the cell and its environment fall 2010 what is a cell? a cell is the basic unit of living things....
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The Cell and Its Environment
Fall 2010
What is a cell?A cell is the basic unit of living things.Some living things are composed of only
one cell and are called UNICELLULAR organsims.
Organisms that have many different cells are called MULTICELLULAR organisms.
Homeostasis – Maintaining a BalanceCells must keep the proper
concentration of nutrients and water and eliminate wastes.
The plasma membrane is selectively permeable – it will allow some things to pass through, while blocking other things.
What is the function of a cell?* All living things obtain energy different
ways through the processes of photosynthesis or respiration.
Since organisms must use energy there are certain things that have to get into and out of the cell to enable the organism to use or convert energy.
Materials that must be able to move INTO ANIMAL cells:1.Oxygen2. Water3. Particles of food4 Minerals and vitamns
for proteins(K, Na, Fe)
Materials that must be able to move OUT of ANIMAL cells:
1. Carbon dioxide2. Waste materials
Materials that must move INTO PLANT cells:
1. Sunlight2. Water3. Carbon dioxide
Materials that must be able to get OUT of PLANT cells:
OxygenWaste products
What lets stuff in and out of the cell?
Cell MembraneDefinition- a membrane that controls how
materials move into or out of a cell. It acts as a gatekeeper to allow things in and out of the cell.Cell
Membrane
Overview
Cell membrane separates living cell from nonliving surroundings thin barrier = 8nm thick
Controls traffic in & out of the cellselectively permeableallows some substances to cross more easily than
othershydrophobic vs hydrophilic
Made of phospholipids, proteins & other macromolecules
What is a cell membrane?Cell membranes are the outside covering of a
cell that allows things in and out of the cell. Cell membranes are composed of 3 things:1. double layer of phosolipid molecules (fats)2. Proteins – moves large molecules.3. carbohydrate chains4. cholesterol
3 Types of Membrane ProteinsTransport large charged molecules!!
1.Receptor Proteins: Determine what particles can pass through the membrane.
2. Enzymes: Serve as enzymes (may speed reactions).
3.Transport proteins:moves substances across the membrane.
This moves K, Na, Fe, Water, amino acids any charged particle.
Phospholipids – allows not charged small particle through!
Fatty acid
Phosphate
Fatty acid tails – hydrophobic
Phosphate group head - hydrophilic
Arranged as a bilayer
Aaaah, one of those
structure–functionexamples
Why does the phosolipid align in 2 layers?
Phosphate head – hydrophilic because it is charged opposite of water and they attract each other. They will be on the outside touching the Water.
Fatty acid tail – hydrophobic because it has no charge and is repelled by water that is charged.They are pushed way from water and align onthe inside.
Molecules that can move through phosolipid part of membrane
Oxygen, carbon dioxide !! ANY PARTICLE THAT IS SMALL AND NOT CHARGED!!!
ttp://www.teachersdomain.org/asset/tdc02_int_membraneweb/
Any particle that is charged cannot move through membrane because of lipid charged tails.
Function of Carbohydrates in Membrane
Attached to the membrane’s proteins act as identification tags. This allows cells to tell each other apart. A heart cell will have different carbohydrates than a heart cell.
Function of cholesterol in Cell Membrane
Cholesterol strengthens the cell membrane.
Outside of cell
Inside of cell (cytoplasm)
Lipid Bilayer
Proteins
Transport Protein Phospholipids
Carbohydratechains
Structure of the Cell Membrane
Go to Section:
Animations of membrane
structure
How does stuff get in and out of the cell?The cell membrane is what allows stuff in
and out of the cell. The membrane is selectively permeable.
Selectively permeable-Definition- means that some substances
can cross the membrane while others cannot.
Proteins
This model
describes the
structure of the
cell membrane!!
Polar heads love water & dissolve.
Non-polar tails hide from water.
Carbohydrate cell markers
Fluid Mosaic Model
How do phosolipids control what can pass through Membrane?
