Photosynthesis & Cellular Respiration

Photosynthesis Equation Uses the energy from sunlight to convert water and carbon dioxide into high-energy sugars and oxygen

How do plants get energy from light? From the chlorophyll!!! A pigment found in plants They absorb light

Through the stoma in their leaves! How do plants get CO2? Through the stoma in their leaves! Opening at the bottom of a leaf that lets CO2 and O2 to diffuse in and out

What else do we need for photosynthesis? Electron carriers! Sunlight excites electrons in chlorophyll and gives them energy Need a special carrier for high-energy electrons NADP+ is an electron carrier

Anatomy of a Chloroplast chlorophyll: pigment inside chloroplasts thylakoid: saclike membranes (light-dependent reactions) stack of thylakoids stroma: area outside thylakoid (light-independent reactions)

Photosynthesis

Light-Dependent Reaction Uses ADP+P & NADP+ from the light- independent reactions to carry electrons 6 H2O & sunlight enter the cycle 6 Oxygen exits the cycle Makes ATP & NADPH

Photolysis-happens in Light-Dependent Reaction Light is absorbed and breaks up water molecules into 3 parts: Energized electrons Hydrogen ions (H+) Oxygen (O2)

Light Independent Reaction aka Calvin Cycle Uses ATP & NADPH from the light- dependent reactions to make high-energy sugars (Glucose) ATP goes in (gives energy) and NADPH goes in (donates electrons) 6 CO2 enter the cycle Glucose exits the cycle

ADP vs. ATP Cells store and release energy with ATP Store=ADP Release=ATP

What can limit photosynthesis? Light intensity Carbon dioxide concentration Temperature

Carbohydrates & Lipids

Monomer vs. Polymer Monomer = 1 unit Polymer = Many units

Carbohydrate Monomer: Monosaccharide Polymer: two kinds Means “simple sugar” Ex. Glucose, fructose, galactose Polymer: two kinds Disaccharide (2 monosaccharides) Ex. Sucrose (table sugar), lactose (milk sugar), maltose (malt sugar) Polysaccharide (3+ monosaccharides) Ex. Cellulose (fiber), starch (how plants store glucose), glycogen (animal starch), chitin (insect exoskeleton)

Function: Provides energy Carbohydrate Function: Provides energy Also can provide structure 2:1 ratio of Hydrogen:Oxygen

Lipids Monomer: Glycerol & Fatty acids Polymer: fats, oils, waxes, steroids, phospholipids Two types of fats: Saturated-no double bonds in the fatty acid tails Unsaturated-at least one double bond in the fatty acid tails Examples of Fats: Triglycerides Sterols-cholesterol & steroids Phospholipids-cell membrane

Lipids Function: long-term energy storage Insulation, membranes, chemical messengers and waterproofing

Cellular Respiration

Cellular Respiration Releases energy by breaking down glucose (or other food molecules) in the presence of oxygen Aerobic Responsible for most of our stored energy All living things do this!

Anatomy of Mitochondria Has two membranes Cristae-Electron Transport Chain Matrix-Krebs Cycle

Chemical Energy ATP: adenosine triphosphate – chemical compound used to store & release energy breaking this bond releases energy when one P is removed, energy is released ATP ADP + P

Step 1: Glycolysis One molecule of glucose is broken in ½ making two molecules of pyruvic acid Release ATP & NADH (notice that it’s not NADPH)

Step 2: Krebs Cycle Pyruvic acid is broken down into CO2 Occurs in the matrix Goes through this cycle twice! High-energy electrons are picked up by carriers and taken to the Electron Transport Chain

Step 3: Electron Transport Chain Uses high-energy electrons from Krebs Cycle to convert ADP to ATP Occurs in the cristae! O2 is the final electron acceptor in the chain-> makes water Most ATP is made in this step!

Photosynthesis vs. Cell Respiration You decide!

Fermentation

What happens if we don’t have Oxygen? Fermentation! Release energy from food molecules by producing ATP without O2 Anaerobic (without oxygen) There are 2 main types: Alcoholic fermentation Lactic Acid fermentation

Alcoholic Fermentation Yeast and other microorganisms do this Ethyl alcohol and CO2 as waste Causes bread dough to rise Only 2 ATP are made

Lactic Acid Fermentation Converting pyruvic acid into lactic acid Muscles, pickles, sauerkraut, sour cream, yogurt, cheese & buttermilk Only 2 ATP are made

Let’s compare! Anaerobic vs Aerobic Respiration Running discussion