Cellular Respiration
(Making ATP from food)
crash-course-bio ATP
RESPIRATION
1
3
All living cells are made up of chemical substances
The processes of living involve reactions between the
substances
A reaction is an event which produces a change in a
substance
For example, a reaction between carbon and oxygen (such
as burning coal in air) changes the carbon in the coal,
and oxygen in the air into carbon dioxide
This reaction can be represented by the equation
C
carbon
+
O2
CO2
oxygen
carbon dioxide
4
plus
an atom of carbon
c
C
a molecule of oxygen
O2
o
o
combine to form a molecule of carbon dioxide
CO2
Metabolizing
Molecules
Metabolism – all the chemical reactions
occuring in your cells at one time

Two types of chemical reactions can occur as
an organism metabolizes molecules:

Anabolic reactions - this type of reaction
builds molecules (specifically, small molecules
are combined into large molecules for repair,
growth or storage).

Catabolic reactions – this type of reaction
breaks down molecules to release their stored
energy
What do you use to get
yourself out of bed in the
morning?
 ENERGY

Where do our cells get energy?


6-C sugars are the MAJOR source of energy for
cell
What type of macromolecule are 6-C sugars?


Carbohydrates
Cells break down glucose a 6-C sugar to make
ATP “energy”
What
is a molecule of energy?
ATP
So, did you eat ATP last night?


Or did you eat pizza?
Food
you eat must be broken
down into carbs (sugar),
protein, and lipids (fat).
Setting the stage…





Eat!
Amylase breaks down
starch
glucose
Digestion
Circulation
Into cells (facilitated diffusion)
Phytosynthesis is done by autotrophs to convert solar energy into chemical energy.
Cellular respiration is the process of converting chemical energy to ATP.
C6H12O6 + 6O2  ATP + 6 CO2 + 6 H2O
At first glance it may appear as if phytosynthesis and cellular respiration are the reverse process
But they occur in different organelles (chloroplasts and mitochondria) and the chemical
reactions are very different.
Transferring Energy with ATP



Cells transfer energy between anabolic and
catabolic reactions by using an energy
middleman -ATP (adenosine triphosphate)
When ATP supplies energy to a process, one of
its phosphates gets transferred to another
molecule, changing it into ADP (adenosine
diphosphate).
Cells can recreate ATP by using a catabolic
reaction to reacttach a phosphate group to
ADP.
Chemical Structure of ATP
Adenine Base
3 Phosphates
Ribose Sugar
How Do We Get Energy From
ATP?
By breaking the
high- energy
bonds between
the last two
phosphates in
ATP
Define Cellular Respiration

Cellular respiration is a
process where oxygen is used
to break down organic
compounds (sugars) to
produce ATP (energy).
7
One of the energy-producing reactions is called
respiration
(Respiration is not the same thing as breathing)
The chemical reactions of respiration take place
in all living cells
The reaction takes place between oxygen and a
substance which contains carbon. The reaction
produces carbon dioxide and water, and releases
energy
8
The carbon-containing substances come from
FOOD
The oxygen comes from the AIR (or water)
The energy is used to drive other chemical
reactions taking place in cells
One example of this is the release of energy in
muscle cells to make them contract and
produce movement
10
Some examples of the use
of energy in organisms
muscle
contraction
Respiration
supplies
the energy for
germination
chemical changes in cells
cell division
Energy use in muscle contraction
11
shoulder blade
The blood stream brings
food and oxygen to the
muscle cells. Respiration
occurs in the cells and
releases energy which
……
upper arm
bone
lower arm bones
12
…….makes the muscle contract
and pull the lower
arm up
15
One example of respiration in ourselves
2.
The lungs absorb oxygen
from the air
1.
1.Food
2.The
stomach and
intestine digest food.
One of the products
is glucose
4
RESPIRATION
Glucose and
oxygen react to
produce energy for
muscle contraction
Air taken in
taken in
3.The
blood stream
carries glucose and
oxygen to the muscles
Carbon dioxide
is carried to the lungs
by the blood
5
Where does cellular respiration occur?
In
the cytoplasm and
mitochondria of cells.
Mitochondria


The matrix where 3carbon pieces that
came from
carbohydrates are
broken down to
(CO2 and water)
The cristae is
where ATP is made
Mini Lab


1. Open and close your hand as many times as
possible for 30 seconds. Have your partner time and
record the results…QUICKLY! After only a 5 second
break repeat this step for a total of 5 trials.
2. After you have completed the 5 trials. Switch jobs
with your partner, and record your partner’s 5 trials.
Trial 1
Name
Name
Trial 2
Trial 3
Trial 4
Trial 5
Observations:

How did your hand feel after the 1st trial?

3rd trial?

5th trial?

How did the amount of times you could open
and close your hand change from the 1st trial
to the 5th trial?
Analysis:

Can you think of a time where your body got tired from
working hard? Give an example.

Why do you think your hand began feeling this way?

