Cellular Energy

Chemical Energy and ATP  Most cell processes use ATP for energy  Do you get energy from eating sugar?  Yes?  No?

All cells use ATP  ATP is a molecule that transfers energy  How is ATP like money in your wallet?  ATP is used to:  Build molecules  Move materials

Structure of ATP  Energy is released when a phosphate group is removed from the molecule  ATP = Adenosine TRI-phosphate

ATP  When the third P is removed, energy is released  Unstable and easily removed for energy  ATP = ADP + P  ADP = Adenosine DI-phosphate

ATP and ADP

Questions  Where are molecules from food involved in the cycle of ADP to ATP?  Describe the relationship between energy stored in food and ATP.

How many ATP?  Carbohydrates offer easy ATP  Carbs are not stored in the body  One glucose = 36 ATP molecules!  Proteins about the same as Carbs  Not typically used for energy but to build more proteins  Fats (lipids) offer the most ATP  One triglyceride = 146 ATP molecules

How do plants eat?  They make their own food  Plants absorb energy from the sun and make sugars to break down for ATP

Chemosynthesis  Some species of bacteria use chemicals to make food  They break the food down for ATP

Solar Energy?  Calculators, homes and cars use energy from sunlight  Energy for people comes from ATP  ATP comes from the breakdown of sugars  How are sugars made?

Photosynthetic organisms  Producers – organisms that produce the source of chemical energy for themselves and for other organisms  Plants  Bacteria  Protists

Basic Food Chains  Animals eat plants = consumers  Animals that eat other animals, bacteria and fungi that decompose organisms  Wolf eats rabbit, rabbits tissues supply energy to wolf, tissues were built from plants, which made the sugars and other carbon-based molecules

Photosynthesis  Plant cells use sunlight energy to make organic compounds  Directly or indirectly, the energy for almost all organisms begins as sunlight

Sunlight and Radiant Energy  Ultraviolet  Microwaves  Visible light  or Radio waves?  Plants absorb visible light

Where does it occur?  In the leaves!

Photosynthesis occurs in the chloroplast.  Anatomy of a chloroplast chloroplast stroma grana (thylakoids)

Chloroplasts  Contain Thylakoids (flattened sacs)  Have pigments in their membranes  Grana - Stacks of thylakoids  Stroma - Fluid inside chloroplast stroma grana (thylakoids)

Pigments  Chlorophyll  Green pigment  Two forms - a and b  Absorb blue and red light, reflect green/yellow  Accessory pigments - absorb and reflect other colors  Can only be seen in the fall of the year

Photosynthesis  General Equation CO 2 + H 2 O --> C 6 H 12 O 6 + O 2  Major Steps 1. Absorb light energy 2.Convert light energy into chemical energy 3.Store chemical energy in sugars

CO 2 in, O 2 out  Stomates open - gas is exchanged  H 2 O is lost, must be replaced by roots  Transpiration - H 2 O diffusion out of plants

Light-dependent Reactions Step 1: Absorb sunlight, split water and transfer energy through the H+ 2 H 2 O  4 H + + O 2 “Electron Transport Chain via Photosystems I and II” Step 2: Transfer energy to ATP “ATP Synthase”

Light-independent Reactions Step 1: CO 2 is converted into larger molecules using ATP from Light- dependent reactions Step 2: The larger molecules are converted into Glucose – C 6 H 12 O 6 “Calvin Cycle”

Why Respiration?  Movement  Transport in cells  Maintenance  Nervous Signals  Biosynthesis

Respiration  Release of energy by breaking down glucose  1 Glucose = 38 ATPs!!!!!!  General Equation C 6 H 12 O 6 + O 2 --> H 2 O + CO 2 + ATP

Life has options…  Aerobic - Uses Oxygen!  Animals  Plants  Anaerobic - Little or no oxygen!  Some animals  Yeast  Bacteria

Major Steps of Aerobic Respiration  Glycolysis  Kreb’s Cycle  Electron Transport Chain

Glycolysis  Simple step in the cytoplasm  Makes 2 ATPs!  Glucose is cut in half!  Yields two Pyruvate molecules (3 carbons each)

Kreb’s Cycle  Occurs inside the mitochondria  Pyruvate molecules get broken into CO 2 and H+  Makes 2 more ATPs!

Electron Transport Chain  Occurs on the cristae (membrane) of the mitochondria  H+ transfer excess energy to ATP synthase  Excess H + + O 2  H 2 O

ATP Synthase  Enzyme responsible for:  ADP to ATP and O 2 to H 2 O

Cellular Respiration Electron transport chain and oxidative phosphorylation Chemical energy Chemical energy (high-energy electrons) Glucose Pyruvic acid Glycolysis Mitochondrial cristae Cytosol of cell Via oxidative phosphorylation H2OH2O Mitochondrion Krebs cycle CO 2 ATP

Fermentation  When you undergo heavy exercise, you force your muscles to use fermentation!  Large amounts of Oxygen for Aerobic Respiration cannot be stored in cells  Cells need energy, so they choose the alternate route!

Can you function without O 2 ?  Glycolysis yields 2 ATP  Glycolysis does not require Oxygen  Yes you can!!  You just get a little bit of energy

Anaerobic Respiration  Two types  Lactic Acid Fermentation  Yeast and bacteria, your muscles  Alcoholic Fermentation  Without fermentation, glycolysis would not continue  Fermentation recycles the molecules that allow glycolysis to continue

Fermentation

A build-up of lactic acid?  That must burn!  It does until you recovery breath, this is why your body breathes hard for several minutes after you stop exercising  You are making up for the oxygen loss  The replenishment of oxygen allows the cells to remove the excess lactic acid

Food Diary  Write down all of the foods you ate in the last 24 hours  Now, cross out…

Lactic Acid Fermentation  What would life be like without:  Cheese, bread and yogurt?  Bacteria and Mold  Convert milk into cheese  Make yogurt go sour

Alcoholic Fermentation  Some yeast and plants  Begins at the same point of lactic acid fermentation  Used to produce  Bread, beer and wine

Microbes in our Digestive System?  Bacteria in your digestive tract rely on fermentation  Without them we would not fully digest food  They allow us to absorb more nutrients from food

All cells need chemical energy.  Processes that make food include:  Photosynthesis  Chemosynthesis  Processes that make energy include:  Respiration (two types)  Fermentation (two types)