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”)

Nucleus – DNA Instructions Mitochondria – Cell Powerhouse Cell Membrane – A Barrier to the Outside

 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 P i.  ADP is the same thing as ATP except that it only has 2 phosphates ▪ P i 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 P i 5. ATP must be re-charged in the mitochondria 1. ATP becomes “re-charged” when ADP and P i are smashed together

 ADP and P i 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

` ATP Synthase Stored Hydrogen Mitochondrial Inner Membrane Mitochondrial Lumen (inside) Flowing Hydrogen

 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 P i into the energy-carrying ATP  The walls of the mitochondria contain many ATP Synthase structures, each producing charged ATP from ADP and P i

 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 (CO 2 ) 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 H 2 O  H 2 O and CO 2 are breathed out when we exhale

1. ATP Synthase is the “wheel” that “smashes” ADP and P i 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 H 2 O and CO 2 are exhaled when we breathe out. CO 2 and H 2 O 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 cold- climate mammals, it heats them!  Brown fat & weight loss? Why might this work?weight loss

 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 CO 2 alters mitochondrial number and chloroplast fine structure. Kevin L. Griffin, et al Plant growth in elevated CO 2 alters mitochondrial number and chloroplast fine structure.  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. “Heat production and lipid metabolism in broiler and layer chickens during embryonic development.”  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.