Vocabulary:

-Glycolysis -ATP

NOTES: 9.1-9.2 Cellular Respiration

-Krebs Cycle

-electron transport chain

-Pyruvic acid

-glucose

-Aerobic / Anaerobic

Review

� What is photosynthesis?� Where does this occur?� What is the difference between ATP and � What is the difference between ATP and

ADP?� What is the difference between NADPH

and NADP+?� Light dependent vs. Light independent

reactions

Chemical Energy & Food

� Organisms get the energy they need from FOOD.

� Energy stored in food is expressed in units � Energy stored in food is expressed in units of CALORIES.

� 1 calorie = the amt. of energy needed to raise the temp. of 1 g of H2O by 1°C.

Chemical Energy & Food

� Different foods are capable of storing different amounts of energy:

� 1 g glucose: 3811 calories (3.811 kcal)� 1 g glucose: 3811 calories (3.811 kcal)

� 1 g beef fat: 8893 calories (8.893 kcal)

� How is the energy in sugar (glucose) molecules released so it can be used by the cells of an organism?

� cellular respiration!

� Cellular Respiration occurs in both plant & animal cells animal cells

� WHERE????

� CYTOPLASM &

MITOCHONDRIA!!!

The POWERHOUSE of the Cell!!

Cellular Respiration…A Controlled Process

� Food (glucose), like fuel, is "burned" by our cells for energy

� however, if it's burned all at once, too � however, if it's burned all at once, too

much energy is released

� therefore, the reaction is broken down into many small steps controlled by ENZYMES

� Cells gradually release the energy from

glucose and other compounds

� the energy is transferred to the bonds of ATP which stores and releases the energy in usable amounts to be used by the cell

� energy is stored in bonds between phosphate groupsphosphate groups

AMP ADP ATP

P

P

Cellular Respiration:

� A process that releases ENERGY by breaking down food molecules in the presence of OXYGENpresence of OXYGEN

� Occurs in both plants and animals

Cell respiration occurs in 3 stages:

� Glycolysis

� Krebs cycle

� Electron transport chain“RESPIRATION”(uses oxygen)� Electron transport chain (uses oxygen)

GLYCOLYSIS(glyco= sugar, lysis = breaks down)

� Process occurs in the cytoplasm� Breaks glucose down from 6-carbon

compound into two 3-carbon compounds compound into two 3-carbon compounds (called PYRUVATEPYRUVATEPYRUVATEPYRUVATE or PYRUVIC ACIDPYRUVIC ACIDPYRUVIC ACIDPYRUVIC ACID)

Equation for glycolysis:enzymes in

C6H12O6 2 pyruvates + 2 ATPcytoplasm

� Glycolysis can occur if oxygen is present (aerobic) or absent (anaerobic)

� Glycolysis is ALWAYS the first step in breaking down glucose

� If oxygen IS present, then cells proceed with Krebs cycle & electron transport chain

� If oxygen is NOT present, then cells will carry out fermentation

Cellular Respiration can be broken

down into 3 processes:

1) Glycolysis: glucose is broken into 2 pyruvate; 2 ATPs produced; electrons from

glucose passed to NAD + ���� NADH

2) Krebs Cycle: pyruvate broken down into CO2) Krebs Cycle: pyruvate broken down into CO2

(waste) & electrons are passed to NAD+ �

NADH; 2 ATPs produced

3) Electron Transport Chain: high energy elec.

from glycolysis & Krebs (NADH) are used to convert ADP ���� ATP; oxygen must be present

GLUCOSE

O2

CO2

H2O & heat

energy

Glucose + Oxygen Carbon Dioxide + Water

C6H12O6 + 6O2 6CO2 + 6H2O

Look familiar???

Krebs Cycle & E.T.C.

� Occur in the MITOCHONDRIA of a cell

� Only if oxygen is PRESENT (aerobic)

� Use the pyruvic acid from glycolysis to produce

carbon dioxide, water, and ATPcarbon dioxide, water, and ATP� Products:

�34 ATP per molecule of glucose

� carbon dioxide

�water

So how does this happen?

� The KREBS CYCLE breaks the bonds of pyruvate; high-energy electrons are passed to NAD + ���� NADH; waste passed to NAD ���� NADH; waste product CO2 produced; 2 ATPs produced.

� ELECTRON TRANSPORT CHAIN: uses high-energy electrons from NADH (&FADH2) from gly. & Krebs to convert ADP ���� ATP

� The NADH and FADH2 (from glycolysis & Krebs cycle) carry energy to the electron transport chain to make more ATP (this requires oxygen; oxygen acts as the final electron acceptor in the chain)electron acceptor in the chain)

Equation for Respiration:

C6H12O6 + 6O2 6CO2 + 6 H2O + 36 ATP

Summary of Cellular Respiration

GLYCOLYSIS

“break sugar”

Krebs Cycle & E.T.C.

Location in the cell:

Cytoplasm Mitochondria

It starts with: C6H12O6

(glucose)

2 pyruvic acid

O(glucose) O2

It ends with: 2 (C3H6O3)

pyruvic acid

H2O, CO2, ATP

Is Oxygen required?

NO

(ANAEROBIC)

YES!

(AEROBIC)

# of ATP’s Produced:

2 (tiny) 34 (lots!)

GRAND TOTAL = 36 ATP!!

� 2 are produced in Glycolysis, 2 in Krebs Cycle, and 32 in Elec. Trans. Chain

�18 times more ATP are produced in the

presence of Oxygen!!

How efficient is this??� The 36 ATP molecules the

cell makes per 1 glucose represents about 36% of the total energy in glucose

� Even though it doesn’t � Even though it doesn’t seem like much, this is more efficient than your car’s gas burning engine

� What happens to the remaining 64%??? � It is released as heat.