Carbs Quiz

  1. Which of the following are functions of carbohydrates?

1) Growth and Repair
2)Storage
3)Energy source
4) Precursor molecules

A. 1, 2 and 3 are correct

B. 1 and 3 are correct

C. 2 and 4 are correct

D. only 4 is correct

E. all are correct

2.What does sucrose consist of?

A)Alpha Gulcose only.

B)Glucose and fructose

C)Alpha and Beta Glucose

D)Normal Glucose

E) Lipids and fatty acids

3.Which of the following is NOT a carbohydrate?

A)Liver

B)Bread

C)Beer

D)Potato

E)Rice

4.Glucose contains an/a

A)Ketose grouping

B)Alcohol grouping

C)Aldehyde grouping

D)Halogen

E)Mg

5.Fructose contains an/a

A)Ketose grouping

B)Alcohol grouping

C)Aldehyde grouping

D)Halogen

E) Mg

6.Maltose consists of

A)Glucose

B)Fructose

C)Beta glucose only

D)Alpha glucose only

E)Gamma Glucose only

7.Which of the following is a true definition for an anomeric carbon?

A)a free carbon

B)Carbon attached to a specific carbonyll grouping

C)one of two stereoisomers of a cyclic saacharide

D)a carbon bonded to four other atoms

E) Carbon displaying annomerism.

8.Glycogen is found in

A)Plants and animals

B)Animals only

C)Plants only

D)Metals

E) Anomeric carbomds

9.Starch is found in

A)Plants and animals

B)Animals only

C)Plants only

D)Metals

E)None of the above

10.lactose consists of

A)Fructose only

B)Glucose only

C)Fructose and glucose

D)Galactose and glucose

E)None of the above

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ATP synthesis and the Mitochondria

Hey guys!

so we just had a little entertaining, CREATIVE, comic about cyanide. A few of you are probably wondering, how is atp made anyways? Yes there were a couple diagrams in the previously ingeniously creative comic strip, however I thought i’d go through a little more in depth with you just about just what REALLY goes on inside our little powerhouses (mitochondria) in our cells.

 

The chemiosmotic hypothesis explains how ATP is generated in the mitochondria :

Within the mitochondria, an ETC, or electron transport chain is found, where NADH and FADH containing electrons, have a high energy potential. This is located within the inner membrane of the mitochondria.

For simplification purposes, one can say that the ETC consists of four complexes which, within the ETC looses an electron, an oxidative process, giving off energy. Complexes 1, 3 and 4 uses this energy to pump protons into the membrane. Complex 2 does not use energy to pump protons even though energy is given off. It instead has succinate dehydrogenase from the TCA cycle, where FADH reacts

The high electrochemical gradient generated by these oxidative processes generates a high proton motive force.

How does it generate this force?

Well, protons cannot cross the inner membrane of the mitochondria matrix. It must therefore pass through an ATP synthase protein molecule, which must undergo a conformational change in order to produce ATP.

ADP + Pi —> ATP

This is generated from the electron motive force.

Cyanide, as seen in the previous comic, bind to comples 4, inhibiting the ETC from functioning.

Glycolysis Paper

Reference :

The Columbia Encyclopedia, s.v. “glycolysis,” accessed April 07, 2013, http://www.credoreference.com/entry/columency/glycolysis

 

In this informative article, the process of glycolysis is described as a metabolic pathway for the degradation of glucose. This important process takes place in most organisms including micro organisms such as yeast and bacteria.

The process is known to be a series of consecutive chemical conversions, containing eleven different enzymes in all. It starts with one molecule of glucose and finishes with the production of two molecules of pyruvic acid. The catabolic pathway involves a six carbon glucose being reduced to the three carbon pyruvic acid. Enery is liberated along the pathway in the form of the molecule adenosine triphosphate also referred to as ATP. It is therefore said that ATP synthesis is coupled into the process of glycolysis.

Usually cellular reactions, especially those involved in the synthesis of different components important to the cell and its functionsm require ATP as a source of energy. Glycolysis acts as a source for this.

The two major stages of this metabolic pathway involves the conversion of glucose to an intermediate sugar, glucose 6- phosphate and finally the conversion to pyruvate. This product is then further metabolized to complete the breakdown of glucose in two possible way based on the organism. In certain organisms, such as bacteria and brewer’s yeast, a process known as homolactic fermentation involves the production of lactic acid as the final product converted from pyruvic acid.

Pyruvic acid can also be converted to ethanol and carbon dioxide by an enzyme-catalyzed two-step process, termed alcoholic fermentation. In the tissues of many organisms, including mammals, glycolysis is a prelude to the complex metabolic machinery that ultimately converts pyruvic acid to carbon dioxide and water with the concomitant production of much ATP and the consumption of oxygen. These are the two different end results of glycolysis

Quiz time !

