Enzymes and Metabolism

Role of enzymes in Metabolism

Some enzymes help to break down large nutrient molecules, such as proteins, fats, and carbohydrates, into smaller molecules. This process occurs during the digestion of foodstuffs in the stomach and intestines of animals. Other enzymes guide the smaller, broken-down molecules through the intestinal wall into the bloodstream. Still other enzymes promote the formation of large, complex molecules from the small, simple ones to produce cellular constituents. Enzymes are also responsible for numerous other functions, which include the storage and release of energy, the course of reproduction, the processes of respiration, and vision. They are indispensable to life.

Each enzyme is able to promote only one type of chemical reaction. The compounds on which the enzyme acts are called ubstrates. Enzymes operate in tightly organized metabolic systems called pathways. A seemingly simple biological phenomenon—the contraction of a muscle, for example, or the transmission of a nerve impulse—actually involves a large number of chemical steps in which one or more chemical compounds (substrates) are converted to substances called products; the product of one step in a metabolic pathway serves as the substrate for the succeeding step in the pathway.

The role of enzymes in metabolic pathways can be illustrated diagrammatically. The chemical compound represented by A (see diagram) is converted to product E in a series of enzyme-catalyzed steps, in which intermediate compounds represented by B, C, and D are formed in succession. They act as substrates for enzymes represented by 2, 3, and 4. Compound A may also be converted by another series of steps, some of which are the same as those in the pathway for the formation of E, to products represented by G and H.

The letters represent chemical compounds; numbers represent enzymes that catalyze individual reactions. The relative heights represent the thermodynamic energy of the compounds; e.g., compound A is more energy-rich than B, B more energy-rich than C. Compounds A, B, etc., change very slowly in the absence of a catalyst but do so rapidly in the presence of catalysts 1, 2, 3, etc.

The regulatory role of enzymes in metabolic pathways can be clarified by using a simple analogy: that between the compounds, represented by letters in the diagram, and a series of connected water reservoirs on a slope. Similarly, the enzymes represented by the numbers are analogous to the valves of the reservoir system. The valves control the flow of water in the reservoir; that is, if only valves 1, 2, 3, and 4 are open, the water in A flows only to E, but, if valves 1, 2, 5, and 6 are open, the water in A flows to G. In a similar manner, if enzymes 1, 2, 3, and 4 in the metabolic pathway are active, product E is formed, and, if enzymes 1, 2, 5, and 6 are active, product G is formed. The activity or lack of activity of the enzymes in the pathway therefore determines the fate of compound A; i.e., it either remains unchanged or is converted to one or more products. In addition, if products are formed, the activity of enzymes 3 and 4 relative to that of enzymes 5 and 6 determines the quantity of product E formed compared with product G.

Both the flow of water and the activity of enzymes obey the laws of thermodynamics; hence, water in reservoir F cannot flow freely to H by opening valve 7, because water cannot flow uphill. If, however, valves 1, 2, 5, and 7 are open, water flows from F to H, because the energy conserved during the downhill flow of water through valves 1, 2, and 5 is sufficient to allow it to force the water up through valve 7. In a similar way, enzymes in the metabolic pathway cannot convert compound F directly to H unless energy is available; enzymes are able to utilize energy from energy-conserving reactions in order to catalyze reactions that require energy. During the enzyme-catalyzed oxidation of carbohydrates to carbon dioxide and water, energy is conserved in the form of an energy-rich compound, adenosine triphosphate (ATP). The energy in ATP is utilized during an energy-consuming process such as the enzyme-catalyzed contraction of muscle.

Because the needs of cells and organisms vary, not only the activity but also the synthesis of enzymes must be regulated; e.g., the enzymes responsible for muscular activity in a leg muscle must be activated and inhibited at appropriate times. Some cells do not need certain enzymes; a liver cell, for example, does not need a muscle enzyme. A bacterium does not need enzymes to metabolize substances that are not present in its growth medium. Some enzymes, therefore, are not formed in certain cells, others are synthesized only when required, and still others are found in all cells. The formation and activity of enzymes are regulated not only by genetic mechanisms but also by organic secretions (hormones) from endocrine glands and by nerve impulses. Small molecules also play an important role (see below Enzyme flexibility and allosteric control).

