Botany Midterms PDF

BOTANY MIDTERMS 2 pyruvate + 2 NAD + 2 CoA → 2 acetyl-CoA + 2 NADH + Pyruvate Oxidation and Krebs cycle 2H2 + 2 CO2 Pyruvate 3 fates: KREBS CYCLE Anaerobic (lactic acid...

BOTANY MIDTERMS 2 pyruvate + 2 NAD + 2 CoA → 2 acetyl-CoA + 2 NADH + Pyruvate Oxidation and Krebs cycle 2H2 + 2 CO2 Pyruvate 3 fates: KREBS CYCLE Anaerobic (lactic acid fermentation): uses NADH Overview of the Krebs cycle to generate NAD+ and should have a continuous Hans Adolf Krebs - German-british scientist who discovered supply of NAD+ (needed) for glycolysis the Krebs cycle in 1930s Anaerobic (alcoholic fermentation) Krebs cycle: Aerobic Oxidation Citric acid cycle Aerobic Respiration: Pyruvate should be broken down Tricarboxylic cycle Oxidative decarboxylation of Pyruvate - Citric acid is the first product of the Krebs cycle, - removal of carbon via carbon dioxide which forms from the reaction between acetyl-CoA - End of krebs cycle, there should be no carbon left from and oxaloacetate glucose Process of Krebs Cycle Pyruvate dehydrogenase complex 1. Citric Synthase: irreversible - simplifies pyruvate formed in the aerobic conditions into a Only cycle reaction with C-C bond formation molecule called acetyl-CoA Produce 6-carbon compound Citrate from C2 unit - bridge between glycolysis and aerobic metabolism (Citric (acetyl) and keto-double bond of C4 acid, acid cycle) oxaloacetate Entry of Pyruvate into the Mitochondrion ❖ acetyl-CoA reacts with oxaloacetate to form citrate - Pyruvate: diffuses through the outer membrane of using citrate synthase mitochondrial matrix through the channels formed by 2. Aconitase: reversible transmembrane proteins called porins Elimination of H2O from citrate to form C=C bond Pyruvate translocase: protein embedded into the inner of cis-aconitate membrane, transports pyruvate from the intermembrane Stereospecific addition of H2O to cis-aconitate to form isocitrate space into the matrix in symport with H+ and exchange 6-carbon to 6-carbon (antiport) for OH- ❖ Citrate is isomerized to isocitrate using aconitase Conversion of Pyruvate to acetyl-CoA 3. Isocitrate Dehydrogenase: irreversible Pyruvate dehydrogenase complex (PDH complex) Oxidative decarboxylation of isocitrate to - multienzyme complex containing 3 enzymes, 5 a-ketoglutarate coenzymes, and other proteins (no changes) Eliminated 4-carbon dioxide - all the enzymes have corresponding genes Oxalosuccinate is decarboxylated to - giant, with molecular mass ranging from 4 to 10 million a-ketoglutarate dollars One of four oxidation-reduction reactions of the Enzymes cycle Hydride ion from the C-2 of isocitrate is E1: pyruvate dehydrogenase transferred to NAD+ to form NADH E2: dihydrolipoyl acetyltransferase ❖ Isocitrate is oxidized into a-ketoglutarate, which E3: dihydrolipoyl dehydrogenase releases carbon dioxide and the reduction of Coenzymes (prosthetic groups of enzymes) 2NAD+ to 2NADH TPP (thiamine pyrophosphate): prosthetic group of 4. A-ketoglutarate Dehydrogenase complex (4C) B1; building block of vitamin B1 (thiamin) Similar to PDH complex; no acetyl-CoA left here Lipoamide: prosthetic group of B2; building block Same coenzymes, identical mechanisms of lipoic acid ○ E1 - a-ketoglutarate dehydrogenase (with TPP) FAD: prosthetic group of B3; building block of ○ E2 - dihydrolipoyl succinyltransferase vitamin B2 (riboflavin) (lipoamide prosthetic group) NAD: building block of vitamin B5 (nicotinamide) ○ E3 - dihydrolipoyl dehydrogenase (with HS-CoA: building block of vitamin B3 FAD) (pantothenic acid) A-keto with the addition of NAD+ and CoA will The oxidative decarboxylation of pyruvate catalyzed by result to succinyl-CoA with Co2 and NADH PDH complex occurs in 5 steps ❖ a-ketoglutarate is oxidized to succinyl-CoA From 6-carbon glucose, 2 carbons will be left and 5. Succinyl-CoA synthetase acetyl CoA Formation of succinate PYRUVATE OXIDATION Lose coenzyme A (COA) Net production: Substrate level phosphorylation: → 2 ATP 2 NADH - electron transport chain Free energy in the thioester bond of succinyl CoA is conserved as GTP or ATP in higher animals (or 2 acetyl-CoA - enter Krebs cycle A TP in plants, some