Photosynthesis and Cellular Respiration

CELLS & ENERGY Chapters 8 & 9 Need energy to: move change shape repair structure make new cell parts transport food expel wastes

The sun is the ultimate source of energy! Autotrophs – make their own food Heterotrophs – eat other organisms Energy is obtained through breaking down food. Photosynthesis & Cellular Respiration are linked chemical reactions! (the product of one is reactant of another…)

2 Important Energy Pathways #1: Photosynthesis- Light energy converted to chemical energy of organic compounds. *Inputs: water + sunlight (energy) + carbon dioxide *outputs: glucose (food) + oxygen Plants = autotrophs (they make their own glucose)

PHOTOSYNTHESIS 6CO2 + 6H20 + solar energy C6H12O6 + 6O2

Where does Photosynthesis occur in plant cells? Occurs in leaves where chloroplasts are abundant

Capturing Light Energy White light made of visible spectrum (different wavelengths)

Plants contain pigments (compounds that absorb light) Chlorophyll – reflects green wavelength (green leaves); uses red & blue Carotenoids – reflect yellow, orange, brown (fruits/flowers)

Converting Light Energy 3 STAGES Energy captured from light splits water to release oxygen Sunlight energy used to make ATP & NADPH (high energy electron carrier) 3. ATP & NADPH used to make glucose from CO2 input

2 Important Energy Pathways #2: Cellular Respiration- Organic compounds broken down to create ATP Inputs: oxygen + glucose Outputs: energy (ATP) + water + carbon dioxide *

CELLULAR RESPIRATION C6H12O6 + 6O2 6CO2 + 6H2O + energy Process by which all organisms (including plants) release energy stored in glucose molecules

Cellular Respiration happens in the mitochondria of plant & animal cells

Several Steps to Cellular Respiration Glycolysis: happens in cytoplasm of cell. No energy or O2 needed a molecule of glucose is split in half ( now 2 molecules called pyruvates).

Electron Transport Chain in Mitochondria The 2 pyruvates travel to mitochondria where they are broken down to make the cell’s fuel….ATP A waste product of this process is carbon dioxide We exhale the CO2 from this process as an output

In the end… 36 ATP are made from 1 glucose The plant or animal cell now has energy to make new cells, repair itself, keep itself working…

Cellular Respiration Sometimes also called: Aerobic Respiration: Occurs with oxygen in eukaryotic mitochondria or in the cytoplasm of prokaryotes Produces 36 ATP’s

Anaerobic Respiration: energy production in the absence of O2 Humans carry out anaerobic respiration, when muscles perform strenuous exercise resulting in oxygen debt. Lactic acid and ATP are produced but the energy net gain is less compared with that in aerobic respiration. Forms lactic acid as an waste product (output).

Prokaryotes Anaerobic respiration known as: Fermentation Forms lactic acid (yogurt / cheese) or ethyl alcohol (beer / wine / bread)

Cell Pictures Label one picture “photosynthesis” and the other “cellular respiration” – you get to decide which is which. Color the inputs yellow and the outputs pink (or whatever color is convenient…just change the key)

Connections!!!