Photosynthesis

PART 1:

Basic Vocabulary & ATP

EnergyEnergy – the ability to make something happenENERGY exists in different forms, but can CHANGE from one form to another.

Some types of energy are: Light (solar) Electrical Chemical Infrared (heat)

“Solar cells” convert LIGHT (solar) energy into ELECTRICAL energy (electricity).Light bulbs convert ELECTRICAL energy back into LIGHT (and heat!) energy.

This is one way humans store ENERGY for later use.

EVERYTHING has some form of energy, or a COMBINATION of different forms of energy.

A light bulb has LIGHT and HEAT energy to offer. Remember: All energy originally comes from the

SUN.Energy CANNOT be created

Energy cannot be DESTROYED

But, energy CAN be transformed

The energy to power your iPodcame from the sun, originally.

Have you thanked your Sun recently???

Have you ever used a solar-powered calculator? No matter where you go, as long as you have a light source, the calculator works. You never have to put batteries in it.

Where does the energy to power the calculator come from? What form (light/heat/chemical/electrical) of energy is this?

A solar cell transforms this energy into ___________ energy, which powers the electrical circuits of the calculator.

Do all calculators run on solar energy?

Have you ever noticed that your body maintains a constant temperature, usually 98o F?

This energy, measured by temperature, is HEAT energy.Which object has more heat energy, an ice cube or a hot cup of coffee?

What happens when you put the ice cube into the hot coffee? It melted, but why?

The energy moved from the coffee (area of higher energy) into the ice cube (area of lower energy), giving it enough energy to melt.

Since energy moves from an area with lots of energy to an area with lower energy, what happens to the air next to your skin on a cold day?

When you use a wood stove to put energy into your house, what happens to the temperature inside your house?

Where did the energy come from to heat the stove? Where did the energy in the wood come from?

The energy in the wood from the last example came from the SUN, originally.

The wood has lots of trapped CHEMICAL energy. Chemical energy is stored in the BONDS between molecules of the

wood. These bonds are BROKEN when wood is burnt. When chemical bonds are broken, energy is RELEASED.

How did the wood transform energy from the sun (light energy) into chemical energy?

Photosynthesis – making chemical energy from light energy

PhotosynthesisPhoto – “light” Synthesis – “making”

Energy in Organisms

Just like our appliances, iPods, and light bulbs have energy flowing through them, energy flows through LIVING things!Energy to power LIFE originally comes from the SUN, just like all other energy.Energy from the sun enters living systems through “producers,” such as autotrophs.

Autotrophs – make their own food by photosynthesis gathers LIGHT energy and stores it as CHEMICAL

energy in GLUCOSE.

What are examples of autotrophs?

Plants Oak tree Grass Wheat Moss Flowers Shrubs Every other plant you can think of.

Algae Algae are not considered plants – they are

unicellular.Certain kinds of bacteria

Photoautotrophs Vs.

Chemoautotrophs

Comparing Autotrophs

Photoautotrophs

Convert light energy into chemical energy stored in organic compounds (usually glucose). This is PHOTOSYNTHESIS Source of energy is the SUN

Examples: Plants, algae, and other “green things” with photosynthetic pigments (such as chlorophyll).

Photoautotrophs

Chemoautotrophs

Use small, inorganic molecules to make larger organic molecules that sustain life Eg) CO2, NH3, NO2

-, H2, Fe2+

Usually don’t need sunlight Many archaebacteria are chemoautotrophs

Found deep in ice-core samples in Greenland Found in extremely salty conditions Found on bottom of ocean in near-boiling water

Heterotrophs

Organisms that must get energy from food instead of directly from sunlight or inorganic substances.

Heterotrophs extract the energy from food through the process of cellular respiration. Cellular respiration produces ATP

Includes: animals, fungi, some protists, some bacteria

Heterotrophs

Autotrophs

ATP

ATP is Adenosine TriPhosphate. Is a nucleotide (but doesn’t form DNA) Is the cell’s energy currency.

Chemical energy held in bonds between phosphates

ATP

ENERGY

RELEASEDADENOSINE TRIPHOSPHATE

ADENOSINE DIPHOSPHATE

ADP ATP

Energy

EnergyAdenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)

Partiallychargedbattery

Fullychargedbattery

ENERGY

PART 2:

PHOTOSYNTHESIS

Tracking the flow of energy where it enters living things: plants.

