Download Cellular Respiration

Cellular Respiration
Cellular Respiration

A quick review…


When we eat, we get ______ from glucose
and other sugars
Food energy is c_______ into usable
energy

Energy used to bond phosphate
groups to ADP to make _____ .
Cellular Respiration

What is cell respiration???


Respiration: the process of breaking down
food molecules into usable energy
THE GOAL:
Create ATP for cells to use
 Free up electrons—have high energy

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy (ATP + heat)
2
2
34
Cellular Respiration

Types of cell respiration

Aerobic Processes:
REQUIRE oxygen to take place
 A lot of energy available (efficient)


Anaerobic Processes:
DO NOT require oxygen to take place
 Get energy quickly (inefficient)

Cellular Respiration
2
2
34
Glycolysis

Involves breaking down 6-carbon sugars

Break sugars into pyruvic acid molecules


This process is ANAEROBIC


3-Carbon molecules
No oxygen necessary
Occurs in the cytoplasm of cells
Glycolysis

You will need to know this…
Glycolysis
Just Kidding… 
Glycolysis

Glycolysis also creates hydrogen ions
and free electrons


H + ions bond with NAD+ to form
NADH + H +


The whole point of respiration = high energy
NADH carries electrons and H + ions
This process uses 2 ATP but
creates 4 ATP molecules
Glycolysis
Glycolysis

TOTAL ATP PRODUCTION:



Glycolysis Step 1 uses 2 ATP molecules
Glycolysis Step 2 converts 4 ADP molecules
into 4 ATP molecules
Net ATP production = 2 ATP for every
glucose molecule
Glycolysis

Oxygen is our
friend…

When oxygen is
present,
aerobic respiration
occurs

Happens in the
mitochondria
Glycolysis

Breaking down Pyruvic Acid…

Occurs in the mitochondria

Pyruvic Acid = 3-carbon compound

Broken down into…
2-Carbon compound—acetic acid
 Carbon Dioxide

Glycolysis

Intermediate Step in Glycolysis

2-Carbon Compound—Acetic Acid
Combined with coenzyme A (CoA)
 Forms compound called acetyl-CoA


This is only an intermediate step—have to
move pyruvic acid into Krebs Cycle
Glycolysis
Glycolysis =
2 ATP
Cellular Respiration
2
2
34
Citric Acid (Krebs) Cycle

Produces more ATP and releases more
electrons

Electrons picked up by NAD + and FAD


Organic carrier molecules
Occurs inside mitochondria

Mitochondrial Matrix
Citric Acid (Krebs) Cycle

Acetyl CoA combines with a 4-carbon molecule
to form a 6-carbon molecule






Citric Acid
NAD becomes NADH
FADH becomes FADH2
CO2 released
ATP is created
The cycle starts again
Citric Acid (Krebs) Cycle
Citric Acid (Krebs) Cycle
Citric Acid Cycle =
2 ATP
Cellular Respiration
2
2
34
Electron Transport Chain

What is the ETC???



A series of molecules along which electrons
are transferred, releasing energy
Occurs in the mitochondria—
mitochondrial matrix
Aerobic process

Oxygen is involved

Acts as the electron acceptor
Electron Transport Chain

As the electrons are passed between
carrier proteins, energy is released


ATP is created
Carbon is given off as carbon dioxide
Electron Transport Chain
ETC =
34 ATP
Electron Transport Chain

A problem exists if there is no oxygen


When oxygen is used up, electrons cannot
be removed


Anaerobic process
Traffic jam in the mitochondria
KEY POINT —Electron Transport Chain
cannot run without oxygen
Anaerobic Respiration

If no oxygen present after glycolysis,
pyruvic acid can still be broken down

This is Fermentation
Only 2 ATP made during fermentation

Uses electrons carried by NADH + H +
so that NAD+ can regenerate for
glycolysis
Anaerobic Respiration
Anaerobic Respiration

**Two types of fermentation

Lactic Acid Fermentation
Glucose

2 Pyruvic
Acid
2 Lactic
Acid
Alcoholic Fermentation (Yeast)
Glucose
2 Pyruvic
Acid
2 Ethanol
+ 2 CO2
Anaerobic Respiration

Lactic Acid Fermentation

Muscle fatigue
When your muscle cells require more energy
than can be produced
 Lack of oxygen
 Lactic acid build up = muscle fatigue


When oxygen is present, lactic acid breaks down
Anaerobic Respiration
Anaerobic Respiration

Alcohol Fermentation



Occurs in bacteria, plants and most animals
Can you think of a bacteria that is used for
fermentation???
Pyruvic Acid is converted into ethanol and
carbon dioxide
Anaerobic Respiration
Cellular Respiration
2
2
34
Cellular Respiration
General Formula
C6H12O6 + 6 O2
6 CO2 + 6 H2O
Often, in attempts to simplify, false paradigms are
created.
Some textbooks do this when introducing
biochemical reactions.
Photosynthesis
H 2O  light  CO 2  H 2O  C 6 H 12O 6  O 2
WEG  WEG
light  O 2  C 6 H 12O 6  CO 2
Respiration
H 2O  C 6 H 12O 6  O 2  H 2O  ATP  CO 2
C 6 H 12O 6  O 2  ATP  CO 2