Where Does Energy Come From?

The Sun = the ultimate energy source on Earth

Everyone needs me,

ha ha.

Ch. 8, PhotosynthesisPhotosynthesis is the most important

biological process on Earth Why? (list ONE reason)

– Transformed Earth’s environment so life could be sustained (gave us O2)

– Fulfils our requirements for food, fiber and building materials

– Learning and controlling photosynthesis rates can lead to greater crop yields of food, fiber, wood, fuel and a better use of our lands

– Can provide efficient energy for our use

Isn’t having more food, wood, fuel, and energy important to you?

Write 1 of the

reasons

Who Uses Sunlight for Energy?

Autotrophs = auto (self), self-sustaining, plants and some other types of organisms use sun’s light energy to produce food

Heterotrophs= hetero (other), animals and other organisms, can’t use the sun’s energy directly, they obtain energy from the foods they consume– Eat grasses (herbivores)– Eat other animals (carnivores)– Eat dead/decomposing things (decomposers)– Eat plants and animals (omnivores- you!)

What am I?

What Kinds of Energy Do You Use?

Coal – decaying fossils of plants and animals

Oil- decaying fossils of plants and animals

Natural Gas- decaying fossils of plants and animals

Wood/Peat/Moss- burning of plant materials

Solar- directly from the sun

All of these come from the Sun’sSun’s energy!There’s no escaping it, photosynthesis IS the most

important biological process for life.

Write 2-3 from this

list

Energy is stored in a chemical form called ATP

ATP = adenosine triphosphate, the main energy compound cells use to store and release energy

ADP= adenosine diphosphate is the base for making ATP, and a 3rd phosphate is added to ADP to make ATP, like charging a battery

By breaking the bonds (shared electrons) between the phosphate groups, energy is released

Chemical Energy- ATP

1 2 3

PhotosynthesisPhotosynthesis = the process

where plants use the sun’s energy to convert H2O and CO2 into high-energy carbohydrates (sugars and starches) and O2 (a waste product)

Photosynthesis Equation =

6CO2 + 6H2O C6H12O6 + O2

Light

carbon dioxide water sugars oxygen+ Light +

Write this equation, both lines!

Pigments = light absorbing molecules in plants

Chlorophyll = a plant’s main pigment2 main types: – Chlorophyll A– Chlorophyll B– They don’t absorb light in the

green spectrum, they reflect it, so plants are green

Other accessory pigments, such as red or orange, also absorb light in other regions of the spectrum

How Is Sunlight Captured?

Light absorbed by chlorophyll A and B is actually energy, and that energy is transferred to electrons in the chlorophyll molecule

Stroma = region outside the thylakoid membranes

What Structures Capture the Light Energy?

Photosynthesis happens in chloroplasts

Thylakoids = saclike photosynthetic membranes

In these stacks, Chlorophyll is organized into clusters

called Photosystems = Light collecting units

Grana (or singular Granum)

= thylakoids stacked on top of each other

Label the chloroplast Define the

terms

What Do Plants Do With the Light Energy?

Photosynthesis is divided into 2 parts:1. Light dependent reactions- happens in

the Thylakoid membranes

- Sunlight energy captured by chlorophyll

- Energy transferred to electrons

- O2 is a waste product of this reaction (whew! Thank goodness!)

2. Light independent reactions (Calvin cycle)- happens in the stroma

- CO2 used to create sugars (carbohydrates)

- ATP and NADPH, energy sources for this part of photosynthesis

NADPH = “carrier” molecule that holds electrons and passes them along (passes the energy)

Calvin Cycle in DetailCO2 comes in

Carbon is “fixed”

ATP usedturns into ADP

NADPH usedturns into NADP+

Product=

Sugars

Label the Calvin Cycle

What You Need To Know….

Shortened version, just for YOU:

Light reactions of Photosynthesis:

Captures Sunlight’s energy and uses H2O to passalong that energy through electrons to make ATP and NADPH, O2 is a waste product

Dark reactions of Photosynthesis:The Calvin Cycle “fixes” carbon from CO2 and, using

ATP and NADPH (from the light reactions) as energy

sources, makes Sugars (food for YOU)

What Can Affect the Rate of Photosynthesis?

What happens when something goes wrong?Too little H2O- can slow or stop photosynthesis

Desert plants have waxy coating on their leaves to reduce H2O loss

Too Hot or too Cold- photosynthesis depends on the temperature being between 0oC and 35oC, above or below this, and it will slow or stop

Too much or too little light- either one can slow or

stop photosynthesis

Ch. 9, Cellular RespirationWe need food.

When you’re hungry, you get weak, tired, cranky, irritable, and you could pass out! Eventually, you can die of hunger!

So, when you’re hungry, your body is actually saying….

“You idiot! I need energy! Feed me!”

How Much Energy Is In Food?

One calorie (cal)= amount of energy needed to raise the temperature of 1 g of H2O 1 degree Celsius

Food labels use a kilocalorie = 1000 cal(Calorie)

Your cells don’t “burn” glucose (sugar), instead they release the energy from glucose in a reaction called….

