Mr. Malinkovich OFFICE: Room 321 -before school -by appointment

Wet-mount Slide

Honors Biology Objective: » SWBAT demonstrate understanding of membranes and molecular movement by writing a 5-paragraph MEL-Con review of literature for the EggSperiment Lab Agenda: -BR -Discuss lab report -Discuss review of lit. -Write review of lit. BR: Update TOC-Review of Literature HW: Type review of literature

Review of Literature 5 paragraphs Provides all background information needed to understand the experiment – After reading review of literature, reader will be able to: Describe cell membrane Understand why diffusion and osmosis occur Predict the direction of molecular movement across a membrane Describe the methods used in the experiment

Review of Literature Vocabulary ALL of the following terms must be used correctly and defined when necessary – (assume the reader knows no more than a 7 th grader) Phospholipids Polar Ionic Proteins Active/passive transport Bilayer Membrane Selectively permeable Hypotonic Hypertonic Isotonic Solute Solvent Solution Osmosis Diffusion Cell Concentration

Microscope

Prokaryotes vs. Eukaryotes

Paramecia and Amoeba ParameciumAmoeba mm.25-.5mm Unicellular

Plasma Membrane

Overview Cell membrane separates living cell from nonliving surroundings – thin barrier = 8nm thick Controls traffic in & out of the cell – selectively permeable – allows some substances to cross more easily than others Made of phospholipids, proteins & other macromolecules

Phospholipids Hydrophilic “water loving” head Hydrophobic “water fearing” tail What is it about the molecular structure that explain this? How does this relate to the arrangement of the membrane?

Polarity An unbalanced charge over a single molecule (molecular dipole) Two molecules of the same charge will – Repel? – Attract?

Semi-permeable membrane  Due to the structure, the membrane is only permeable to certain molecules  This permeability influences movement both into and out of the cell  Which ones may pass, and which may not? Why?

Channels through cell membrane Membrane becomes semi-permeable with protein channels – specific channels allow specific material across cell membrane inside cell outside cell sugaraa H2OH2O salt NH 3

Diffusion across cell membrane Cell membrane is the boundary between inside & outside… – separates cell from its environment IN food carbohydrates sugars, proteins amino acids lipids salts, O 2, H 2 O OUT waste ammonia salts CO 2 H2OH2O products cell needs materials in & products or waste out IN OUT Can it be an impenetrable boundary? NO!

Diffusion 2nd Law of Thermodynamics governs biological systems – universe tends towards disorder (entropy)  Diffusion  movement from high  low concentration  Diffusion  movement from high  low concentration

Osmosis is diffusion of water Water is very important to life, so we talk about water separately Diffusion of water from high concentration of water (low solutes) to low concentration of water (high solutes) – across a semi-permeable membrane

freshwaterbalancedsaltwater Managing water balance Cell survival depends on balancing water uptake & loss

Cell (compared to beaker)  hypertonic or hypotonic Beaker (compared to cell)  hypertonic or hypotonic Which way does the water flow?  in or out of cell.05 M.03 M Osmosis-Understanding Check

Types of Membrane Transport Membrane transport—movement of substances into and out of the cell Two basic methods of transport 1.Passive transport No energy is required 2.Active transport Cell must provide metabolic energy (ATP)

Transport summary simple diffusion facilitated diffusion active transport ATP

EggSperiment 3 eggs Vinegar Corn Syrup Water An egg is 1 huge cell Shell is dissolved in vinegar – Membrane is exposed » Osmosis can be studied » Diffusion will not occur, WHY?