Tag: photosynthesis

Carbs: All are not Bad

When the humans were evolving they didn’t know the art of agriculture. So they didn’t know to grow the edible plants. At this stage their diet was obtained from killing the animas. Thus their diet consisted mainly of fats and proteins. When agriculture was established, then humans added the carbohydrates into their food menu.

Carbs or Carbohydrates have become much maligned food from sometime. Many people say they are not good for health. These are mostly sugars. Sugars they say lead to diabetes, obesity and tooth decay.

Carbohydrates are one of the three essential categories of food along with fats and proteins. Carbohydrates provide energy to the body, fats also provide energy and fat and proteins build the bony structure of the body.

What are the carbohydrates?

Chemically carbohydrates are compounds made from Carbon, hydrogen and oxygen. There are many categories of the carbohydrates. Carbohydrates are synthesized in nature by plants and trees by a process called photosynthesis. This way they convert carbon dioxide and water into Glucose which is the starting material for making higher or complex carbohydrates like disaccharides, starches and cellulose. Human beings can’t digest cellulose.

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Monosaccharides

Monosaccharides are the simplest sugars. Two of the most popular ones are Glucose and Fructose. Whereas Glucose contains only sugar, Fructose contains vitamins and minerals alongwith sugar. These are derived mostly from fruits. Thus Fructose are better than glucose.

Disaccharides

Disaccharide means their skeleton is made of two Glucose units. Examples are Sucrose, lactose and maltose.

Starches

Starches are very complex molecules made from large numbers of Glucose units joined together. These are obtained from grains like wheat, barley and maize etc. Due to their complex structure, they are slow to breakdown into human consumable monomers.

How Carbohydrates provide energy?

Carbohydrates are like fuel in a vehicle. Carbohydrates are oxidised by Oxygen we inhale. During oxidation energy is released alongwith water and carbondioxide which are exhaled and again caught by plants and trees for making sugars for themselves and humans and animals.

Why body prefers carbohydrates than fat?

Fat provides about thrice the energy than same amount of carbohydrate. Even then body prefers it especially for giving instant energy to the brain. The reason is the ease with which carbohydrates can be broken down into energy. Also the byproducts are easy to get rid by the body.

Complex carbohydrates like starch take much longer to get hydrolyzed. First of all when we eat them, an enzyme called Amylase which is present in our saliva catalysis the starch breakdown in the belly. Thus the breakdown is slow and not instant and sustained over a longer period of time thus providing lower but sustained amounts of energy.

So in the nutshell the whole foods grains are better and useful to be taken. Carbohydrates from these are not harmful but useful.

Changing Colors of Leaves

Nature is a great chemist. It is playing with chemical pigments to present vivid colors. Even a single leaf is a piece of art. There are many classes of pigments present inside it but their amount and times of breakdown and synthesis decides the resultant color.

The different colors are on display during autumn season. The leaves begin to look less and less green. They can take yellow, orange and red hues depending upon the ratios of the amounts of different pigments present in the leaves.

Most important pigment in the leaves is of course the chlorophyll. It is this pigment which imparts the green color to the leaf and helps in photosynthesis. It’s amount is dictated by the warmth and amount of sunlight the plant receives.

It’s presence is the indication that plant is alive and carrying out photosynthesis to convert carbondioxide and water into sugars and oxygen. Sugars contain energy from the sun which is harvested by tree or plant during photosynthesis.

What happens when it is not sunny. We see a kaleidoscope of different colors in leaves. There are yellow, orange and red hues. These colors are attributed to other pigments present inside the leaves. These were there throughout the life of the leaf but there colors were masked by the strong green color.

In the autumn, when sunlight is not available in plenty, the production of chlorophyll is halted. Chlorophyll present in the leaves begins to breakdown. At this time, color contribution from other pigments begin to show up.

Chlorophyll is a type of complex with Magnesium as the central metallic ion. There are 4 nitrogen atoms which are Lewis bases and thus trap the positively charged Magnesium ion. Chlorophyll is synthesized in the warm and sunny conditions by the plants.

It’s green color dominates the color in the leaves. During autumn, the sunlight is not fully available and hence the production of chlorophyll halts and since it is not required the already present chlorophyll in the leaves begins to breakdown and hence result is the decrease in green color of the leaves.

Carotenoids and flavonoids are the other pigments which are always present in the leaves but their color is masked by the green color of the chlorophyll.

When during autumn, the chlorophyll begins to breakdown, the color of these two classes of compounds begins to show up.

Xanthophylls which are oxygenated carotenoids are responsible for the yellow color of leaves. They do not require light for synthesis, so that xanthophylls are present in all young leaves as well as in etiolated leaves.

A class of carotenoids known as beta carotene is responsible for the orange color in leaves. It absorb light of green and blue wavelengths and reflects red and yellow wavelengths light thus causing the orange color in leaves during autumn.

Beta-carotene are also responsible for this color in carrots. They begin to degrade at the same time as chlorophyll but at a slower rate thus showing up the orange color gradually.

There is another class of compounds called anthocyanins which begins to get synthesized in the mature leaves due to the high amount of sugars in them. These are red in color. These are thought to prolong the falling of leaves.

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