TAKS Objective 2 TEKS 4B

Presented by:

Alexander FedorovComposite Science Teacherwww.myscienceparty.org

Applicable Text: Prentice Hall Biology: Chapter 19

All life is composed of cells. Three basic types of cells you will need to know (plus viruses)

•Prokaryotes (Bacteria)•Plants Cells•Animal Cells•Viruses

•(not considered living organisms)

•Prokaryotes (Bacteria) do not have a membrane bound nucleus!

Not a Living organism

HomeostatisHomeostatis

This is a term to describe “constant This is a term to describe “constant internal enviornment.” All living internal enviornment.” All living things want to maintain a constant things want to maintain a constant internal enviornment; for example, internal enviornment; for example, your normal temperature does not your normal temperature does not fluctuate with the outside fluctuate with the outside temperature. We always maintain a temperature. We always maintain a temperature around 98.6temperature around 98.6o C.

Occurs at the cell membrane

Passive Transport:Passive Transport: requires no energy. requires no energy.• Examples of passive transport:Examples of passive transport:

1. 1. diffusion:diffusion: movement of molecules movement of molecules from high concentration to low from high concentration to low

concentration.concentration.2. 2. osmosis:osmosis: movement of water across a movement of water across a

permeable membrane from an area of high permeable membrane from an area of high concentration to low concentration.concentration to low concentration.

BUT: There are some molecules that BUT: There are some molecules that are too large to pass through the are too large to pass through the phospholipid bilayer.phospholipid bilayer.

Therefore, some molecules must Therefore, some molecules must undergo passive transport by means of undergo passive transport by means of transport proteins.transport proteins.

This is called:This is called:FACILITATED FACILITATED DIFFUSIONDIFFUSION

There are two types of transport There are two types of transport proteins:proteins:

  

1. channel proteins1. channel proteins

2. carrier proteins2. carrier proteins

Channel proteins Channel proteins are tubelike and are tubelike and provide openings provide openings through which through which particles can particles can diffuse.diffuse.

Carrier proteins have Carrier proteins have a specific shape that a specific shape that

fits a specific fits a specific molecule. molecule.

When the proper When the proper molecule combines molecule combines with the protein, it with the protein, it changes shape and changes shape and moves the molecule moves the molecule across the membrane.across the membrane.

Facilitated diffusion is passive and Facilitated diffusion is passive and requires no energy.requires no energy.

Can a cell ever move particles Can a cell ever move particles from a region of lesser from a region of lesser concentration to a region of concentration to a region of greater concentration?greater concentration?

   Yes, but energy must counteract the Yes, but energy must counteract the

tendency of the molecules to move tendency of the molecules to move in the opposite direction.in the opposite direction.

The transport of materials against a The transport of materials against a concentration gradient requires concentration gradient requires energy (ATP) and is called energy (ATP) and is called ACTIVE ACTIVE TRANSPORTTRANSPORT..

First a transport protein binds with the First a transport protein binds with the substance to be transported.substance to be transported.

Energy from the cell is used to change the Energy from the cell is used to change the shape of the proteins so that the particle is shape of the proteins so that the particle is released on the other side of the released on the other side of the membrane.membrane.

Once the particle is released, the protein Once the particle is released, the protein regains its’ original shape.regains its’ original shape.

Some cells can Some cells can take in large take in large molecules, groups molecules, groups of molecules, or of molecules, or even whole cells even whole cells through through ENDOCYTOSISENDOCYTOSIS..

The reverse The reverse process of process of endocytosis is endocytosis is EXOCYTOSISEXOCYTOSIS. . Cells use this to Cells use this to expel wastes, and expel wastes, and secrete cellular secrete cellular products.products.

                                                                   

PASSIVE PASSIVE TRANSPORT:TRANSPORT:

1. no energy1. no energy 2. movement of 2. movement of

molecules from high molecules from high concentration to low concentration to low concentration.concentration.

3. Examples:3. Examples: diffusion, osmosis, diffusion, osmosis,

facilitated diffusionfacilitated diffusion

ACTIVE TRANSPORT:ACTIVE TRANSPORT: 1. requires energy1. requires energy 2. movement of 2. movement of

molecules from low molecules from low concentration to high concentration to high concentration.concentration.

3. use of transport 3. use of transport proteinsproteins

4.exocytosis and 4.exocytosis and endocytosis are active endocytosis are active transport for large transport for large molecules, wastes, and molecules, wastes, and cellular products.cellular products.  

The movement of molecules from an The movement of molecules from an area of high concentration to an area area of high concentration to an area of low concentration is called of low concentration is called diffusiondiffusion..• Ex. Perfume diffusing through the airEx. Perfume diffusing through the air• Food coloring diffusing in waterFood coloring diffusing in water

II.PermeabilityII.Permeability A material is permeable if it allows A material is permeable if it allows

molecules to pass through.molecules to pass through. The cell membrane (plasma The cell membrane (plasma membrane) is permeable.membrane) is permeable.

Hey, sponges are permeable too!!

III. OsmosisIII. Osmosis Osmosis is the diffusion of water Osmosis is the diffusion of water

molecules across a permeable molecules across a permeable membrane. membrane.

In osmosis, like diffusion, water In osmosis, like diffusion, water molecules move from an area of high molecules move from an area of high concentration to low.concentration to low.

Hypotonic solutions-Hypotonic solutions-Solutions which contain Solutions which contain

a lower concentration a lower concentration of dissolved of dissolved substances than a substances than a solution to which it is solution to which it is being compared.being compared.

In a hypotonic In a hypotonic solution the cell solution the cell swells or possibly swells or possibly explodesexplodes

Red blood cell placed in distilled water

Hypertonic SolutionHypertonic Solution• Solutions which Solutions which

contain a higher contain a higher concentration of concentration of dissolved dissolved substances that the substances that the solution to which it solution to which it is being comparedis being compared

• In hypertonic In hypertonic solutions the cell solutions the cell shrinksshrinks

Red blood cell placed in salt water solution

Isotonic solutionsIsotonic solutions• When the solution in When the solution in

side the membrane side the membrane is the same is the same concentration as the concentration as the solution outside the solution outside the membrane.membrane.

• An isotonic solution An isotonic solution is at equilibriumis at equilibrium

• In an isotonic In an isotonic solution there is solution there is no change in the no change in the cellcell

Red blood cell in an isotonic solution

A B C D E

1. Which is the most hypertonic solution?

2. Which is the most hypotonic solution?

3. Which solution is isotonic?

Mitochondria: cell energy is producedChloroplasts: create sugar by sunlight (plant cells)Lysosomes: the stomach of a cell, digests food.Ribosomes: creates protienNucleus: stores genetic information (DNA)Cytoplasm: the cells circulation (fluid)Endoplasmic Reticulum: modifies protiensGolgi Body: packages protiens for export

Where they occur:•Kreb Cycle: Mitochondria•Calvin Cycle: Chloroplasts•Glycolysis: cytoplasm•Fermentation: cytoplasm•Protein Synthesis: ribosomes•Transcription: Nucleus•Translation: ribosomes