Digestion continued...

The liver is responsible for the production of bile. Bile is a chemical made from dead red blood cells. Bile breaks down the fats that we eat.
After bile is produced it is stored in the gall bladder, it is released in the presence of fats

in order to break them down.

THIS IS ONLY ONE OF MANY FUNCTIONS THAT THE LIVER IS RESPONSIBLE FOR SUCH AS THE POISON CONTROL OF THE BODY

The pancreas breaks down carbohydrates and further breaks down proteins. The peptidases that are made by the pancreas are called

Trypsin, Chymotrypsin, and carboxypeptidase.these are then changes to their inactive form which are trypsinogen,chimotrypsin, and procarboxypeptidase. This change occurs in order to protect the pancreas from getting digested. When needed tripsinogen is changed back into tripsen by the small intestine then tripsen activates the other enzymes to change.

The small intestine is the major organ of digestion and absorption.

The small intestine is over 6m and has a alot of surface area for absorption due to the thousands of villi against its lining.

The small intestine is made of 3 parts the Duodenum where most digestion occurs.

Jejunam and Ileum where absorption of nutrients and water occur.

The nutrients from the food are absorbed through the capillary walls which are only one cell thick

What ever the body cannot put to use gets sent to the large intestine. Products such as cellulose which or body cannot digest is sent here. The large intestine has a bunch of good bacteria

that prduce vitimans and help digest cellulose.

The liver also re-absorbs water back into the blood stream so we dont dehydrate.

The last section of the large intestine is the rectum which eliminates the pheces and undigested materials from the body

and lastly you end up with...

Digestion

Chemical digestion occurs once food has

entered the stomach from the esophagus.

Most people believe that the stomach's function is digestion. The true function of the stomach is to store food, the stomach makes it possible for us to eat meals through out the day. The stomach also disinfect anything that is not suppose to come down with the food. HCl make the disinfection possible, with a ph of 2 it kills bacteria and begins to break apart food.

The enzyme that digests protein is called pepsin

Luckily we have mucus that is secreted to protect

our stomach lining. If we didn't then the pepsin would digest our stomachs since the stomach is made out of protein.

A Gastric ulcer is when ones stomach begins to digest itself. Gastric Ulcers are caused by a bacterial infection known as Helicobacter Pylori. Gastric Ulcers are cured with weeks of antibiotics.

While all of this is occuring the food

stays put in the stomach due to 2

sphincters. One is called the cardiac sphincter

which keeps the food from going up.

The 2nd is called the pyloric sphincter which keeps the food from going down.

The liver is responsible for the production of bile.

Bile is a chemical made from dead red blood cells.

Bile breaks down the fats that we eat.

After bile is produced it is stored in the gall bladder, it is released in the presence of fats in order to break them down.

PPPPP

Nutrition

All animals need to consume food to live. Oxygen and some sort of food source are needed for animals to grow. The raw materials are gained through eating and the oxygen is used in respiration which makes the energy needed for the synthesis of those raw materials into larger molecules.

Animals get their food in four different ways-

~Bulk Feeding~

Bulk Feeding is cosuming large concentrated portions of your food source.

~Fluid Feeding~

This is when organisms get theier nutrients from a liquid like blood or sap.

~Substrate Feeding~

Substrate feeding is when the organism spends part of its' life living in its food source.

~Filter Feeding~

This mode envloves the intake of huge amounts of your food source straight out of the environment.

Your digestive system is basically a really long tube where food products are broken down and the needed parts are absorbed the rest excreted as extracellular waste because it never actually entered your cells.


Food is pushed through the digestive track by involuntary muscle contractions known as peristalsis. According to Paige this is like an utter.

Digestion starts with Ingestion

Swallowing starts off the process the epiglottis (cartilage flap) closes securing itslef over your trachea preventing food from "going down the wrong pipe". Waves of muscle push the food towards the stomach which is where we finished our lesson.

Stage One: Glycolysis

Whats the point? To make ATP!!

Glycolysis literally means splitting two sugars. This name is appropriate because this is exactly what happens during the first stage of cellular respiration; glucose is digested.


Glycolysis is an ancient process. Bacteria where the first to do this.
Glycolysis is where energy transfer first evolved. It is a transfer of energy from organic molecules to inorganic molecules.

But its inefficient!
A working muscle use millions of molecules of ATP a second. Glycolysis only makes 2 ATP's.

Who were the first to do glucolysis?
Prokaryotes!
Billions of years ago there was no free oxygen in the atmosphere.Oxygen had to be captured by organic molecules such as glucose.