Why do you think your muscles get sore after a hard work
out?
Cellular Respiration
Cellular Energy
•The Stages of Cellular Respiration- Cellular
respiration has two main stages:
•Glycolysis The first stage of cellular respiration is
called glycolysis.
•Aerobic and Anaerobic Respiration The second
stage of cellular respiration is either aerobic respiration
(in the presence of oxygen) or anaerobic respiration (in
the absence of oxygen). A large amount of ATP is made
during aerobic respiration.
Flowchart
Cellular Respiration
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
+
ATP
THE BIG PICTURE
Cellular Respiration
Glycolysis
Aerobic
ATP
Krebs
ATP
Anaerobic
Alcohol
Fermentation
ATP
ATP Electron Transport Chain
Lactic Acid
Fermentation
ATP
Key Terms:
Aerobic
– occurs with oxygen
Anaerobic – occurs without
oxygen
Cellular Respiration (3-stages
when oxygen is present)



Glycolysis
Krebs Cycle (Citric Acid Cycle)
Electron Transport Chain (ETC)
Glucose
Glycolysis
Krebs
cycle
Fermentation
(without oxygen)
Electron
transport
Alcohol or
lactic acid
A little help with some important
terms we will need:



Enzymes are proteins BUT many need a
nonprotein partner in order to do their job.
Inorganic partners such as iron, potassium,
magnesium and zinc are called cofactors.
Organic partners are called coenzymes. They are
small molecules that can separate from the
protein and participate directly in the chemical
reaction. Examples of coenzymes include many
derivatives of vitamins.



Oxidation is a chemical process that removes
electrons from molecules.
Reduction is the process that gives electrons to
molecules.
During cellular respiration enzymes remove
electrons from food molecules and transfer the
electrons to coenzymes.
Glycolysis (Splitting Sugar)

Begins with a 6-carbon molecule, usually glucose,
ends with 2, 3 carbon molecules of pyruvate.
 Produces 2 ATP and occurs in the cytoplasm of
prokaryotic and eukaryotic cells.
 Will occur with or without oxygen.
Glucose
Pyruvate
C
C
C
C
C
C
C
C
C
2 ATP
C
C
C
Glycolysis


Glucose (and phosphate
from 2 ATP molecules
are required to get it
started) is broken down
into two - 3 carbon and
phosphate groups, which
is then broken down into
pyruvic acid and 4 ATP.
Net gain of 2 ATP.

During cellular
respiration, enzymes
remove electrons
from food molecules
and then transfer the
electrons to the
coenzymes
nicotinamide adenine
dinucleotide (NAD+)
and flavin adenine
dinucleotide (FAD).

NAD+ and FAD
receive the electrons
as part of hydrogen
(H) atoms, which
change them into
their reduced forms:
NADH and FADH2

NAD+ and FAD act
like electron shuttle
buses for the cell.

The empty buses NAD+
and FAD collect
electron passengers.
The “H” sign goes up
to show that the bus is
full – NADH and
FADH2
The bus drives over
to the reactions that
need the electrons,
drop off the
passengers and go
back to the oxidation
reaction to collect
new passengers.
Glycolysis Summary



Where? Cytoplasm
Oxygen required? No
In
Glucose (6-C)

Out
2 pyruvate (3-C)
2 NADH
2 ATP (net)
Glycolysis:
Step 1
Figure 9–
3 Glycolysis
Glucose
2 Pyruvic acid
To the electron
transport chain
A Little Krebs Cycle
History



Discovered by
Hans Krebs in
1937
He received the
Nobel Prize in
physiology or
medicine in 1953
for his discovery
Forced to leave
Germany prior to
WWII because he
was Jewish
Krebs Cycle (Citric Acid Cycle)
 Begins
with two, 3 carbon molecules of
pyruvate which go from the cytoplasm into
the mitochondrial matrix. Together two
pyruvate molecules produce: 2 ATP, 2 CO2
and then two types of electron carriers:
NADH and FADH2
Electron Carrier - NADH
Pyruvate
C
C
C
ATP
+
+
Electron Carrier – FADH2
O
C
O
Krebs Cycle Summary
Where? Mitochondrial matrix
 Oxygen required? Yes
 Out
 In
2
CO
(as
waste)
2
2 Pyruvate
NADH
FADH2
2 ATP

Pyruvate is broken into a two carbon molecule called acetyl-coA. The Krebs cycle breaks
down acetyl-coA into carbon dioxide.
Cells use the Krebs cycle for breaking down fatty acids and amino acids.
The Krebs Cycle
Citric Acid
Production
Mitochondrion
Aerobic Respiration
Glycolysis
Aerobic
ATP
Krebs
ATP Electron Transport Chain
ATP

In the inner membranes of the mitochondria
in your cells, hundreds of little cellular
machines are busy working to transfer energy.

The machines are called electron transfer
chains. They are made of a team of proteins
that sit in the membranes, transferring energy
and electrons.



