Photosynthesis Unit 6 Unit 6 Packets and “What’s in a Leaf?” POGILs are at the desks already – grab one. Turn in completed Winter Break assignments and be ready to get some notes!

Unit 6 Overview Day 1 – Notes on Photosynthesis and “What’s in a leaf?” POGIL Day 2 – Photosynthesis GIZMO and set up Photosynthesis Research Notebook/LAB Day 3- Carry out Photosynthesis Lab (must bring notebooks and dress properly) Day 4 – Quiz on Photosynthesis and continue to work in class on lab Day 5 – Lab Notebooks Due, take Cell Respiration notes in class Day 6 – Compare and Contrast Photosynthesis and Cell Respiration. Complete POGIL in Class and review for test. Day 7 – Unit 6 Test Day 8 – SOL Diagnostic (Not Graded)

Autotrophs & Heterotrophs Autotrophs – organisms use can make their own food Some autotrophs capture light energy from the sun in the process of photosynthesis Heterotrophs – obtain energy from the foods they consume

ATP & Energy Structure of ATP ATP (Adenosine Triphosphate) – shuttles energy for cells ATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups

ATP & Energy The bond between the terminal phosphate groups of ATP’s can be broken, releasing organic phosphate and leaving ADP (adenosine diphosphate). Energy is released from ATP when the terminal phosphate bond is broken. This release of energy comes from the chemical change to a state of lower free energy (stabilizing), not from the phosphate bonds themselves.

ATP & Glucose ATP is not good for storing energy for a long time. Cells only have a small amount of ATP. One Glucose can store more than 90 times more energy than one ATP. Cells store glucose, and use glucose to regenerate ATP as needed (cellular respiration).

*Photosynthesis – process of capturing light energy from the sun to convert water & CO2 into oxygen and high energy carbohydrates (food, ex: glucose, starch, & other sugars)

Investigating Photosynthesis Van Helmont’s Experiment – do plant’s grow by taking material from the soil? Found mass of dry soil Planted a seedling, watered it at regular intervals until it grew to a mass of 75kg. Found mass of soil to be unchanged Concluded the mass the plant gained came from the water he added. Partially correct, but did not determine where the carbon in the carbohydrate comes from

Priestley’s Experiment – oxygen is produced by plants Determined that oxygen was required to keep a flame lit/burning. Removed oxygen from a jar by placing a lit candle under it until the flame went out. Then placed a sprig of mint in the jar (empty of oxygen) After a few days, he found he could relight a candle in this jar and it would remain lit for a while!

Jan Ingenhousz – light is essential to photosynthesis! Showed the effect observed by Priestley occurred only when the plant is exposed to light! Together, Priestly and Ingenhousz showed the plants need light and water to produce oxygen.

Photosynthesis Basics – occurs in the chloroplasts of plants, protists, and some bacteria cells. Chloroplast – organelle where photosynthesis occurs Surrounded by 2 membranes. Thylakoid – flattened sac made of membrane inside the chloroplast Granum – stack of multiple thylakoids Stroma – fluid that surrounds the grana and fills the chloroplast

B. Pigments – compound that absorbs light 1. Chlorophyll – pigment on thylakoid membrane that absorbs light for photosynthesis Chlorophyll a – absorbs less blue and more red light; directly absorbs sunlight Chlorophyll b – absorbs more blue and less red light; helps chlorophyll a absorb light Both chlorophyll a and b reflect green light Caretenoid – another pigment that absorbs blue and green light, but not orange; also helps chlorophyl a absorb light.

**Equations are also the reverse! C. Photosynthesis is chemically the opposite of Respiration. Respiration Photosynthesis Uses glucose to make ATP 1st converts light to ATP 2nd uses ATP to make glucose **Equations are also the reverse!

NADPH As chlorophyll absorb sunlight, their electrons become excited (gain a lot of energy). These high energy electrons require a special carrier called NADP+ NADP+ holds and carries 2 high energy electrons, along with a H+ ion to become NADPH

Light-Dependent Reactions – first step, converts sunlight to ATP Occurs on the thylakoid membrane & is made of PHOTOSYSTEM I and PHOTOSYTEM II Light is absorbed by chlorophyll in PHOTOSYSTEM II.