The hydrophobic tails will not let any substance pass through that has a charge(ion)(hydrophilic).Only substances that are not charged (hydrophobic)can pass through. If they cannotpass through the membrane, then they must go through the must get in another way.
Fluid Mosiac Model of Cell MembraneFluid Mosiac Model of Cell Membrane
This model describes the structure of the cell membrane because it acts likes a liquid. 1.The cell membrane is flexible not rigid. The phosolipids move from side to side.
2.There are so many molecules that make up the membrane that it looks like a mosiac.
Outside of cell
Inside of cell (cytoplasm)
Lipid Bilayer
Proteins
Transport Protein Phospholipids
Carbohydratechains
Structure of the Cell Membrane
Go to Section:
Animations of membrane
structure
Cell Transport
To understand cell transport, you must understand how molecules move.All molecules move. Even solids vibrate.Most of the cell environment is liquid.Molecules want to reach EQUILIBRIUM!Equilibrium – equal amount of molecules
everywhere(across cell membrane).
Diffusion
Movement of molecules moving from an area of higher concentration to an area of lower concentration.
Example: air freshener, perfume, food cooking, food coloring in water.
Increase temperature; increase rate of diffusionDiffusion occurs in liquids and gases.
Which direction will molecules flow?
Concentration Gradient
Difference in concentration of molecules that makes the molecules move. They move from highest level to the lowest level.
The greater the difference the faster the molecules move.
Concentration Gradient
Diffusion video
http://video.search.yahoo.com/search/video;_ylt=A0SO8ZpVTNdMKS8AS3H7w8QF;_ylu=X3oDMTBncGdyMzQ0BHNlYwNzZWFyY2gEdnRpZAM-?p=diffusion&ei=utf-8&fr2=tab-img&n=21&tnr=21&y=Search
How does stuff get in and out of the cell?
Substances that move into and out of a cell do so by means of one of two processes: PASSIVE TRANSPORT or ACTIVE TRANSPORT.
Types of Cell Transport
No Energy EnergyPassive Transport Active Transport
Diffusion
Faciliated diffusion(osmosis)
Bulk transportendocyotsis
exocytosis
Passive Transport
http://video.search.yahoo.com/search/video;_ylt=A0PDoX1LTNdMKyoAZayJzbkF?ei=UTF-8&p=passive%20transport&fr2=tab-img&fr=The Cell and Its Environment 2010.ppt
Passive Transport
Definition: is the movement of dissolved materials across a cell membrane without using the cells energy.
Energy required: NOType of Transport: PASSIVEDiffusion or facilitated diffusion(osmosis)
Passive Transport
Diffusion – passive transportDefinition: is the process by which molecules
move from an area of higher concentration to an area of lower concentration(liquids or gases).
Ex: If a bacteria lives in a pond, the water in the pond contains oxygen molecules. The area inside the bacteria cell has a lower amount of oxygen than the pond. So, the oxygen molecules outside of the cell will freely move into the cell.
Diffusion CONT’D
Energy required: NOType of Transport: PASSIVE
Faciliated Diffusion- Type of Passive TransportMovement of molecules across the cell
membrane but using a carrier molecule(protein)
NO ENERGY Follows the same rules as diffusion but
these molecules cannot slip through the phosolipid tails.
Osmosis – facilitated diffusion
Definition: is the diffusion of water molecules across a selectively permeable membrane(sometimes uses carrier protein).
-Many life processes require water, therefore; all cells must have the appropriate amount of water in them to function.
Energy Required: NOType of Transfer: PASSIVE
Osmosis – Type of Faciliated DiffusionMovement of WATER across the cell
membrane. Cells are 75 – 90 % water so osmosis is an important process.Water molecules will continue to move
until EQUILIBRUIM is reached.NO ENERGY NEEDED!!
Click on link below to see the flow of water during osmosis.
http://people.eku.edu/ritchisong/RITCHISO/osmosis3.gif
What Makes Water Move?
