METABOLISM IN PLANTS.pptxMetabolism in plants Defination- Metabolism is the process through which living systems acquire and use free energy to carry out functions.

Metabolism in plants
Defination- Metabolism is the process through which living systems acquire and use free energy to carry out functions. Metabolism requires highly coordinated cellular activity. Metabolism performs 4 functions 1. Obtain energy for the cell. 2. Convert nutrients into macromolecules. 3. Assemble macromolecules into cellular structures. 4. Degrade macromolecules as required for biological function. Metabolism consists of catabolism and anabolism. Catabolism is the degradation pathways to salvage components and energy from biomolecules such as nucleotides, proteins, lipids and polysaccharides. The process generates energy. Anabolism is the biosynthesis of biomolecules such as nucleotides, proteins, lipids and polysaccharides from simple precursor molecules. This process requires energy. Biomolecules are composed predominantly of carbon, hydrogen, oxygen and nitrogen. All living things require a source of energy, carbon, oxygen and nitrogen.

1. METABOLISM PHOTOSYNTHESIS (ANABOLISM), RESPIRATION (CATABOLISM)

2. METABOLISM IN PLANTS - Definition - Metabolism is the process through which living systems acquire and use free energy to carry out functions. Metabolism requires highly coordinated cellular activity. Metabolism performs 4 functions Obtain energy for the cell. Convert nutrients into macromolecules. Assemble macromolecules into cellular structures. Degrade macromolecules as required for biological function. Metabolism consists of catabolism and anabolism. Catabolism is the degradation pathways to salvage components and energy from biomolecules such as nucleotides, proteins, lipids and polysaccharides. The process generates energy. Anabolism is the biosynthesis of biomolecules such as nucleotides, proteins, lipids and polysaccharides from simple precursor molecules. This process requires energy. Biomolecules are composed predominantly of carbon, hydrogen, oxygen and nitrogen. All living things require a source of energy, carbon, oxygen and nitrogen.

3. Energy and Carbon Autotrophs - self feeding. Autotrophs are prokaryotes that can produce all of their cellular components from simple molecules such as 1-120, C02, NH and I-IS. These are self sufficient cells that utilize C02 from tine atmosphere as the carbon source. Chemolithotrophs -obtain free energy via the oxidation of inorganic compounds such as NH3, H2S or Fe+2. Photoautrophs - obtain free energy from light photons via photosynthesis. Heterotrophs - Feeding on others. Heterotrophs obtain energy by oxidation of organic compounds (carbohydrates, lipids, or protein). Heterotrophs obtain carbon from glucose, proteins and lipids. Ultimately Heterotrophs depend on autotrophs for these organic compounds, Plant cells are of two types: Autotrophic-the green leaf cells are autotrophic. Heterotrophic-root cells are example of heterotrophic cells of plants.

4. 2.) Oxygen Living organisms can obtain oxygen from the atmosphere or from water. Aerobes - live in the presence of oxygen. They use oxygen to oxidize organic nutrients. Anaerobes - Live in the absence of oxygen. Catabolize nutrients without molecular oxygen . Obligate anaerobes- are poisoned by oxygen. Facultative - Some organisms can live in either aerobic or anaerobic conditions. They are called facultative. Examples are yeast and E. coli.

5. Nitrogen All living things require nitrogen. Most animals obtain nitrogen from amino acids. Plants are able to use ammonia or nitrates as nitrogen sources . Nitrogen (N2) is the major gas component of our atmosphere (80%). It is relatively inert. The Earth's crust contains very little nitrogen. Only a few organisms can fix N2. All living organisms depend on these nitrogen fixing microorganisms such as cyanobacteria and blue-green algae. Many nitrogen fixing bacteria live in the soil. Some nitrogen fixing bacteria live symbiotically in the nodules of the roots of plants. Nitrifying Bacteria - oxidize ammonia into nitrates. Denitrifying Bacteria - reduce nitrates into ammonia.

6. Metabolic Pathways Enzymes are the basic units of metabolism. The substrates of these enzymes are called metabolites. A metabolic pathway is a series of connected enzymatic reactions that produce a specific product. Metabolic pathways consist of sequential steps. There are more than 2,000 metabolic reactions, each catalyzed by a distinct enzyme. The enzymes may be physically separate requiring the intermediate metabolites to diffuse from one active site to the next or enzymes may form a multi-enzyme complex where the intermediate metabolites are passed directly from one active site to the next. Some pathways reside within membranes. In this case the enzyme and the substrates diffuse in the two dimensions of the bi-lipid membrane.

7. Catabolism Complex metabolites are degraded into simpler products such as acetyl units linked to coenzyme A. The degradation process releases free energy. The free energy is conserved by the reduction of NADP+ NADPH or by coupling exergonic reactions to ATP synthesis. The striking characteristic of catabolic pathways is that a divergent range of biomolecules converge by forming common intermediates. Anabolism Complex biomolecules are synthesized from simple precursors. This process is endergonic. This process requires the free energy of ATP hydrolysis, ATP ADP + Pi or NADH oxidation, NADH NAD + The striking feature of anabolic pathways is that they begin with a few common metabolites as starting materials and diverge into a wide range of biomolecules.

