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!)