C ELL P ROCESSES AND ENERGY Cells Unit 2, Part II H. Carter

E LEMENTS AND COMPOUNDS Elements Any substance that cannot be broken down into simpler substances Smallest unit= atom Carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur= found in living things Compounds Two or more elements that are chemically combined Smallest unit= molecule Water two-thirds of your body most chemical rxns w/in cell take place when dissolved water help cells keep size and shape keeps cell from changing temperature too rapidly

Inorganic compound Do not contain carbon Water, sodium chloride (table salt) Organic compounds Contain carbon Carbohydrates Made of carbon, hydrogen, and oxygen Sugars and starches Energy Found in cell walls, cell membranes Lipids Made of carbon, hydrogen, and oxygen Fats, oils, waxes Energy-rich (more than carbs) for later use

Proteins Made of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur Meat, fish, eggs, nuts, beans Made of amino acids Enzyme- speeds up or slows down a chemical rxn Nucleic Acids Made of carbon, hydrogen, oxygen, nitrogen, phosphorus Contain instructions for cell  DNA (deoxyribonucleic acid)- genetic material, directs all cell functions; found in chromatin  RNA (ribonucleic acid)- role in production of proteins; found in cytoplasm and nucleus

C ELL TRANSPORT *Cell membrane is selectively permeable which means that certain things can pass w/in the cell while others cannot Diffusion Process by which molecules move from an area of greater concentration to lesser concentration ( high to low ) Molecules are always moving and collide with each other Collisions cause the molecules to move away from each other to more open space

Osmosis Diffusion of water molecules through a selectively permeable membrane Because cells cannot function properly w/out adequate water, many cell processes depend upon osmosis V:\hcarter\Cell Processes\Diffusion_and_Osmosis.asf V:\hcarter\Cell Processes\Diffusion_and_Osmosis.asf

Normal red blood cell High water concentrationLow water concentrationoutside cell

Passive Transport Movement of materials through the cell membrane that does not require cellular energy V:\hcarter\Cell Processes\Passive transport 4.00.asf V:\hcarter\Cell Processes\Passive transport 4.00.asf Active Transport Movement of materials through the cell membrane using cellular energy Low to high ( lesser concentrated to greater)

Methods of Active Transport Transport Proteins proteins in the cell that “pick-up” molecules outside cell and carry them in or molecules inside of cell and carry them out Engulfing cell membrane surrounds and encloses a particle *Cells are the small size that they are in order for them to have an easier job in doing their jobs V:\hcarter\Cell Processes\Active transport 5.33.asf

PHOTOSYNTHESIS Process by which a plant captures energy from the sun and uses it to make food Nearly all living things obtain energy either directly or indirectly from the sun Stage 1 Capturing the sun’s energy Green pigments in chloroplasts called chlorophyll absorb sunlight In plants, mostly occurs in the leaves

Stage 2 Using energy to make food Cell uses the captured energy to make sugars Needs water and carbon dioxide to do this (reactants) Produces a sugar and oxygen (products) light energy 6 CO H 2 O C 6 H 12 O O 2 Carbon dioxide water a sugar oxygen V:\hcarter\Cell Processes\Photosynthesis.asf

CELLULAR RESPIRATION Process by which cells obtain energy from glucose Cells break down simple food molecules such as sugar and release the energy they contain When cells need energy, they “withdraw” it by breaking down the carbs in the process of respiration Stage 1 Takes place in the cytoplasm Molecules of glucose are broken down into smaller molecules Oxygen is not involved Small amount of energy released

Stage 2 Takes place in the mitochondria Small molecules are broken down into even smaller molecules Requires oxygen and releases a large amount of energy Uses sugar and oxygen (reactants) Releases carbon dioxide, water, and energy (products) C 6 H 12 O O 2 6 CO H 2 O + energy sugar oxygen carbon dioxide water V:\hcarter\Cell Processes\Cellular_Respiration.asf

C OMPARING P HOTOSYNTHESIS AND CELLULAR RESPIRATION They are OPPOSITES!

FERMENTATION An energy releasing process that does not require oxygen Provides energy for cells Energy release is much lower than for cellular respiration Alcoholic Fermentation: occurs when yeast and other unicellular organisms break down sugars Bakers, brewers Lactic Acid Fermentation: occurs in muscles when your muscle cells use up oxygen faster than it can be replaced Product is lactic acid; causes pain, soreness