By C. Kohn, Waterford WI

Last year, Mr. Kohn’s class grew two kinds of
chickens
 The first kind were layers. They are bred to lay
eggs and grow slowly.
 The second kind are broilers. They are bred for
meat production and grow quickly.


Why would two breeds of the same bird grow
at very different rates?
Think, Pair, Share – what causes the
differences in growth? See next slide first.

You might be tempted to respond with short
answers like “genetics” or “diet”.
 Avoid these kinds of answers – they do not help us
to solve a problem.


Instead, try to suggest a hypothesis that
might explain this.
What might be different about their
bodies, organs, or cells that could cause
one kind of chicken to grow twice as fast?

So why does one kind of chicken grow so
much faster than the other?

Answering this question requires an
understanding of the most universal aspects
of agriculture.

To begin, let’s focus on the simplest unit of
life – the cell.

The cell is the smallest unit of life
 This means that the smallest something can be and
still be alive is a cell
 Molecules can’t be alive, but they can be part of
something alive
 The smallest thing that can be alive is one cell

There are two kinds of cells
 Prokaryotic – bacteria – simple and basic
 Eukaryotic – the cells of complex organisms that have
organelles (cellular structures)

Eukaryotic cells all have similar key
ingredients . Some are…
 Nucleus w/ DNA instructions
 Cell membrane to maintain constant conditions
 Mitochondria – powerhouse of the cell
 Ribosomes – protein factories
 Vacuoles – storage and waste removal
 Plants Only: Chloroplast (sugar production), Cell
Wall (a plant’s “skeleton”)

In this part of the class, we’ll focus on the
mitochondria.

The mitochondria are the “POWERHOUSES” of
the cell.

They create the energy that powers the cellular
activity of all living things.
 Your body uses the energy created by your
mitochondria.
 All plants, animals, and fungi use mitochondria to
create their cellular energy.

ATP is the energy of the cell (not sugar!)
 ATP stands for Adenine TriPhosphate

ATP consists of…
1. Three phosphate molecules
2. A ribose sugar molecule
3. An amino acid – Adenine

A simpler way to remember ATP is:
A
Triple
Phosphate

ATP is like a rechargeable battery
 It is re-used over and over again and can be re-
charged each time in the mitochondria

When ATP gives up its “charge”, it becomes ADP
and Pi.
 ADP is the same thing as ATP except that it only has 2
phosphates
▪ Pi is the third unattached phosphate. It has to be “smashed”
back on to re-charge ATP
 ADP = “A Double Phosphate” = ‘uncharged battery’
1.
Eukaryotic Cells are the cells of complex organisms like
plants, animals, and fungi.
2.
Eukaryotic Cells all have Mitochondria, the powerhouse
of the cell
3.
Mitochondria produce ATP, the energy of the cell.
1.
ATP powers all cellular activity in any kind of cell
4.
ATP carries energy; when it gives up its energy, it
becomes ADP and Pi
5.
ATP must be re-charged in the mitochondria
1.
ATP becomes “re-charged” when ADP and Pi are smashed
together

ADP and Pi are ‘smashed’ together in a special
structure in the mitochondria called ATP
Synthase.
 ATP Synthase is a tiny molecular structure that turns

ATP Synthase is just like a water wheel on a
dam.
 As water flows over the dam, the
waterwheel turns
 ATP Synthase turns when hydrogen
flows past it
`
`
Stored
Hydrogen
Mitochondrial
Inner Membrane
ATP
Synthase
Mitochondrial
Lumen (inside)

Just like water flowing over a dam powers a
waterwheel, hydrogen flowing through
ATP Synthase turns its “wheel”
 The turning of this wheel combines ADP
and Pi into the energy-carrying ATP

The walls of the mitochondria contain
many ATP Synthase structures, each
producing charged ATP from ADP
and Pi

The wheel of ATP Synthase requires constantly
flowing hydrogen

This hydrogen comes from the food you eat

Carbohydrates provide
most of this hydrogen

Carbohydrates include
simple sugars, starches,
and fiber

Starches, simple sugars, and fiber are all
made from chains of sugar molecules.

In order for your body to use a carbohydrate,
it must be broken down into individual sugar
molecules – glucose

White bread tastes sweeter than whole grain
bread because it is made of shorter chains of
sugar that break down more easily
(the shorter the chain, the easier to break it)

When you eat carbohydrates, they are broken down into
individual glucose molecules (click)

These molecules are absorbed into the blood and are
absorbed by cells.

Once in the cell, the individual glucose molecules are
broken down.
 The hydrogen is moved inside the mitochondrial membranes to
power ATP Synthase
 Carbon Dioxide (CO2) is the waste created from respiration.
To Blood

In the mitochondria, the stored hydrogen powers
the wheels of ATP Synthase.

After it powers the wheel, each hydrogen atom
must be removed from the mitochondria.
 If hydrogen was not continuously removed, it would
stop flowing. (Imagine if people stopped inside a
revolving door!)

To remove the hydrogen, we breathe in oxygen
 The oxygen binds to two hydrogen molecules to
make H2O
 H2O and CO2 are breathed out when we exhale
1.
ATP Synthase is the “wheel” that “smashes” ADP and Pi back
into charged ATP
2.
Flowing hydrogen from the mitochondrial membrane powers
this wheel.
3.
The hydrogen comes from the food we eat, particularly
carbohydrates
4.
Carbohydrates must be broken down into individual glucose
molecules to be used by cells.
5.
Hydrogen is taken from glucose to power ATP Synthase.

Both H2O and CO2 are exhaled when we breathe out.
CO2 and H2O are the waste products of respiration.

Babies have lots of what is called brown fat.
 Fat typically is used to store energy for ATP
production.

Brown fat is found in babies and animals in
cold climates.
 Brown fat is brown because it has a large number
of mitochondria
 It is actually created from muscle, not fat.

Brown fat produces heat. It does this because it
has leaky mitochondria
 The hydrogen atoms stored in mitochondria can leak
out instead of going through ATP Synthase
 This creates friction, which creates heat

Brown fat doesn’t just insulate babies and coldclimate mammals, it heats them!

Brown fat & weight loss?
Why might this work?

Growth and Mitochondrial Respiration of
Mungbeans (Phaseolus aureus Roxb.)
Germinated at Low Pressure 1
 Mary E. Musgrave, et. al.

Beans grew more with higher oxygen levels.
 Why? TPS
 Why would oxygen improve
growth?
 How does oxygen affect ATP
production?

Plant growth in elevated CO2 alters mitochondrial
number and chloroplast fine structure. Kevin L.
Griffin, et al

Increasing CO2 concentrations led to increased
mitochondrial concentrations in plants

Increased CO2 led to an…
Increased amount of mitochondria, leading to…
Increased plant productivity.

Why? TPS

“Heat production and lipid metabolism in broiler
and layer chickens during embryonic
development.” Momoka Sato, et. al.

Consumption of the yolk sac was faster in
broilers than in layers.
 Note: The egg yolk is the food for
the baby chick

Why might broiler chickens consume
their egg yolk faster than a layer?

How could we use mitochondria, ATP, or ATP
synthase to improve chicken growth and
performance?

On your whiteboards, write 5
ways in which we could change
the cells of a chicken so that it
grows faster.
 Be prepared to defend why your
treatment might work.