bacteria) 2 H+ - diffuses in the matrix ❖ when succinyl coa, it releases the coenzyme A and 2 CO2 - diffuses out of cell produces GTP 6. Succinate Dehydrogenase Complex: reversible - 2 NADH and glucose Produces FADH2, which will go to ETC Krebs cycle: 6 NADH and 2 FADH2 and glucose 2 FAD → 2 FADH2 Complex of several polypeptides, an FAD Electron Transport Chain prosthetic group and iron-sulfur clusters Groups of redox proteins Only trans isomer is formed Inner mitochondrial membrane ❖ Oxidation of succinate into fumarate, which Have binding sites for NADH and FADH2 causes two hydrogen molecules to be released. ○ On matrix side of membrane These H molecules are transferred to FAD, which is ○ NADH is reoxidized to NAD+ | FADH2 is reduced to form FADH2. reoxidized to FAD+ 7. Fumarase: reversible 4 COMPLEXES Stereospecific trans addition of water to the double Electrons are passed from one complex to another bond of fumarate to form L-malate which releases H+ or protons Only the L isomer of malate is formed ○ Can’t cross the plasma membrane so there ❖ Water is added to fumarate to form malate will be an increase in concentration = 8. Malate Dehydrogenase concentration gradient Lower the concentration: let it pass through an ❖ Malate is oxidized to form oxaloacetate, which enzyme called ATP synthase; generating ATP causes the reduction of NAD+ to NADH Process Overall reaction Transition 2 pyruvate + 2 coenzyme A + 2 reaction NAD+ = 2 acetyl CoA + 2 CO2 + 2 NADH Krebs 2 acetyl CoA + 6 NAD+ + 2 FAD + 2 cycle ADP + 2 Pi = 4 CO2 + 2 CoA + 6 NADH + 2 FADH2 + 2 GTP Complex I: NADH Dehydrogenase 6 NADH and 2 FADH2 will take hydride ions to the ETC Has NADH binding site where they will be used to produce ATP by oxidative NADH reductase activity: 6 NADH → 6NAD+ phosphorylation. 4 H+ is being pumped (to the intermembrane space from the mitochondrial matrix) Take note: Krebs cycle happens twice for each round of Coenzyme Q: takes e- from complex 1 and 2 and glycolysis. pass the e-to complex 3 Goal of Krebs cycle: to generate FADH2 and NADH that is ○ Flavoprotein: first molecule that accepts vital in ETC the electron from NADH; prosthetic group = flavin mononucleotide (FMN) ELECTRON TRANSPORT AND OXIDATIVE ○ FMN is reduced when it receives the PHOSPHORYLATION electron from the oxidation of NADH to - All reduces down to water NAD+ - Occurs in the cristae ○ Iron-sulfur protein (Fe-S): where the Mitochondria electrons from FMN is transferred Outer membrane: relatively permeable ○ Electrons are then transferred to Inner membrane: permeable only to those thing ubiquinone (labeled as Q) thus producing with specific transporters QH2 ○ Impermeable to NADH & FADH2 (should 1 NADH = 2.5 or 3 ATP have a mechanism for it to be utilized) Complex II and ubiquinone: Succinate Dehydrogenase ○ Permeable to pyruvate Does not release H+ Compartmentalization 2 FADH2 → 2 FAD + H+ ○ Krebs and B-oxidation in matrix Succinate - FAD - ubiquinone ○ Glycolysis: cytosol Contains coenzyme Q Most energy from Redox (Reduction and Oxidation) FADH2 binding site Electrons during metabolic reactions sent to NAD ○ FAD reductase activity & FAD Succinate dehydrogenase and Fe-s receives 1. Glycolysis: cytosol electrons from the oxidation of FADH2 to FAD - Produces 2 NADH The electrons from the Fe-S are transferred to Q, 2. Pyruvate dehydrogenase reaction: then to ETC mitochondrial matrix Complex III  4 H+ is pumped out accept the e- from coenzyme Q and pass it on to Oxidative Phosphorylation cytochrome C. - Combination of the electron transport chain and Also contains cytochromes b chemiosmosis ○ Adds to gradient: 8 H+ / NADH | 4 H+ / Phosphorylation FADH2 - Occurs when we transfer a phosphate group to CYT C transfers the electron to Complex IV but something one electron at a time only, second electron is transferred to Cyt b then Q is reduced in. Both NADH and FADH2 are oxidized in the electron Electrons from complex 1 and 2 are car transport chain Cytochrome C What about NADH from glycolysis? - accept e- and pass it to complex 4 - Can't get into matrix of mitochondria - Cytochrome 3 ; give the electrons to cytochrome C. - 2 