Rosalind Elsie Franklin

Rosalind Franklin

Rosalind Elsie Franklin (25 July 1920 – 16 April 1958) is probably the most famous yet controversial female scientist in terms of the critical contributions to the understanding of molecular structure of DNA. Apart from her most known work, she also dedicate her life to the investigation of viruses, coal and graphite.

Franklin was educated at a private school in London where she studied physics and chemistry from an early age, at an advanced level, especially so for a woman at that time. An excellent and dedicated student, she earned a Ph.D. in physical chemistry in 1945 from Cambridge University. Early in her career, it was Rosalind Franklin who painstakingly conceived of and captured "Photograph 51" of the "B" form of DNA in 1952 while at King's College in London. It is this photograph, acquired through 100 hours of X-ray exposure from a machine Dr. Franklin herself refined, that revealed the structure of deoxyribonucleic acid, DNA.

The discovery of the structure of DNA was the most important advance of modern biology. Quite simply, it changed the future of healthcare forever. James Watson and Francis Crick, working at Cambridge University, used Photograph 51 as the basis for their famous model of DNA which culminated in their Nobel Prize in 1962. 

Photo 51

Franklin was responsible for much of the research and discovery work that led to the understanding of the structure of DNA. The story of DNA is a tale of competition and intrigue, told one way in James Watson's book The Double Helix, and quite another in Anne Sayre's study, Rosalind Franklin and DNA. James Watson, Francis Crick, and Maurice Wilkins received a Nobel Prize for the double-helix model of DNA in 1962.
In the summer of 1956, while on a work-related trip to the United States, Franklin found she could no longer do up her skirt because of a lump around her abdomen. It was too much exposure to X-ray radiation when she was working with in order to get the photo of DNA caused the illness. She fell ill again and again afterwards, and she died on April 16, 1958, in Chelsea, London.

Things About Triglyceride

Triglycerides are the chemical form in which most fat exists in food as well as in the our bodies. They're also present in blood plasma and, in association with cholesterol, form the plasma lipids. We eat lipid on a daily basis. When we eat, our body converts calories it doesn't need to use into triglycerides. The triglycerides are then stored in fat cells, which can be used  as an energy source when there's no enough food ingested later on. So, if one regularly eat more calories  than one burn, particularly "easy" calories like carbohydrates and fats, one may have high triglycerides. 

Triglycerides in plasma are derived from fats eaten in foods or made in the body from other energy sources like carbohydrates. They help enable the bidirectional transference of adipose fat and blood glucose from the liver. Calories ingested in a meal and not used immediately by tissues are converted to triglycerides and transported to fat cells to be stored. Hormones regulate the release of triglycerides from fat tissue so they meet the body's needs for energy between meals.

Structure of tryglyceride

From a chemical respective of view, triglyceride is an ester composed of glycerol and three fatty acids connected by ester bonds. Triglycerides are different from other biological macromolecules because they do not fit the monomer-polymer relationship based on their basic structure. Triglycerides vary each other from the three fatty acids bonded the glycerol. There are different lengths and bonding of three fatty acids. When the bonding between carbon atoms are all single bonds (C-C), they are called saturated compounds. If there is(are) double bond(s)  between carbon atoms(C=C), they are refer as unsaturated compounds.

Unsaturated fats have a lower boiling point than saturated fats. Also, unsaturated fats are usually liquids under room temperature whereas saturated fats are usually solid. Animal fats are typically saturated while vegetable oil are typically unsaturated, which unsaturated fats are known as more healthier than saturated ones. In addition, triglycerides are the main components of human skin oils. 

One of the very important functions of triglycerides and, even more so, the related phospholipids is that they contribute to the structure of membranes by forming a lipid bilayer. The membranes serve as a barrier to keep the inside of a cell from the outside. The triglycerides and the phospholipids help to achieve this by having the polar head facing the outside which is hydrophilic, and the non-polar fatty acids tails facing inside of the cell membrane which is hydrophobic. Because the non-polar tails tend to dissolve into one another and form a layer that is resistant to water, thus keeping the solution outside the cell from the inside. Cell membranes made in this way is not rigis, but quite fluid and flexible, which is a considerable value to cells. 

Structure of bilayer

Digestive System in Rabbit

The rabbit, as an herbivore, is uniquely designed to consume large amounts of plant material.  The plants that rabbits eat are high in fiber, which is indigestible to mammalian digestive enzymes.  This means that humans and many other animals cannot utilize the nutrients found in these plants.  However, the rabbit’s digestive system makes it able to consume these plants and make the most of their nutrients. 

Because rabbits consume fibrous plant materials, they must eat a lot to meet their nutrient needs. However, their gastrointestinal tract is small compared to other herbivores, such as horses and cattle. So to accommodate large amounts of plants, food moves through the tract relatively quick.  Their digestive system is designed to make the most efficient use of the nutrients found in their diet.

