Movement of Substances Movement of Substances

MovementMovement

Substances move in and out of cells in 2 waysSubstances move in and out of cells in 2 ways

DiffusionDiffusionmovement of molecules from a region of higher movement of molecules from a region of higher concentration to a region of lower concentration. concentration to a region of lower concentration.

Active TransportActive TransportMovement of molecules from a less crowded to a more Movement of molecules from a less crowded to a more crowded area WITH the use of energy.crowded area WITH the use of energy.

Molecules are “carried" into or out of the cell using some of Molecules are “carried" into or out of the cell using some of

the cell's energy.the cell's energy.

Movement in cells takes place Movement in cells takes place through membranesthrough membranes

All the membranes in a cell act in the same All the membranes in a cell act in the same wayway

Mitochondrial membranes

Cell Membranes

Chloroplast membranes

Nuclear membranes

Learning checkLearning check

What type of movement in cells requires What type of movement in cells requires energy?energy?

What type of movement in cells does What type of movement in cells does not require energy?not require energy?

Diffusion is the movement of substances Diffusion is the movement of substances from an area of ....... Concentration to from an area of ....... Concentration to an area of ......... Concentrationan area of ......... Concentration

Name 3 different types of membranesName 3 different types of membranes

PermeabilityPermeability

Membranes can beMembranes can be

PermeablePermeable – let everything in and out – let everything in and out

Semi PermeableSemi Permeable - let some things in and - let some things in and outout

ImpermeableImpermeable – let nothing in and out – let nothing in and out

Diffusion in everyday lifeDiffusion in everyday life

Smell of perfumeSmell of perfume Bread bakingBread baking Stink bombStink bomb Food colouring in waterFood colouring in water Sugar in teaSugar in tea

Learning CheckLearning Check

What type of permeability allows free What type of permeability allows free movement of substances?movement of substances?

What type of permeability allows What type of permeability allows some movement of substances?some movement of substances?

What type of permeability allows no What type of permeability allows no movement of substances?movement of substances?

Can you name a few common Can you name a few common examples of diffusion?examples of diffusion?

OsmosisOsmosis

Osmosis is the movement of Osmosis is the movement of water across a semi-permeable water across a semi-permeable membrane from a region of high membrane from a region of high water concentration to a region water concentration to a region of low water concentrationof low water concentration

Osmosis is a special type of diffusion Osmosis is a special type of diffusion that does not require energythat does not require energy

Osmosis is Osmosis is passivepassive

If pure water is separated If pure water is separated from salt water the from salt water the following ocurrsfollowing ocurrs

The water molecules move The water molecules move randomly on both directionsrandomly on both directions

The salt molecules cannot The salt molecules cannot move out so more water move out so more water moves in to the salt solutionmoves in to the salt solution

What you have is water What you have is water moving from where there is moving from where there is a high concentration of a high concentration of water to where there is a water to where there is a lower concentration of lower concentration of water this is water this is osmosisosmosis

Learning CheckLearning Check

What is osmosis?What is osmosis? Does osmosis require energy?Does osmosis require energy?

Osmosis and Animal CellsOsmosis and Animal Cells

Animal cells are only enclosed by a Animal cells are only enclosed by a membranemembrane

If an animal cell is surrounded by a If an animal cell is surrounded by a solution that is the same solution that is the same concentration as the cytoplasm in concentration as the cytoplasm in the cell water will move in and out at the cell water will move in and out at the same rate and the cell will the same rate and the cell will remain intactremain intact

Many animals that live in the sea Many animals that live in the sea have cytoplasm with a similar have cytoplasm with a similar concentration to sea waterconcentration to sea water

It is the function of our kidneys to It is the function of our kidneys to make sure the fluid in our bodies that make sure the fluid in our bodies that surrounds our cells (plasma) has a surrounds our cells (plasma) has a stable concentrationstable concentration

Animal cells in a less Animal cells in a less concentrated solutionconcentrated solution

If an animal cell is in a solution that If an animal cell is in a solution that is less concentrated than its is less concentrated than its cytoplasm (ie if there is more water cytoplasm (ie if there is more water outside than inside the cell) the outside than inside the cell) the water from outside will move into the water from outside will move into the cell and may cause it to burst or diecell and may cause it to burst or die

AmoebasAmoebas

Animal Cells in a more Animal Cells in a more concentrated solutionconcentrated solution

If animal cells are in a solution that is If animal cells are in a solution that is more concentrated than their more concentrated than their cytoplasm (ie if there is more water cytoplasm (ie if there is more water in their cytoplasm than in the in their cytoplasm than in the solution outside) then the water may solution outside) then the water may leave the animal cell and the cells leave the animal cell and the cells shrivel up and may die shrivel up and may die

Shrivelled Animal CellsShrivelled Animal Cells

Learning checkLearning check

What surrounds an animal cell?What surrounds an animal cell? How does water move in and out of How does water move in and out of

an animal cell?an animal cell? What will happen to animal cells in a What will happen to animal cells in a

very dilute (watery) solution?very dilute (watery) solution? What will happen to animal cells in a What will happen to animal cells in a

very concentrated solution?very concentrated solution?