mechanisms : - Cytochrome C receives electrons,it - In muscle and brain: Glycerol phosphate shuttle becomes reduced - In liver and heart: Malate / aspartate shuttle - It reduces cytochrome C by giving it electrons - Mobile electron carrier THE POINT IS TO MAKE ATP! - A surface protein Electron Transport Chain - Cytochrome C will now give it electrons to Complex 4 - Series of molecules built into inner mitochondrial Complex IV membrane: mostly transport proteins reduction: last place where electrons are - Transport of electrons down ETC linked to ATP synthesis transferred before they reduce oxygen to form a - yields ~36 ATP from 1 glucose! water molecule Oxygen is the final electron acceptor ATP produced so far.: Glycolysis → 2 ATP | Kreb's cycle Cytochrome oxidase → 2 ATP 2 H+ is pumped out; reduction of oxygen cyt a+a3 red → oxidized state Electrons flow downhill oxygen → water - Electrons move in steps from carrier to carrier ○ 2H+ + 2e + ½ 02 →→ 2 H,0 downhill to 02 Total of 10 H+ / NADH - each carrier more electronegative Total of 6 H+ / FADH, - controlled oxidation - controlled release of energy GENERATION OF ATP - Proton dependant ATP synthetase What happens if O2 is unavailable? - Uses proton gradient to make ATP - ETC backs up - Protons pumped through channel on - ATP production ceases enzyme - Cells run out of energy - From intermembrane space into - And you die! matrix - 4 H+ / ATP PHOTOSYNTHESIS - Called chemiosmotic theory Chemiosmotic Theory Metabolism: sum of all chemical reactions in a cell - As H+ move from high to low concentration, the Divided by two pathways: ATP synthase absorb some of that potential energy from that movement and use that energy to convert 1. Anabolism: build up ADP and P to make ATP 2. Catabolism: break down - Through oxidative Phosphorylation Photosynthesis Concepts - energy from the sun is harnessed and with the aid of As the protons are pumped into the chlorophyll, is transformed from light energy to biochemical intermembrane space energy ○ The intermembrane space will develop a - Oxygen is given off as by product positive charge - Plants store energy as sugar (short term) and starch (long ○ The mitochondrial matrix will be more negative with respect to the term) intermembrane space Site of photosynthesis Protons will enter the ATP synthase due to the - takes place in the leaves, within the chloroplast attractive force Chloroplast: contain chlorophyll (pigment that captures As the protons flow down, they will create a light energy from the Sun) mechanical force that will smash ADP and Chloroplast: most abundant in the mesophyll cells of leaves phosphate to produce ATP - phosphorylation Requirements for photosynthesis CHEMIOSMOSIS: Using diffusion of protons as it flows 1. Carbon dioxide to ATP synthase to create ATP  - Reaches the chlorophyll in the mesophyll cells by Reduced NADP to form NADPH which carries diffusing through the stomata in the leaf interior hydrogen and is used in the second phase: - Increased CO2 levels may enhance photosynthesis light-independent reactions and increase food production. 2. Light-Independent reactions (Calvin cycle) - But, insects and viruses that proliferate with Carbon-fixing and reducing reactions, completes warmer temperature can offset these potential gains the conversion of light energy to chemical energy (this accelerates plant respiration and by using ATP and NADPH to form sugars. decomposition of plant and animals) Does not require light but it is still used for the - Increased CO2 will result in rise in temperature and enzymes being used in the calvin cycle. longer growing seasons in middle and higher Occurs during daytime and outside of the grana in latitudes hence, increasing global photosynthesis the stroma of chloroplast 2. Water May start in different ways but will all undergo - Less than 1% of all the water absorbed by plants Calvin Cycle - Source of electrons involved in photosynthesis Light-Dependent Reexamined - Sole source of oxygen as it is released as Sir Isaac Newton by-product - produced a spectrum of colors from visible light - Short supply of water: may indirectly become a - corpuscles