Download Cellular Respiration

NOTES: 9.1-9.2
Cellular Respiration
Vocabulary:
-Glycolysis
-ATP
-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
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
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 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


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
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 groups

AMP
ADP
P
P
ATP
Cellular Respiration:

A process that releases ENERGY by
breaking down food molecules in the
presence of OXYGEN

Occurs in both plants and animals
Cell respiration occurs in 3 stages:



Glycolysis
Krebs cycle
Electron transport chain
“RESPIRATION”
(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
(called PYRUVATE or PYRUVIC ACID)
Equation for glycolysis:

C6H12O6
enzymes in
cytoplasm
2 pyruvates + 2 ATP
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
(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
CO2
H2O & heat
energy
O2
Glucose + Oxygen
C6H12O6
+ 6O2
Carbon Dioxide + Water
6CO2
Look familiar???
+
6H2O
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 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
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)
Equation for Respiration:
C6H12O6 + 6O2
6CO2 + 6 H2O + 36 ATP
Summary of Cellular Respiration
GLYCOLYSIS
“break sugar”
Location in the
cell:
Krebs Cycle &
E.T.C.
Cytoplasm
Mitochondria
It starts with:
C6H12O6
(glucose)
It ends with:
2 (C3H6O3)
pyruvic acid
NO
(ANAEROBIC)
2 (tiny)
2 pyruvic acid
O2
H2O, CO2, ATP
Is Oxygen
required?
# of ATP’s
Produced:
YES!
(AEROBIC)
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
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.