Phytochem Class 4 PDF

Class 4 • Carbohydrate linkages • Recall from Introduction to Biochemistry • That carbohydrates will always use the same building blocks i.e., glucose • This then allows for the easy production of larger sugars i.e., polysaccharides • Creation of larger carbohydrate molecules is made possible by...

Class 4 • Carbohydrate linkages • Recall from Introduction to Biochemistry • That carbohydrates will always use the same building blocks i.e., glucose • This then allows for the easy production of larger sugars i.e., polysaccharides • Creation of larger carbohydrate molecules is made possible by the element C • They contain various points of attachment • Cs tend to be numbered • When that is the case, you are being shown a point of attachment • A glycosidic bond (creation of polysaccharides) is created through covalent bonding (sharing of electron pairs) • Glucose • What is this molecule composed of? • C, H, O • Made up of two G3P molecules, which each have 3 C • What is the purpose for a plant to use ATP and NADPH to create glucose? • Glucose is the ideal form of storing energy long-term within a plant • Flexibility • This carbohydrate is malleable, meaning it can be partially broken down, rebuilt, or combined with other molecules • The number of C and linkages this molecule possess allows for it to be easily modified • It can also be reused to produce energy Class 4 • Fructose • Storage of Energy • Similarities between Glucose and Fructose • Monosaccharides • Assembled from G3P • Animals • Prefer glycogen, dehydrated glucose, within the liver and MSK or fatty acids are produced to then be stored within white adipocytes • Differences between Glucose and Fructose • Significantly sweeter, it does a fantastic job of this • Fungi • Store their food reserves as glycogen and can repackage this carbohydrate into small globules of oil (spores and vesicles) for further safe keeping • Increased sweetness • Has been used successfully by plants as attractants • Plants • Store energy in the form of polysaccharides, longchain sugars. These molecules contain many chemical bonds and therefore store a great deal of chemical energy Class 4 • Sucrose • This is made up of glucose + fructose • This is typically found abundantly within fruit (used as an attractant) and leaves of plants • Sucrose is used to assist with storing energy along with moving it throughout the plant • When the plant uses sucrose, it is redirected from fruit or leaves to new areas of growth i.e., roots, stem, etc. • While this sugar can react, thankfully, it is more stable than glucose or other simpler sugars • The attachment points are the most reactive portions • While this is a form of storage energy in plants it does not mean that it’s the only one • Starch • This is the preferred storage form of energy in most plants • Here you can pack more glucose, fructose, G3-, ATP, NADPH, etc. into a cell • Why can more of this be fit into a cell than other carbohydrates? • You would think as it is larger the answer would clearly be no • Due to its structure, it has a difficult time dissolving in water, therefore it does not dissolve or hydrate easily, it is quite compact • E.g. think of when you are cutting a tuber and look at the knife you used 1-2 minutes after. Once the small amount of water on the knife has evaporated you can see starch crystals deposited on the blade, largely insoluble • Kinds of starch • Amylose – is more difficult for us to digest, can be referred to as resistant starch, but much more efficient for plants as it is less soluble and accessible (can be found in corn, barely, potato, etc.) • Amylopectin – is very easy for us to digest, possess a higher glycemic index, due to its increased solubility rendering it less stable as a form of energy long-term (can be found in waxy potato starch, glutinous rice, etc.) Class 4 • Cellulose • Callose and Beta-glucans • What is this made up of? • Almost entirely of glucose • What is the role of callose in a plant? • To repair damaged tissue i.e., cell wall following mechanical destruction • Acts like the fibrin matrix animals produce that is then reinforced with collagen • When is it used? • During the growth of new tissue in a plant, acts as support • Can be identified as green plant tissue • This is also used in plant cell walls • How can this carbohydrate become digested? • Chemical digestion – use of an enzyme called cellulase. Unfortunately, it is unable to break down the entire cell wall. Glucose is not readily broken down in this process • This carbohydrate is indigestible to us but plays an important role as fiber • Callose is made of glucose, this is a beta-glucan • What are beta-glucans and their role in a plant? • This is another carbohydrate composed of glucose • They play a crucial role in the activation of functional plant innate immune system by triggering chemical cascades • In humans, glucans have been found to • Lower the amount of cholesterol or saturated fat absorbed • ONLY when consumed as the exact same time as the lipid rich food Class 4 • Lipids • Fatty acid synthesis in plants • In animals • Preferred form of energy storage, temporary energy (glycogen) • Lipids are more efficient but less stable than starch (i.e., lipids spoil) • Lighter material • Recall that various kinds of lipids exist i.e., cholesterol, phospholipids, glycerolipids, steroids, etc. • In plants • Prefer to use carbohydrates when storing energy • Carbohydrates are heavier and denser; plants prefer this for structure. They store this within their root system • Carbohydrates do not offer the same type of storage as lipids • Pollen, some seeds and fruits possess a higher percentage of lipids • What we will focus on though is just fatty acids • This is produced in a similar way to animals • Begin with G3P then modify it to produce acetylCoA (important for the formation and digestion of fats) • Plants then build these acids 2 C at a time, repeating