limiting factor in photosynthesis (stomata close, - light consisted of a series of discrete thus, CO2 supply is decreased) particles 3. Light - Partially explain light phenomena - Exhibit properties of both wave and particles James Maxwell (and others) - Longest wave: radio waves, shortest: gamma rays - showed that light travels in waves - violet to blue are used extensively and red-orange Photoelectric effect to red | light in the green range is reflected by the - proposed by Albert Einstein chlorophyll. - photoelectric effect results from photons - Longer wavelength, low frequency (ROYGBIV) - discrete particles of light energy - Higher light intensities & temperature = accelerate - wave and particles energy of a photorespiration - photon is not the same for all 4. Chlorophyll: contains an atom of magnesium kinds of light Types: emitted part is in the red part ○ extract of chlorophyll placed in light will - Chlorophyll a: blue green in color (C55H72MgN4O5) appear red - Chlorophyll b: yellow green in color (C55H70MgN4O6) phosphorescence - Chloroplast has three times more chlorophyll a than ○ absorbed energy emitted as light after a chlorophyll b (more chlorophyll a, more brighter delay green the cell and tissue) - Other photosynthetic pigment: Carotenoids, Internal Organization of Chloroplast phycobilins, etc. Within the thylakoid membrane, I and II are noted - Photosynthetic unit: light harvesting complex of as photosystems; these have different electron about 250-400 pigment (two types of this will acceptors. function together to start the first step of Photosystems: embedded in the thylakoid photosynthesis) membrane. large complexes of pigments that WHAT HAPPENS IN PHOTOSYNTHESIS optimize light reaction. Photosystem I and In the process of photosynthesis, the absorbed light photosystem II. energy converts carbon dioxide and water into The pigments contain light energy, antenna glucose, which oxygen is released as a by-product pigments: when photon from light energy strikes Consists of two series: light-dependent reaction this pigment; it becomes excited which releases and light-independent reactions electrons then passes it to neighboring pigment 1. Light-dependent reactions (Robin Hill) until it is passed to the special chlorophyll a Initiated when units of light energy (photons) molecules striked the chlorophyll embedded in the thylakoid Afterwards, it will go to their own electron membrane acceptor and electron transport system. Steps: Water molecules are split apart, releasing electrons and hydrogen ions, and oxygen gas is released Electrons from the split water are passed along an electron transport system ATP is produced 1. PHOTOSYSTEM I WHAT HAPPENS IN PHOTOSYSTEM I Consist of 200 or more molecules of chlorophyll a, when it arrives at P700, it will be passed to the small amounts of chlorophyll b, carotenoid pigment primary electron acceptor = iron sulfur protein with protein attached and P700 (special chlorophyll Afterwards, electrons will be passed to FD or molecules) ferredoxin. Then, electrons will be passed to FAD Iron-sulfur proteins is the primary electron (flavin adenine dinucleotide). acceptor for PSI From FAD, it is connected to the flavoprotein 2. PHOTOSYSTEM II which has the enzyme NADP reductase. This will entire process of photosynthesis begins here then reduce NADP to NADPH. Consists of chlorophyll a, beta carotene attached to NADPH will then be used for the light-independent protein, little chlorophyll b and P680 (special reactions for photosynthesis. The proton gradient chlorophyll molecule) will now generate the ATP synthase (this atp will Pheophytin is the primary electron acceptor be used for photosynthesis) WHAT HAPPENS IN THE PHOTOSYSTEM II light will hit the pigments or the antenna pigments (they collect and gather light energy which is passed to the special chlorophyll molecule = P680) Once P680 is released, it will transfer electrons to the primary electron acceptor which is pheophytin. From pheophytin, it will pass the electron to plastoquinone which then becomes reduced. After this, it will be passed to the cytochrome complex. Then, it will go to plastocyanin. Then go to the PHOTOSYSTEM I. TAKE NOTE: movement of electrons from In the Oxygen-Evolving Complex: water will split PHOTOSYSTEM II TO PHOTOSYSTEM I is called (electrons lost by OEC replace the electrons lost by noncyclic photophosphorylation. Since the passage of the P680 molecule.) electrons is unicellular. ○ Products of Water Splitting Cyclic electron flow happens in Photosystem I and 2 water molecules split produces only ATP. 1 oxygen molecule - instead of producing NADPH, it will go back to produced plastoquinone, plastocyanin and to the cytochrome bf 4 protons produced complex. 