Passive Transport

Passive Transport Cell Membranes help to maintain homeostasis Substances are able to cross through Without using energy Passive Transport

Diffusion The most simple form of passive transport is called Diffusion The movement of molecules from a higher concentrated area to a lower concentrated area How does diffusion work? Kinetic energy of molecules

Diffusion Concentration Gradient – the difference in the concentration of molecules across a distance Once the two areas are of equal concentration equilibrium is reached Example

Simple Diffusion The diffusion of molecules across a membrane Only some can diffuse across Size – they can fit through the pores Type – they can be dissolved in lipids (Carbon dioxide, Oxygen) Type of membrane

Osmosis Every solution has two parts Solute- the sugar Solvent – the water Both of these can diffuse to maintain homeostasis Osmosis- water molecules going from a higher concentration to a lower concentration

Osmosis The direction of osmosis depends on the solution Hypotonic- solution has less solute molecules than cytoplasm of the cell Hypertonic- solution has more solute molecules than the cytoplasm of the cell The water is going to try and create homeostasis. Draw it!

Osmosis Water will always move from Hypotonic to Hypertonic! Isotonic– concentrations are equal inside and outside of the cell http://www.youtube.com/watch?v=AYNwynwaALo&feature=related.

Adaptations How do cells deal with a hypotonic environment? Unicellular freshwater organisms Don’t need as much water in their cytosol Contractile vacuoles pg. 99 (not passive transport)

Adaptations Plant cells and their environment hypotonic Turgor pressure – the pressure that water molecules exert on the cell wall How do plant cells keep from exploding? Cell walls!

Adaptations What happens to plant cells in a hypertonic environment? Plasmolysis- when turgor pressure is lost, and the cell shrinks away from the cell wall Reason for plants wilting

Adaptations Some cells do not have any adaptations (Red blood cells) No contractile vacuoles No solute pumps No cell walls How are they affected? Cytolysis – the bursting of cells

Facilitated Diffusion Facilitated Diffusion – passive transport for molecules not able to diffuse through the membrane To big to fit through the membrane Not able to be dissolved in lipids Glucose is a good example

Facilitated Diffusion Carrier Proteins – assist molecules through the membrane Molecules bind to the protein The protein changes shape The molecule is released on the other side The protein returns to its original state http://www.youtube.com/watch?v=OV4PgZDRTQw&feature=related.

Ion channels Ion Channels- specific proteins that allow certain ions to pass (sodium, potassium, calcium, chloride) Each channel is specific to a certain ion Some have gates http://www.youtube.com/watch?v=x-3R58Rrzac.

Active transport

Active Transport Cells must move materials from areas of lower concentration to areas of higher concentration Active Transport– the movement of materials from low concentrations to high concentrations Up the concentration gradient How is this different from passive transport?

Cell Membrane Pumps Move molecules from low concentrations to high concentrations Carrier Proteins – we meet again… Facilitated diffusion vs. sodium potassium pump What is the difference?

Cell membrane pumps Sodium-Potassium pump– specific carrier protein, only carries Sodium and Potassium (page 104) pumps Sodium (Na+) out Pumps Potassium (K+) in Animal cells need more Sodium outside of the cell, and potassium inside of the cell to function properly http://www.youtube.com/watch?v=yz7EHJFDEJs&feature=related.

Sodium-Potassium Pump Three Na+ ions (sodium) attach from inside cell ATP drops off some energy Carrier protein changes shape (Na+ released) Two K+ ions (Potassium) attach from outside the cell The dropped of energy is released Carrier Protein changes back (K+ released) Cycle starts all over again 450 Sodium (Na+) per second! How many Potassium?

Movement in Vesicles Some things are to large for proteins to assist What should they do? Vesicles– membrane bound organelle containing materials for the cell The materials never become part of the cell Why not?

Movement in Vesicles Endocytosis– the process by which cells ingest external fluid (page 105) they fuse to membrane bound organelles to deliver the contents Pinocytosis– transport of solutes (fluids) Phagocytosis– transport of large particles (cells) Phagocytes– ingest bacteria and allow lysosomes to destroy it http://www.youtube.com/watch?v=1w10R9lv7eQ.

Movement in Vesicles Exocytosis– substance is released from the cell through a vesicle Proteins, waste products, toxins Exit is very similar to entrance It is the reverse of Endocytosis

The Krebs Cycle The Electron Transport Chain Aerobic Respiration!

Mitochondria What is Aerobic Respiration? The Mitochondria is where energy comes from Energy is formed in these two cycles The Krebs Cycle The Electron Transport Chain

Mitochondria The Krebs cycle happens within the Matrix The Electron Transport chain happens on the inner membrane

Krebs Cycle Krebs Cycle- A six step process that produces CO2, ATP, NADH, and FADH2 Produces 2 Carbon Dioxide molecules Produces 2 ATP Molecules Produces 6 NADH molecules (transporter) Produces 2 FADH2

Krebs Cycle The Krebs Cycle uses a broken down form of glucose to create energy Even though the Krebs Cycle only produces 2 ATP It provides the Electron Transport Chain with the molecules it needs to make energy

Krebs Cycle NADH and FADH2 are sent to the inner membrane They make more ATP through the Electron Transport Chain Proteins in a membrane that transfer electrons to each other

The Electron Transport Chain In Depth Explanation of the Electron Transport Chain Discuss what is happening Where were the Carrier Proteins? What was the Concentration Gradient? Active or Passive?

Electron Transport Chain ATP synthase– large protein that creates ATP Creates ATP by sending the Protons (H+) back across the membrane What is the concentration gradient? ATP Synthase in action

Electron Transport Chain 4 Carrier Proteins 4 Electrons 2 Electron Carriers 2 FADH or NADH 2 Oxygen A Lot of Hydrogen!!!