The site for photosynthesis• Photosynthesis

occurs in the leaves.

• The leaves also serve as the site where CO2 and O2 are absorbed and released.

• Water is absorbed by the roots of the plant

PHOTOSYNTHESIS

Process that converts LIGHT energy into CHEMICAL energy.

MEMORIZE THE FORMULA!!!

H2O + CO2 + LIGHT C6H12O6 + O2

Water Carbon Dioxide Glucose Oxygen

Leaf plant organ where photosynthesis occurs

Stomata small pores underneath the plant leaf where carbon dioxide and oxygen to diffuse in and out

Guard Cells cells that surround stomata that open and close according to water pressure

How does the plant get CO2 and release O2?

Equipment Used

The Chloroplast is where photosynthesis occurs in the plant The chloroplast has an inner

and outer membrane. The inner membrane forms

disk-shaped structures called thylakoids which has chlorophyll embedded in it. Thylakoids arranged in

stacks called grana The space around the

thylakoids is the stroma

THYLAKOID

STROMA

Pigments

Pigments (such as CHLOROPHYLL) reflect the colors that they can NOT absorb. Ex: a red shirt can absorb orange, yellow, green,

blue, indigo, and violet but can NOT absorb red so it reflects (and appears) red to your eyes.

QUESTION: Which color light will be more effective for plant growth? Yellow Green Red

Absorption of Light byChlorophyll a and Chlorophyll b

V B G YO R

Chlorophyll b

Chlorophyll a

• There are two types of chlorophyll. • Chlorophyll A and Chlorophyll B

• What color of light is absorbed the most by Chlorophyll b?

• What color of light is absorbed the most by Chlorophyll a?

Pigments

Chlorophyll isn’t the only pigment in plants. Accessory pigments - absorb different

wavelengths (colors) of light than chlorophyll allowing the plant to absorb more light energy during photosynthesis. Carotenoids – appear orange and yellow

Give the fall leaves their colors

Pigments inspire art

PHOTOSYNTHESIS: STEP 1

Step 1 – Light-Dependent Reactions Chlorophyll in the thylakoid membrane absorbs

photons (light energy), which excites electrons Electrons bounce down an “electron transport chain” (ETC)

ETC – a group of integral membrane proteins that ferry electrons As electrons pass through, these proteins pump H+ across the

membrane

Water is broken to resupply lost electrons Byproducts: Oxygen and H+

H+ gradient powers ATP formation Electrons hop off the chain and onto NADP+, forming

NADPH.

Products of Light Reactions

ATP and NADPH (high-energy compounds) Needed to power the next step

Oxygen (released into atmosphere)

PHOTOSYNTHESIS: STEP 2

STEP 2 – Dark Reactions aka. Calvin cycle Occurs in the stroma Does NOT require light The ATP and NADPH produced in the light-

dependent reactions is used to power the conversion of CO2 into glucose (C6H12O6) NADPH converted back into NADP+ ATP converted back into ADP

Both NADP+ and ADP go back to the light reactions to get recharged

Chloroplast – Overview of Light-Dependent Reactions and Calvin Cycle

LIGHT ENERGY

H2O

LIGHT ENERGY

H2O

ATP

NADPH

O2

LIGHT ENERGY

H2O

ATP

NADPH

O2

CO2

CALVIN CYLE/DARK REACTION

LIGHT ENERGY

H2O

ATP

NADPH

O2

CO2

CALVIN CYLE/DARK REACTION

C6H12O6 (Glucose)

ADP

NADP+

LIGHT ENERGY

H2O

ATP

NADPH

O2

CO2

CALVIN CYLE/DARK REACTION

C6H12O6 (Glucose)

ADP

NADP+

REACTANTS

LIGHT ENERGY

H2O

ATP

NADPH

O2

CO2

CALVIN CYLE/DARK REACTION

C6H12O6 (Glucose)

ADP

NADP+

REACTANTS

PRODUCTS

Chloroplast

Water

O2

Glucose

CO2

Light-Dependent Reactions

CalvinCycle

NADPH

ATP

ADPNADP+Chloroplast

HydrogenIon Movement

Photosystem II

InnerThylakoidSpace

ThylakoidMembrane

Stroma

ATP synthase

Electron Transport Chain Photosystem I ATP Formation