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Cells

Cells. Chapter 3. Plasma Membrane . Transport Across the Plasma Membrane. Fluids in average body = ~60% ICF -- inside the cell (cytosol) ECF – outside the cell Interstitial fluid (between cells of tissues) Plasma (blood vessels) Lymph (lymphatic vessels)

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Cells

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  1. Cells Chapter 3

  2. Plasma Membrane

  3. Transport Across the Plasma Membrane • Fluids in average body = ~60% • ICF -- inside the cell (cytosol) • ECF – outside the cell • Interstitial fluid (between cells of tissues) • Plasma (blood vessels) • Lymph (lymphatic vessels) Materials dissolve into these body fluids; direction of movement dependent upon concentration (amount of solute in solution) 

  4. Penetration Chart

  5. Concentration Gradients • Differences between ICF and ECF in solute concentration 3% salt solution 5% salt solution ??? Water ??? Water PassiveActive High to low Low to high No energy needed Energy needed

  6. Concentration Gradients • Differences between ICF and ECF in solute concentration 3% salt solution 5% salt solution 97% Water 95% Water Passive High to low until dynamic equilibrium reached Down concentration gradient No energy needed

  7. Two types of diffusion • Simple diffusion: lipid-soluble substances, simple cross membrane down the gradient • Facilitated diffusion: ions, through pores of ion channels of integral proteins

  8. Osmosis • Net movement of water down the gradient; lower solute concentration to higher solute concentration through • Lipid bilayer • Integral proteins 20% sucrose 80% water

  9. Osmotic Pressure • Exerted on cell membrane due to a solution containing solute particles that cannot pass through membrane • Higher solute concentration = higher osmotic pressure • Lower solute concentration = lower osmotic pressure • Volume of cell remains the same, why???

  10. Osmotic Solutions • Isotonic solution: cells maintain normal shape and volume; concentration of solutes equal on both sides of membrane • Hypotonic solution: higher concentration of water outside; higher concentration of solutes than cytosol inside cell • Water molecules will enter cell faster than they leave it = cell will swell, eventually burst • Bursting of red blood cells referred to as hemolysis • Hypertonic solution: higher concentration of water inside; lower concentration of solutes than cytosol inside cell • Water molecules will leave cell faster than they enter it = cell will shrink • Shrinkage of red blood cells referred to as crenation

  11. Short Video Review http://www.hartnell.edu/tutorials/biology/osmosis.html

  12. Passive or Active? • Have I been talking about passive, active, or passive and active transport?

  13. Active Transport • From low to high concentration; ‘up the gradient’ • Requires the use of energy • Comes from splitting of ATP molecule • Changes shape of transporter protein, called a pump • Transports ions: Na+, K+, H+, Ca+2, I-, Cl- • 40% of a cell’s ATP expended on active transport • Drugs like cyanide can turn off ATP production--FATAL

  14. Cyanide • Cyanide can be a colorless gas, such as hydrogen cyanide (HCN) or cyanogen chloride (CNCl), or a crystal form such as sodium cyanide (NaCN) or potassium cyanide (KCN). • Cyanide sometimes is described as having a “bitter almond” smell, but it does not always give off an odor, and not everyone can detect this odor. • You could be exposed to cyanide by breathing air, drinking water, eating food, or touching soil that contains cyanide. • Cyanide enters water, soil, or air as a result of both natural processes and industrial activities. When present in air, it is usually in the form of gaseous hydrogen cyanide. • Smoking cigarettes is probably one of the major sources of cyanide exposure for people who do not work in cyanide-related industries.

  15. Transport in Vesicles • Vesicles small sacs formed by budding off of membranes • Transport substances within the cell from one structure to another • Energy source again is ATP • Take in substances from ECF and transport substances out to ECF • Endocytosis: materials moved into cell • Phagocytosis  ‘to eat’ - solids • Bulk-phase endocytosis(pinocytosis)  liquids • Exocytosis: materials moved out of cell

  16. Endocytosis • Endocytosis: capturing substance or particle from outside the cell by engulfing it within membrane folds from the cell membrane and releasing it into cytosol. There are two main kinds of endocytosis: • Phagocytosis ”cellular eating,” dissolved materials enter the cell. The plasma membrane engulfs solid material, forming phagocytic vesicle or pseudopod. • Occurs only in phagocytes (certain white blood cells and macrophages), cells specialized to engulf and destroy bacteria, viruses, aged dying cells, and foreign matters protecting body from disease • Bulk-phase endocytosis (pinocytosis) ”cellular drinking,” plasma membrane folds inward, forms a channel allowing dissolved substances to enter the cell. When the channel is closed, the liquid is encircled within a pinocytic vesicle. • Takes in tiny droplets of ECF fuses with lysosomes to degrade solutes (ex: to amino acids, fatty acids) then released for reuse

  17. Exocytosis • Exocytosis: process of vesicles fusing with the plasma membrane and secretes their contents to the outside of the cell. • All cells do exocytosis process, but most important in: • Secretory cells • Release digestive enzymes, hormones, mucus, and other secretions • Nerve cells • Release neurotransmitters

  18. Cytoplasm & nucleus • Functions and identification of the organelles are your responsibility since this a total biology review area • Information found on pages 52-60 of your textbook

  19. Lysosomes • May contain up to 60 different digestive enzymes • Recycle the cell’s own structures  autophagy • May destroy own cell  autolysis • This cause tissue deterioration after death • Faulty lysosomes can contribute to certain diseases, i.e. Tay-Sachs disease

  20. Releasing Energy From Food • Recall ultimate source of all energy on Earth comes from the sun • Plants capture and store energy as food (glucose) • Glucose is converted to ATP during cellular respiration in order to store chemical energy for later release

  21. ATP • ATP is broken down to ADP to release stored chemical energy A—P~P~P enzyme A –P~P + P + energy • Released energy is used for: • Movement (warmth) • Chemical reactions • Electrical impulses • Active transport

  22. Cellular Respiration • Glycolysis anaerobic process in cytoplasm • Glucose + 2ATP  pyruvic acid + 4ATP + NADH • Followed by aerobic process in mitochondria (Kreb’s cycle) • Pyruvic acid enters cycle changes releasing CO2 and creates NADH, FADH2, and ATP • ETC >>> NADH and FADH2 from glycolysis and Kreb’s used to make additional 36 ATP…

  23. Protein Synthesis

  24. Cell Division- Somatic Cells

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