1) How many reversible enzymes are involved in the process of glycolysis

a) 2

B)4

C)5

D)10

E)8

 

2)How many enzymes are involved in the preparatory phase?

a) 2

B)4

C)5

D)10

E)8

 

3)How many enzymes are used in the pay off phase?

a) 2

B)4

C)5

D)10

E)8

 

4)Select the correct answer using one of the keys as follows for the question

A. 1, 2 and 3 are correct

B. 1 and 3 are correct

C. 2 and 4 are correct

D. only 4 is correct

E. all are correct

Which of the following reactions are reversible?

1. Glucose 6 phosphate —-> Fructose 6 – phosphate

2. Fructose 1,6-bisphosphate —> Glyceraldehde 3 phosphate

3. Fructose 1,6-bisphosphate —> Dihydroxyacetone

4. Phosphienolpyruvate —> Pyruvate

 

5)  Why is glucose converted to glucose 6 phosphate in glycolysis?

a) to be glycolysized

B) to keep glucose in the cell and reduce reactivity with other metabolic processes

C) to produce ATP

D)to oxidize NADP

E) to increase the reaction rate of the process since glucose 6 phosphate is more reactive

 

6) Which enzyme is responsible for the conversion of Glucose 6 phosphate to Fructose 6 phosphate

a) amylase

B)polymerase

C)hexokinase

Dketoglutarmate

E) No enzyme

 

Enzymes : Interactions

Hey!

We’re back on to a side note about the different types of interactions in enzymes :). So let’s get started shall we

Interactions between side chains can either stabilize or destabilize the structure of an enzyme. Since side chains can either be negative or positive in charges which can either repel each other, when they are alike, or attract each other when they are opposite in charge. This can either prevent, or allow the specific structure of an enzyme.

Examples of amino acids, which can prevent the formation of a particular helix structure include: 

  • Glutamate
  • Lyseine
  • Argeine

Large bulky side chains next to each other can result in steric hinderance, or interference preventing the formation of the helical structure. Steric hindrance, also known as steric interference has to do with the fitting together properly of the structures.

Normally, positive charges of amino acids are most times found three or four residues away from the negative charge, forming anion pair which can stabilize a helical structure.

Finally in helical structures, the four amino acids at the end of the helic do not fully hydrogen bond. The net macro dipole moment goes from negative to positive. That is, the carbonyll part of the group, to the amino or nitrogen part of the amino acid molecule.

And for a final Note: Helicies often prefer to interact in an antiparrallel manner, so that their macro dipoles interact favorably.

Enzymes! :)

References:

See J. E. and E. T. Bell, Proteins and Enzymes (1988).

The Columbia Encyclopedia, s.v. “enzyme,” accessed March 16, 2013, http://www.credoreference.com/entry/columency/enzyme

Hey guys!

So previously we had covered amino acids and their linkages, that is polypeptides bonds and the structures that are formed along with them. This Week we’ve moved on to a somewhat more exciting topic. ENZYMES!

Now this is a HUGE topic, but to help us along i came across a little article that could help us.

According to “Credo Reference” an enzyme, also known as a biological catalyst, accelerates the rate of a reaction without being permanently chemically changed. Enzymes achieve this phenomenon by providing a different reaction pathway for the reaction to occur, thus lowering the activation energy required for the reaction to take place.

Factors which affect the rate at which the enzyme work include specific temperature ranges, pH ranges. The efficiency of a particular enzyme can also be measured usually by a turnover rate, measuring the number of molecules of compound opon which the enzyme works per molecule of enzyme per second. A useful example given in the article was of Carbonic anhydrase which has a turnover rate of 106  for removal of carbon dioxide from the blood binding it to water. Thus this rate means that one molecule of the enzyme can cause a million molecules of carbon dioxide to react in one second.

Also briefly mentioned in the helpful post, is the occurence of denaturation, where a denatured enzyme refers to an enzyme which has been altered in its chemcial and physical structure, so much so that it can no longer serve its purpose. Once an enzyme loses its shape, it can no longer catalyze its reactions since enzymes are selective for the molecules upon which they act, known as substrate molecules. Most enzymes will react with a small group consisting of closely related chemical compounds, demonstrating absolute specificity, thus having one substrate molecule, appropriate for the reaction.

An interesting fact, about enzymes is that some require non protein molecules, not excluding coenzyme molecules. These nonprotein components which are tightly bound to the protein are also referred to as prosthetic groups.

The active site is known as the region on the enzyme where the catalytic event takes place. Prosthetic groups, as mentioned above are usually located there. The side-chain groups of amino acid residues make up the enzyme molecule also participating in the catalytic event.

Another example given is in the enzyme trysin which brings together a histidine residue from one section of the mlecule with glycine and serine residues from another. Conclusively the side chains of these residues in this particular geometric arrangement produce the active site which accounts for the enzyme’s reactivity.

One may ask the question: How can these enzymes be identified and classified? Well, through crystalization of the amino acid sequence, and X-ray crystallography.

The informative post also mentions enzyme deficiency, where a number of metabolic diseases are known to be caused by deficiencies or malfunctions of the enzyme. An example of this is in albinism, caused by the enzyme responsible for the production of cellular pigments.