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 HeterotrophsAutotrophs are organisms that make their own food.Heterotrophs are organisms that need to ingest food

to obtain energy.

MetabolismAll 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 EnergyAdenosine 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

Photosynthesis

Overview of PhotosynthesisPhotosynthesis occurs in two phases.

Light-dependent reactionsLight–independent reactions (Calvin Cycle)

light6CO2 + 6H2O C6H12O6 +6O2

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 ReactionsThe absorption of light is the first step in photosynthesisChloroplasts capture light energy.

Chloroplast

Chloroplast

Calvin Cycle

Electron transportLight 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 O2 as a waste product.

No I will not…

Electron TransportThe 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 TransportPhotosystem 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+ ATPThe H+ from the split of water is used by ATP Synthase to produce ATP from ADP+.

Electron Transport

http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120072/bio13.swf::Photosynthetic%20Electron%20Transport%20and%20ATP%20Synthesis

Phase Two: The Calvin CycleIn 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 pathwaysC4 plants

CAM plants

C4 and CAM 4Plants

PhotosynthesisThe Musical

8.2 – Section Review

8.3 Cellular RespirationOverview of Cellular RespirationOrganisms obtain energy in a process called cellular

respiration.The equation for cellular respiration is the opposite of

the equation for photosynthesis.C6H12O6 + 6O2 6CO2 + 6H2O + Energy

Cellular respiration occurs in three main parts.1.Glycolysis2.The Kreb Cycle3.Electron Transport

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

Electron TransportFinal step in the breakdown of glucosePoint at which most ATP is producedProduces 34 ATP

What happens when we run out of OXYGEN?

Anaerobic RespirationThe anaerobic pathway that follows

glycolysis.Two main types

Lactic acid fermentationAlcohol fermentation

Fermentation

Fermentation

Chemiosmosis

Electron Transport

Photosynthesis and Cellular Respiration