Transcript Bio_Membranes_1_ - Kenwood Academy High School

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 7th grader)
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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
• Paramecium
• .05-.35 mm
Amoeba
.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
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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
NH3
H2O
salt
aa
sugar
outside cell
Diffusion across cell membrane
• Cell membrane is the boundary between
inside & outside…
– separates cell from its environment
Can it be an impenetrable boundary?
OUT
IN
food
carbohydrates
sugars, proteins
amino acids
lipids
salts, O2, H2O
NO!
OUT
IN
cell needs materials in & products or waste out
waste
ammonia
salts
CO2
H2O
products
Diffusion
• 2nd Law of Thermodynamics
governs biological systems
– universe tends towards disorder (entropy)
 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
Managing water balance
• Cell survival depends on balancing water uptake &
loss
balanced
freshwater
saltwater
Osmosis-Understanding Check
.05 M
.03 M
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
Types of Membrane Transport
• Membrane transport—movement of
substances into and out of the cell
• Two basic methods of transport
1. Passive transport
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No energy is required
2. Active transport
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Cell must provide metabolic energy (ATP)
Transport summary
simple
diffusion
facilitated
diffusion
active
transport
ATP
EggSperiment
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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?