The light energy provides electrons for the Electron Transport Chain (chain of proteins). Electrons in PHOTOSYSTEM II split water (H+ & O2 are released). Some H+ is added to NADP+ and produces NADPH as electrons move from PHOTOSYSTEM II to the ETC The O2 is released to the atmosphere. A photon of light is absorbed by chlorophyll in PHOTOSYSTEM I and combines with electrons from ETC

*Chemiosmosis and the ETC happen at the same time!!! Also happens on the membrane of the thylakoids. Electrons from PHOTOSYSTEM II provide the energy for pumping H+ into the thylakoids Rest of the H+ (from the splitting of water) turn ATP Synthase proteins (like a turbine) to make ATP. *Chemiosmosis and the ETC happen at the same time!!! * ATP and NADPH are products of the Light Reactions

Uses ATP & NADPH to make Glucose Cycles 6 times to make 1 Glucose Calvin Cycle – the 2nd step of photosynthesis. Also called the Light-independent Reactions (used to be called Dark Reactions), as light does not play any direct role. Uses ATP & NADPH to make Glucose Occurs in the Stroma Cycles 6 times to make 1 Glucose

Steps of the Calvin Cycle RuBP (carbohydrate in plants) reacts with NADPH, 6 CO2 (from the atmosphere), and ATP to make Glucose. Catalyzed by the enzyme Rubisco In the final step, RuBP is remade so the cycle can occur again. Overall, uses 6 CO2 to make 1 glucose and cycles 6 times.

Factors Affecting Photosynthesis Water – is a needed raw material; shortage of water slows or even stops photosynthesis Temperature – photosynthesis relies on enzymes, which only function between 0oC and 35oC Intensity of Light – up to a specific level, as light intensity increases, so does the rate of photosynthesis

Amoeba Sister Video! https://www.youtube.com/watch?v=uixA8ZXx0KU

Glycolysis & Fermentation Harvesting Chemical Energy Cellular Respiration – the break down of organic compounds (food, glucose, etc.) in cells to make energy, ATP molecules C6H12O6 + 6O2  6CO2 + 6H2O + Energy

Glycolsysis Biochemical pathway that always starts cellular respiration!!! Does produce a small amount of ATP. Other products can follow two other pathways, depending on whether oxygen is present not.

Glycolysis ATP Oxygen Absent Oxygen Present Fermentation (anaerobic) Aerobic Respiration

Cellular Respiration Overview   Carbon Glucose Electron Dioxide (C6H12O2) → Glycolysis Krebs Transport (CO2) + Cycle Chain Oxygen Water (O2) (H20)

Two (2) Types of Cellular Respiration Fermentation– respiration without oxygen Can also be called anaerobic respiration Aerobic Respiration – respiration with oxygen Aerobic = “with oxygen” like aerobic workouts Anaerobic = “without oxygen” like weightlifting workouts

II. Glycolysis Basics of Glycolysis glyco: sugar lysis: break up Begins to break down glucose & releases a small amount of energy (ATP) Occurs in the cytoplasm. All types of cellular respiration begin with glycolysis!!!!!!!!!!

Major events in Glycolysis Start with (invest) 1 glucose, 2 NAD+, and 2 ATP molecules. Glucose, a 6-carbon molecule, is split into 2 PGAL, or glyceraldehyde-3-phosphate, molecules (each a 3-carbon molecule). Hydrogens are transferred from the 2 PGAL molecules to the 2 NAD+ molecules. This produces 2 NADH molecules. 4 ATP molecules are then produced (2 ATP overall). This also produces 2 pyruvic acid molecules. Ends with 2 pyruvic acid, 2 ATP, 2 NADH molecules.

Glycolysis

III. Fermentation Basics Also known as Anaerobic Respiration Does not make any ATP! Does remake NAD+, which goes back through Glycolysis to make 2 more ATP.