Glycolysis

Cellular RespirationIn the presence of O2……..

Gycolysis, the Krebs Cycle, and the electron transport chain make up a process called Cellular Respiration

Cellular Respiration = process that releases energy by breaking down glucose (sugar) and other food molecules (O2 present)6O2 + C6H12O6 6CO2 + 6H2O + Energy

oxygen + glucose Carbon dioxide + water + energy

Equation for cellular Respiration:

Write this equation, both lines!

Yes! O2 is present!!!

Overview of Cellular Respiration

Cytosol Mitochondrion

Glycolysis Krebs Cycle

Electron Transport

Chain

Electrons carried By NADH

Electrons carried byNADH and

FADH2

ATPATP ATPATP ATPATP

Glycolysis1st set of reactions in cellular

respiration

Glycolysis = the process where 1 molecule of glucose is broken in half, producing 2 molecules of pyruvic acid, a 3-carbon compound

At the beginning of the pathway, 2 ATP molecules are invested

At the end of the pathway, 4 ATP molecules are produced

Net Gain of 2 ATP molecules

This occurs in the Cytoplasm

2 Pyruvic acidmolecules

cc

c

c

c c

c

c

c

2ATPs

+ 4ATPs

I’m waiting!

Glycolysis cont….With or without O2, NADH production

occurs:

4 high-energy electrons are removed from glucose and passed on to an electron transport carrier called NAD+

NAD+ = waiting on electronsNADH = holding a pair of electrons (energy)

Ah, thank you.

FermentationWhen O2 isn’t present………

Fermentation = in the absence of O2, releases energy from food molecules by producing ATP

2 main types of fermentation:1. Alcoholic (bread, beer)

2. Lactic Acid (what makes your muscles sore after exercise)

Pyruvic acid + NADH Alcohol + CO2 + NAD+

Pyruvic acid + NADH Lactic Acid + NAD+

No O2 = anaerobic

The Next Step…After glycolysis, 90% of the chemical

energy in glucose is still in the form of pyruvic acid

O2 is a powerful electron acceptor, it loves electrons

The 2nd step in Cellular Respiration is the Krebs Cycle and

Krebs needs O2 to work= aerobic

Because Cellular Respiration needs O2 to be present, we call it “Respiration” like breathing, but for the cell

c

c

c

Pyruvic Acid

The Krebs CycleKrebs Cycle = pyruvic acid is broken

down into CO2 (carbon dioxide) in a series of energy-extracting reactions

A.K.A., the Citric Acid Cycle

The Krebs Cycle occurs in the matrix (inner portion) of the Mighty Mitochondria

c

c

c

Outer MembraneInnerMembraneMatrix

Cristae = folds in the inner membrane

Pyruvic Acid

Energy Produced by Krebs

Pyruvic Acid(from glycolysis)

CO2

CO2

3 NADH

3 NAD+

KrebsCycle

ADPATP

FAD

FADH2

Acetyl CoA

NAD+

NADH

Krebs occurs in the matrixof the Mitochondria

Fill in the boxesin your notes

And then….Krebs Cycle makes high energy electrons

that are passed on to NADH and FADH2

The electrons are passed from these carriers to the Electron Transport Chain or System

Electron Transport Chain (ETC) = uses the high energy electrons from Krebs Cycle to convert ADP to ATP

ETC occurs in the inner membrane of the mitochondria

Electron Transport Chain

Electron Transport Chain

Cytosol

Mitochondria Matrix

ADPATP

NADHNADP+

FADH2

FAD

ATPSynthase

InnerMitochondrialMembrane

OuterMitochondrialMembrane

e-e-e-

e-

e- e- e-

e-

e-

e-e-

e-

e-

e-

OH H

e-

electrons

H+

H+

H+

H+

H+

H+

CytoplasmThe gradient of H+ ions

“charges” ATP synthase, an enzyme, so it can

make ATPATP

How much chemical energy does cellular respiration yield from a single molecule of glucose?

Energy Totals

1 Glucose

2 ATP2 NADH 4 ATP

2 ATP

Glycolysis

2 Pyruvic Acid

KrebsCycle

2 NADH 6 ATP

2 ATP

18 ATP6 NADH

6 FADH2 4 ATP

Total 36 ATP !!!!!!

Krebs Cycle and ETC

Energy and ExerciseQuick Energy- when you need to run!

(sprinting)

Cells store enough ATP to last only the few seconds of a sprintOther ATP is formed through lactic acid fermentation (why you get sore!)

Long Term Energy- endurance runningCells use cellular respiration only to generate energy needed for longer periodsEnergy stored as Glycogen, and it’s used

first then your cells go for the fat storage

Photosynthesis vs. Cellular Respiration

Photosynthesis•Supplies energy plants get from sunlight

•Removes CO2 from the air

•Releases O2 into the air•Occurs only in plants, algae, and some bacteria

Cellular Respiration•Uses energy to break down food

•Puts CO2 back into the air

•Removes O2 from the air•Occurs in ALL eukaryotes and prokaryotes