movement in and out of cells

 

Class notes

 

 

 

Diffusion

Biology

  • Gases

  • In plants and animals

Chemistry

  • Particles movement

 

Osmosis

  • Movement of water

  • Concentration gradient

  • Effect of water movement

    • The potential in cells

  • Water potential

    • Amount of water molecules in a given area

 

Using, the term water potential,

The water molecules will move from a region of high water potential to low water potential through a partially permeable membrane.

 

Definition

  • Movement of particles

  • From high concentration to low concentration / concentration gradient

  • (Particles move randomly using their own internal energy )

  • Until equilibrium is reached

  • The nature/type and size of molecules/particle also determines whether the molecule will/can move across the membrane

 

 

 

Element of error is the pieces were randomly spaced

 

Piece of litmus

Time(sec)

1

5.0

2

6.2

3

 

4

 

5

 

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|

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High con.         Low con.

Dotted line - cell membrane

Dots - cotton wool with ammonia

 

Active transport

  • Movement of particles/molecules

  • Against a concentration gradient

    • Up a concentration gradient

  • Using energy

 

  • It uses carrier proteins which are found in cell membrane

 

If you put a respiratory poison it will affect active transport

  • No aerobic respiration will happen

    • Substances can't move

 

 

Chapter 3

 

Diffusion                                                                                                                                                                

Movement of particles from an area of high concentration to an area of low concentration

  • Particles are always moving

  • Higher temperature, faster movement

    • More kinetic energy

  • Cells need energy to help them build their cell structure

    • Water and mineral ions

    • Food

    • Helps with respiration for energy

      • Helps with active transportation

        • Actively

  • Substances pass through cell membrane through diffusion

    • Passively

  • Spreading around evenly in given space

  • High concentration to low concentration

    • Until spread everywhere

  • Make molecules diffuse into cells

    • Until at equilibrium

      • Inside and outside at same concentration

 

Diffusion down a concentration gradient

  • Spread as evenly as they can

    • Moving randomly

  • High to low concentration

    • Net movement

  • Close to spread out

  • High concentration at the top of slope, low concentration at bottom of slope

 

Diffusion in living organisms

  • Some of the substances organisms need are diffused

  • Gets rid of waste

    • Plants diffuse air into the leaves

      • Higher concentration of air is outside the leaf

  • Important in gas exchange

    • Gases diffuse in and out of cells

 

Osmosis                                                                                                                                                                

Movement of water molecules across a partially permeable membrane from higher water concentration to lower water concentration

  • Water is important

    • It is in and out of the cells

    • Used for chemical reactions

    • Used as a solvent

  • Concentration gradient

    • Down

  • Pass through partially permeable membrane

 

  • Diffusion of water through a partially permeable membrane

    • Membrane

      • Has holes in it

        • Very small

  • Particles move from high to low concentration

  • High to low water potential

 

Water potential

Measure of the tendency of water molecules from one place to another

  • High water potential

    • A lot of water

      • Oros that is diluted

  • Low water potential

    • Less water

    • Concentrated solution

      • Oros that isn't diluted

 

Osmosis and animal cells

  • In a case the cytoplasm can be more concentrated solution that the solution outside it

  • Water molecules will diffuse into the seal

    • The more that enters, the more it will swell

      • It will strain then burst

  • In another case the cytoplasm can be less concentrated than the solution outside it

    • Water diffuses out of the cell

      • Cell becomes smaller

 

Osmosis and plant cells

  • Don't burst in pure water

  • Cell wall is fully permeable

    • Lets anything through

  • Put in a solution less concentrated that the cytoplasm

    • Cell swells

      • This is because the cell wall is strong to stop it from bursting

      • The cytoplasm and vacuole swell

      • Turgid

        • A description of a plant cell that is tight and firm

      • Pressure pushed onto the cell wall

        • Turgid pressure

          • The pressure of the water pushing outwards on a plant cell wall

  • Places in a solution that is more concentrated than the cytoplasm

    • Water leaving the cell

    • Cytoplasm and vacuole shrink

    • Cytoplasm pulls away from the cell wall

      • Pulls the cell membrane too

      • Flaccid

        • A description of a plant cell that is soft

    • When the cell membrane pulls away from the cell wall completely

      • Plasmolysed

        • A description of a cell in which the cell membrane tears away from the cell wall

 

Active transport                                                                                                                                                        

 

  • Movement of molecules or ions through the cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration

  • Some cells need to take in substances which are only present in small quantities

  • Lower concentration outside

    • We'd expect diffusion out the cell

  • If the cell needs it, the cell needs to do something about it (yurr)

    • Cell uses energy

  • Provided by respiration

    • Aerobic

  • Use the help of carrier proteins

    • Protein carriers

    • Protein molecules in cell membranes that can use energy to shape and move ions or molecules into or out of a cell