Day 3

Cell Transport: Passive Transport

Passive Transport• Cell uses no energy • Random movement of particles along a

concentration gradient from high to low concentration. (HighLow)

1. Diffusion

• Diffusion: -random movement of particles from high to low concentration.

– continues until molecules at equilibrium (equal)

Simple Diffusion

Animation

• Facilitated diffusion: diffusion of specific particles from High Low conc. with help of proteins in membrane. a. Carrier Proteins -bind to

specific molecules, carry across membrane.a. Transport large particles that

can’t pass through on own. Ex. Glucose

b.Ion Channels Protein - transports ions (charged particles)a. Ex. Na+, K+, Cl-

Facilitated

diffusion (Channel Protein)

Diffusion

(Lipid Bilayer

)

: 2. Facilitated

Diffusion

Carrier Protein

A B

• http://bio.winona.edu/berg/Free.htm

High Concentration

Low Concentration

Cell Membrane

Glucosemolecules

Proteinchannel

Facilitated Diffusion

Go to Section:

Transport Protein

Through a

Cellular Transport From a- HigHig

hh

LowLow

• Channel Proteins animations

• Osmosis: diffusion of water– Moves from a high concentration

to low concentration of water

• Cell cannot control movement of water through cell membrane

Osmosis animation 3. Osmosis

Effects of Osmosis on Life

• Water moves freely through pores.

• Substances dissolve well in water.

– Solute: what is being dissolved– Solvent: what dissolves the solute

• In salt water, the solute is the salt and the solvent is the water

• Cells can be placed in 3 kinds of water solutions that affect their homeostasis.

1. Hypotonic Solution

Hypotonic: Solution has lower concentration of solutes and higher concentration of water

than inside the cell. (Low solute; High water)

Result: Water moves from the solution to inside the cell: Cell Swells and bursts open

( called lyse)!

• Osmosis Animations for

isotonic, hypertonic, and

hypotonic solutions

2. Hypertonic Solution

Hypertonic: Solution has higher concentration of solutes and lower

concentration of water than inside the cell. (High solute; Low water)

Result: Water moves out of the cell into the solution: Cell shrivels or

shrinks!

• Osmosis Animations for

isotonic, hypertonic, and

hypotonic solutions

shrinks

Isotonic SolutionIsotonic: Concentration of solutes in solution is equal to concentration of solutes inside cell.

Result: Water moves equally in both directions and the cell remains same size!

(Dynamic Equilibrium)

• Osmosis Animations for

isotonic, hypertonic, and

hypotonic solutions

In what type of solution are these cells?

A CB

Hypertonic

Isotonic

Hypotonic

Real Life Examples

If you are stranded in the ocean, should you drink the water to stay alive?

Why do we wrinkle when we are in the tube too long?

Why does it help to gargle salt water when we have a sore throat?

What happens to a snail when you put salt water on it?

Cell Transport: Active Transport

Active Transport

• Requires the cell to use energy • Actively moves molecules to where they are

needed• Molecules move against the concentration

gradient - from area of low concentration to area of high concentration

• (Low High)

Types of Active Transport

1. Protein Pumps -transport proteins that require energy to do work

•Example: Sodium / Potassium (Na+/K+)

Pumps•important in nerve responses.

Sodium Potassium

Pumps (Active Transport using

proteins)

Protein changes shape

to move molecules: this

requires energy!

Types of Active Transport

• 2. Endocytosis: takes bulky materials into a cell by forming a vesicle.• Uses energy• Cell membrane in-folds

around particles• “cell eating”

• Forms vacuole & digests the particle

• This is how white blood cells eat bacteria!

Types of Active Transport

3. Exocytosis: Forces material out of cell in bulk• Membrane surrounds

material then fuses with cell membrane

• Cell changes shape – requires energy• Ex: Hormones or wastes

released from cell

Endocytosis & Exocytosis animations

Comparison

Photosynthesis

How Do Plants Make Their Own Food?

• Photosynthesis - process by which light energy is converted to chemical energy.– Plants, algae, and some bacteria use this process.

• Called Autotrophs or Producers– “Food” plants make is a sugar called glucose (C6H12O6).

• Can be stored as sugar or made into starch or cellulose.

– Plants use carbon dioxide (CO2), water (H2O), and sun’s energy to make food.

6CO2 carbondioxide

6H2O water

C6H12O6

glucose (sugar)

6O2

oxygen++

Sun (light energy)

Reactants - In Products - Out

3 Stages of Photosynthesis

• Stage 1 -Absorption of Light Energy – energy is captured from sunlight.– Occurs in chloroplasts found in leaves.– Pigments – found in cholorplasts absorb light. Different

pigments absorb certain wavelengths and reflect others.• Chlorophyll – (a &b) primary pigment. Absorbs mostly blue and red

light; reflects green and yellow light. • Carotenoids- (carotene, xanthrophyll) pigments that reflect yellow

and orange colors. – Clusters of pigments found in Thylakoids in chloroplast.

