AP Test Cellular Respiration and Photosynthesis

Cellular Respiration How our body turns food and oxygen into

ENERGY called ATP

3 Steps:GlycolysisKreb’s CycleETC (Electron Transport Chain)

Redox ReactionsChemistry review:Oxidation = losing an electronReduction = gaining an electronA redox reaction is a chemical reaction in

which one molecule gains electrons and one loses them

Example of cellular respiration: glucose is oxidized into carbon dioxide, oxygen is reduced to water

GlycolysisGlycolysis is the first step of cellular

respirationIt means “splitting sugar”One molecule of glucose is split in half into

2 molecules of pyruvic acid (pyruvate)C6H12O6 2 C3H6O3

GlycolysisInput: glucoseOutput: 2 molecules of

pyruvate, 2 ATP, and 2 NADH

NADH is a molecule that carries electrons from glycolysis and the Kreb’s Cycle to the ETS (it gains electrons = reduced)

Once there, it releases the electrons to make ATP (it is oxidized to NAD+)

Kreb’s CycleStep 2 of Cellular Respiration is called the

Kreb’s Cycle, and is also known as the Citric Acid Cycle

It ONLY occurs in the presence of oxygenIt takes place in the mitochondrial matrix,

the space between the inner folded membranes of the mitochondria

Kreb’s CycleAcetyl coA undergoes a series of redox

reactions in the Kreb’s cycle, rearranging its formula and transferring electrons

The net output for 2 TURNS of Kreb’s is: 6 NADH, 2 FADH2 (another electron carrier), and 2 ATP

A byproduct, carbon dioxide, is released

Electron Transport ChainThe last step is called the electron

transport chain (ETC) or system (ETS), or oxidative phosphorylation (means losing electrons and adding a phosphate group to ADP to make ATP)

It occurs in the cristae of the mitochondria, on the membranes on the inside

ETC As ADP is getting phosphorylized (called chemiosmosis), the electrons

have reached the bottom of the waterfall The electrons are attracted to a super electronegative atom, oxygen Oxygen is the final electron acceptor. It gains electrons (is reduced)

and joins with the H+ ions coming through ATP synthase to make water

We breathe out the water (along with the CO2 from Kreb’s)

ETCAt the end of the ETC, approximately 34

ATP are generated through the processes of Oxidative Phosphorylation (the electrons moving down the waterfall) and chemiosmosis (the diffusion of H+ ions through ATP synthase)

SummaryOxygen we breathe in becomes waterGlucose we eat is used to make ATP and

CO2 (waste)A total of approximately 38 ATP are made

per glucose molecule

stroma

thylakoid

ATP

I ’m green with envy!

It’s not easy being green!

NADPADP

CO2 H2O C6H12O6 O2lightenergy + ++

SugarBuildingReactions

Energy BuildingReactions

Plants make both:energy

ATP & NADPH

sugars

sunlight

O2

H2O

sugars

CO2

ADP

ATP

NADPH

NADP

photosynthesis

photorespiration