4 electrons produced Afterwards, it will enter the electron transport system Evolutionary Significance ○ Metabolic pathway evolved in photosynthetic bacteria (cyanobacteria) ○ Abundance of water facilitated oxygen generation as by-product ○ Increased oxygen supply in Earth's atmosphere Light Independent Reexamined ○ Enabled evolution of energy-efficient aerobic respiration Key Features - Calvin cycle (C3 photosynthesis) - Carbon fixation - Reduction of CO2 to glucose Note: The Calvin cycle is the primary pathway for carbon fixation in C3 photosynthesis, resulting in glucose production. CALVIN CYCLE C3 PATHWAY or photosynthetic carbon reduction (PCR) pathway Carbon dioxide is fixed and converted to organic molecules happens in light-independent reactions Carbohydrates produced during this reaction facilitates growth, including the development of leaves, stems, roots, flowers, and other plant structures. Main biosynthetic pathway through which carbon enters the web of life. Steps: Stage 1: carbon fixation 1 molecule of carbon dioxide will combine with OTHER PHOTOSYNTHETIC PATHWAYS RuBP (5-carbon sugar molecule) and it will be fixed. C4 PHOTOSYNTHESIS: Rubisco: catalyze the reaction then produce 6 Advantage: major reduction of photorespiration carbon molecules but this is so unstable that's why High concentration of PEP carboxylase: mesophyll it immediately separates to form 2 molecules of cells; conversion of CO2 to carbohydrates is 3-phosphoglycerate (3PGA) carbon molecule possible in lower concentrations. Molecules of 3-phosphoglyceric acid, first stable Optimum temperature for C4 photosynthesis are compound in photosynthesis much higher than those for C3 Stage 2: reduction stage The light dependent and light independent are ATP came from the light-dependent reaction. physically separated. NADPH and ATP supply energy and electrons to This is called kranz anatomy, producing a 4-carbon reduce the 3 PGA to molecules of glyceraldehyde compound and oxaloacetic acid. 3-phosphate (GA3P, 3-carbon sugar phosphate) Lightdependent: occurs in mesophyll cells | Light 3 PGA with the use of ATP, it will receive another independent: occurs in bundle sheath cell phosphate group thus forming 1,3 BPG. What happens: instead of using 3 carbon Afterwards, NADPH comes from light-dependent molecules. It uses 4 carbon molecules. So, it forms reactions, so 1,3 BPG will be converted to form 6 oxaloacetate which is a 4 carbon molecule. NADP reduced form and Enzyme used: (PEPC) Phosphoenolpyruvate Glyceraldehyde-3-phosphate carboxylase. Stage 3: Regeneration of Ribulose Phosphoenolpyruvate, with carbon dioxide, will be One molecule of G3P can form glucose but it is fixed to form C4. only 1/2 since G3P only has 3 carbon but it requires If oxaloacetate is converted to malate, it is split to 2 molecules of G3P sa glucose. release carbon dioxide so that this will be used to It will now require the use of ATP: the rest of G3P undergo carbon dioxide (5 molecules of G3P) will regenerate to 3 SUMMARY: 3 carbon molecules which is a carbon dioxide molecules RuBP or Ribulose 1,5-bisphosphate. atom is fixed into this to form 4 carbon molecules which is 2 molecules of G3P = 1 glucose oxaloacetate. This will be converted to organic acids. How much CO2 is required to produce one molecule of Afterwards, C4 is split to go to the bundle sheath cell to glucose? produce carbon dioxide that will be used in the calvin cycle 6 CARBON DIOXIDE which happens in the bundle sheath cell. Oxygenase of Rubisco - it will undergo the process of photorespiration which is wasteful for photosynthesis so it CAM PHOTOSYNTHESIS should be carboxylase. Crassulacean acid metabolism Properties of Desert plants Night time: The stomata is open since the humidity is higher, so there is a movement of carbon dioxide. After CO2 enters stomata, CO2 will be fixed to form 4 carbon molecules which is the oxaloacetate. From oxaloacetate, it will be converted to malate or malic acid. Malic acid: accumulate at night and break down during the day, releasing carbon dioxide.  