It is determined by the type of surroundings the cell is placed that determines the concentration gradient
Solution: mixture in which molecules of one substance are evenly dispersed.
Solvent: substance that makes up the greatest part of the solution.(usually water)
Solute: substance dissolved in the solvent.(K, NaCl, O Na, Amino acids)
Types of solutions cell can be placed
IsotonicHypertonicHypotonic
IsotonicConcentration of solutes are EQUAL
inside and outside the cell.Why do they give a person who is
dehydrated a saline(minerals and salt) drip(IV) vs. distilled 100% water.
Hypertonic
Solutes on the outside of cell is higher. Water leaves cell
This is why slugs shrivels up with salt.Animals that leave in salt water have
adaptations to deal with the salt in the water.
This is why you do not drink salt water.How will road salt affect roadside plants?
Hypertonic Solution
Cells are shrinkingbecause moresolute outside so water leaves cell.
Hypotonic
Concentration of solute is greater inside the cell so water moves in.
Animal cell will burst.Plant cells fill vacuole creates RIGOR!This is what causes plant to stand up.
Hypotonic Solution
Hypotonic Blood Cells
What do cells look like when they have too much or too little water?
Video – diffusion, osmosis & solutionshttp://video.search.yahoo.com/search/
video;_ylt=AgiX5UpIi9KIAFvWdkNyYsubvZx4?p=diffusion&toggle=1&cop=mss&ei=UTF-8&fr=yfp-t-701
Facilitated Diffusion CONT’D
Active Transport
Sometimes cells need materials to flow the opposite direction of the flow of diffusion. In this case the cell would need to use ACTIVE TRANSPORT to carry these materials in and out.
DEFINITON: is the movement of materials a cross a cell membrane against the gradient using cellular energy.
The cell uses its’ energy so the transport proteins “pick up” materials and “carry” them across the membrane.
Examples of substances that are carried in and out of the cell this way are: calcium, potassium, and sodium.
ENERGY REQUIRED: YESTYPE OF TRANSPORT: ACTIVE
Active Transport – the energy changes the shape of the protein to match the molecule
Once the molecule
is through the
membrane the
protein will change
its shape back!
http://video.search.yahoo.com/search/video;_ylt=A0SO8ZrQT9dMlgEAXAD7w8QF;_ylu=X3oDMTBncGdyMzQ0BHNlYwNzZWFyY2gEdnRpZAM-?p=active+transport&ei=utf-8&fr2=tab-img&n=21&tnr=21&y=Search
Bulk Transport – No energy
Particles too large to move through the membrane.(Particle of food, proteins)
2 Types of Bulk Transport1. Endocytosis2. Exocytosis
Steps of Endocytosis1. Molecules move into the cell by the cell
surrounding the particle and forming a vacoule around it.
2.Once vacuole is in cell, lysosomes will place digestive juices in the vacoule and break up the food or particles.
Pinocytosis: liquid is surrounded brought into cell.
Phagocytosis: solids are surrounded and brought into the cell.
SOLID LIQUID
Endocytosis
http://video.search.yahoo.com/search/video;_ylt=A0SO8Z1uUddMelcAfjn7w8QF;_ylu=X3oDMTBncGdyMzQ0BHNlYwNzZWFyY2gEdnRpZAM-?p=endocytosis&ei=utf-8&fr2=tab-img&n=21&tnr=21&y=Search
Steps of Exocytosis
1. Opposite of endocytosis2. Vacoule send to the cell membrane
with waste and particles and ejected out of
cell membrane.
Exocytosis
Exocytosis
http://video.search.yahoo.com/search/video;_ylt=A0SO8ZrfUddMOygAFNj7w8QF;_ylu=X3oDMTBncGdyMzQ0BHNlYwNzZWFyY2gEdnRpZAM-?p=exocytosis&ei=utf-8&fr2=tab-img&n=21&tnr=21&y=Search
Types of Cell Transport
No Energy EnergyPassive Transport Active Transport
Diffusion
Faciliated diffusion
Bulk transport
endocyotsis
exocytosis
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