Ecology Part 2 The Carbon & Oxygen Cycles Chapters 8 & 9

Photosynthesis Chapter 8 Photosynthesis What cycle(s) does photosynthesis tie in with?

CO 2 and O 2 are recycling

Why is photosynthesis important? Characteristic of all living things –Use & Obtain Energy Autotrophs can make their own food Heterotrophs consume others Where does this energy come from? The sun –Autotrophs can directly harness this energy, heterotrophs cannot

Sun’s Energy The sun’s energy = one million Hiroshima- sized atomic bombs per day –Photosynthesis harnesses about 1% of that energy Life is a set of coordinated chemical reactions to get the sun’s energy to other living things/cells. –What are these chemical reactions?

Building and Breaking Bonds Catabolism= breaking bonds –Get energy Anabolism = building bonds –Store energy

Definition: Photosynthesis It is the conversion of sunlight (energy) into chemical energy. The energy is then held in the bonds of carbohydrates (ex. glucose).

Carbohydrates Living things use carbohydrates as their main source of energy. –Ex: starches & sugars Plants and some animals also use carbohydrates for structural purposes. –Cell walls of plants are made of cellulose

Types of Carbohydrates Monomer = single unit –Monosaccharide = single sugars Ex: Glucose, galactose, fructose Polymer = more than one unit –Polysaccharide = large sugars (more than 2 units) used to store excess energy Starches (plants like potatoes & grains) Glycogen (animals) Cellulose (plants use it for structure & support; woods) Chitin (insects & the cell walls of fungi)

Common Polysaccharides

So let’s get back to how plants make those carbohydrates like glucose and starch. Photosynthesis!!!

The Basics Do you see parts of the cycles? What’s needed? –Carbon dioxide –Water –Light –chloroplasts What’s made? –Carbohydrates –oxygen

The Equation 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Carbon water glucose oxygen dioxide sunlight

Let’s review some organelles and plant characteristics…

Typical Plant Cell Where are the chloroplasts?

Under the microscope… Sec 8.3

How does a chloroplast trap light? Chloroplasts contain pigments that help it trap and harness the sun’s energy –colored substances that absorb or reflect light –Wavelengths of light = energy –Chlorophyll principal pigment in green plants reflects green wavelengths while absorbing red/blue to make food.

What’s the purpose of accessory pigments? They pick up other wavelengths of light that chlorophyll doesn’t capture

The Basics (a review) What’s needed? –CO 2 + water + light + Chloroplasts What’s made? –carbohydrates + oxygen

What was the GOAL of photosynthesis?

Transpiration

Name processes in the Human Body that use energy. Breathing Thinking Walking/running Heart beating Digestion Breaking down and building molecules

Cellular Respiration Chapter 9 Cellular Respiration What cycle(s) does cellular respiration tie in with?

CO 2 and O 2 are recycling

Which organisms do cellular respiration? Autotrophs can store energy in glucose & other carbohydrates during photosynthesis. Cellular Respiration is the opposite reaction –Releasing that stored energy for USE –BOTH autotrophs & heterotrophs have to do this

Cellular Respiration A process that releases energy by breaking down glucose (& other food molecules) in presence of O 2 6O 2 + C 6 H 12 O 6  6 CO 2 + 6H 2 O + Energy **Notice – the equation is the opposite of Photosynthesis!!**

Where in a cell does this happen? Mitochondria Present in almost all eukaryotes –Autotrophs & heterotrophs alike! –Contains the enzymes and molecules needed for these chemical reactions

How does cellular respiration release the energy from glucose? The bonds in glucose are broken Energy is transferred to the bonds of ATP –Adenosine triphosphate

Why does photosynthesis make glucose and not ATP? ATP cannot store large amounts of energy, and is unstable. Glucose is stable and holds 90 times more energy than ATP

ADP & ATP act like a battery

Glucose Glycolysis Krebs cycle Electron transport chain Fermentation (no oxygen) Alcoholic OR Lactic acid 2 possible Chemical Pathways to use glucose and make ATP All cells start out here Whether or not you have O 2 depends where you go next Oxygen Present NO Oxygen Present

Glycolysis Means glucose breaking Bonds hold energy - breaking them gives energy to charge ATP Does NOT require oxygen Happens in cytoplasm All living things do this NOT part of Cellular Respiration –It’s the warm-up step Produces only 2 ATP

Steps of Cellular Respiration Step 1 – Krebs Cycle –breaks the bonds holding the sugar together –the energy released (by breaking bonds) is carried by electrons –the electrons “carry” the energy to step 2 using special molecules Step 2 – Electron Transport Chain –releases the energy in these electrons and converts it into ATP

Would a baseball player running to first base and a cross country runner use the same or different pathways to release energy? Explain which pathway, cellular respiration or fermentation, they would use and why.

What type of foods would you eat before a marathon? A sprint? Hint, what is oxygen breaking down during cellular respiration?

Carbohydrates: energy conversions To prepare for a marathon, you might eat a carrot or starchy foods (polymer). Your body can then slowly break them down, using enzymes, into glucose (monomer) to use during cellular respiration. To prepare for a sprint, you might eat oranges that contain glucose (monomer). Your body can then use them immediately for cellular respiration since they are already in a simple form.

Fats are also used in energy conversions. Lipids don’t just make up cell membranes, they are used for long term energy storage. When you need energy and you don’t have sugars, use your stored lipids…..send them to the Krebs Cycle.

Glucose (C 6 H ) + Oxygen (0 2 ) Glycolysis Krebs Cycle Electron Transport Chain Carbon Dioxide (CO 2 ) + Water (H 2 O) Cellular Respiration One last look at how glucose energy makes ATP with oxygen Lipids and proteins can enter here. Only sugars enter here.

How much ATP do you really make? This represents about 38% of the energy stored in a molecule of glucose The rest of the energy is “lost” meaning it’s released as heat energy This is still more efficient than a car!

Glucose Glycolysis Krebs cycle Electron transport chain Fermentation (without oxygen) Alcohol or lactic acid Chemical Pathways Everyone starts out here Whether or not you have O 2 depends where you go next Oxygen Present NO Oxygen Present

The Anaerobic Pathway Fermentation is anaerobic - does NOT require oxygen. Provides cells with a back-up plan if no O 2 around –No additional ATP made 2 kinds: –Alcoholic (bacteria, yeast) –Lactic acid (animals)

Alcoholic Fermentation 3-C sugar is broken apart releasing CO 2 and a 2-C alcohol

Alcoholic Fermentation Yeast and bacteria can do this –the CO 2 causes dough to rise & bubbles in alcoholic beverages –Brewers also want the alcohol in their product

Lactic Acid Fermentation 3-C sugar  Lactic acid Exercise… muscles don’t have enough oxygen (hence you breathe harder), so cells resort to lactic acid fermentation. Muscles get sore because the lactic acid builds up and causes pain.

Glycolysis Fermentation Alcoholic Lactic Acid 2 ATP No O 2 present 0 ATP Krebs Cycle Electron Transport Chain 2 ATP 32 ATP Total 36 Total 2 O 2 present

CO 2 and O 2 cycle