It will be stored in the vacuole since it will not Why do they have similar structure? Because they undergo CALVIN CYCLE. have the same signals so they will also have the Enzyme: PEPC is responsible for converting CO2 same function to carbohydrates plus PEP to organic acids at night These groups of cells function together as a unit. when the stomata are open. Intercellular matrix: separates cells from each other DAYTIME: malic acid will be released into the | like the inter membrane space in the animals | vacuole. Malate will split to release carbon dioxide basic contact of the cells to the environment and go to CAC to produce sugar or glucose Different tissues make up an organ This can still undergo photosynthesis even though their stomata are closed during daytime. Figures Joseph Priestley - demonstrated a sprig of mint “restored” oxygen Jan Ingen-Housz - showed that air was restored only when green parts of plants were receiving sunlight - carbon went into the nutrition of the plant Jean Senebier - photosynthetic process required CO2 Nicholas Theodore de Saussure - final component of the overall pho TYPES OF TISSUES (Based on complexity) 1. Simple tissues:: made up only one type of cell function will based on what type of cells that are available 2. Complex tissue: made or two or more types of cell More than one function and has dynamics so it is going to be a system PLANT TISSUES AND THE MULTICELLULAR PLANT TISSUE SYSTEMS (Based on location) PLANT BODY 1. Dermal tissue system- epithelial tissues outer layer THE PRIMARY PLANT STRUCTURE of the plant, serves as protection 2. Vascular tissue system - transport of nutrients, Root and Shoots water, minerals Shoot system 3. Ground tissue system - skeletal tissues of the photosynthesis animals | supportive tissues, site for photosynthesis Reproduction ❖ Ex: (leaf): dermal tissue: upper epidermis | ground Storage tissue: mesophyll | dermal tissue: lower epidermis | Transport vascular tissue: xylem and phloem Hormone production All the tissue systems are found in all the different Root syatem parts of the plants. Anchorage- making sure plant is not ambot Meaning: similar functions all throughout Absorption regardless of where it is found Storage: Synergic relationship ambot 1. GROUND TISSUE SYSTEM Transport Parenchyma tissue Hormone Collenchyma tissue Sclerenchyma tissue CELLS AND TISSUES OF THE PLANT BODY makes up the bulk of an herbaceous plant (hindi TISSUE naging wood, example is banana tree) The ancestors of banana supposedly have seeds, but group of cells that have similar structure (structure we do not need them to be planted as seeds because defines function) there is a tissue culture so shoot lang ang iplant Parenchyma cells: Tracheids and vessel elements conduct water and minerals have thin primary cell walls Composed of four cells: tracheids, vessel, xylem Most common type of cell and tissue and is found fibers, and xylem parenchyma Gymnosperms lack vessels throughout the body Provide mechanical strength to different parts of Functions: photosynthesis, storage, secretion plant Photosynthetic parenchyma: contain chloroplast | At maturity, are dead non-photosynthetic parenchyma: no chloroplast, usually for storage 1. Tracheids: Can differentiate into other types of cells (same like epithelial cells or stem cells) chief conducting cells of gymnosperms and seedless vascular plants Has intracellular spaces, basic Long tapering cells in patches or clumps | water passes through pits Collenchyma cells always occur in pairs Support and water conduction have unevenly thick primary cell walls Functions: provide support in soft