2 Types of Fermentation Alcoholic Fermentation A CO2 molecule is removed from each pyruvic acid, creating acetaldehyde. 2 H+ are removed from 2 NADH to make NAD+. Acetaldehyde is converted into ethyl alcohol by gaining the 2 H+. NAD+ goes back through glycolysis to make more ATP.

  2 ADP  2 P i 2 ATP Glucose Glycolysis 2 Pyruvate 2 NAD 2 NADH Figure 9.17a 2 ADP  2 P i 2 ATP Glucose Glycolysis 2 Pyruvate 2 NAD  2 NADH 2 CO2  2 H  Figure 9.17 Fermentation. 2 Acetaldehyde 2 Ethanol (a) Alcohol fermentation

Lactic Acid Fermentation 2 H+ are removed from 2 NADH to make NAD+. Pyruvic acid is converted into lactic acid by gaining the 2 H+. NAD+ goes back through glycolysis to make more ATP.

(b) Lactic acid fermentation 2 Lactate 2 Pyruvate 2 NADH Glucose Glycolysis 2 ADP  2 P i 2 ATP 2 NAD  2 H Figure 9.17 Fermentation.

Mitochondria Review Structure Surrounded by a double membrane The 2nd, inner membrane, is highly folded to increase surface area. Each fold is called a cristae The very interior of the mitochondria is called the mitochondrial matrix.

IV. Cellular Respiration (aerobic) Basics Cellular Respiration requires oxygen (O2)! Produces nearly 20 times more ATP than glycolysis alone. Begins with Glycolysis, followed by the Kreb’s Cycle, the Electron Transport Chain, and Chemiosmosis.

Pyruvic acid is converted into Acetyl CoA. Glycolysis Converts glucose into 2 pyruvic acids. Makes 2 NADH and a net of 2 ATP. Occurs in the cytoplasm Pyruvic acid is converted into Acetyl CoA. The 2 Pyruvic Acids pass through both mitochondrial membranes into the mitochondrial matrix. As this happens, the 2 pyruvic acids reacts with a molecule called coenzyme A to form Acetyl CoA. 2 NADH’s and CO2 are produced.

Kreb’s Cycle Each Acetyl CoA is broken down to make 1 ATP, 3 NADH, and 1 FADH2. 1st product is remade in the last step, so the Kreb’s Cycle can happen again. Remember, there are 2 Acetyl CoA’s, so the Kreb’s cycle will happen twice. Our totals are therefore: 2 ATP, 6 NADH, and 2 FADH2.

Citric acid cycle Acetyl CoA Oxaloacetate Malate Citrate Isocitrate NADH 1 Acetyl CoA Citrate Isocitrate -Ketoglutarate Succinyl CoA Succinate Fumarate Malate Citric acid cycle NAD FADH2 ATP + H H2O ADP GTP GDP P i FAD 3 2 4 5 6 7 8 CoA-SH CO2 Oxaloacetate Figure 9.12 A closer look at the citric acid cycle.

Electron Transport Chain Occurs across the inner membrane of the mitochondria (cristae). H+ ions are released from NADH and FADH2 into the mitochondrial matrix. The electrons in the hydrogen atoms are at a high energy level! The high energy electrons are passed along a series of molecules called the Electron Transport Chain.

Electron Transport Chain (cont.) As the electrons move from molecule to molecule, they lose some of their energy. This energy pumps H+ out of the mitochondrial matrix, into the space between the two mitochondrial membranes. A high concentration of H+ builds up in this space.

Electron Transport Chain

Chemiosmosis H+ ions diffuse from the high area of concentration made in between the 2 mitochondrial membranes to the low are in the matrix. Specifically the H+ ions move through a protein called ATP Synthase. As H+ ions move through ATP Synthase, ATP is made! 32 ATP are made in chemiosmosis. The H+ ions then combine with oxygen to form water.

Electron Transport Chain

Summary of Cellular Respiration Total ATP made aerobically: 36 ATP’s Glycolysis = 2 Kreb’s Cycle = 2 ETC/Chemiosmosis = 32