Photosynthesis and Cellular Respiration

Photosynthesis in nature According to the way they obtain energy, all living things

can be divided into : Autotrophs: producers; obtains organic food without

eating other organisms Heterotrophs: consumers; obtains organic food by eating

other organisms or their by-products (includes decomposers)

How are they connected?

glucose + oxygen carbon + water + energydioxide

C6H12O6 6O2 6CO2 6H2O ATP+ + +

Heterotrophs

+ water + energy glucose + oxygencarbondioxide

6CO2 6H2O C6H12O6 6O2lightenergy

+ ++

Autotrophsmaking energy & organic molecules from light energy

making energy & organic molecules from ingesting organic molecules

Where’s the ATP?

oxidation = exergonic

reduction = endergonic

NPK

…

H2O

What does it mean to be a plplantant• Need to…

– collect light energy

– store light energy

– need to get building block atoms from the environment • C,H,O,N,P,K,S,Mg

– produce all organic molecules needed for growth• carbohydrates, proteins, lipids, nucleic acids

ATP

glucose

CO2

The chloroplast

Sites of photosynthesis Pigment: chlorophyll Plant cell: mesophyll Gas exchange: stomata Double membrane Thylakoids, stack-granum Stroma-fluid-filled interior

Photosynthesis

• Light reactions– light-dependent reactions– energy conversion reactions

• convert solar energy to chemical energy

• Calvin cycle– light-independent reactions– sugar building reactions

• uses chemical energy (ATP) to synthesize glucose (C6H12O6)

It’s not theDark Reactions!

Light reactions• Convert solar energy to chemical energy

– ATP

– NADPH

• What can we do now?

energy

reducing power

build stuff !!

photosynthesis

ATP

The Calvin CycleWhoops! Wrong Calvin…1950s | 1961

How is that helpful?• Want to make C6H12O6

– synthesis– How? From what?

What raw materials are available?

CO2

C6H12O6

NADPH

NADPreduces CO2carbon fixation

NADP

RuBisCo • Enzyme which fixes carbon from air

– ribulose bisphosphate carboxylase – the most important enzyme in the world!

• it makes life out of air!

– definitely the most abundant enzyme

I’m green with envy!

It’s not easy being green!

Putting it all together

CO2 H2O C6H12O6 O2lightenergy + ++

SugarBuildingReactions

Energy BuildingReactions

Plants make both: energy

ATP & NADPH sugars

sunlight

O2

H2O

sugars

CO2

ADP

ATP

NADPH

NADP

H2O

Energy cycle

Photosynthesis

Cellular Respiration

sun

glucose O2CO2

plants

animals, plants

ATPThe Great Circleof Life,Mufasa!

CO2 H2O C6H12O6 O2lightenergy + ++

even thoughthis equationis a bit of a lie…it makes a better story

CO2 H2OC6H12O6 O2ATPenergy+ ++

2007-2008

You can grow if you Ask Questions!

2006-2007

What’s thepoint?

The pointis to makeATP!

ATP

Cell Respiration

What is Cell Respiration? • A series of reactions that break down molecules to produce

energy – OR the catabolism of glucose to produce ATP

C6H12O6 6O2 ATP 6H2O 6CO2+ + +

CO2 + H2O + heatfuel(carbohydrates)

COMBUSTION = making a lot of heat, energy by burning fuels in one step

RESPIRATION = making ATP (& some heat)by burning fuels in many small steps

CO2 + H2O + ATP (+ heat)

ATP

glucose

glucose + oxygen energy + water + carbondioxide

resp

irati

on

O2 O2

+ heat

enzymesATP

The reactions are called REDOX Oxidation & reduction

• Oxidation– adding O– removing H – releases energy– exotermic

• Reduction– removing O– adding H – stores energy– endotermic

C6H12O6 6O2 6CO2 6H2O ATP+ + +

oxidation

reduction

(1)Glycolysis • Breaking down glucose

– “glyco – lysis” (splitting sugar)

– but it’s inefficient

• generate only 2 ATP for every 1 glucose

– occurs in cytoplasm

glucose pyruvate2x6C 3C

In thecytoplasm?Why doesthat makeevolutionarysense?

That’s not enoughATP for me!

Is that all there is?• Not a lot of energy…

– for 1 billon years+ this is how life on Earth survived• no O2 = slow growth, slow reproduction

• only harvest 3.5% of energy stored in glucose– more carbons to strip off = more energy to harvest

Hard wayto makea living!

O2

O2

O2

O2

O2

glucose pyruvate

6C 2x 3C

NADH

pyruvate

acetyl-CoA

lactate

ethanol

NAD+

NAD+

NADH

NAD+

NADH

CO2

acetaldehyde

H2O

Krebscycle

O2

lactic acidfermentation

with oxygenaerobic respiration

without oxygenanaerobic respiration“fermentation”

How many types of Cell Respiration?

which path you use depends on who you are…

which path you use depends on who you are…

alcoholfermentation

Fermentation (anaerobic)• Bacteria, yeast

1C3C 2Cpyruvate ethanol + CO2

Animals, some fungi

pyruvate lactic acid3C 3C

beer, wine, bread

cheese, anaerobic exercise (no O2)

NADH NAD+

NADH NAD+

back to glycolysis

back to glycolysis

recycleNADH

Alcohol Fermentation

1C3C 2C

pyruvate ethanol + CO2

NADH NAD+

Count thecarbons!

Dead end process at ~12% ethanol, kills yeast can’t reverse the reaction Generates only 2 ATP!

bacteria yeast

back to glycolysis

recycleNADH

Reversible process once O2 is available, lactate is converted back to

pyruvate by the liver Generates only 2 ATP

Lactic Acid Fermentation

pyruvate lactic acid3C 3C

NADH NAD+

Count thecarbons!

O2

animalssome fungi

back to glycolysis

Pyruvate is a branching pointPyruvate

O2O2

mitochondriaKrebs cycleaerobic respiration

fermentationanaerobicrespiration

ATP accounting so far…• Glycolysis 2 ATP

• Kreb’s cycle 2 ATP

A working muscle recycles over 10 million ATPs per second

There’s got to be a better way!

I need a lotmore ATP!

It is called ELECTRON TRANSPORT CHAIN and makes LOTS of ATP !!!

Counting the energy released in AEROBIC RESPIRATION

• Glycolysis brings : 2 ATP • Kreb’s Cycle brings: 2 ATP)• Electron transport brings: • From glycolysis = 6ATP • From acetyl CoA = 6ATP

From Kreb’s cycle = 22 ATP

• 38 TOTAL ATP/one molecule of glucose