non woody plant 2. Vessel elements: organs (since it has thick primary cell walls) Usually elongated chief conducting cells of angiosperms with few Found near stem surfaces and leaf veins, (kaya siya tracheids Cylindrical cells stacked on each other malapit here because they are for protection) bigger diameter, they have pores or perforations beneath the epidermis Water conduction, Sclerenchyma cells Phloem have both primary and secondary cell walls Composed of four cell types: Sieve-tube elements, Secondary wall is extremely thicker than primary companion cells, parenchyma cells and fiber Functions: provide support in woody parts of the Transports food materials from leaves to other parts plant 1. Sieve tube elements Expect that this tissue is stronger than other tissues Often dead at maturity conduct food solution: Two types: Stacked end on end to form sieve tubes (salaan) Sclereids: common in shells and stones of fruits, Have sieve plates which contain holes support and protection, stiffness and rigidity Alive at maturity, can function without nuclei Fibers: long tapered abundant in wood inner bark and leaf ribs, mechanical strength 2. Companion cells assist sieve tube elements living cell with nucleus Plasmodesmata connects companion cells and sieve tube elements (can exchange material and information through the channel) Loads food material into sieve tube elements Xylem and phloem are always side by side. Together, they are called vascular bundle 3. Dermal tissue system 2. Vascular tissue system external tissue layer of plants Xylem Provides protection from the elements (loss of Phloem water) embedded in the ground tissue Skin is highly keratinized meaning hindi siya basta Transports material throughout the plant basta naga absorb ng water or naglabas ang water Dicot stem: arrangement of vascular bundles is ring (happens if long ang exposure sa water) Monocot system: grasses or rice, arrangement is Epidermis scattered Periderm Xylem Epidermis ○ Certain plants have limited secondary growth primary composed of unspecialized living cells: embedded are hair cells (trichomes) and guard cells PRIMARY GROWTH Most plants: single layer, but are thicker than other cells happens in the apical meristems, It does not perform photosynthesis since they have ○ shoot apical meristem: pataas no chloroplast and is transparent ○ Root apical meristem: pababa or digging Secretes cuticle (waxy substance that deters water, Apical meristem give rise to three primary waterproofing and protects the plants from other meristems: protoderm, ground meristem, and elements) procambium Guard cells serve as gate for gas exchange (opens and close) SECONDARY GROWTH ○ Stomata: pores between guard cells ○ Gases diffuse into and out of stomata Happens in the lateral meristems (cambium) Guard cells open and close depending on plant ○ Areas that extend along the entire length internal water supply of the stem and roots Trichomes serve a variety of functions: protection, Vascular cambium: give rise to secondary xylem may increase reflection, remove excess salt and secondary phloem Leaf epidermis: abaxial underside | adaxial: upper Cork cambium: give rise to cork cells and cork side parenchyma all part of periderm Periderm replaces the epidermis in woody plants ○ formed from cork cambium Protective covering of older stems and roots Composed of cork cells (phellem); and cork parenchyma (phelloderm) Cork is dead at maturity and is coated in suberin (wax and a fatty acid) Order: under epidermis is: cork cells (phellem), cork cambium (phellogen) cork parenchyma (phelloderm) PLANT MERISTEM MERISTEM: THE SOURCE OF ALL PLANT CELLS in animals, all parts grow but in plant, growth depends on location ○ These locations are meristems Meristematic cells retain the ability to divide mitotically Totipotent: become whatever it is that they can become Meristems has potential to differentiate into different cells responsible for plant growth Two types of meristematic growth Primary growth ○ increase in length, all plants (ex. Height in human) Secondary growth ○ increase in girth, only gymnosperms and woody eudicots (ex. Gain weight)