PASSIVE TRANSPORT: DIFFUSION  Diffusion is a random movement of particles from an area where there are many particles of the substance to an area where there are fewer particles of the substance  Brownian motion the random movement of particles dissolved in water

continued  Concentration gradient is the level of movement of particles in a substance on two spectrums….few to high  When is equilibrium reached?  When the particles of the two substances mixed are evenly mixed  Facilitated Diffusion occurs when transport proteins are used to move ions (elements with a change) and small molecules across the plasma membrane  Examples of diffusion  Smell of baked goods, candles, perfume, laundry soap, food coloring

continue  Two types of transport proteins  Channel Proteins- water filled channels that open and close  Carrier proteins- change shape as the diffusion process continues  What kind of molecules use facilitated diffusion or transport proteins?  Glucose, sodium ions, chlorine ions

PASSIVE TRANSPORT OSMOSIS  Osmosis the diffusion of water across selectively permeable membrane, from an area of high concentration to an area of lower concentration until equilibrium is reached  What are the two parts of a solution?  Solute is the substance that is dissolved  Solvent is the substance in which something is dissolved  In the cell water is the solvent Pressure generated as water flows through the plasma membrane is called osmotic pressure

continue  Isotonic Solution when the cell is in a solution that has the same concentration of water and solutes inside and out of the cell  The cell remains healthy  Hypotonic solution when the cell is in a solution that has lower concentration of solutes and more solvent than found in the cytoplasm inside the cell  Water will rush in causing the cell to swell  Hypertonic Solution when a cell is placed in a solution where the concentration of solute outside the cell. This causes the water to leave the cell.  Water will rush out and cause the cell to shrink

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Active transport  Active transport is the movement of substances across the plasma membrane against a concentration gradient. It requires energy  Process of the Na/K ATPse Pump  Found on the plasma membrane on animal cells  It is an enzyme that catalyzes the break down of an energy-storing molecule  Uses energy to transport 3 Na ions out of the cell while moving 2 K ions into the cell  1. protein in the membrane binds intracellular sodium ions  2. ATP attaches to the protein with bound Na ions  3. the breakdown of ATP causes shape change in protein allowing sodium ions to leave  4. extracellular K ions bind to exposed sites  5. binding of K causes release of P from proteins  6. P release changes protein back to its original shape, and K ions move into the cell

continue  Endocytosis the process by which a cell surrounds a substance in the outside environment, enclosing the substance in the plasma membrane and release it in the cell  Exocytosis the process by which a cell surrounds a substance in the cell, enclosing it in a vesicle which binds with the plasma membrane to be released outside the cell.  Pinocytosis is using exocytosis or endocytosis to move liquids through the cell membrane  Phagocytosis is using exocytosis or endocytosis to move solid materials through the cell membrane

Overview of Photosynthesis Photosynthesis occurs in two phases. In the light-dependent phase, light energy is converted into chemical energy. In the light-independent phase, chemical energy used to synthesize glucose.

Phase One: Light Reactions The absorption of light is the first step in photosynthesis. Once light energy is captured, it can be stored as ATP or NAPDH. Chloroplasts Organelles that capture light energy Contain two main compartments: Thylakoids: flattened saclike membranes Stacks of thylakoids are called grana. The fluid filled space outside the grana called the stroma

Pigments Light-absorbing colored molecules called pigments are found in the thylakoid membranes. Different pigments absorb specific wavelengths of light. Most common pigment in plants is chlorophyll. Plants also have accessory pigments.

Electron transport The thylakoid membrane has a large surface area, providing space for a large number of electron transporting molecules and two types of protein complexes called photosystems. Photosystems house the light-capturing pigments. Light energy excites electrons in photosystem II. This light energy causes a water molecule to split – releasing an electron into the electron transport system, a hydrogen ion (H + or proton) into the thylakoid space, and oxygen as a waste product

Electron transport The activated electrons move from photosystem II to an acceptor molecule in the thylakoid membrane. The electron acceptor molecule transfers the electrons along a series of electron carriers to photosystem I. In the presence of light, photosystem I transfers the electrons to a protein called ferrodoxin. Ferrodoxin transfers the electrons to the carrier molecule NADP +, forming the energy storage molecule NADPH.

Electron transport ATP is produced in conjunction with the electron transport system through chemiosmosis. ATP is produced through the flow of electrons down a concentration gradient. The breakdown of water provides the necessary protons for ATP synthesis.

Phase Two: The Calvin Cycle In the second phase of photosynthesis, called the Calvin cycle, energy is stored in organic molecules such as glucose. The first step of the Calvin cycle is called carbon fixation. CO 2 molecules combine with 5-carbon molecules to form 3-phosphoglycerate (3- PGA) In the second step, chemical energy stored in ATP and NADPH is transferred to the 3- PGA to form glyceraldehyde 3-phospate (G3P).

In the third step, some G3P molecules leave the cycle to be used for the production of glucose and other organic compounds. In the fourth and final step, an enzyme called rubisco converts the remaining G3P molecules into 5-carbon molecules called ribulose 1,5-bisphospates (RuBP). These molecules combine with new CO 2 and continue the cycle.

Overview of Cellular Respiration Cellular respiration occurs in two main parts: glycolysis and aerobic respiration. Glycolysis is an anaerobic process, meaning it does not require oxygen. Aerobic respiration involves the Krebs cycle and electron transport. Aerobic processes require oxygen.

Glycolysis Glucose is broken down in the cytoplasm through the process of glycolysis. Two molecules of ATP and two molecules of NADH are formed for each molecule of glucose that is broken down.

Krebs Cycle Glycolysis has a net result of two ATP and two pyruvate. Most of the energy from the glucose is still contained in the pyruvate. In the presence of oxygen, pyruvate is transported into the mitochondrial matrix, where it is converted into carbon dioxide. The series of reactions in which pyruvate is broken down into carbon dioxide is the Krebs cycle, also know as the tricarboxylic acid (TCA) cycle

Steps of the Krebs cycle - Prior to the Krebs cycle, pyruvate reacts with coenzyme A (CoA) to form acetyl CoA. - Acetyl CoA moves into the mitochondrial matrix. - Acetyl CoA combines with a 4-carbon compound to form citric acid. - Citric acid is broken down releasing two molecules of carbon dioxide and generating one ATP, three NADH, and one FADH 2. - Finally, acetyl CoA and citric acid are generated and the cycle continues

Electron Transport In aerobic respiration, electron transport is the final step in the breakdown of glucose. NADH and FADH 2 from the Krebs cycle are used to convert ADP to ATP. Electron transport and chemiosmosis in aerobic respiration are similar to the processes of photosynthesis Prokaryotic cellular respiration Some prokaryotes undergo aerobic respiration. They do not have mitochondria, so they use the cellular membrane as the location of electron transport

Anaerobic Respiration When oxygen is unavailable, cells cannot follow glycolysis with the aerobic respiration (Krebs cycle and electron transport). The anaerobic process that follows glycolysis is anaerobic respiration, or fermentation. Fermentation occurs in the cytoplasm of the cell, and produces NAD + and ATP. Lactic acid fermentation Enzymes convert the pyruvate made during glycolysis into lactic acid. Skeletal muscles produce lactic acid when the body cannot supply enough oxygen, such as during periods of strenuous exercise.

Alcohol fermentation Occurs in yeast and some bacteria Converts pyruvate into ethyl alcohol and carbon dioxide