8.1 How Organisms Obtain Energy Mr. Purcell Biology I

Transformation of Energy Energy is the ability to do work. Thermodynamics is the study of the flow and transformation of energy in the universe.

Laws of Thermodynamics First law – Energy can not be created nor destroyed only changed. Second law – Energy cannot be converted without the loss of usable energy.

Autotrophs and Heterotrophs Autotrophs are organisms that make their own food. Heterotrophs are organisms that need to ingest food to obtain energy.

Metabolism All of the chemical reactions in a cell. Photosynthesis –light energy from the sun is converted to chemical energy for use by the cell. Cellular respiration – organic molecules are broken down to release energy for use by the cell

ATP: The Unit of Cellular Energy Adenosine Triphosphate (ATP) – Cells use ATP to store & use for Energy (Battery fully charged) Adenosine Diphosphate (ADP) – Stores Energy (Battery Not fully Charged)

ATP & ADP -To release the Energy, the Phosphate Bonds are Broken -Cells only have very small amounts of ATP on hand, most is in ADP & is easily converted to ATP.

ATP Synthesis

8.2 Photosynthesis

Photosynthesis… …way simplified

Photosynthesis

Overview of Photosynthesis Photosynthesis occurs in two phases. Light-dependent reactions Light–independent reactions (Calvin Cycle) light 6CO 2 + 6H 2 O C 6 H 12 O 6 +6O 2

Light Dependent Reactants Need the light dependent reactants 3:25 clip Have on Hadorn chapter 8 Light dependent reactants

Photosynthesis – Absorption Spectra

Chlorophyll

Chlorophyll…

Phase One: Light Reactions The absorption of light is the first step in photosynthesis Chloroplasts capture light energy.

Chloroplast

Calvin Cycle

Electron transport Light energy excites electrons in photosystem II and also causes a water molecule to split, releasing an electron into the electron transport system, H + into the thylakoid space, and O 2 as a waste product.

No I will not…

Electron Transport The excited electrons move from photosystem II to an electron –acceptor molecule in the thylakoid membrane. That transfers the electrons along a series of electron – carriers to photosystem I.

Electron Transport Photosystem I transfers the electrons to a protein called ferrodoxin. Ferrodoxin transfers the electrons to the electron carrier NADP + forming the energy – storing molecule NADPH.

Need electron chain clip

ADP+  ATP The H+ from the split of water is used by ATP Synthase to produce ATP from ADP+.

Electron Transport

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Phase Two: The Calvin Cycle In the second phase of photosynthesis, called the Calvin cycle, which takes place in the stroma, ATP and NADPH from the light-dependent reactions are used to produce high-energy sugars.

The ‘Melvin’ Calvin cycle works steadily to remove carbon dioxide from the atmosphere and turns out energy-rich sugars. Six carbon dioxide molecules are needed to make a single 6-carbon sugar. Phase Two: The Calvin Cycle

The Calvin Cycle

Photosynthesis

Alternative pathways C 4 plants CAM plants

C4 and CAM 4 Plants

Photosynthesis The Musical

8.2 – Section Review

8.3 Cellular Respiration Overview of Cellular Respiration Organisms obtain energy in a process called cellular respiration. The equation for cellular respiration is the opposite of the equation for photosynthesis. C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Energy

Cellular respiration occurs in three main parts. 1. Glycolysis 2. The Kreb Cycle 3. Electron Transport

Glycolysis Glucose is broken down in the cytoplasm through the process of glycolysis. Two molecules of ATP and two molecules of NADH are formed for each molecule of glucose that is broken down.

Glycolysis

Krebs Cycle Glycolysis has a net result of only two ATP and 2 pyruvate. Most of the energy from the glucose is still contained in the pyruvate. This series of reactions in which pyruvate is broken down into carbon dioxide is called the Krebs cycle.

Krebs Cycle The net yield from the Krebs cycle is six CO 2 molecules, two ATP, eight NADH, and two F ADH2.

Electron Transport Final step in the breakdown of glucose Point at which most ATP is produced Produces 34 ATP

What happens when we run out of OXYGEN?

Anaerobic Respiration The anaerobic pathway that follows glycolysis. Two main types Lactic acid fermentation Alcohol fermentation

Fermentation

Chemiosmosis

Electron Transport

Photosynthesis and Cellular Respiration