Here are the processes of rabbit digestion as summarized in the diagram below. The food goes into the stomach, but the real action is not there.  The stomach stores the food and the contents are sterilized and moved to the small intestine. While in the small intestine up to 90% of the protein, starches and sugar are absorbed from the food. Then the undigested fiberous material moves on and is sorted. The fiber goes to the colon forming hard waste. The remaining food is then ready for digestion goes into the cecum which is larger than the stomach. Then the hard waste that bypasses the cecum is moved through the colon in a circular motion and forms perfectly round hard balls. There are two scent glands and either side of the anus. The cecum is a complicated organ that redigests the food.  It is filled with enzymes and bacteria that breakdown food. Every 3 to 8 hours the cecum contracts and forces the material back into the colon where it is coated with mucus, then passed through the anus (looks like a clump of small brown grapes) and the rabbit eats these "cecotrophes" directly. This is a very important part of the digestive process and keeps rabbit healthy.

For proper digestive health, a rabbit’s diet should be designed with its unique gastrointestinal system in mind. The diet should be high in fibrous materials to provide for proper dental health, as well as to ensure movement through the digestive system and for fermentation in the cecum to occur to produce cecotropes.  This fiber should come from high-quality plant materials to allow for sufficient nutrient utilization as the passage rate in the rabbit is relatively rapid. 

Meaning of Carbon

All life on earth is based on carbon. But why?

Let's look at some facts about carbon before we actually answer the question stated above. The chemical symbol for carbon is the capital letter, C. The atomic number for carbon is six. Its atomic weight is 12.11. Usually carbon is found in combination with other elements as in carbon dioxide, limestone, coal, and petroleum. Only less than one percent (0.32%) of the earth's atmosphere and 0.2% of the earth's crust are carbon. However, it is this rare element that makes the basis of all living things on earth.

Carbon has significant meaning to lives because its molecular structure, which determines its diverse function. It is capable of making such diverse compounds because carbon can bond to four other groups around it, and to other carbon molecules. For this reason it can form long chain molecules, each with different properties. This allows very long chains of complex molecules to form that are specific enough in their functions, shapes, and binding properties that can enable living organisms to do many things. Even at 30 carbons, there are millions of ways in which the molecule can be arranged. Also, carbon readily forms bonds with many other molecules: hydrogen, oxygen, halogens... and even some metals!

Pure carbon only exists in three forms: diamonds, graphite, and carbon black (charcoal, for example). However,  almost all living things on earth is comprised of carbon. That includes human beings, plants, and animals. Like all animals, humans have a metabolic need for carbon. We get it by eating carbohydrates which are produced in plants during photosynthesis, when carbon dioxide combines with water. Because carbon is so intrinsic to all forms of life, the study of organic carbon compounds is a primary emphasis of organic chemistry.

Forms of Carbon

Silicon (though it is not as abundant) is capable of forming the same sorts of bonds and structures, but opinion is divided on whether silicon-based life forms are a realistic prospect. In part because it needs higher energies to form them, and also because whereas carbon dioxide (one of the main by-products of respiration, a process essential to all known life) is a gas and therefore easy to remove from the body, its counterpart silicon dioxide (silica) has an inconveniently high melting point, posing a serious waste disposal problem for any would-be silicon-based life form. In addition, because silicon has one more layer of electrons than carbon, which means that the attraction of nucleus to electrons is weaker, making the bonding between silicon and other molecules weaker. 

The field of organic chemistry is just the study that based on carbon. The compounds carbon forms with metals are generally considered inorganic. Chains and rings are fundamental to the way carbon-based life forms, that is, all known life forms build themselves. 

Carbon has quite a few industrial uses as well. First and foremost, carbon is the key ingredient in fossil fuels. Carbon in filters absorbs impurities. It is found in carbon paper, paint, and ink. Carbon, added to tires, helps them to wear evenly so they last longer. Finally, by measuring the ratio of carbon to nitrogen and by measuring the amount of carbon-14 that remains in a piece of organic material such as a fossil or a piece of wood, scientists can get a good idea of the age of an item.

Water Water Water

Water, as the source of life, is extraordinarily important to us and to all life on earth. We see it, use it and drink it in our daily lives. But why is water essential for life? In other words, what properties of water make it the prime ingredient of life?

Water with its molecular formula, H2O, has as many as 20 properties, making it the essential basis of life. But only 5 properties, which I personally think is quite unique and significant,  are going to be discussed.

1. universal solvent

Scientists often call water "universal solvent" simply because it can dissolve more substances than any other liquids. Since water is a polar molecule, its positive end is attracted to negatively charged ions or the negative sides of other polar molecules, and its negative side is attracted to positively charged ions or the positive sides of other polar molecules. For example: if table salt (NaCl) is added in water, it quickly falls apart. The positively charged sodium ion (Na⁺) will  be surrounded by eager water molecules with the negative sides and the negatively charged chlorine ion (Cl^-) will be surrounded by other water molecules with positive sides. This properties of water allows transport of nutrients vital to lives. 

