Science Warm-up 9/6/2011

• What are some ways that you get energy? Is this the same for everyone? What about everything around the world?

• Write a paragraph response to this prompt. (minimum of 5 sentences)

Chapter 8: Cellular Energy

Biology BMr. Wood

Section 1: How Organisms Obtain Energy

• Thermodynamics

• Autotrophs vs Heterotrophs

• Metabolism

• ATP

What is energy? (p.218)

• Energy is the ability to do work.

• Thermodynamics is the study of the flow and transformation of energy in the universe.

The Laws of Thermodynamics

• There are 2 main laws:1) Energy can be transformed,

but energy cannot be created or destroyed.

2) Energy cannot be converted without the loss of usable energy.

• Examples:Recharging a cell phone battery

Buying a new car

How do organisms get energy? (p.219)

• 2 different varieties:

Auto-trophsHetero-trophs

Self-eaterOther-eater

Both are based on the Sun

Autotroph•Self Eater

Heterotroph•Other eater

Metabolism (p.220)

• Metabolism is all of the chemical reactions in a cell.

• Catabolic vs. Anabolic

• Breaking down vs Building up

The Metabolism of Ecosystems

• There is a cycle of energy in an ecosystem.

ATP: The Unit of Cellular Energy

• Adenosine triphosphate is the cell’s currency for energy

• ATP stores energy, and then releases energy when it is turned into ADP

Section 2: Photosynthesis

• Overview

• Phase 1: Light Reactions

• Phase 2: Dark Reactions

Overview of Photosynthesis (p.222)

• Photosynthesis is turning light energy into chemical energy.

• Turns sunlight into sugar

Phase One: Light Reactions (p.223)

• The first step is to absorb light energy

• This process happens in the pigments of the chloroplasts.

Where photosynthesis starts

• Why are chloroplasts green?

Phase Two: The Calvin Cycle

• This is where energy for the plant is stored for the long term.

• Most plants store energy in the form of glucose.

Review of photosynthesis

• Sunlight splits a water molecule.

• Hydrogen ion is passed through an electron transport.

• The CO2 moves through the Calvin Cycle.

• Excess energy is stored in glucose.

Alternative Pathways

• C4 Pathway

• CAM Plants

• Commonly found in desert plants. This is more efficient in very high temperatures, drought and CO2 limitations.

Section 3: Cellular Respiration

• Organisms obtain energy in a process called cellular respiration.

• The equation for cellular respiration is the opposite of the equation for photosynthesis.

Phases of Cellular Respiration

• There are 2 main phases of cellular respiration:GlycolysisAerobic respiration

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 (2 total) that is broken down.

• Glycolysis results in a net gain of 2 ATP molecules.

• Most of the energy from the glucose is still contained in the pyruvate.

• The series of reactions in which pyruvate is broken down into carbon dioxide is called the Krebs cycle.

Electron Transport

• The final step for the glucose molecule.

• Point at which ATP is produced

• Produces 34 ATP

Molecular Yield of ATP per Glucose Molecule

Reaction ATP Used ATP Gained

Glycolosis 2 4

Production of Acetyl-CoA

2 0

Krebs Cycle 0 2

Electron Transport Chain

0 34

Aerobic vs Anaerobic

• Aerobic- with oxygenLong distance running

• Marathon

• Anaerobic- without oxygenSprinting

• 100 meter dash

Anaerobic respiration

• After glycolysis, one of the following 2 processes occurs:Alcohol fermentation

• Wine

Lactic acid fermentation• Muscles