• Stack of Thylakoids called a grana or granum

How is light captured?Stage 1 cont.– Light strikes thylakoids in chloroplast.

Electrons get excited and jump around. – Electrons jump out of chlorophyll into other

nearby molecules in thylakoid and go to 2nd stage.• Electrons (H) lost replaced by stealing

them from water molecules forming O2.

What is done with energy that is captured?

• Stage Two: Electron transport chain-light energy is converted to chemical.– Electrons enter Electron transport chain in

thylakoid membrane (series of rxns where ATP is made through transfer of electrons).• Produces ATP (energy) and NADPH

(electron carrier)Stage 1 and 2 are called Light-dependent

reactions.

Electrons Jumping

What is energy?

• In cells, energy is stored as ATP (adenosine triphosphate)– delivers energy to other cells

• When the energy released, ATP becomes ADP – loses a phosphate atom.– Therefore, the energy is stored in the phosphate bond!

ATP ADP + P + energy

Copyright Cmassengale

Electrons lose energy as go through protein in membrane.Energy lost from electrons used to pump Hydrogens into thylakoid through Active transport.

This creates concentration gradient of H which then starts to pass through an ion channel that is also an enzyme (ATP Synthase).

As H passes through channel, the protein catalyzes a reaction that adds a phosphate group to ADP to form ATP.

A second electron transport chain makes NADPH by adding a H to an electron acceptor called NADP+.Produces ATP (energy) and NADPH (electron carrier)

All this from the light hitting the chlorophyll to making ATP is called the Light-dependent reaction

Electron Transport Chain- how does it work?

• Stage Three: Calvin Cycle– Through carbon fixation, CO2 is used to make glucose.

• Carbon fixation – transfer of CO2 to organic compounds (sugars)• Calvin Cycle – series of enzyme-assisted chemical reaction that produces a

3-carbon sugar.– Enzyme Rubisco converts inorganic carbon dioxide molecules into organic molecules that

can be used by the cell.

Stage 3 is called a Light-independent reaction or Dark reactions.

Factors affecting Photosynthesis• Amount of Light.• Amount of CO2 & H2O.

• Amount of temperature.

Electron Transport Chain Animation

Copyright Cmassengale

Cellular Respiration

How Do Organisms Get Energy From Food?• BOTH plants and animals must break down (digest) food in order to get energy from it (so they can live, grow, &

develop)– Cellular Respiration - process that makes energy (ATP) from organic compounds like glucose; done in mitochondria

• 2 types: Aerobic and Anaerobic• Food (glucose) is broken down into CO2 and H2O and energy is released• C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy (ATP)• This energy can be used for:

– Keeping constant body temperature (Homeostatsis)– Storage (ATP) - to be used later for things like growth

What Do You Notice?

Check It Out!

• Did you notice that cellular respiration is just the opposite of photosynthesis?

Aerobic Respiration

• Requires oxygen• Carried out by plants, animals, and some bacteria• 3 stages

– 1. Glycolysis - Breakdown of Glucose– Occurs in cytoplasm– Enzymes break down glucose into 2 sugars called pyruvate, 2 ATP also

made.

– 2. Krebs Cycle– Occurs in mitochondria– Pyruvate made in stage 1 enters mitochondria and is converted to a 2

C compoound.– Produces CO2, 2 ATP, NADH, Acetyl-CoA, and FADH2(electron carrier)– Electrons carried by NADH and FADH to stage 3

– 3.Electron Transport Chain– Occurs in mitochondria membrane– Electrons move down electron transport chain– Electrons combine with oxygen to make water.– 32 ATP made

2 ATP 2 ATP 32 ATP

Anaerobic Respiration

• No Oxygen required.• Organisms such as yeast and bacteria use it and

organisms that normally require oxygen can do it if their cells can’t get enough oxygen.

• Also called Fermentation.• 2 types: alcoholic and lactic acid

– Both start with glycolysis• Pyruvate and 2 ATP produced

– No Krebs or electron transport chain.

Lactic Acid

• Pyruvate lactic acid– Carried out by your muscles

when you’re exercising hard and can’t get enough oxygen fast enough (can’t do aerobic respiration)

– Causes muscle cramps and soreness

Alcoholic

• Pyruvate ethyl alcohol– Carried out by yeast and

some bacteria.– Used in brewing beer, making

wine, and baking bread and cakes