Cellular Energy

Cellular Energy Every organism must be able to obtain energy from its environment Autotrophs: make food from sunlight Examples? Heterotrophs: get food from elsewhere (Which are you?)

ATP (Adenosine Triphosphate) Energy molecule used by cells Composed of: Nitrogen Base (Adenosine) Sugar (Ribose) 3 phosphate groups

Forming and Breaking ATP Energy is RELEASED when a phosphate group(P) is REMOVED/BROKEN Energy is stored in the bond between the 2nd and 3rd phosphate group. When P is ADDED back, energy is ADDED/STORED ATP  ADP + P + Energy ADP: adenosine diphosphate The P can be reused!

Photosynthesis Photo: light Synthesis: to put together Process that uses the sun’s energy to make simple sugars (glucose) All energy originates with the sun

Photosynthesis Equation (Do you know it?) What do plants need? What do plants produce or give off?

Photosynthesis Reaction 6CO2 + 6H2O  C6H12O6 + 6O2 Carbon Dioxide + Water  Sugar + Oxygen Gas Autotrophs carry out photosynthesis!

Chloroplast Organelle where photosynthesis occurs

Chloroplast Thylakoids: Storage sacs of chlorophyll Grana: Stack of thylakoids Stroma: Area outside the thylakoids

Trapping Light Thylakoid membrane traps the light using pigments: Molecules that absorb specific light wavelengths Chlorophyll absorbs most wavelengths of light except for green Makes plants look green! (Other plant pigments: Xanthophyll: yellow Carotene: orange)

Photosynthesis Processes 2 phases Light-dependent reactions Convert light energy into chemical energy ATP produced is used to fuel the light-independent reactions Light-independent reactions Produces simple sugars So, photosynthesis

Light Reactions (light-dependent reactions) Requires Sunlight, Chlorophyll (to gather the suns energy) and Water Happens in the thylakoid membrane of the chloroplasts. Sunlight and water goes in Oxygen, ATP and NADPH comes out ATP: Cellular Energy NADPH: Energy needed in the Light Independent Reactions to remove a P group from ATP.

Calvin Cycle (light-independent reactions) Does not require sunlight Occurs in the stroma of the chloroplast CO2, ATP and NADPH goes in Glucose (C6H12O6), ADP + P, and NADP+ comes out NADP+ Energy needed in the light reactions to bond a P+ group to ADP (Used to be called dark reactions, but that is misleading.)

Photosynthesis Requirements Where does the plant get… sunlight? water? carbon dioxide (CO2)?

Stomata

Products of Photosynthesis Light Independent Light Dependent Sugar (glucose) ADP + P Oxygen (O2) ATP

Cellular Respiration C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy Occurs in ALL living organisms Process in which mitochondria break down sugar to produce ATP C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy Photosynthesis reversed!

Stages of Respiration (with O2) Glycolysis: in cytoplasm This step is anaerobic (no oxygen needed) Citric Acid Cycle (Kreb’s Cycle): in mitochondria Electron Transport Chain: inner membrane of mitochondria

Mitochondria

Glycolysis Needs 2 ATP to start Produces 4 ATP Breaks glucose into ATP and pyruvate

Citric Acid Cycle (Kreb's Cycle) Produces 2 ATP and CO2 Breaks down a molecule of pyruvate

Electron Transport Chain Produces 32 ATP (sometimes 34) Occurs in the inner membrane of the mitochondria (cristae) Energized electrons release energy as they pass from one protein to another

Cellular respiration makes a total of: 36-38 ATP

Fermentation If oxygen is not present ATP can still be made in small amounts using this anaerobic process.

Fermentation Types Many foods are made this way. 2 Types of fermentation Lactic Acid Alcoholic

Lactic Acid Fermentation Produces lactic acid and only 2 ATP Occurs when the body is under stress and not getting enough oxygen

Alcoholic Fermentation Used by yeast cells and some bacteria to produce: CO2 Ethyl alcohol This process is used to make bread and wine

Summary Photosynthesis Cellular Respiration Food synthesized Food broken down Energy from sun stored as glucose Energy of glucose released Carbon Dioxide taken in Carbon dioxide given off Oxygen given off Oxygen taken in Produces sugar Produces CO2 & H2O Requires light Does not require light Occurs only in the Chloroplast Occurs in all living cells

The cycle of energy