Honors Biology Ch. 5 Class Notes

Honors Biology, Period 5 Chapter 5 Notes Section 5.10 A.) selective permeability – allows some substances to cross more easily than others Section 5.11 A.) Phospholipids are the main components of membranes saturated head - will dissolve in water

polar

Fatty acids

nonpolar

(can be sat+sat, unsat+sat, or unsat+unsat

unsaturated

- hydrophilic - phosphate group

O O

P

hydrophobic

O

O B.) amphipathic – a term that describes a molecule that is both polar and nonpolar Section 5.12 A.) phospholipid bilayer – as a result of their amphipathic nature, phospholipids form a bilayer (a two-layer sheet) Hydrophilic heads

Hydrophobic tails

water

*figure 5.12  label for test B.) Why are membranes selectively permeable? 1. They are hydrophobic 2. Hydrophilic molecules can’t move across (like dissolves) C.) Fluid Mosaic Model 1. mosaic – the membrane has such a diverse collection of proteins embedded in the bilayer (figure 5.12) 2. fluid – the individual molecules can drift laterally D.) What influences fluidity? 1. manipulating the types of fatty acids in their phospholipids (plants) 2. add or remove cholesterol (animals) E.) The Surface of the Plasma Membrane Key molecules: 1. glycoprotein 2. glycolipids a. The oligosaccharide chains are specific to the individual - purpose: self recognition - cells can decide which cells are their own vs. intruder  Examples: 1. organ transplant 2. blood types

Type A

Type B

Type A protein

Type AB

Type O

Type B protein

ERYTHROCYTES – Red blood cells F.) Are you positive or negative? 1. The Rit factor

85%

RH+

15% RH¯

Erythroblastosis (fetal) is when the mother’s immune system kills her own baby because they have different blood types.

G.) Antigens and Immune Response 1. antigen – only substances that trigger an immune response 2. antibodies – protein produced by the body in response to an antigen YOUR BLOOD TYPE Type A Type B Type AB Type O RH+ RH-

ACCEPT A, O

REJECT B, AB

B, O A, B, AB, O O RH+, RHRH-

A, AB N/A A, B, AB N/A RH+

Section 5.13 Functions of Membrane Proteins: 1. attachment 2. identification 3. enzyme (is a catalyst) 4. receptors - of protein that has a shape that fits the shape of a specific messenger, such as a hormone. *signal transduction - the message-transfer process of the chain reactions between proteins. Case study: Epinephrine (hormone)  is a neurotransmitter Epinephrine can cause a liver to hydrolyze its stored glycogen and release sugar without even entering the [liver] cell. (Causes chemical changes) Activity 5F Receptor proteins have specific shapes that fit specific chemical messengers A.) hypotonic – less solute to dissolve B.) hypertonic – more solute to dissolve C.) isotonic – has equal amount of solute and solvent GRAPE EXPERIMENT Grapes in: H2O

1. HYPOTONIC

50 g sugar

0 g sugar

100 mL H2O

100 mL H2O

Corn Syrup

2. HYPERTONIC

50 g sugar

100 g sugar

100 mL H2O

100 mL H2O

Grape Juice 3. ISOTONIC 50 g sugar

50 g sugar

100 mL H2O

100 mL H2O

Transport Section 5.14: Passive Transport A.) Passive Transport – transport that does not require energy (ATP) from the cell Types of Passive Transport: 1. diffusion (5.14) 2. osmosis (5.16) [u-tube] 3. facilitated diffusion (5.15)* - requires the aid of transport proteins for the diffusion of polar molecules and ions across the cell membrane * can have more than one substance equal out at one time Hypotonic solution

Hypertonic solution H2O

Solute molecule Selectively permeable membrane

Osmosis – the diffusion of water 1. U-Tube 2. Fig 5.17 Key terms: 1. hypotonic 2. hypertonic 3. isotonic 4. lysis 5. crenation 6. flaccid 7. turgid 8. plasmolyisis (figure 5.16) Animal Cell Terms A.) lysis – too much H2O causes the cell to burst and die (hypotonic solution) B.) crenation – looses too much H2O. The cell shrivels and dies (hypertonic) Plant Cell Terms A.) flaccid – exchange of H2O (isotonic); wilting plants B.) turgid – bursting with H2O (hypotonic); healthy plants C.) Plasmolysis – the cell membrane shrivels, pulls away from the cell wall, and the cell dies (hypertonic) Section 5.18: Active Transport A.) active transport – transport that requires energy (ATP) from the cell. Movement of molecules against their concentration gradient 1. requires a transport protein (enzyme) 2. requires ATP 3. see figure 5.18 B.) phosphorylation – the addition of a phosphate group to a protein Section 5.19: [Active] Transport of Large Molecules A.) Exocytosis – the transport of large molecules out of the cell - vesicles produced by the Golgi travel to the cell membrane. Once there, the vesicles fuse with the membrane and the contents are released from the cell a. insulin b. tears

B.) endocytosis – the transport of large molecules into the cell 1. phagocytosis 2. pinocytosis 3. receptor-medicated Endocytosis C.) phagocytosis (5.19 c) “cellular eating” - engulfing of food resulting in the formation of a food vacuole A. macrophages B. amoeba (pseudopod formation  false/fake foot formation) D.) pinocytosis “cellular drinking” 1. absorbing droplets of liquid from the surroundings 2. not specific E.) Receptor-medicated Endocytosis 1. very specific 2. receptor proteins on the plasma membrane join with specific molecules in the blood stream. • Case study: cholesterol (fig 5.20) LDL – low density lipids (bad cholesterol) HDL – high density lipids (good cholesterol)