Transcript Membrane structure, I - UNT's College of Education

Cell Membrane
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
TAKS
Objective 2 – The student will
demonstrate an understanding of living
systems and the environment.
TEKS Science Concepts
4 -The student knows that cells are the basic
structures of all living things and have specialized
parts that perform specific functions, and that
viruses are different from cells and have different
properties and functions. The student is expected t
(B) investigate and identify cellular processes
including homeostasis, permeability, energy
production, transportation of molecules, disposal
of wastes, function of cellular parts, and synthesis
of new molecules
Engage
Explore
Semi-Permeability Lab
Eggactly What I Predicted
Cell Membrane Manipulative
Membrane structure
 Semi-Permeable
 Selectively Permeable
 Amphipathic~
hydrophobic & hydrophilic
regions
 Fluid Mosaic Model
The Structure of the Cell Membrane
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
Protein
of cell
(cytoplasm) channel
Lipid bilayer
Membrane structure
 Phospholipids~ membrane fluidity
 Cholesterol~ membrane stabilization and
fluidity
 “Mosaic” Structure~
 Integral proteins~ transmembrane proteins
 Peripheral proteins~ surface of membrane
proteins
 Membrane carbohydrates ~ cell to cell
recognition;
Random movement results in
Solution – mixture of solute and solvent
Solute – substance being dissolved
Solvent – substance dissolving solute

Living Things (Universal Solvent)-Water
Membrane traffic
Passive transport~ diffusion
of a substance across a
biological membrane
(NO ENERGY)
[] = concentration
Diffusion~ the overall
movement of particles from a
region of high [] to an area of
low []

Osmosis~ the diffusion of
water across a selectively
permeable membrane
Results of Diffusion
Dynamic equilibrium

Once diffusion has evenly distributed the solute
throughout the solvent; movement of particles
continues with no change in []
Homeostasis

Preservation of equilibrium
Diffusion depends on [] gradient
[] gradient: the difference in [] of a
substance across space
Diffusion is said to move down a []
gradient
Diffusion continues until there is NO []
gradient
Ex: O2 diffuses into oxygen depleted blood
Diffusion
molecules like WATER,
OXYGEN, AND CARBON
DIOXIDE can move in and out
freely.
Small
Large
molecules like
PROTEINS AND
CARBOHYDRATES CANNOT
Charged
IONS CANNOT
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Osmosis
Osmosis~ the diffusion of water across a
selectively permeable membrane
Questions
Osmosis is the diffusion of _______ across a cell
membrane.
Osmosis and Diffusion are both types of
__________ transport.
Passive transport does or does not require energy?
Small molecules can not move across freely. T or F
Large molecules can move freely. T or F
Three Different Types of
Solutions
Isotonic Solution
Hypotonic
Solution
Hypertonic
Solution
Isotonic Solution
The solute outside the cell is equal in
concentration to the solute in the cell.
The cell retains its shape.
water moves equally in both directions
Hypotonic Solutions
Solution outside the blood cell contains a lower [] of
solute than inside of the cell.
Water will diffuse in.

cell will lyse (burst).
Animal cells - cytolysis.
 Plant cells do not burst- turgur pressure—
grocers use this idea
Cells in a Hypotonic Solution
Hypertonic Solutions
The solution outside the cell has a higher [] of
solute than inside of the cell.
Water will diffuse out of the cell,


causing the cell to shrink
or crenate
Why should you not salt meat before cooking?
CRENATION
PLASMOLYSIS
Cells in a Hypertonic Solution
In what type of solution would these
cells be found?
Water balance Summary
Osmoregulation~
control of water balance
Hypertonic~ higher
concentration of solutes
Hypotonic~ lower
concentration of solutes
Isotonic~ equal
concentrations of solutes
Water balance Summary
Osmoregulation~ control
in cells with cell walls:
 Turgid (very firm) - Hypo
 Flaccid (limp) - Iso
 Plasmolysis~ Hyper

plasma membrane pulls away
from cell wall
Plasmolysis
QuickTime™ and a
Cinepak decompressor
QuickTime™ and a
are needed toCinepak
see thisdecompressor
picture.
are needed to see this picture.
Turgidity
Other Ways to Transport Molecules
Across the
Plasma Membrane
Selective Transport
Review Covered Passive
Transport
Osmosis
Does it require energy?
NO!!!
Diffusion
Does it require energy?
NO!!!
Osmosis
What is osmosis? WATER
The movement of ___________ across the
cell membrane.
Is it the movement of any other substance?
NO!!!!
Diffusion
Mixing of two substances by the random
motion of molecules.
Molecules move from a region of high
concentration to an area of low
concentration.
How do other molecules cross the
cell membrane???
Selective Transport


Facilitated Diffusion (Another Passive Transport)
Active Transport
• Protein Pumps
• Endocytosis
• Exocytosis
Selective Transport
There are two types of selective transport

Facilitated Diffusion
• DOES NOT require the use of energy

Active Transport
• DOES require the use of energy
Facilitated Diffusion
Glucose
molecules
High
Concentration
Cell
Membrane
Low
Concentration
Protein
channel
Facilitated Diffusion
Does facilitated diffusion require the use of
energy?
NO!!!!
It uses a [] gradient to transport molecules
The molecules move from an area of high [] to an
area of low []
Most SUGAR molecules pass across the cell
membrane by this method of transport
Carrier Proteins Carry Molecules
Across the Membrane
Good Example - transport of Glucose into the Cell
Active Transport
Does active transport require the use of
energy?
YES!!!
It uses ATP
Transports against the [] gradient.
Low to High []
Sodium Potassium Pump, Endocytosis and
Exocytosis
Active Transport
Molecule to
be carried
Energy
Molecule
being carried
Active Transport:
Sodium Potassium Pump
Move Sodium out of the
cell
Move Potassium into the
cell
Uses energy (ATP)
Causes the protein to
change shape
Move against a [] gradient
Sodium Potassium Pump
Bulk Transport-Active
Endocytosis


Pinocytosis
Phagocytosis
Exocytosis
Endocytosis
During
ENDOCYTOSIS the
Cell Membrane folds
into a POUCH
(Vescicle) that
Encloses the Particles.
Two Types of Endocytosis:
Pinocytosis and Phagocytosis
PINOCYTOSIS ---"CELL DRINKING“—Small
Particles
PHAGOCYTOSIS---- "CELL EATING“-Large
Particles
Treatments
Exocytosis
EXOCYTOSIS is the
opposite OR reverse of
ENDOCYTOSIS.
EXOCYTOSIS, wastes and
cell products leave the cell.
Specialized Transport Summary
Transport proteins
 Facilitated diffusion~
passage of molecules and
ions with transport
proteins across a
membrane down the []
gradient
 Active transport~
movement of a substance
against its [] gradient with
the help of cellular energy
Elaborate
Cell Membrane Bubbles
Cellular Transport Flow Chart