The document provides information about cell biology, specifically transport across the cell membrane. It discusses: 1. The structure and functions of the cell membrane, including the phospholipid bilayer, proteins, glycoproteins, glycolipids, and cholesterol. 2. Types of transport across the membrane, including passive transport processes like diffusion, osmosis, and facilitated transport, as well as active transport processes. 3. Factors that affect the rate of diffusion and the effects of different external environments (hypertonic, isotonic, hypotonic) on osmosis in cells.

16. Note: Lack of permeability to ions sets up membrane potential (See C11: Nerve transmission).

20. Some have channels/gates/pores to allow passage of H 2 O, dissolved ions, and small molecules.

21. Some are receptors that a specific molecule can bind to, e.g. hormones such as insulin, thyroxin, aldosterone, estrogen, testosterone etc. or neurotransmitters such as acetylcholine (ACh), norepinephrine (NE). http://www.mhhe.com/biosci/genbio/espv2/data/cells/003/index.html

25. Note: Cytoskeleton (Recall Unit B1) is an internal framework of protein fibres that gives the cytoplasm strength and flexibility and provides movement of organelles. Some protein filaments attaches to the integral proteins of the CM. Attachment of the Cytoskeleton

28. Summary of Cell Membrane Structures and Functions Amino acids Allows/selects certain molecules in/out of cell through channels/gates/pores . E.g. H 2 O, O 2 , CO 2 , ions. Carries molecules selectively in/out of cell by carriers. E.g. Na + , K + , C 6 H 12 O 6 , áá’s, HCO 3 - , Ca 2+ . Proteins Unit molecules Functions Molecules

30. Backbone of 4 fused C-H rings Stiffen CM and provide flexibility Cholesterol Chains of carbohydrates attached to lipid or protein (a) Used in cell identification . (b) Glycoproteins can form a carbohydrate coat that envelops the cell membrane (glycocalyx). Glycolipids and Glycoproteins 2 fatty acids (saturated/ unsaturated) & 1 glycerol, N and phosphate group (a) Allows for diffusion of lipid soluble molecules. E.g. O 2 , CO 2 , and alcohol. (b) Allows for flexibility & fluidity of cell membrane. E.g. Vesicle formation. (c) Excludes H 2 O and ions. (d) Acts as a boundary keeping organelles within the cell. Phospholipids

42. Diffusion

43. Osmosis

44. examples of lab equipment which demonstrate diffusion and osmosis, i.e. the osmometer and U-tube apparatus .

62. Isotonic If the concentration of solute (salt) is equal on both sides, water will move back in forth but it won't have any result on the overall amount of water on either side. " ISO " means the same.

63. Hypotonic " HYPO " means less. There are less solute (salt) molecules outside the cell, which causes water to move into the cell by osmosis (high to low). The cell will gain water & grow larger. In plant cells, the central vacuole will fill and the plant becomes stiff and rigid, i.e. turgor. The cell wall keeps the plant from bursting. In human animal cells, the cell is in danger of lysis or bursting.

64. Hypertonic

67. Isotonic 95% H 2 0 5% salt 95% H 2 O 5% salt Isotonic Solution 95% H 2 O 5% salt H 2 O moves in/out of red blood cells (RBC) at equal rates and the shape remains as biconcave.

71. Example of a RBC placed in a hypotonic solution . RBC shape in the beginning of the experiment? After 2 minutes?

73. Hypertonic H 2 O moves OUT of the RBC’s by osmosis causing it to shrivel and undergo crenation .

87. Cellular Activity/Process?

101. Ions, sugars, and amino acids. Carrier protein and ATP energy towards higher concentration active Active Transport Water 0nly. Concentration gradient, channel proteins optional towards lower concentration passive Osmosis Water, glucose, and amino acids. Concentration gradient, plus channel or carrier proteins towards lower concentration passive Facilitated Diffusion Water, gases (0 2 and CO 2 ), and steroid hormones. Concentration gradient towards lower concentration passive Diffusion Examples Conditions Direction of Movement Type of Transport Name Comparison of the ways molecules move into & out of cells.