All cells undergo glycolysis!


The Reaction:
1. Begins with one glucose molecule (six carbons)
2.Fructose-16bP takes off Phosphate from 2 ATP and place a phosphate on either side of the glucose.
3. The carbons pull apart due to oxygen's high electronegativity. This forms 2 pyruvates or two 3 carbon molecules.
4. 4 ATP's and 2NADH's (piggy bank) are formed. However 2ATP's were used to start the process (the match).
5. Net: 2ATP's and 2NADH's

What is the point? TO MAKE ATP

Guys today we learned how our body makes energy. Well what is the point? POINT IS TO MAKE ATP.

Energy is really important because we need it to reproduce, synthesis, to move, to grow, and to regulate our temperature.

The work of life is done by energy coupling, which is using exergonic reactions to fuel the endergonic reactions.

Whatever we eat, we have to digest or break it down to simpler molecules that can enter our cells and they can eventually use them. We need something in our body which helps to pass this energy around. And the best answer is ATP!!!.

ATP stands for Adenosine Triphospate. Where do we see Adenine before? In RNA and DNA.

ATP has three phosphate group attaches to an adenine and ribose.

First we start out with adenosine, and ribose, and when we attach one phosphate to this, this is named AMP or adenosine monophosphate, which means one phospate.

Then when we add another phosphate group to the adenine, ribose, and previous phosphate group, we make adenosine diphosphate, meaning two phosphates.

Third, we make ATP by adding another phosphate group, thus making adenine triphosphate.

Adding all these phosphates requires A LOT of energy and I mean A LOT.

BUT, the question is why does it require so much energy? Well lets see an example, remember when we hold magnets together towards the same poles, WHAT DO THEY DO? THEY REPEL EACH OTHER. This is the same reason for the phosphates. The phosphates are highly negative and do not want to be with another molecule which is also highly negative. This is due to the oxygen. AND WHAT IS OXYGEN? HIGHLY ELECTRONEGATIVE.

The phosphate bonds make ATP an excellent energy donor.

HOW DOES ATP TRANSFER ENERGY?

The word is PHOSPHORYLATION. This is when phosphate is taken off of ATP. This released phosphate can be transferred to other molecules. And enzyme that helps in this is kinase.

Building polymers from monomer is a perfect example of phosphorylation. The bonds holding the monomer have to be destabilized in order to make it a polymer.

The first step of cellular respiration is glycolysis. This is the breaking of glucose to make ATP. First the bonds of glucose have to be destabilized in order for it to be broken down. And whenever a carbon to carbon bond is broken, energy is released!!

Activators and Inhibitors

Hey guys, yesterday we finished our lecture on enzymes by talking about how activators and inhibitors affect enzyme activity. We also talked about allosteric regulation, cooperativity, metabolic pathways and how these pathways are efficient for the cell.

Enzyme activity is sensitive to the presence of specific substances that bind to the enzyme and cause conformational change in the enzyme (conformational change is the change in the shape of the molecule, in this case the active site of the enzyme). Through these substances, a cell is able to regulate which of its enzymes are active and which are inactive at a particular time. This allows the cell to increase its efficiency and to control changes in its characteristic during development.

The first type of substance that we will talk about is an activator which binds to the active site of the enzyme and increases the activity of the enzyme. Enzyme function is often assisted by additional chemical components known as cofactors and coenzymes.

Cofactors are non-protein, small inorganic compounds and ions. Inorganic compounds are compounds that do not have carbon to carbon bonds. These small molecules are usually metals and bind within the enzyme molecule. For example zinc is used by some enzymes to draw electrons away form their position in covalent bonds in the substrate, making the bonds less stable and easier to break the bonds between the substrate. *Remember glucose, it is stable and needs something to disrupt the bond well here the metals in the enzyme draw the electrons away from the substrate molecules, disrupting the bonds between the substrate.*

Coenzymes are nonprotein, organic molecules which are molecules that have carbon to carbon bonds. These molecules bind temporarily or permanently to the enzyme near its active site. Many vitamins are parts of coenzymes. In numerous ozidation reduction reactions that are catalyzed by enzymes, the electrons pass in pairs from the active site of the enzyme ot a coenzyme that serves as the electron acceptor. The coenzyme then trasfers the electrons to a different enzyme, which releases them to the substrates in another reaction. These electrons have energy with them. One of the most important coenzymes is the hydrogen acceptor nicotinamide adenine dinucleotide (NAD+).

