Cell Processes

1. Chemical reactions take place inside cells There are more than 120 elements-25 are needed for life Water is needed for chemical reactions. About 2/3 of every cell is water Many form the 4 basic molecules for life Carbohydrates-sugar and starch used for quick energy Lipids-fats, oils and waxes needed for stored energy Proteins- for the growth and repair of tissues and to fight infections Nucleic Acids-DNA and RNA that have instructions for everything-especially reproduction

2. Cells and Energy a. All cells need energy. Chemical energy is stored in the bonds of molecules like glucose. b. Photosynthesis A process used by plants and other autotrophs to convert the energy of sunlight into sugars. It requires sunlight, water, and carbon dioxide. It occurs in the leaves of plants in organelles called chloroplasts.

EQUATION FOR PHOTOSYNTHESIS WATER OXYGEN 6CO2 + 6H2O + ENERGY C6H12O6 + 6O2 CARBON DIOXIDE GLUCOSE

c. Cells release energy in two ways Cellular Respiration-cytoplasm and mitochondria converts glucose into energy, CO2 and water Fermentation-allows cells to release energy without oxygen Alcoholic fermentation- makes alcohol Lactic Acid fermentation- makes lactic acid; milk , cheese and sore muscles

EQUATION FOR RESPIRATION CARBON DIOXIDE GLUCOSE C6H12O6 + 6O2 6CO2 + 6H2O + ATP OXYGEN ENERGY WATER *Photosynthesis and Cellular Respiration are opposite processes

3. Transport through cell membranes a. Certain things MUST enter the cell for it to survive. This can occur in 2 major ways: 1. PASSIVE TRANSPORT -requires no energy 2. ACTIVE TRANSPORT-requires energy

b. Important Molecules that move through cell membranes Oxygen Carbon dioxide Water

c. Types of Passive Transport 1 c. Types of Passive Transport 1. Diffusion- molecules move from a higher concentration to a lower one. It does not require energy so it is passive Cell membrane Outside cell Inside cell

Diffusion through a membrane Cell membrane diffusion Outside cell Inside cell

Diffusion through a membrane Cell membrane Outside cell Inside cell EQUILIBRIUM

2. Osmosis-diffusion of water across the cell membrane (also passive) The Plasma Membrane 4/12/2018 2. Osmosis-diffusion of water across the cell membrane (also passive) High H2O potential Low solute concentration Low H2O potential High solute concentration G. Podgorski, Biol. 1010

Diffusion of Liquids The Plasma Membrane 4/12/2018 G. Podgorski, Biol. 1010

d. Types of Active Transport The movement from lower concentration to higher concentration Active transport requires the use of energy 2 ways that materials are moved 1. Endocytosis -very large molecules are brought into the cell 2. Exocytosis-materials are moved out of the cell (usually wastes)

4. What affects Transport of materials? Temperature Size of materials Surface area of a cell* Volume* *The surface area can sometimes increase faster than the volume or the cell’s ability to hold materials so it stops growing Cell Shape

SUMMARY Cells need four large molecules to function: Carbohydrates, lipids, proteins and nucleic acids. 2/3 of all cells are water Cells capture energy through photosynthesis and release energy through cellular respiration and fermentation Materials are moved from areas of high concentration to low concentration through passive transport that does not require energy. Diffusion and osmosis are examples. In active transport, energy is required to move materials from areas of low concentration to high concentration. Endocytosis and exocytosis are examples Things that affect transport are: shape, size, volume, surface area, material size and temperature