Moving Cellular Material

Science 7

Darren Nigh

Cells Chapter 2

Lesson 3 and 4

Cells and Spacesuits

• What do spacesuits and cells have in common?

• They both support life

• Sometimes in difficult

external environments

• What are some similarities

and differences?

Produced 1930’s

Spacesuit FeaturesSpacesuit FeaturesStrong outer material protection from

space particles

A jetpack to help astronaut

move about

A tank of

compressed provide oxygen

air

Cell FeaturesCell Features• Outer membrane to keep

harmful particles out

• Tail-like flagella on help cell move

outside of some cells

• Tiny openings in cell let oxygen and

membrane water into cell

Important TermsA solute is a type of molecule dissolved in another

type of substance; that substance is called a…Solution

A Solvent is a substance that dissolves the solute

CONCENTRATIONCONCENTRATION

• Concentration refers to how much of some substance is present, compared to another substance.

• For instance, a high solute concentration has a relatively high amount of solute and low amount of solvent.

CONCENTRATION EXAMPLESCONCENTRATION EXAMPLES

• High solute concentration: lots of sugar dissolved in a relatively small amount of water

• Low solute concentration: little sugar dissolved in a relatively high amount of water

Diffusion

• Diffusion is the process by which a solute passes through pores in a cell membrane

• Diffusion also occurs within a specific area (no membrane) as solute

travels from one area of

space to another

How do particles move?

1. Fill a beaker with tap water

2. Add five drops of food coloring to the water

3. After 10 minutes or so observe what has happened.

What happens to color dye dropped into a container of purewater? It disperses evenly!

Direction of Diffusion

• Molecules ALWAYS diffuse in both directions at once (into and out of a cell)

• Net Flow is ALWAYS from greater concentration to lesser concentration

What direction will molecules diffuse across this membrane?

What is the net flow?

Diffusion in the air

• Molecules may diffuse through the air environment

• Example: aromas

• Diffusion tendencies - the tendency of molecules to move from a higher concentration to a lower concentration until equilibrium is reached.

Higher concentration on the left Equalizing Equal-Fully diffused

What is Osmosis?What is Osmosis?

• Osmosis is a form of diffusion.

• It is a passive process because it does not require outside energy to start the process.

• It is the movement of water molecules Water molecules always flow in both directions at once (into and out of a cell)

How does it Work?How does it Work?

• The cell is a closed structure protected by its semi permeable bi-lipid membrane.

• This membrane will allow certain molecules to enter or leave the cell.

• Water will enter or leave the cell based upon its concentration on either side of the cell’s membrane.

• Always from higher to lower concentrations

Osmosis Animation

Osmosis in Plant CellsOsmosis in Plant Cells

• The cell wall of a plant will prevent the cell from exploding if placed in a hypertonic solution.

• Instead the extra water will push against the wall making the cell stiff or turgid.

Cell MembraneCell Wall

Tonoplast

Chloroplast

Nucleus

Why Salt Water Fish die in Fresh Water.

• The cells of a salt water fish are hypertonic to the fresh water that surround them.

• The water will move into the cells causing them to swell and lyse.

• The gill and blood cells die, eventually killing the fish.

Atlantic Cod

Why a Fresh Water Fish die in Salt Water.

• The cells of a freshwater fish are hypotonic to the salt water that surround them.

• The water will move out of the cells causing them to shrink or crenate.

• The gill and blood cells die, eventually killing the fish.

Black Crappie

PASSIVE vs. ACTIVE PASSIVE vs. ACTIVE TRANSPORTTRANSPORT

• Diffusion and osmosis are examples of passive transport, which occurs without a cell using energy.

• Cells can move molecules in the opposite direction across a membrane by utilizing energy. Substances can move from low concentration to high concentration

• This is known as active transport.

Important Terms• Passive Transport

– Movement across a membrane without using energy through diffusion and osmosis from high to low concentration

• Facilitated Diffusion– Movement through a cell

membrane using special transport proteins.

Carrier proteins move large molecules across the membrane

Exocytosis & Endocytosis

Cells need to move large molecules. Molecules move into the cell through endocytosis and out of it through exocytosis. Both cases, the cell membrane encloses the molecule in a pocket, pinches off the pocket and moves it by active transport.

For molecules too large to pass through the cell membrane

Cell size affects transport. All materials needed by the cell must move through the cell membrane.

If the ratio of volume to surface area is too large and the cell doesn’t change shape there will not be enough membrane area to transport necessary materials into and out of the cell

• Cells avoid this problem by one of three adaptations:

• staying small

• dividing

• changing shape

Lesson 4

Cells and Energy

Some cells capture light energy. • Plants capture light energy from the sun

through photosynthesis. This process takes place in plant cells that have chloroplasts

Plants take water from the soil and carbon dioxide from the air. In chloroplasts a pigment called chlorophyll absorbs light. The cell uses energy to break water into hydrogen and

oxygen

• The freed hydrogen and the carbon dioxide from the air are combined to make glucose. Most the oxygen from water is released into the air.

All cells release energy • All plant and animal cells break down

glucose for energy. In cellular respiration the mitochondria in cells convert small glucose molecules into usable energy called ATP.

• This process is called Glycolysis

******Oxygen is used during Glycolysis for the releasing of energy for use

Fermentation • Fermentation allows cells to release

energy without oxygen. It releases small amounts of energy and can produce either carbon dioxide and alcohol or lactic acid.

• When you run out of oxygen while exercising, your muscles use fermentation to break down sugar. This results in a lactic-acid buildup, which

makes muscles sore

Does Fermentation release any material?

1. Add 1 packet of yeast to the empty water bottle.

2. Fill the bottle ¾ full with a sugar solution.

3. Place the balloon tightly around the mouth of the bottle.

4. Gently swirl the bottle to mix the yeast and sugar solution

5. After 20 minutes, observe the balloon.

You are now prepared to begin preparation for the Chapter 2 Common Assessment