Osmosis and Plant CellsOsmosis and Plant Cells

Plant cells have a membrane which is Plant cells have a membrane which is surrounded by a cell wallsurrounded by a cell wall

Cell walls are fully permeable and will Cell walls are fully permeable and will allow all substances in and out of the cellallow all substances in and out of the cell

If a plant cell is surrounded by a less If a plant cell is surrounded by a less concentrated solution then water from concentrated solution then water from outside will move into the cytoplasm and outside will move into the cytoplasm and vacuole of plant cellsvacuole of plant cells

This is how roots absorb water by This is how roots absorb water by osmosisosmosis

Water entering roots by Water entering roots by osmosisosmosis

The water outside is less The water outside is less concentrated than the water in the concentrated than the water in the cytoplasmcytoplasm

TurgorTurgor

When the outside water enters the When the outside water enters the plant cell the vacuole becomes plant cell the vacuole becomes bigger and the cytoplasm swellsbigger and the cytoplasm swells

This causes the membrane to be This causes the membrane to be pushed out towards the cell wallpushed out towards the cell wall

When cells are fully “swelled” like When cells are fully “swelled” like this with the membranes pushing this with the membranes pushing against the cell wall they are against the cell wall they are described as described as TurgidTurgid

Turgid CellsTurgid Cells

Turgor pressureTurgor pressure

This turgor pressure gives plants This turgor pressure gives plants their strengththeir strength

If plants did not have this they would If plants did not have this they would be wiltedbe wilted

Plants that don’t have wood such as Plants that don’t have wood such as lettuce and house plants rely on lettuce and house plants rely on turgor pressure for strengthturgor pressure for strength

Plant cells in a more Plant cells in a more concentrated solutionconcentrated solution

If plant cells are surrounded by a If plant cells are surrounded by a more concentrated solution (for more concentrated solution (for example if plant cells were example if plant cells were surrounded by salt water) the water surrounded by salt water) the water inside the cell would move out to the inside the cell would move out to the more concentrated solution outsidemore concentrated solution outside

Learning CheckLearning Check

What surrounds the membrane of a What surrounds the membrane of a plant cell?plant cell?

Can this structure control what moves Can this structure control what moves in and out of cells?in and out of cells?

How does water enter roots of a plant?How does water enter roots of a plant? What is meant by a turgid cell?What is meant by a turgid cell? How could you identify a turgid cell?How could you identify a turgid cell?

PlasmolysisPlasmolysis

When this happens the cell wall stays When this happens the cell wall stays intact but the membrane shrivels up intact but the membrane shrivels up away from itaway from it

This is called This is called PlasmolysisPlasmolysis Cells in this condition are called Cells in this condition are called

plasmolysed cells we can look at this plasmolysed cells we can look at this easily by placing a layer of red onion easily by placing a layer of red onion cells in salt watercells in salt water

Plasmolysed red onion cellsPlasmolysed red onion cells

Osmosis and Food Osmosis and Food PreservationPreservation

Bacteria and Fungi are the most Bacteria and Fungi are the most common causes of food spoilagecommon causes of food spoilage

Both these cells are enclosed by a Both these cells are enclosed by a membranemembrane

If a food is placed in a sugary or salty If a food is placed in a sugary or salty solution then any bacteria or fungi solution then any bacteria or fungi present will lose the water in their present will lose the water in their cells to the more concentrated cells to the more concentrated solution outsidesolution outside

When this happens the cells will When this happens the cells will shrivel and die and the food will not shrivel and die and the food will not become contaminated with loads of become contaminated with loads of bacteria nad fungibacteria nad fungi

ExamplesExamples

Fish and Meat (bacon) may be stored Fish and Meat (bacon) may be stored in a salty solution in a salty solution

Jams, marmalades and tinned fruits Jams, marmalades and tinned fruits are stored in a sugary solutionare stored in a sugary solution

Learning CheckLearning Check

What is meant by plasmolysis?What is meant by plasmolysis? What kind of a solution would you put What kind of a solution would you put

plant cells in to cause them to plant cells in to cause them to palsmolyse?palsmolyse?

How is plasmolysis used to preserve How is plasmolysis used to preserve food?food?

Give an example of some types of Give an example of some types of food preserved in this way?food preserved in this way?

Syllabus Can you?.....Syllabus Can you?.....

Define the term: Selectively permeableDefine the term: Selectively permeable Explain the role of selectively permeable Explain the role of selectively permeable

membranes.membranes. Define the terms: osmosis & diffusionDefine the terms: osmosis & diffusion Give examples of diffusion and osmosis.Give examples of diffusion and osmosis. Define the term: turgor.Define the term: turgor. Explain turgidity in plant cells.Explain turgidity in plant cells. Describe the application of high salt or sugar Describe the application of high salt or sugar

concentration in food preservation.concentration in food preservation.