Those were activators but there are also substances that bind to he an enzyme and decreases the activity of the enzyme and these substances are called inhibitors. There are four types of inhibition: competitive inhibition, noncompetitive inhibition, irreversible inhibition, and feedback inhibition.

competitive inhibitor

Competitive inhibitors compete with the substrate for the same active site, displacing a percentage of substrate molecules from the enzymes. One example of this type of inhibitors is the medicine penicillin. Penicillin blocks the enzyme bacteria use to build their cell wall. To overcome competitive inhibition is to increase the substrate concentration because if there is higher concentration of substrates than the inhibitor, then there would be more collisions between the enzyme and the substrate; the enzyme will more frequently collide with the substrate.

noncompetitive inhibitor

Noncompetitive inhibitors bind to the enzyme in a location other than the active site, changing the shape of the active site of the enzyme making the enzyme unable to bind to the substrate. Most noncompetitive inhibitors bind to a specific portion fo the enzyme called an allosteric site. A substance that binds ot an allosteric site and reduces enzyme activity si called an allosteric inhibitor. When this substance binds to this site, it causes a conformational change in the active site which is no longer a functional binding site.

Irreversible inhibitors are the same thing as competive and noncompetitive inhibitors, however irreversible inhibitors are inhibitors that permanently bind to the enzyme. So competitor would bind permanently to the active site while the allosteric (noncompetive) will permanently bind to the allosteric site of the enzyme.

Before we can talk about the last inhibitor, it is important if we get the understanding about metabolic pathways. Organisms contain thousands fo different kinds of enzymes that catalyze a wide variety fo reactions. Many of these reactions in a cell occur in sequences called metabolic or biochemical pathways. In such pathways, the product of one reaction becomes the substrate for the next reaction. Metabolic pathways creates organization and efficiency amongst the cell.

Now we can talk about feedback inhibition. Feedback inhibition is a process where the end production of a biochemical pathway acts as an inhibitor of an early reaction. Not only is it unnecessary to synthesize a compound when plenty is already present, but doing so would waste energy and raw materials. It is therefore advantageous for a cell to temporarily shut down biochemical pathways when their products are not needed and this is when feedback inhibition comes in. The end product of the pathway binds to an allosteric site on the enzyme that catalyzes the first reaction in the pathway, causing conformational change and preventing the enzyme from functioning properly.

For a better understanding of the biochemical pathway and the feedback inhibition please go to http://www.explorebiology.com/apbiology/resources/ and go under enzymes and metabolism and click on the second biochemical pathway animations.

Allosteric regulation is conformational changes by regulatory molecules like inhibitors that keep enzyme in an inactive form and activators that keep the enzyme in an active form. Cooperativity is when a substrate acts as an activator because it causes a conformational change in the enzyme and this makes it easier for other substrates to bind to the enzyme.

Well I hope I had helped you out.

Metabolism and Enzymes

Metabolism and Enzymes!

Chemical Reactions:

Metabolism is a chemical reaction of life. Bonds forming and breaking between molecules are both involved.


Forming bonds are known as dehydration synthesis, and anabolic reactions. This synthesis requires an enzyme and the release of H2O, while bringing two molecules together.

This diagram shows the dehydration synthesis of sucrose. An enzyme combines Glucose and Frustose, while releasing H2O, to form the compound Sucrose.

Breaking bonds is known as hydrolysis, digestion and catabolic reastions. Breaking of bonds requires a different enzyme, and H2O, to breakdown a compound into two molecules.

This diagram shows Hydrolysis. An enzyme, as well as H2O, is used breakdown the compound into two seperate molecules.

Energy is present is both breaking and forming of bonds. Some reactions release energy, for example hydrolysis, the digesting of polymers. When reactions release energy, it is known as Exergonic.

While some reactions release energy, others require energy. Dehydration Synthesis, the building of polymers, is an example of a chemical reaction requiring energy. These chemical reactions are known as Endergonic.

Activation Energy:

Since reactions don't just happen spontaneously, since covalent bonds are stable, energy is needed to initiate a chemical reaction. This energy is known as Activation Energy. Sometimes the amount of energy needed to destabilize a bond is too much for life. An example of this is lighting a match to burn a piece of paper, like Ms. Foglia did in class.

When there is too much activaton energy in a reaction, a catalyst can be added to reduce the amount of activation energy used to start a reaction. For a cell to reduce energy, an enzyme is added. The enzyme acts as a catalyst for the cell. As Philmore said "Call in the ENZYMES!"