If an enzyme is defective in some respect, disease may occur. The enzymes represented by the numbers 1 to 4 in the diagram must function during the conversion of the starting substance A to the product E. If one step is blocked because an enzyme is unable to function, product E may not be formed; if E is necessary for some vital function, disease results. Many inherited diseases of man result from a deficiency of one enzyme. The disease called lbinism, for example, results from an inherited lack of ability to synthesize the enzyme tyrosinase, which catalyzes one step in the pathway by which the pigment for hair and eye colour is formed.

Enzymes identified with hereditary diseases
disease name defective enzyme
albinism tyrosinase
phenylketonuria phenylalanine hydroxylase
fructosuria fructokinase
methemoglobinemia methemoglobin reductase
galactosemia galactose-1-phosphate uridyl transferase
Related Readings
Publicado en Uncategorized | Deja un comentario

The Lockheed SR-71


The  SR-71 Blackbird accrued about 2,800 hours of flight time during 24 years of active service with the U.S. Air Force. On its last flight, March 6, 1990, Lt. Col. Ed Yielding and Lt. Col. Joseph Vida set a speed record by flying from Los Angeles to Washington, D.C., in 1 hour, 4 minutes, and 20 seconds, averaging 3,418 kilometers (2,124 miles) per hour. At the flight’s conclusion, they landed at Washington-Dulles International Airport and turned the airplane over to the Smithsonian Museum.

The Blackbird is one of the most magnificent military jets ever developed. People have been fascinated with the aircraft for decades, and not only because of the aircraft’s capabilities. The aircraft has played an important military role in international conflicts for nearly thirty years.

The Lockheed SR-71Blackbird” is a long-range, Mach 3+ strategic reconnaissance aircraft that was operated by the United States Air Force (USAF)…

Ver la entrada original 280 palabras más

Publicado en Uncategorized | Deja un comentario

The Lockheed SR-71

The  SR-71 Blackbird accrued about 2,800 hours of flight time during 24 years of active service with the U.S. Air Force. On its last flight, March 6, 1990, Lt. Col. Ed Yielding and Lt. Col. Joseph Vida set a speed record by flying from Los Angeles to Washington, D.C., in 1 hour, 4 minutes, and 20 seconds, averaging 3,418 kilometers (2,124 miles) per hour. At the flight’s conclusion, they landed at Washington-Dulles International Airport and turned the airplane over to the Smithsonian Museum.

The Blackbird is one of the most magnificent military jets ever developed. People have been fascinated with the aircraft for decades, and not only because of the aircraft’s capabilities. The aircraft has played an important military role in international conflicts for nearly thirty years.

The Lockheed SR-71Blackbird” is a long-range, Mach 3+ strategic reconnaissance aircraft that was operated by the United States Air Force (USAF). It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the 1960s by Lockheed and its Skunk Works division. Renowned American aerospace engineer Clarence “Kelly” Johnson was responsible for many of the design’s innovative concepts. During reconnaissance missions, the SR-71 operated at high speeds and altitudes to allow it to outrace threats. If a surface-to-air missile launch was detected, the standard evasive action was simply to accelerate and outfly the missile. The SR-71 was designed to have basic stealthy characteristics and served as a precursor to future stealth aircraft.

The SR-71 served with the U.S. Air Force from 1964 to 1998. A total of 32 aircraft were built;  Only 12 were lost in accidents, but none lost to enemy action. The SR-71 has been given several nicknames, including Blackbird and Habu. Since 1976, it has held the world record for the fastest air-breathing manned aircraft, a record previously held by the YF-12.

Air Plane Physical Description:
Twin-engine, two-seat, supersonic strategic reconnaissance aircraft; airframe constructed largley of titanium and its alloys; vertical tail fins are constructed of a composite (laminated plastic-type material) to reduce radar cross-section; Pratt and Whitney J58 (JT11D-20B) turbojet engines feature large inlet shock cones.

