Photosynthesis and Cellular Respiration Chapter 5

Autotrophs Energy and Living Things I. Energy in Living Systems Autotrophs make their own food by using energy from sunlight or inorganic substances to build organic compounds. Many autotrophs make food by the process of photosynthesis. Autotrophs can use the sun’s energy directly Euglena

Heterotrophs Energy and Living Things I. Energy in Living Systems C. Breaking Down Food for Energy: Energy from sunlight flows through living systems, from autotrophs to heterotrophs. D. Heterotrophs release the energy in food through the process of cellular respiration. E. Heterotrophs are organisms that can NOT make their own food F. Heterotrophs can NOT directly use the sun’s energy 3 3

Energy and Living Things II. ATP ATP supplies cells with energy needed for metabolism. Energy is released upon the breakdown of ATP to ADP. ATP Consists of: 1. Adenine(amino acid) 2. Ribose(sugar) 3. 3 phosphates (Triphosphates) Adenosine 5

It supplies YOU with ENERGY! What Does ATP Do for You? It supplies YOU with ENERGY! 5

How Do We Get Energy From ATP? By breaking the high- energy bonds between the last two phosphates in ATP 6

Releasing Energy From ATP A. Adding A Phosphate Group To ADP stores Energy in ATP B. Removing A Phosphate Group From ATP Releases Energy & forms ADP Loose Gain 7 7

Photosynthesis Involves the Use Of light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches

Photosynthesis: It Begins with Sunlight! 9 9

Photoautotrophs Absorb Light Energy 10 10

The Photosynthesis Equation

Pigments In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments Chlorophyll is the primary light-absorbing pigment in autotrophs Chlorophyll is found inside chloroplasts

Inside A Chloroplast 13 13

Structure of the Chloroplast Double membrane organelle Outer membrane smooth Inner membrane forms stacks of connected sacs called thylakoids Thylakoid stack is called the granun (grana-plural) Gel-like material around grana called stroma 14 14

Photosynthesis III. Using the Energy in Sunlight Photosynthesis has three stages: Energy is captured from sunlight. Energy is temporarily stored in ATP and NADPH. 3. Organic compounds are made using ATP, NADPH, and carbon dioxide. 6 CO2 + 12 H2OC6H12O6+6O2+6 H2O Carbon dioxide + water  glucose +oxygen +water 7

Photosynthesis 1. Stage One: Absorption of Light Energy A. Pigments, such as chlorophyll, absorb light energy during photosynthesis. B. During photosynthesis, water molecules are split to release oxygen by an enzyme inside structures called thylakoids. 8

Photosynthesis 2. Stage Two: Conversion of Light Energy A.Electrons excited by light travel through electron transport chains, in which ATP and NADPH are produced. 9

Photosynthesis 3. Stage Three: Storage of Energy A. Through carbon dioxide fixation, often by the Calvin cycle, carbon dioxide in the atmosphere is used to make organic compounds, which store energy. 10

The Calvin Cycle Step 1: In carbon dioxide fixation, each molecule of carbon dioxide, CO2 is added to a five-carbon compound by an enzyme. Step 2: The resulting six-carbon compound splits into two three-carbon compounds. Phosphate groups from ATP and electrons from NADPH are added to the three-carbon compounds, forming three-carbon sugars.

The Calvin Cycle Step 3: One of the resulting three-carbon sugars is used to make organic compounds-including starch and sucrose-in which energy is stored for later use by the organism. Step 4: the other three-carbon sugars are used to regenerate the initial five-carbon compound, thereby completing the cycle.

Photosynthesis Overview 22 22

Photosynthesis Overview 23 23

Energy and Living Things IV. Cellular Energy – Cellular Respiration Cellular respiration releases much of the energy in food to make ATP, the energy “currency” inside cells. C6H12O6 +6O2 +6 H2O 6 CO2 + 12H2O +36 ATP Glucose+ oxygen+ water Carbon + water + ATP gas dioxide 4

Cellular Respiration A. Cellular respiration has two stages: Stage One: Glycolysis in the cytoplasm Stage Two is either: 1. Aerobic respiration (in the presence of oxygen) - Kreb’s Cycle and Electron Transport Chain in the mitochondria OR: 2. Anaerobic respiration (in the absence of oxygen). A large amount of ATP is made during aerobic respiration. NAD+ is recycled during the anaerobic process of fermentation. (2 types of fermentation) 12

Cellular Respiration 1. Stage One: Breakdown of Glucose Glycolysis: Glucose is broken down to pyruvate during glycolysis, making some ATP. Glycolysis produces 2 ATP’s and no oxygen is present for this step. The Pyruvate then enters the mitochondria where it is broken down into 2 Acetyl-CoA (coenzyme or helper enzymes) 13

Cellular Respiration 2. Stage Two: Production of ATP The Acetyl-CoA enters the Krebs cycle or Citric Acid Cycle. The cycle is a series of reactions that produce energy-storing molecules during aerobic respiration. The total products of the Kreb’s cycle are: 24 Hydrogen (24H); 6 carbon dioxide (6CO2); 2 ATP’s b. During aerobic respiration, large amounts of ATP are made in an electron transport chain. The total amount of ATP produced here are 32 ATP’s A TOTAL of 36 ATP’s for the entire process 14

Cellular Respiration: Diagram of the Process Occurs across Cristae of mitochondria Occurs in Cytoplasm Occurs in Matrix of Mitochondria 29

Cellular Respiration Fermentation in the Absence of Oxygen When oxygen is not present, fermentation follows glycolysis, regenerating NAD+ needed for glycolysis to continue. Two types of Fermentation: 1. lactic acid fermentation 2. alcoholic fermentation 15

Cellular Respiration Fermentation in the Absence of Oxygen contd. In lactic acid fermentation, pyruvate is converted to lactate. Lactate is what builds up in muscle cells and makes you sore. Glucose  Lactic Acid + Energy 16

Cellular Respiration Fermentation in the Absence of Oxygen contd. In alcoholic fermentation, pyruvate is broken down to ethanol, releasing carbon dioxide. Ethanol is a type of alcohol and is primarily done by yeast. 2. Although a small amount of ATP is made during fermentation, most of a cell’s ATP is made during aerobic respiration. Glucose  Ethyl Alcohol +Carbon Dioxide +Energy 16

Cellular Respiration 16

Comparing: Photosynthesis & Cellular Respiration Occurs in all cells & goes on with or without light Releases energy from sugars CO2 & H20 are products. Glucose & 02 are raw materials ( reactants) Photosynthesis Occurs only in the presence of chlorophyll & light Stores energy in sugars CO2 & H2O are raw materials (reactants) Glucose & O2 are products 16