8. WHAT is photosynthesis (Anabolic PROCESS IN PLANTS) The process by which green plant leaves having chloroplast in the presence of sunlight , carbon dioxide and water from soil synthesise carbohydrate is called Photosynthesis. Photosynthesis (" 02 +6 1-120 --9 C6H1206 +6 02) ( Nearly) all life on Earth depends on this process, yet it is very inefficient. Half of all energy from the Sun is used to evaporate water; 15% is reflected and 32% passes through the leaf untouched. There are two parts to this process: 1 )-The light-dependent reactions (which take place in the thylakoid membranes, or grana, of the chloroplasts), in which light energy, trapped by chlorophyll, is used: to split water into 02 and H+ ions, stored as reduced NADPH and to be stored as chemical energy by converting ADP + Pi to ATP. 2 )-The light-independent reactions, (take place in the stroma of the chloroplasts) in which: the ATP and reduced NADP (from the light-dependent reactions) are used to reduce C02 to glucose .

9. The thylakoid membranes provide a large surface area (to trap light), and contain molecules of chlorophyll arranged in clusters called photosystems. Each photosystem contains several hundred molecules of chlorophyll and acts as a single light- harvesting system.

10. H2O ˄ 2H ++2E- + 7 2O2 NADP + 2H+ + 2e- reduced NADP The electrons are used to generate ATP, by passing them along a series of electron carriers, losing energy as they do so, before they join Photosystem I, replacing electrons lost there.

11. Photosystem I also traps light energy, and uses it to excite electrons along a series of carrier molecules. The end-products of the light reaction are thus ATP and reduced NADP, (also called NADPH) which move into the stroma of the chloroplast ready to act as the raw materials for the light-independent reactions (see right ). Combined with the H+ ions formed in Photosystem l, they react with NADP to produce reduced NADP (also known as NADPH2):

12. The end-products of the light reaction are thus ATP and reduced NADP, (also called NADPH) which move into the stroma of the chloroplast ready to act as the raw materials for the light-independent reactions ( see right) 2. The light-independent reactions The diagram (below) shows very clearly all that AQA expect you to know! The cycle involves: A 5-carbon sugar ( ribulose bisphosphate - RuBP ) combines with C02, forming two molecules of a 3-carbon compound, glycerate 3-phosphate, GP (2 x The GP is then reduced to triose phosphate, T P, which requires both ATP and reduced NADP (which were made in the light-dependent reactions). Some of the TP is used to make glucose, amino-acids and lipids, whilst the rest is converted back into RuBP - which requires another molecule of ATP. The sequence is thus: RuBP + C02 GP + ATP + NADPH2 RuBP + C02 GP + ATP + NADPH2 (thus completing the cycle) TP glucose etc or - rp + ATP A RuBp

13. When answering a question on this cycle, remember that an increase in the level of a substance o means that the next step is blocked. So, for example, if there is an increase in RuBP levels, it would suggest that there is a lack of C02, The same applies for the other stages a buildup of GP suggests a lack of ATP ( i.e the light reaction is not working). and NOT NAD!!! o Note that it is NADP that is used in Photosynthesis ,

14. Respiration (C6H1206 + 602 A 6C02 + 6H20 (forming 38 ATP) o This is the process by which all living things obtain energy. We are only interested in the version of the process that takes place inside Eukaryotic cells. The many steps of the whole process allow small amounts of energy to be released at each step and also allows for substances other than glucose (fatty- acids, glycerol, amino-acids) to be used for respiration when needed .

15. There are 4 main stages: Glycolysis : Glucose A 2 x pyruvate (in the cytoplasm, no oxygen required). A net gain of 2 molecules of ATP and two molecules of reduced NAD (NADH). The Link Reaction: Pyruvate Acetyl COA + NADH + C02 The 'link' to mitochondria The Krebs (or TCA) Cycle: In the mitochondrial matrix, this uses oxygen to breakdown the Acetyl COA through a complex cycle to release C02 and 'store' hydrogen as reduced NAD (NADH) and reduced FAD (FADH). Two molecules of ATP are also made per glucose molecule. The Electron Transport Chain (E.T.C.): On the mitochondrial cristae, this uses oxygen to oxidize all the NADH molecules and FADH molecules made in all the earlier stages to water and release a great deal of energy - stored as ATP. By far the main site of ATP synthesis (34 molecules of ATP).

16. forming only 2 molecules of ATP per glucose. There are two different types of anaerobic respiration, or fermentation: o Animals (only!): Glucose 2 x lactic acid + 2ATP o Plants and Fungi: + 2C02 + 2ATP Glucose 2 x ethanol o BOTH forms of anaerobic respiration recycle the reduced NAD (NADH) back to NAD, thus allowing glycolysis to continue: o The lactic acid animals produce is broken down in the liver (aerobically), causing the oxygen debt we experience at the end of violent (anaerobic) exercise .

17. The Krebs cycle (or TCA cycle) Now, since two molecules of acetyl COA were formed from each molecule of glucose, it follows that there are two turns of Kreb's cycle for each glucose molecule. That means that all the above numbers need to be doubled to get the overall totals: 0 6 molecules of NADH and 0 2 molecules of FADH and 0 2 molecules of ATP o all from one molecule of glucose !