Cell Energy: Photosynthesis & Respiration

Autotroph or Heterotroph? Why? How does it make its own food? PHOTOSYNTHESIS

Overview of Photosynthesis and Respiration Photosynthesis –Use sunlight to make carbon compounds (food) Cellular Respiration – Turns the food into ATP (energy) Autotrophs Photosynthesis and Cellular Respiration Why both? Because autotrophs have to make their food first and then break it down. Heterotrophs Cellular Respiration

How Does a Plant Make It’s Own Food? Plants use carbon dioxide (CO2), water (H2O), and sun’s energy to make food. This is called “photosynthesis” The food gives plants energy Animals get the energy stored in plants when they eat them.

What “Food” do Plants Make? The “food” plants make is a sugar called glucose (C6H12O6). Glucose and oxygen (O2) are made during photosynthesis.

The Stages of Photosynthesis 1. Energy is captured from sunlight on the chloroplast. 2. Light energy is converted to chemical energy through the electron transport chain. 3. The chemical energy in ATP and NADPH powers the formation of organic compounds (food) using carbon dioxide.

Review of ATP What are the components of an ATP molecule? What does it look like?

ATP Molecule

Stage One “Light Reactions” Leaves contain light-absorbing substances called pigments located in the chloroplast. Chlorophyll is the primary pigment used. Why is it green? It absorbs mostly blue and red light and reflects green and yellow. Pigments are stored in thylakoids.

Stage One: Light Reactions What Happens? Light strikes a thylakoid in a chloroplast and energy is transferred to the electrons found in the chlorophyll. The electrons jump to a higher energy level and are said to be “excited”.

Stage Two: Electron Transport Chain The series of molecules through which excited electrons are passed along a thylakoid membrane are called Electron Transport Chains. What Happens: 3. The electron moves down the chain and makes NADPH which carries the electron to the next stage. The excited electrons cause hydrogen to come into the thylakoid. 2. This sets up a concentration gradient of Hydrogen that provides the energy to make ATP.

Stage 3: Calvin Cycle ATP, NADPH and carbon dioxide are used to make carbon compounds (food) What Happens? Calvin Cycle- a series of enzyme-assisted chemical reactions that produces a three-carbon sugar (food).

What affects photosynthesis? Light Intensity Temperature Carbon Dioxide Concentration Water Availability

REVIEW What are the three stages of photosynthesis and what do they do? 1. Light reactions Captures sunlight 2. Electron Transport Chain Makes ATP (stored energy) and NADPH (electron carrier) 3. Calvin Cycle Uses CO2 , ATP and NADPH to make carbon compounds (food)

Photosynthesis and Cellular Respiration Which processes do plants cells perform? Both Why? Make food, then make energy Which processes do animal cells perform? Just cellular respiration.

How Do Organisms Get Energy From Food? Animals cannot make their own food like plants can. But, BOTH plants and animals must break down (digest) food in order to get energy from it (so they can live, grow, & develop) Where does this happen? In the Mitochondria

Aerobic Cellular Respiration Aerobic vs. Anaerobic Metabolic processes that require oxygen are called Aerobic. Metabolic process that DO NOT require oxygen are called Anaerobic. Most eukaryotes (ex. Plants and animals) get their energy through aerobic cellular respiration. Aerobic Cellular Respiration oxygen (O2) to break down food Cellular respiration releases more energy from food than Fermentation. Fermentation does not use oxygen Produces lactic acid and alcohol

Process of Cellular Respiration Food (glucose) is broken down into CO2 and H2O and energy is released C6H12O6 + 6 O2  6 CO2 + 6 H2O + energy (ATP) This energy can be used for: Keeping a constant body temperature Storage (ATP) - to be used later for things like growth

Stages of Cellular Respiration 1. Glycolysis 2. Krebs Cycle and Electron Transport Chain Or 2. Fermentation

Glycolysis The primary fuel for cellular respiration comes form glucose (from food) Enzymes break down glucose into 2 pyruvates (3 –carbon molecule) Result- 2 NADPH molecules (from the electron carrier, NAD+) and 2 ATP molecules produced.

Krebs Cycle (with oxygen) When oxygen is present, pyruvate enters the mitochondrion and is converted to NADH and acetyl-CoA (an enzyme) Acetyl-CoA goes through the Krebs cycle in enzyme assisted reactions and produce NADH and FADH2 (electron carriers) Energy is stored in the form of electrons in NADH and FADH2

Electron Transport Chain (with oxygen) Electrons donated by NADH and FADH2 pass through the electron transport chain. Electrons cause Hydrogen ions to accumulate on the outside of the membrane. Hydrogen ions diffusing back in create ATP (stored energy)

What Do You Notice?

Check It Out! Did you notice that cellular respiration is just the opposite of photosynthesis? Cellular Respiration

Fermentation Happens when cells cannot get the oxygen they need for aerobic cellular respiration Fermentation is a way to get energy when NO oxygen is available Lactic Acid Fermentation In short, fast races you might get a burning feeling in you leg muscles because of a build up of lactic acid (made during fermentation) Alcoholic Fermentation Alcoholic fermentation by yeast, a fungus, is used in the preparation of wine and beer.

Photosynthesis vs Cellular Respiration

Cellular Respiration Versus Fermentation

ATP Production Comparison How many ATP molecules…?

Particulars of Alcoholic & Lactic Acid Fermentation If oxygen is not available for too long with glycolysis what occurs:______________________________ 2 Forms _______________________________________ Alcoholic Fermentation What is produced: ________________________________________________________________ What does the CO2 cause yeast to do: ________________________________________________

Particulars of Alcoholic & Lactic Acid Fermentation How does it differ from alcoholic fermentation: _________________________________________ Which cells in our bodies are most adapted to this process: _______________________________

Aerobic Respiration vs. Fermentation Aerobic Respiration produces 34 ATP Anaerobic/Fermentation produces 2 ATP

Chemiosmosis Chemiosmosis - the pumping of protons through special channels in the membranes of mitochondria It is the process that actually produces ATP in cellular respiration

Cellular Respiration and Chemiosmosis

Review Create a concept map with the following words: Cellular respiration, glycolysis, with oxygen, without oxygen, krebs cycle, electron transport chain, fermentation, lactic acid fermentation, alcoholic fermentation