Country of Origin
United States of America
Clarence L. “Kelly” Johnson
Lockheed Aircraft Corporation
Steven F. Udvar-Hazy Center, Chantilly, VA
Boeing Aviation Hangar
Overall: 18ft 5 15/16in. x 55ft 7in. x 107ft 5in., 169998.5lb. (5.638m x 16.942m x 32.741m, 77110.8kg)
Other: 18ft 5 15/16in. x 107ft 5in. x 55ft 7in. (5.638m x 32.741m x 16.942m)
Related Readings
Publicado en Uncategorized | Deja un comentario

Why there is a Reason to Live in Costa Rica?

Why Costa Rica? I find this hard to put into words but here goes:  The UK, Europe & USA are deeply rooted capitalist society’s that prioritises financial growth over ( and mainly against ) human wellbeing. Europe Welfare State is now in demolition process, via  the BundesMerkel System. The system relies on good little citizens that work hard and live payday to payday. Consumerism needs people to having a burning desire for the best car, the best brand of clothes or the latest iPhone. Which is funny because when people finally get those things, they just want the next thing rather than being happy/content with what they already have. If you have ever felt like a slave to the system, it is because you are. From the day we are born to the day we die consumerism and capitalism is drilled into us by parents, teachers, friends, press, music, films, media & everywhere you look. Christmas is a great example of that. All this actually creates though is greed, corruption & selfishness at the cost of social values, community and well-being. In Costa Rica there is no capitalist driven rat race for money. People are open, kind, friendly and treat each other with respect. There is a real sense of community & you might bump into the president. There is a huge value on quality of life. I realised that even with a bottomless pit of money you could not achieve the same quality of life in the UK as you could in Costa Rica on a shoestring budget. The people of Costa Rica live by the saying ‘Pura Vida’ which means Pure Life. It is clear the pura vida mindset is drilled into them from day one. It really is the happiest country in the world. As a marketer that’s takes advantage of the capitalism/consumerism mindset it was inspiring to discover a place still existed where people treat each other like people. Plus just look at the place- And that was in rainy season!


As I mentioned in a previous articles we are used to being self-sufficient here. We can grow almost everything we eat and the people have been living off the land here for hundreds of years. Costa Ricans are used to living with a lot less which is good. Most people who retire here adopt the frugal style of the locals and learn to spend less money. Fortunately, consumerism isn’t as big as in the U.S. so there are less things to waste money on.

Costa Rica seems to be out of the mainstream of the world news . You never hear anything negative mentioned in the U.S. media about Costa Rica. The country has a low profile when it comes to world events. No news is good news for us. However, there was a great story on the evening news recently about the area of Nicoya, Costa Rica that has a huge number of centenarians due the healthy lifestyle of the people who live there.