till they achieve the final product they were looking for • Acetyl-CoA can also be obtained through breaking down other metabolites (sugars, amino acids, etc.) Class 4 • Seeds • Seeds • This is defined as • A flowering plant’s unit of reproduction, capable of developing into another such plant • It is viewed as the embryonic stage of the plant life cycle • How are they organized? • Embryo (Fe, K, and Zn + tiny root, stem, and one or more leaf-like part called a cotyledon), endosperm (rich in macronutrients), and seed coat (mostly Ca and some P) • What is the purpose of distributing a seed further away from the parent plant? • They may not receive enough light, water, or nutrients from the soil due to competition • It increases their chances of survival, possibly due to competition or they are transported to more favourable environments • How are seeds distributed? • Animals (trapped in hair, fur, clothing, or ingested orally), ballistic (forcefully ejected by explosive dehiscence of the fruit), gravity (falling from the plant toward the earth), water (seeds float away from their parent plant – typically live near water), and wind (carried further away from the parent plant) • Where do lipids come into play here? • Recall – lipids are lighter than the other macronutrients • Mass conversion of lipids occurs during the final stages of ripening in some fruits and most seeds • The increased total weight (1/3 to ½ of the seed or fruits weight can consist of this macromolecule) of lipids allow for seeds to be carried further via ballistic, gravitational, water, and windy means Class 4 • Avocado • Waxes • This is a medium-sized, evergreen tree in the laurel family • It is native to the Americas • First domesticated over 5,000 years ago • It has been prized for humans over millennia for its high lipid content (primarily oleic acid – monounsaturated fatty acid) • The avocado appeared to have hyper fixated on its weight, lipids are light, but is far too large to be dispersed via wind • The high fat concentration is used as an attractant, instead of carbohydrates • This is composed of various substances, not made of the same building block • They are solid at room temperature and must be hydrophobic • • One thought as to how this fruit developed • Follows the giant ground sloth, now extinct • Around 10ft long and weighed over 2 tons • This animal was enormous, slow moving, and required an energy dense source of food • Thankfully, its bowels were large enough to allow for the seeds to not become CRUSHED during mechanical digestion Since this mega fauna's extinction humans have appeared to take over the role of seed dispersal, agriculture • What are they made of? • For the most part they are constructed from lipids, but you can also find terpenes, esters, primary alcohols, ketones, etc. • Commercial sources of plant-based wax • Bayberry wax, Candelilla wax, Carnauba wax, Castor wax, and Sunflower wax Class 4 • Plant Cuticles • This can be viewed as “water-proofing” for plants • It is composed of mixed waxes and can be found covering the exterior surface of the plant • While this is composed of various compounds one stands out • Cutin – this is made from various long-chain fatty acids. One after another is added to create this macromolecule • This protective waxy layer not only keeps things from getting into the plant but also out • Minimizing water loss • Suberin Class 4 • Respiration in Plants • Mangrove Tree • When does this process occur? • It takes place day and night (light-independent reactions) • Cellular respiration is not limited by sunlight, directly, in plants • • Photosynthesis • Light-dependent reactions can only take place during the day, when the sun is up • While the sun is out • Photosynthesis overwhelms cellular respiration, therefore more O2 is released than consumed • Nonetheless cellular respiration is constant • What parts of a plant can uptake O2? • All parts of a plant can respire • In leaves, the gases enter through tiny pores, inferior surface, referred to as stomata • When it comes to roots, they aim to find this precious gas in pockets throughout soil Plants live in varying environments • • • Some areas are quite dry while others are very humid Those that choose to live in standing water, at least part of the year, are referred to as semi-aquatic • They tend to possess a hollow stem or leaves that act as a snorkel • This allows for plants to breath even while this organ is below the surface Mangrove trees • Contain thousands of cell-sized pores in their bark and roots called lenticels • They close tightly during high-tide, preventing mangroves from drowning • Then open up during low-tide, to allow for breathing Class 4 • Shikimic Acid Pathway • Amino Acids • Autotrophs • All amino acids are non-essential • They can produce whatever they need so long as their base nutrition is taken care of (in-organic sources) • Heterotrophs • We must obtain certain amino acids from other sources to be able to produce proteins • Some amino acids we can produce on our own, but not all • N is going to be a key nutrient • This is assimilated as either ammonia or nitrate (soluble form) • Amino acids are then created from various pathways • Used by bacteria, archaea, fungi, algae, some protozoans, and plants for the creation of folates and specific amino acids • This pathway is not found in animal cells and is thought to be evident as we lack the necessary pathways to perform this reaction and must obtain these products through diet rather than produce on our own • What happens if this pathway is inhibited? • It is important to note that the enzyme EPSPS becomes inhibited during the final step of this process • Once this is occurring an accumulation of shikimic acid occurs and the production of amino acids ceases • Eventually leading to the death of a plant • The chemical agent glyphosate targets this enzyme and ultimately inhibits the final step of this pathway