - The transition stage is a short biochemical pathway that links glycolysis with the Krebs cycle - The pyruvate molecules move from the cytoplasm to the mitochondria, where the remaining steps of cellular respiration are carried out - Each mitochondrion contains a membrane that is folded back and forth many times

TRANSITION STAGE - This extensive membrane is studded with hundreds of thousands of enzymes that direct cellular respiration - The numerous enzymes enable great quantities of ATP to be produced simultaneously in one mitochondrion - Without mitochondria or a similar structure, most cells could not generate enough ATP to survive

TRANSITION STAGE - In this brief stage, enzymes transfer hydrogens and electrons from the two pyruvate molecules to two molecules of NAD+ to form two more molecules of NADH - Another enzyme breaks off one carbon and two oxygen atoms from each pyruvate molecule

TRANSITION STAGE - These atoms combine to form carbon dioxide, the primary waste product of cellular respiration, which diffuses out of the cell - As a result of these reactions, each pyruvate molecule is transformed into a two-carbon compound called an acetyl group

TRANSITION STAGE - The two acetyl groups unite with two molecules of coenzyme A to form two acetyl coenzyme A molecules - The acetyl coenzyme A molecules are the molecules that enter the Krebs cycle

SIR HANS ADOLF KREBS

KREB’S CYCLE - During the Krebs cycle, the acetyl coenzyme A molecules are processed - As this complex pathway progresses, six molecules of NADH are formed - Additional carbon dioxide is created, and this process releases energy that is used to build two molecules of ATP from a pool of ADP and phosphate groups in the mitochondria

KREB’S CYCLE - Hydrogens and electrons then are transferred to a molecule of flavin adenine dinucleotide (FAD++)to form FADH2, a molecule like NADH that temporarily stores hydrogen and electrons for later use

KREB’S CYCLE - By the end of the Krebs cycle, most of the usable energy from the original glucose molecule has been transferred to ten molecules of NADH (two from glycolysis, two from the transition stage, and six from the Krebs cycle); two molecules of FADH2; and four molecules of ATP, two of which were formed in glycolysis

ELECTRON TRANSPORT CHAIN - The reactions of the electron transport chain occur in several closely spaced molecules embedded in the mitochondrial membrane - the NADH and FADH2 molecules dump off their load of electrons and hydrogen ions near these electron transport chain molecules

ELECTRON TRANSPORT CHAIN - The first molecule in the chain has an attraction for electrons and grabs them, but the molecule next to it in the chain has an even stronger attraction and grabs the electrons away from the first molecule - The electrons are passed down the chain in this manner, until they reach oxygen, the final molecule in the chain

ELECTRON TRANSPORT CHAIN - Oxygen has a stronger appetite for electrons than any molecule in the chain, and the electrons therefore are held by oxygen - They are joined by the hydrogen ions that were dropped off by NADH and FADH2 at the beginning of the electron transport chain - The combination of the electrons, hydrogen ions, and oxygen forms water, used by the cell in other biochemical

ELECTRON TRANSPORT CHAIN - As NADH and FADH2 release hydrogen and electrons in the electron transport chain, they are converted back to NAD+ and FAD++, respectively, providing the cell with a steady supply of these molecules so that cellular respiration can be carried out over and over again

ELECTRON TRANSPORT CHAIN - As the electrons flow down the electron transport chain, they release a veritable windfall of energy that is used by an enzyme to make more ATP - In most cells, the electron transport chain produces 32 molecules of ATP

ELECTRON TRANSPORT CHAIN - Together with the two ATP molecules gained in glycolysis and the four generated in the Krebs cycle, cellular respiration produces a grand total of 38 molecules of ATP for every molecule of glucose processed

ELECTRON TRANSPORT CHAIN - Glucose molecules enter the cell by the hundreds of thousands and are processed simultaneously to generate millions of ATP molecules every second - Some of the ATP molecules remain in the mitochondria to supply it with energy, but most stream from the mitochondria to the cytoplasm, where they fuel the cell’s activities

ELECTRON TRANSPORT CHAIN - It is estimated that a single human brain cell uses a staggering 10 million ATP molecules per second to carry out its tasks - Although glucose is the primary fuel for cellular respiration, cells can rely on other molecules to produce ATP

ELECTRON TRANSPORT CHAIN - The cellular respiration pathway is connected to other metabolic pathways that can donate molecules to cellular respiration at different steps along the way - For example, glycerol, a breakdown product of fat, can enter the cellular respiration pathway in the middle of glycolysis

ELECTRON TRANSPORT CHAIN - Another product of fat digestion, fatty acids, can enter at the transition stage - Glycerol is modified in glycolysis to pyruvate, and fatty acids are modified to acetyl coenzyme A in the transition stage. The pyruvate and acetyl coenzyme A are processed through the remaining steps of cellular respiration to yield ATP

ELECTRON TRANSPORT CHAIN - The cellular respiration pathway is connected to other metabolic pathways that can donate molecules to cellular respiration at different steps along the way - For example, glycerol, a breakdown product of fat, can enter the cellular respiration pathway in the middle of glycolysis

Please bring out any piece of paper and prepare for a quiz..

question: 1. What is responsible for the green color of plants as well as their ability to photosynthesize?

question: 2. What type of pigments enhance the light-absorption capacity of the leaf?

question: 3. What color of light is NOT absorbed by the plants?

question: 4. What is this molecule?

question: 5-6. What are two critical ingredients required for cellular respiration?

question: 7. What are the molecules that enter the Kreb’s cycle?

question: 8. What is the stage of respiration wherein glucose is the primary fuel?

question: 9. Cellular respiration sometimes is referred to as ___________________, meaning that it occurs in the presence of oxygen.

question: 10. The electrons are passed down the electron transport chain in a manner, until they reach ______, the final molecule in the chain.

question: 11. Who identified the Kreb’s Cycle?

question: 12. The Kreb’s Cycle is also known as what?

question: 13. What is a stack of thylakoids called?

question: 14. What is the process by which green plants and certain other organisms use the energy of light to convert carbon dioxide and water into the simple sugar glucose?

question: 15. What do bacteria use for photosynthesis since they do not have chloroplasts?

question: 16. What molecule has three carbon, three oxygen, and three hydrogen atoms?

question: 17. Cellular respiration transfers about ______ percent of the energy of glucose to ATP?

question: 18. In which stage does glycerol enter the cellular respiration process?

question: 19. Cellular respiration produces a grand total of ____ molecules of ATP for every molecule of glucose processed

question: 20-21. What colors of light wavelengths are most effective in photosynthesis?

question: 22-25. What are the four stages of cellular respiration?

question: 26. What is the process wherein carbon dioxide molecules link to sugar molecules called ribulose bisphosphate (RuBP)?

question: 27. Light independent reaction is also known as __________ after the American chemist who discovered it.

question: 28-29. What molecules produced in the light dependent reaction supply the chemical energy required for the light-independent reaction?

question: 30. Photosynthesis also convert glucose to ____________, the structural material used in their cell walls.

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