See also the newest in blog del Ing. Ernesto Ibánez

Publicado en Uncategorized | Deja un comentario

Pink BirthDay Cake Made Easy

Growing up.  It happens to the best of us.  Often I feel that there is too much “leaving behind” and “getting older” associated with growing up, and not enough “ripening” and “getting plain ole awesomer!”.  It is, undoubtedly, a struggle sometimes, but it can also be one amazing ride.  I like to lean towards the awesomer side and do my best to ignore the little creaks and crankiness of the former.
Besides, growing up doesn’t mean letting go of everything.  On the contrary, I believe we shouldn’t let go.  There are precious treasures in childhood that will never come again – wonder, curiosity, unbiased-ness, simplicity, the ability to be happy with only a shovel and a mound of sand.  I say take them with you – you’ll be happy for their company on this journey.  If you’d also like to keep a ratty old pillow that has been smoothed down to an impossible silkiness and whose smell can heal almost any hurt…well, I promise I won’t tell 😉
And sugar spun confections too…let’s definitely not outgrow those.  Layer cakes in whimsical colors, made and sampled right before dinnertime.  We all need a bit of whimsy and irrationality in our lives, perhaps even more so when we are all grown.
As time passes, it is not our own growing up that surprises us so and catches us totally unawares, but that of our children.  Little C changes so fast that I’m wont to press the slow motion button and just hold on to moments as tight as I can.  And my little godchild Z is growing as well.  That little girl we made bakies with now has more make-up than her mother and I combined (and she is quite the expert with it too…I am definitely taking her up on her free makeover offer)!  She is an artist up, down and sideways, with music running through her veins.  It’s nice to see that she hasn’t outgrown sugar spun confections either.
We (godchild Z, her mom – best friend K, and I) baked this cake late Sunday afternoon, dividing the batter into three and trying vainly to get three different shades of pink while breathing in the scent of butter and sugar.  It was delicious, like our bakies, but different too, like us.  We used the recipe I used for little C’s first birthday cake – we divided the batter into three and tinted each batch with a different amount of pink food coloring.  The batter was enough for 3 8-inch cake layers.  The icing was a simple vanilla frosting we got here.  I have to say again what a fantastic party cake this makes – yummy and easy to adapt in terms of theme and appearance.  The greatest testament however is the raves it got from K’s husband – when a man raves about a pink cake you know that it’s more than just cute.
Now, speaking of children, and super spun dreams, my beloved blog grows too.  After more than 6 years, I’ve finally updated its look and feel!  I am still in the process of cleaning up (odd links, a more detailed About Me page, and so forth) but so far I love it!  I hope you do too 🙂  It wouldn’t have been possible without the awesome talents of Patricia of Fancy Girl Designs.  Thank you Patricia!  And thanks as well to Dainty Mom, who led me to her.
So here’s to growing up while still keeping those parts that never grow up!  To pink cakes and friends!  To old things that keep us comforted and new things that make us giddy!  Cheers!
Related Readings


Lady Gaga Pictures

Publicado en Uncategorized | Deja un comentario

Protests against Monsanto all over the world

Protesters rallied in dozens of cities Saturday 25, 2013 as part of a global protest against seed giant Monsanto and the genetically modified food it produces, organizers said.

Organizers said “March Against Monsanto” protests were held in 52 countries and 436 cities, including Los Angeles where demonstrators waved signs that read “Real Food 4 Real People” and “Label GMOs (Genetically Modified Organisms), It’s Our Right to Know.”

Genetically modified plants are grown from seeds that are engineered to resist insecticides and herbicides, add nutritional benefits or otherwise improve crop yields and increase the global food supply.

Most corn, soybean and cotton crops grown in the United States today have been genetically modified. But critics say genetically modified organisms can lead to serious health conditions and harm the environment. The use of GMOs has been a growing issue of contention in recent years, with health advocates pushing for mandatory labeling of genetically modified products even though the federal government and many scientists say the technology is safe.

The ‘March Against Monsanto’ movement began just a few months ago, when founder and organizer Tami Canal created a Facebook page on Feb. 28 calling for a rally against the company’s practices.

“If I had gotten 3,000 people to join me, I would have considered that a success,” she said Saturday. Instead, she said an “incredible” number of people responded to her message and turned out to rally.

“It was empowering and inspiring to see so many people, from different walks of life, put aside their differences and come together today,” Canal said. The group plans to harness the success of the event to continue its anti-GMO cause.

“We will continue until Monsanto complies with consumer demand. They are poisoning our children, poisoning our planet,” she said. “If we don’t act, who’s going to?”

Protesters in Buenos Aires and other cities in Argentina, where Monsanto’s genetically modified soy and grains now command nearly 100% of the market, and the company’s Roundup-Ready chemicals are sprayed throughout the year on fields where cows once grazed. They carried signs saying “Monsanto-Get out of Latin America”

In Portland, thousands of protesters took to Oregon streets. Police estimate about 6,000 protesters took part in Portland’s peaceful march, and about 300 attended the rally in Bend. Other marches were scheduled in Baker City, Coos Bay, Eugene, Grants Pass, Medford, Portland, Prineville and Redmond.

