photosynthesis ch. 8

Photosynthesis – Ch. 8

Ch. 9 - Cellular Respiration

Checking Prior Knowledge

Molecules

- atoms chemically bonded to one

another (ionic or covalent)

Ways Organisms Obtain Energy

- autotrophs – “self feeders”

- heterotrophs – “other feeders”

Energy and Living Organisms

Energy cannot be recycled, or used

again – it simply changes form

Energy flows through an ecosystem

from the sun to producers and then

to consumers

Two Main Reactions Supply Energy

Photosynthesis

autotrophs convert the energy of sunlight

into the energy in chemical bonds of

sugar

Cellular Respiration

autotrophs and heterotrophs convert the

stored chemical energy of sugar/food

molecules to more readily available

chemical energy

Natures Rechargeable Batteries

Just like battery operated machines,

living organisms use molecules that

act like rechargeable batteries to

store energy

Compounds that store energy:

ATP, NADH, NADPH, and FADH2

ATP – Primary Rechargeable

Cells need a constant supply of energy

Production of ATP

ATP is produced by phosphorylating an ADP molecule

Production of ATPThe energy in ATP drives three main types of cellular work.


Converting Chemical Energy

into Energy for Cellular Activity

How do organisms capture and use energy?

This chapter (9)

focuses on how all organisms convert food energy into ATP – the energy cells use

Energy

cannot be recycled – it simply

changes form.

flows one way through an

ecosystem - from the sun to

producers and then to consumers.

Equal but

Opposite

Net Reactions

Photosynthesis


PHOTOSYNTHESIS

the net chemical reaction is oppositeBUT

the steps and organelles are not

AEROBIC CELL RESPIRATION

ochondriain the Mitenergy chem.O6H6CO6OOHC 2226126

oroplastin the Chl

2612622 6OOHCenergylight O6H6CO

Getting Energy from Food

Both autotrophs and

heterotrophs need to

convert organic

compounds into

usable forms of

chemical energy

Food and Energy

Turning Glucose into Energy

Complex Carbohydrates (polymers = starch, glycogen)

converted into glucose monomers through digestion

Glucose transported to cells and broken down to release the energy stored in the chemical bonds


The process of converting glucose into

usable cellular energy

2 Pathways for ATP Production

Without Oxygen

Anaerobic Respiration

Fermentation

Ancient form

Location: Cytoplasm only

With OxygenAerobic Respiration


Modern form

Location: Cytoplasm and Mitochondria

Whether or not there is oxygen,

BOTH forms of respiration begin

with

GLYCOLYSIS

ATP Pathways

Stage 1 - Glycolysis

O2 No O2

Fermentation(Anaerobic Respiration)

Aerobic Cellular Respiration

Stage 2 – Krebs Cycles

Stage 3 – Electron Transport Chain

2 Types of Cellular Respiration

Aerobic

Anaerobic ATP 2Glucose 1 nrespiratiocellular anaerobic

ATP 38-36Glucose 1 nrespiratiocellular aerobic

ATP Production is very different in each type, but both begin with glycolysis

Glycolysis

Requires:

Glucose, 2 ATP, 4ADP, 2NAD+

Produces:

4 ATP, 2ADP, 2 NADH,

2 Pyruvic Acid (Pyruvate) molecules

Where?

In the cytoplasm

Net gain is only 2 ATP!

Glycolysis in Action

Anaerobic Ways to Get Energy

No Oxygen? No Problem! (sort of)

Anaerobic – Without O2

Fermentation is the extraction of

energy without the use of oxygen

Both forms of anaerobic fermentation

are energetically poor for the

organisms that use them

Both forms start with glycolysis

Anaerobic Respiration

NOT energetically effective

Only 2 ATP from each

glucose molecule as a result

of glycolysis

YOU NEED TO DISCHARGE THE NADH BATTERIES!

So you have 2 ATP? And you can’t get any more. Why would

you need fermentation (anaerobic respiration)?

Quick Recall!!!

Point of Fermentation?Discharging the Batteries!

Fermentation:

Reactants Pyruvic Acid, NADH

Products

Alcoholic Fermentation: alcohol, NAD +, CO2

Lactic Acid Fermentation: lactic acid, NAD+

KEY: both types of fermentation are needed to

discharge the NADH battery so it can be

returned to glycolysis as NAD+ for continued

production of ATP

Fermentation and Glycolysis

GLYCOLYSIS

1 Glucose 2 NAD+2 ATP

** 4 ATPNet 2 ATP

2 Pyruvic Acid 2 NADH

FERMENTATION

Alcohol / Lactic Acid

Anaerobic Fermentation

Both forms of anaerobic fermentation begin

with the 3 carbon molecule Pyruvic Acid

(Pyruvate) from Glycolysis

Because 2 pyruvate molecules are formed in glycolysis, the process

happens twice, so there is double this amount in the end.

2CO NAD EthanolNADH Pyruvate

NAD Acid LacticNADH Pyruvate

Ethanol Fermentation

Can be used for a variety of

applications

– beer and wine

– bread production

– microbial biofuel

production

Lactic Acid Fermentation

Occurs in animal cells, some

fungi and bacteria

– can be used for• yogurt, sourdough breads,

sauerkraut, cucumber pickles

and olives

– causes the muscles in

your body to hurt during

strenuous exercise

Always the first stepof respiration

Then make a decision:O2 or no O2?

Fermentationis the answer if there isno O2

Now! On to the O2 !


Review of ATP PathwaysStage 1 - Glycolysis

O2 No O2

Fermentation(Anaerobic Respiration)


Stage 2 – Krebs Cycles

Stage 3 – Electron Transport Chain

Aerobic Respiration

Requires:

Glucose and 6O2

Produces:

36 ATP, 6CO2 and 6H2O

Where?

Inside mitochondria (eukaryotes)

On the cell membrane (prokaryotes)

Location, Three Phases of Aerobic CR, Electron Carriers and ATP Production

In the Cytoplasm In the Mitochondria

glycolysis Electron

Transport

2 ATP 2 ATP 32 ATP

NADH

Krebs

Cycle

NADH & FADH2

Location of the Kreb’s Cycle and Electron Transport Chain

Krebs Cycle

Requires:

2 Pyruvic Acid (Pyruvate) molecules,

2ADP, 8 NAD+, and 2 FAD

Produces:

2 ATP, 8 NADH, 2FADH2 , 6CO2 for each

Glucose

Where?

In the matrix of the mitochondria

Turns 2 times for each GLUCOSE MOLECULE!

Kreb’s Cycle in Action

Electron Transport

This is where MOST of the energy of CR is made

NADH and FADH2 from glycolysis and the Kreb’s cycle are used to create a H+ gradient to power ATP synthase

ET –

Produces 32 ATP

Electron Transport in Action

photosynthesis ch. 8

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