The coenzymes NADH and FADH2 carry
energy and electrons from glycolysis and the
Kreb’s cycle to the electron transport chain.
The coenzymes transfer the electrons to the
proteins of the electron transport chain, which
pass the electrons down the chain.
The bucket is the protein, the water the electrons.

Oxygen collects the electrons at the end of the
chain. While oxygen accepts the electron, it also
picks up protons (H+) and forms H2O.

While electrons are transferred along the
electron transport chain, the proteins move
protons (H+) across the membranes of the
mitochondria.
These protons flow back across the membrane
through a protein called ATP synthase.




It adds phosphate molecules to ADP forming
ATP.
Process is also called oxidative phosphorylation.
At the end of this entire process, the energy
transferred from glucose is 36 to 38 molecules of
ATP.
Electron Transport Chain





Where? Inner membrane of mitochondria
Oxygen required? Yes
Energy Yield Total of 32 ATP
O2 combines with TWO H+ to form H2O
Exhale - CO2, H2O comes from cellular
respiration
 In
 Out
32 ATP
NADH
electron carriers
FADH2
Electron Transport Chain
Electron Transport
Hydrogen Ion Movement
Channel
Mitochondrion
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production
Summary of Aerobic Respiration
ATP is then used to move muscles and
complete other cellular activities.
 Glycolysis, Krebs and Electron transport
chain together make up aerobic
respiration, starting with glucose and
ending with ATP.

Up to 36 ATP
Aerobic Respiration
Glycolysis
2 ATP
Aerobic
Krebs
Total of up to
36 ATP
2 ATP
Electron Transport Chain
Up to
32 ATP


The first two processes Glycolysis and the
Krebs cycle break down food molecules.
The third pathway oxidative phosphorylation
transfers energy from the food molecules to
ATP.
Anaerobic Respiration
Cellular Respiration
Glycolysis
ATP
Anaerobic
Alcohol
Fermentation
ATP
Lactic Acid
Fermentation
ATP
Cellular Respiration
Fermentation in the Absence of Oxygen
•Fermentation When oxygen
is not present, fermentation
follows.
•Lactic Acid Fermentation
In lactic acid fermentation,
pyruvate is converted to
lactate.
Anaerobic Respiration
23
25
Anaerobic respiration can be represented by the
equation
C6H12O6
glucose
energy
2C2H5OH
+
2CO2
alcohol
The energy released by anaerobic respiration is considerably
less than the energy from aerobic respiration.
Anaerobic respiration takes place at some stage in the cells
of most living organisms.
For example, our own muscles resort to anaerobic
respiration when oxygen is not delivered to them fast
enough.
Anaerobic Respiration (low oxygen or no oxygen)
3 types of anaerobic respiration:
1.Lactic Acid Fermentation – occurs when you
run without proper warm-up. Carbon dioxide and
lactic acid are produced from pyruvic acid.
Results in muscle soreness.

2. Alcohol Fermentation – pyruvic acid is
broken down into ethyl alcohol (ethanol) and
carbon dioxide. Results in food/beverages
that are high in calories.

3. Acetic Acid Fermentation – Pyruvic acid is
broken down into acetic acid (vinegar) and
carbon dioxide. Cabbage becomes sauerkraut.
Alcohol fermentation


Used by bacteria and
yeast (a type of fungus).
Alcohol and CO2 are
products of this reaction.
For thousands of years,
humans have used yeast
in brewing, winemaking
and baking. The bubbles
(CO2) generated by
baker’s yeast allow bread
to rise.
Lactic Acid Fermentation

Lactic acid fermentation is
used by certain fungi and
bacteria in the dairy
industry to make cheese
and yogurt. Lactate is the
product of this reaction.



Lactic acid fermentation is
also used by human
muscles.
Muscles make ATP by
lactic acid fermentation
when oxygen is scarce.
(For instance, opening and
closing your hand many
times over short periods
of time, or lifting a weight
for many repetitions.)

As your muscles run out of
oxygen, they need a quick
way to make more ATP.
Lactic acid fermentation
provides the ATP but
produces lactate which
accumulates causing
muscle soreness.
Eventually, the lactate is
carried away by blood to
the liver where it is
converted back to pyruvate.
THE BIG PICTURE
Cellular Respiration
Glycolysis
Aerobic
ATP
Krebs
ATP
Anaerobic
Alcohol
Fermentation
ATP
ATP Electron Transport Chain
Lactic Acid
Fermentation
ATP
Aerobic vs. Anaerobic

Anaerobic DOES
NOT require oxygen
Simple
 fast
 produces smaller
amounts of energy
(ATP)


Aerobic requires
oxygen
Yields large
amounts of
energy
 What is this
energy molecule?
 ATP, ATP,
ATP

Lactic Acid Fermentation

bacteria, plants and most animals

After glycolysis


2 pyruvic acid changed to lactic acid
Sometimes happens in your muscles, cramps----Exercise
Alcoholic Fermentation

Bacteria and fungi (yeast)

Ethyl alcohol and carbon dioxide are the
end products

Process used to form beer, wine, and other
alcoholic beverages
Also used to raise dough, bread
