BZ 110 1st Edition Lecture 1Outline of Last Lecture I. Syllabus reviewOutline of Current Lecture II.What are cells?III. Why are most cells small?IV. Components of Plasma MembraneV. Function of Cell MembranesVI. Movement across membranesCurrent LectureWhat are cells?- Cells are functional units of life- Amebas are single celled organisms- Bacteria cells (cilli) (prokaryotic)- Two types of cells: prokaryotic, eukarotic- Prokaryotic cells:o Have no nucleuso Outnumber eukaryotico No cytoplasmic organelleso Usually found in rare enviornments- Eukaryotic cells:o Have a nucleuso More complex organismso Make up animals, fungi, plants, etc.o More compartmentalization within the cellsWhy are most cells small?- To maintain the ratio of the volume of the cell’s nucleus to the volume of the cytoplasm- Cells are small because if they get too big the nucleus cannot control all the activities of the cell- To maintain surface area/ volume ratioThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.What is the Plasma membrane?- The way nutrients and gasses get into the cell- Provides the surface of the cells- The fluid mosaic model- Singer and Nicolson (1972)- Phospholipid- will form a bilayer Phospholipid “head”- polar head, water soluble Phospholipid “tail”- hydrophobic (non- polar)- Cholesterol molecules- found in plasma membrane Provide strength to plasma membranes- Membrane Proteins Peripheral protein- extends from either from surface of the cell or into the interior of the cell toward the cytoplasm Intrinsic proteins- imbedded in the plasma membrane- Glycocalx (cell coat) Numerous molecules that extend from the surface of the plasma membrane Cell recognition, provide a molecular “finger print” Sugar molecules attached to proteins make glycoprotein Sugar molecules attached to lipid forming glycolipidWhat is the purpose of cell membranes?1. Regulate: - what goes in and out of each cell, - what goes in and out of each organelle of the cell2. Separate: - one cell from other cells- separate organelles within the cell3. Provide a large surface area for chemical reaction4. Cell identification- GlycocalyxMovement across membranes:- Simple diffusion: Does not require energy (ATP) Simple diffusion accounts for most of the short distance transport of substances moving into and out of cells Requires a concentration difference Gases can diffuse through a membrane through simple diffusion- Facilitated diffusion (transport) Does not require energy (ATP) Requires a concentration difference Requires a protein Inability to transport: caused by abnormal proteins that cant transporto EX: cystic fibrosis- Osmosis:- Diffusion of water across a selectively permeable membrane- Tonicity: relative concentration of solutes in water, inside the cell and outside the cell- Filtration: process that forces small molecules across selectively permeable membranes with the aid of hydrostatic pressure or some other externally appliedforceo Ex: blood pressure- Active transport:- process that moves molecules across a selectively permeable membrane against a concentration gradient- Uses energy (ATP)- Sodium potassium pump- maintains proper concentrations of Na and K ions inside nerve