Cellular RespirationMs. Napolitano & Mrs. HaasCP Biology

Recall:

The photosynthesis equation is 6CO2 + 6H2O + light 6O2 + C6H12O6

FoodFood – source of raw material for

the cells of the body◦Energy source

calorie – amount of energy needed to raise 1 gram of water 1 degree Celsius

Calorie = kilocalorie = 1000 calories

Cellular RespirationCellular respiration – the process

that releases energy by breaking down glucose & other food molecules in the presence of oxygen

The equation for cellular respiration is: 6O2 + C6H12O6 6CO2 + 6H2O + Energy

Look familiar?!?!?!?!

3 Parts of Cellular Respiration:1. Glycolysis

◦ Cytoplasm

2. Krebs cycle (AKA citric acid cycle)

◦ Mitochondrial matrix

3. Electron transport chain◦ Inner mitochondrial matrix

PART IGlycolysis

GlycolysisGlycolysis – process in which one

molecule of glucose is broken in half◦Produces 2 molecules of pyruvic acid

= 3C compound◦Anaerobic - does not require O2

ATP & NADPH ProductionThe cell needs to input some energy

before more can be produced◦ 2 ATP used up, 4 ATP made = 2 ATP net

gain

High-energy electrons are carried by NAD+

◦ Makes NADH◦ Similar to NADP+ in photosynthesis

Overall glycolysis equation: glucose 2 pyruvic acid + 2 ATP + 2 NADH

PART IIThe Krebs Cycle

The Krebs CycleRecall: 2 pyruvic acid molecules

were made during glycolysisKrebs cycle – pyruvic acid is

broken down into CO2

Steps of the Krebs Cycle:1C from pyruvic acid becomes CO2

Other 2C’s joined to a coenzyme to make acetyl-CoA

Acetyl group (2C) is converted to citric acid (4C)◦ 6C compound

Citric acid becomes 4C again◦ C’s become CO2

◦ ADP ATP ◦ NAD+ NADH

◦ FAD FADH2

High-energy electron carriers

Final Products of the Krebs Cycle:8 NADH2 FADH2

2 ATP6 CO2

PART IIIThe Electron Transport Chain

The Electron Transport ChainThe electron transport chain –

uses high-energy electrons from the Krebs cycle to convert ADP into ATP

Product: H2O

e- are passed from one protein to the next

Enzyme at the end combines e-

with H+ and O2 to form H2O

Product: ATPWhen 2e- pass through ETC,

energy transports H+ across the membrane

ATP synthase pumps H+ to the other side of the membrane via facilitated diffusion

ATP synthase rotates like a turbine, making ADP + P ATP

Other Stuff!

Totals

Glycolysis = 2 ATP (net)Krebs cycle + ETC = ~36 ATP

Total = ~38 ATP molecules from 1 glucose molecule!

FermentationFermentation – process by which ATP

is made in the absence of O2

AKA anaerobicGoes through glycolysis, then picks a

different pathwayAlcoholic fermentation

◦ Alcohol & CO2 is made as wastes

◦ Made by yeast - causes bread to riseLactic acid fermentation

◦ Lactic acid is made as a waste◦ Causes muscle soreness or helps make

dairy products

Energy & ExerciseQuick energy

◦ Only enough ATP in muscles for ~50m sprint (few seconds)

◦ Lactic acid fermentation – ATP made for ~200-300m sprint (~90s)

◦ Lactic acid removal requires extra O2

Long-term energy◦ Cell respiration is the only way to make ATP for

the long-term◦ Pace yourself!◦ Energy stored in muscles as glycogen◦ Stored glycogen - ~15-20 min of activity, then

other energy forms get broken down (ex. fats – weight control!)