2. cohesion and adhesion
Hydrogen bonds between water molecules make them stick together, which is called cohesion. This results in high surface tension at the surface of water, which means that it’s actually pretty hard to break the surface of water compared to other liquids. Surface tension is what allows some things to float on water even if they’re denser than water. Adhesion is the the sticky nature of water to other substances rather than to itself. You can see this property when some water drops stays inside of the glass when you try to pour out the water. This is the same as how water clings living things. Most plants have adapted to take the advantage of water's adhesion to help transport water from the roots to the top. In one of the tallest plant: redwood tree, water moves more than 310 feet above the ground from its roots to leaves. 

3. high specific heat capacity
Water absorbs/ releases more heat than other substances for each degree Celcius increase/decrease. This property of water makes it excellent for cooling and transferring heat in thermal and chemical processes. This is also why the temperature at coastal area is relatively constant than that of inland. Thus, organisms living in the ocean, river are provided with a constant environmental temperature, and high water content of plants and animals living on land also helps them to maintain a relatively constant internal temperature. 

4. unique density
We all know that for most compounds, the solid is denser than the liquid, meaning that the solid will sink to the bottom of the container holding the liquid. But this is not for water. The truth is that water actually becomes less dense when it freezes, which allows the solid form: ice, to float on the liquid form: water. This explains why a pond freezes from the surface down, rather than from the bottom up. This property of water is quite important for organisms that live underwater. If frozen water sunk, small bodies of water would be more likely to freeze completely in the winter. But thank to density, a layer of ice instead insulates the underlying water effectively, allowing many aquatic organisms to survive through the winter. 

5. buffer nature
Before I start, it is important to know that water molecules have tendency to ionize, that is they dissociate into hydrogen ions (H+) and hydroxide ions (OH-), which are weak acid and weak base. And we know that buffer happens between a weak acid and a weak base, which it resist pH changes by donating or accepting hydrogen ions (H+) as needed. This is important because, as you’ll learn later, most of the chemical processes that occur in living organisms are highly sensitive to pH, and drastic changes in pH can cause some serious trouble. The dissociated water molecules are what give water its buffering ability. If  an acid is added to solution, some of the free OH^- ions will bind to the newly added H⁺ ions, which will moderate the decrease in pH. Similarly, if a base is added, the base will bind to the free H⁺ ions in solution, which will moderate the increase in pH. 

Themes of Biology

Biology is known as the study of lives. It is also a field of science that can be unified by some fundamental themes. These themes are:  evolution, levels of organization, structure and function, regulation, unity and diversity and continuity and change. Certainly, all of them have significant meanings in which biology no longer makes sense without any of them.

First I'm going to talk about evlution, which is considered as the "core theme of biology". Evolution can be simply said as change of species over time. The central ideas is that all living organisms on earth share a common ancestor, and as time passes, huge diversity of lives are created through the process of mutation and modification. Mutation is just the permanent change of DNA sequence in a gene. It happens when organisms are producing offsprings, their genes that're inheritted have been altered due to various reasons, such as: enviromental agents, duplication error. A small change of DNA sequences can causes significant changes in organism's looking, behavior and physiology. Therefore, diversity of lives are formed in populations over generations.In addition, organisms' appearence is affect not only by the genetic makeup, but also by its living enviroment.

An exmaple of mutation in DNA

However, evolution is'nt just about mutation and diversity. Another important idea  about evolution is natural selection and adaptation. The enviroment on earth changes over a certain period of time, and only those organisms with certain characteristics that help them to adapt the new enviroment the best are likely to live the longest and produce the most offspring and therefore passing on their certain characteristics. This is called natural selection, the key mechanism of evolution proposed by Charles Darwin. There are many evidences for this theory, the most famous ones are the fossil records, DNA studies and artifical election.


Charles Darwin

In biology, the unity of life refers to all the varitation and forms that characterize various organisms. However, all living things came from one organism, relate to ecolution. These two ideas make up the theme of "unity and diversity". Although lives have huge variations, ranging from bacteria to fungi to animalia, all of them are united by some properties: replication, heritability, catalysis and energy utilization. These four common basic  properties chracterize all living organisms on earth.

Unity and diversity of all living organisms

Another important idea about biology I've learnt is the close correlation between structure and its function. Structure and function are correlated at all levels of biological organization, in which structure determines function. For example: protein (amino acids) structure directly effects its function. It is a lock and key method that cannot work unless the structure fit together. When they fit they can carry out the function of speeding up a chemical process. The components and physical properties (structures) of a certain cell have huge influence on its function.


Structure and function of protein

I've only talked a small section of biology, and there are much much more for us to learn. Biology has a wide range and some we still don't understand so far, which is waiting for us discover and explore.