Across the country in Orlando, about 800 people gathered with signs, pamphlets and speeches in front of City Hall. Maryann Wilson of Clermont, Fla., said she learned about Monsanto and genetically modified food by watching documentaries on YouTube.

“Scientists are saying that because they create their own seeds, they are harming the bees,” Wilson told the Orlando Sentinel. “That is about as personal as it gets for me.”

Chrissy Magaw was one of about 200 protesters who walked from a waterfront park to the Martin Luther King Jr. memorial in Pensacola.

She told WEAR-TV that knowing what you eat and put into your body is the most important decision you make every day.

The Truth about Monsanto and DuPont

French Study shows that Monsanto foods leads to cancer


Publicado en Uncategorized | Deja un comentario

Why the USA wants Assange? WANTED: DEAD or DEAD

Swedish judge explains big obstacles to US Assange extradition.

Wikileaker’s bizarre bonking behaviour revealed, along with likely legal escapes

By Simon Sharwood, APAC Editor

Posted in Law, 4th April 2013 03:14 GMT

A senior judge from Sweden’s supreme court, Justice Stefan Lindskog, has told an Australian audience that Julian Assange’s argument he cannot stand trial in Sweden without being extradited to the USA is not as black and white as the wikileaker would have us believe.

Lindskog yesterday told an audience at the University of Adelaide that unless Assange is charged with a crime that directly correlates to a law on the books of both Sweden and the USA, the Scandinavian nation won’t be able to hand him over.

A video of Lindskog’s talk is online here. At about the 25:00 mark he explains some rather lurid details of events that took place inside Stockholm bedrooms and have since become so contentious that Assange last year holed up in Ecuador’s London embassy. Assange remains there to this day, reportedly because he fears he cannot get a fair trial in Sweden. The leaker-in-chief has also said that once in Sweden he will be charged with other crimes by the USA and extradited to face those charges. Assange has said the US charges could carry the death penalty.

Starting at the 51:00 mark in the talk, Lindskog addresses the theory that facing trial in Sweden will mean extradition to the USA, and almost dismisses it.

“Extradition is permitted provided the offence for which extradition is requested is equivalent to a crime punishable under Swedish law by imprisonment of at least one year,” Lindskog says. “Thus, extradition requires firstly an offence punishable under the law of both countries – dual criminality – and secondly that the offence is of a certain degree of seriousness.”

Lindskog also says “extradition may not be granted for military or political offences” and explains that Swedish law won’t permit extradition if the subject of such a request is likely to experience persecution or “is serious in any other respects” or “is contrary to fundamental humanitarian principles”.

“We have some specifics when it comes to extradition to the United States,” Lindskog added, including prohibitions on extradition for political or military acts.

Lindskog then says he doesn’t know what crimes Assange could be charged with in the USA for leaking US secrets and hypothesises unlawful communication of secret material will be the basis of any charge. Sweden does have such an offence on its books, but “it can be debated” leaking American documents is not a crime under Swedish Law. Even “aiding the enemy” provisions of US and Swedish laws may be hard, as the USA’s enemies are not necessarily Sweden’s enemies. Nor is Lindskog satisfied that publishing secret documents to the world constitutes aiding the enemy, possibly making it hard to establish dual criminality.

Another legal issue is the source privilege that protects journalists from having to reveal their sources. Lindskog says the law is unclear on whether Assange can enjoy that protection.

Lindskog doesn’t say so explicitly, but his talk certainly outlines there are many legal barriers to be overcome before the USA could extract Assange.

His personal view, enunciated at 1:04:30, is that Assange has done good works.

“At the end of the day Assange will be thought of as someone who made public certain pieces of information,” Lindskog says, adding that he feels many of Wikileaks’ leaks “were good for society and should not be punished.”

“The good made by leakage of such information cannot be underestimated,” he says. “It should never be a crime to make known the crime of a state.”

If the extradition case comes before Lindskog, it seems Assange may have a sympathetic ear

Publicado en People today | Deja un comentario