Where have we been?

PHOTOSYNTHESIS TYPE II WRITE the BALANCED equation for photosynthesis LABEL the inputs (reactants) and outputs (products) EXPLAIN what will happen to each of the products and reactants

Cells and Energy Release Cellular Respiration Cells and Energy Release

MORE FUN WITH TIM & MOBY http://www.brainpop.com/science/cellularlifeandgenetics/cellularrespiration/preview.weml

Question… Why do we breathe? 4th grade answer: “so we don’t die” 7th grade answer: “to take in oxygen, and breathe out carbon dioxide” 10th grade answer: TO FUEL CELL RESPIRATION!

Basic ideas Breaking down high energy, large molecules into lower energy, smaller molecules. If this process stops, cells DIE!!!! Requires oxygen to fully occur. Three step process; Step 1 occurs in the cytoplasm of the cell Steps 2 & 3 occur in the mitochondria of the cell

Here’s where it Happens! "MIGHTY Mitochondria"

This is the equation! C6H12O6 +6O2 -> 6CO2 + 6H2O + energy (ATP& heat) How does this look familiar? Where do the “ingredients” (reactants) come from? What happens to each of the “leftovers” (products)

WHAT’S ATP GOT TO DO WITH IT? Adenosine Triphosphate Chemical energy source for the cell Think of it as cellular “money”

Three Stages of Cellular Respiration STEP 1: Glycolysis (“GLUCOSE SPLITTING”) 1st stage of ALL energy releasing pathways. Occurs in cytoplasm A couple of ATP “coins” made If you’re fermenting, stop here! STEP 2: Krebs Cycle (citric acid cycle) Occurs in the mitochondria A few more ATP “coins” made STEP 3: Electron Transport Chain (phosphorylation) Occurs in the mitochondria (membranes) ATP JACKPOT!!!!!!!!!!!!!!

CELL RESPIRATION OVERVIEW Convert glucose to ATP Accomplished in 3 steps: Glycolysisin cytoplasm Krebs Cyclein mitochondria Electron Transport Chainin mitochondria Remember: this requires Oxygen

Glycolysis Food must have been transported to cells via the bloodstream digested food gets into the bloodstream by diffusing through the intestinal walls into the capillaries. 1st stage in energy release from food Input = glucose, Outputs = small amount of ATP and pyruvates These outputs are the inputs for the next stage

Krebs Cycle Series of chemical reactions ATP (energy) released CO2 (waste) released

Electron Transport Chain Series of reactions Releases LOTS more ATP

CASHING IN… Total energy released from 1 GLUCOSE MOLECULE DURING CELL RESPIRATION: 38 ATP

CELL RESPIRATION OVERVIEW Convert glucose to ATP Accomplished in 3 steps: Glycolysisin cytoplasm Krebs Cyclein mitochondria Electron Transport Chainin mitochondria Remember: this requires Oxygen

UH, OH…PROBLEM 1.) What if you don’t have mitochondria? 2.) What if there isn’t much oxygen around?

FERMENTATION TO THE RESCUE! 2 KINDS: Alcoholic Lactic Acid These are ANAEROBIC processes Little to no oxygen required

BIG PICTURE: When are these used? CELL RESPIRATION Eukaryotes with mitochondria Adequate oxygen Ex. Animals Plants PRODUCES LOTS OF ATP! FERMENTATION Prokaryotes (no mitochondria) AND/OR Inadequate or no oxygen available Ex. Yeast Bacteria Overworked Human muscles (no, your brain is not a muscle!) Produces very little ATP, but hey, some is better than none!

Where ARE we GOING?