Cell Energy

Main Topics Photosynthesis Cellular Respiration

Objectives Know the roles of photosynthesis and cell respiration in the ecosystem Describe reactants and products in both photosynthesis and cellular respiration Compare and contrast systems in plants and animals for nutrient absorption, hormone response, and gas exchange

Vocab Photosynthesis Cellular Respiration Autotroph Heterotroph Aerobic Anaerobic

How do organisms obtain and use energy?

All cells use chemical energy carried by ATP

Autotroph- can make their own food Ex: plants, algae Heterotroph- cannot make their own food Must eat others for food Ex: animals, humans

Photosynthesis A process that captures energy from sunlight to make sugars that store chemical energy. Sun’s energy >>> Chemical energy (sugar) Takes place in the chloroplast Note: energy for almost all organisms begins as sunlight.

Photosynthesis

Factors that affect photosynthesis Water Temperature Light intensity

Chlorophyll A molecule in chloroplasts that absorbs some of the energy in visible light Two main types of chlorophyll (a and b) Absorb mostly red and blue wavelengths of light Reflect green wavelength of light

Chloroplast

Chloroplast overview Two main parts of the chloroplast needed for photosynthesis are the grana and the stroma. Grana (granum)- stacks of coin-shaped compartments called thylakoids. Stroma- fluid that surrounds the grana inside a chloroplast. Thylakoids- membranes of thylakoids contain chlorophyll.

Photosynthesis in detail Light-dependent reactions Capture energy from sunlight Take place in membrane of thylakoids Water and sunlight needed Light-independent reactions Also called the Calvin Cycle Uses energy from light-dependent reactions to make sugars Take place in the stroma Carbon dioxide needed

Light-dependent reactions Water molecules are broken down Oxygen molecules are released Energy carried along thylakoid is transferred to ATP

Light-independent reactions Calvin cycle Carbon dioxide is added Energy from light-dependent reactions is used Sugar is formed (usually glucose)

Photosynthesis video

Plant anatomy (nutrient absorption)

Plant anatomy (gas exchange)

Cellular Respiration Process that releases chemical energy from sugars and other carbon-based molecules to make ATP when oxygen is present. Aerobic process- it requires oxygen Takes place in the mitochondria

Mitochondria

3 steps of cell respiration Glycolysis Krebs Cycle Electron Transport

Glycolysis Splits glucose into two three-carbon molecules and makes two molecules of ATP Anaerobic process- does not require oxygen Takes place in the cell’s cytoplasm (not in the mitochondria)

Krebs cycle Takes place in the interior space, or matrix, of the mitochondrion Uses the three-carbon molecules from glycolysis Small number of ATP molecules are made Carbon dioxide given off as waste Energy is transferred to the electron transport chain

Electron transport Takes place in the inner membrane of the mitochondrion Energy from the Krebs cycle is transferred to the inner membrane Oxygen enters the process Large number of ATP molecules are made Water and heat are given off as waste

Cellular Respiration Up to 38 ATP molecules are made from the breakdown of 1 glucose molecule Used when oxygen is present

Fermentation Does not make ATP, but it allows glycolysis to continue Used when oxygen is not present Produces lactic acid, which causes your muscles to burn during hard exercise

Crash Course: Cell Respiration