Biology 10

CELLULAR RESPIRATION

POP QUIZ

• 1. The process of cellular respiration begins with _______________.

• 2. ____________ and _____________ are the reactants for cellular Respiration.

• 3. Glycolysis breaks down ______________ molecules.

• 4. How many ATP molecules are needed to start Glycolysis

• 5. How many ATP molecules are made by the end of glycolysis?

• 6. T or F: Animals cannot photosynthesize.

• 7. T or F: Plants undergo Cellular Respiration.

• 8. What is the energy needed to raise 1 g of water by 1 degree Celsius?

• When no oxygen (anaerobic) is present, this pathway follows glycolysis.

Living things get the energy they need from food. Both plants and animal cells carry out the final stages of cellular respiration in the mitochondria

Chemical Energy and Food• How much energy is actually present in food?

• One gram of the sugar glucose (C6H12O6), when burned in the presence of oxygen, releases 3811 calories of heat energy.

What is a calorie?

Cellular Respiration Begins….

• There are three stages of cellular respiration

• Glycolysis

• The Krebs Cycle

• The Electron Transport Chain

Gly

coly

sis

Glycolysis and Cellular Respiration

Glycolysis

ATP Production Add 2 molecules of ATP to start process

Investment: 2 ATPsFinal balance: 4 ATPsNet gain: 2 ATPs

NADH Production

GYLCOLYSIS RECAP

glucose oxidized yields pyruvic acid

reactions take place in cytosol

NAD+ to NADH (electron acceptor)

Pyruvic acid yields 4 ATP but 2 used in process (so net yield is 2 ATP)

Fermentation• When oxygen is NOT present, glycolysis is followed by a different

pathway: Fermentation.

Alcoholic Fermentation

Drunk Squirrel

Lactic Acid Fermentation

Sauerkraut

Fermentation•fermentation is the formation of alcohol from sugar.

•Occurs in cytosol when “NO Oxygen” is present (called anaerobic).

•Remember: glycolysis is part of fermentation.

•Two Types:

1. Lactic Acid (animal cells)

2. Alcohol (plant cells)

Lactic acid fermentation

•NADH oxidized to NAD+

e.g. Yogurt, cheese

•*in muscle – not enough oxygen so switch

to anaerobic respiration b/c oxygen is

depleted which makes cytosol acidic so

produces cramps

Lactic Acid Fermentation

Animals (pain in muscle after a workout).

2 Lacticacid

2NADH 2 NAD+

CCC

Glucose

GlycolysisCCC

2 Pyruvicacid

2ATP2ADP+ 2

2NADH

P

2 NAD+

CCCCCC

Lactic Acid Fermentation

End Products: Lactic acid fermentation

2 - ATP (phosphorylation)

2 - Lactic Acids

Alcoholic Fermentation

•convert pyruvic to ethyl alcohol by

removing CO2

e.g. bread, beer, wine - need enzymes in

yeast

Alcohol Fermentation

Plants and Fungi beer and wine

glucose

Glycolysis

CCCCCC

CCC

2 Pyruvicacid

2ATP2ADP+ 2

2NADH

P

2 NAD+

CC

2 Ethanol2CO2

released

2NADH 2 NAD+

Alcohol Fermentation

•End Products:

2 - ATP (phosphorylation)

2 - CO2

2 - Ethanol’s

•glycolysis is not efficient but unicellular

organisms don’t need much energy to function

•E.g. paramecium, ameoba

•probably evolved early in history of life

• kilocalories – 1 kcal = 1000 cal