Buffer solution is able to retain almost constant pH when small amount of acid/base is added. Quantitative measure of this resistance to pH changes is called buffer capacity.
Buffer capacity can be defined in many ways. You may find it defined as "maximum amount of either strong acid or strong base that can be added before a significant change in the pH will occur". This definition - instead of explaining anything - raises a question "what is a significant change?" - sometimes even change of 1 unit doesn't matter too much, sometimes - especially in biological systems - 0.1 unit change is a lot. Buffer capacity can be also defined as quantity of strong acid or base that must be added to change the pH of one liter of solution by one pH unit. Such definition - although have its practical applications - gives different values of buffer capacity for acid addition and for base addition (unless buffer is equimolar and its pH=pKa). This contradicts intuition - for a given buffer solution its resistance should be identical regardless of whether acid or base is added.
http://www.chembuddy.com/?left=pH-calculation&right=pH-buffer-capacity
In the cell have the chemical components which maintain the pH. So it always in optimum pH. The chemical components of solution is mineral salts in the form of phosphate salt solution.
The phosphate buffer system operates in the internal fluid of all cells. This buffer system consists of dihydrogen phosphate ions (H2PO4-) as hydrogen-ion donor (acid) and hydrogen phosphate ions (HPO42-) as hydrogen-ion acceptor (base). These two ions are in equilibrium with each other as indicated by the chemical equation below.
H2PO4-(aq) -----> H+(aq) + HPO42-(aq)
Enzymes are structured protein compounds which function as a catalyst and is known as bio-catalyst. Enzymes act as catalysts that catalyze chemical reactions that occur in biological systems.
In performing its role as a bio-catalyst in the body, how the enzyme is influenced by several factors, one of which is the degree of acidity or better known as the pH, this is because the enzyme is only willing and able to work at certain pH conditions. A pH conditions where the enzyme can work with the highest activity as may be named with the optimum pH.
In contrast at a certain pH of the enzyme at all is no longer active or even damaged. This can be explained * for us to know that enzymes are molecules of protein, the protein molecule stability could be affected by the level of acidity of the environment, in conditions of extreme acidity of the protein molecules from the enzyme will be damaged.
Hence, in an effort to maintain the cells occur in order to keep the optimum pH.
Cells can maintain pH chemically by using buffers. Buffers are molecules that easily interconvert between acidic and basic forms, donating or accepting protons as conditions change.
Two important biological buffer systems are the dihydrogen phosphate system and the carbonic acid system.
The phosphate buffer system operates in the internal fluid of all cells. This buffer system consists of dihydrogen phosphate ions (H2PO4-) as hydrogen-ion donor (acid) and hydrogen phosphate ions (HPO42-) as hydrogen-ion acceptor (base). These two ions are in equilibrium with each other as indicated by the chemical equation below.
H2PO4(aq) + H (aq) ----> H(PO4)2(aq)
Cells must constantly maintain their pH in order to function properly. In animals, for example, the maintainence of blood pH is crucial for life. A slightly acidic pH (6.95) would result in coma and death. A slightly more basic pH (7.7) would result in convulsions and muscle spasms. As another example, the pH of cellular organelles such as lysosomes (around 5) is lower than the pH of the cytoplasm (around 7.2). Lysosomes contain enzymes that function optimally in an acidic environment. Such an acidic environment, however, would be detrimental to biological processes in the cytoplasm. Each must maintain the appropriate pH.
A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. It has the property that the pH of the solution changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. Many life forms thrive only in a relatively small pH range; an example of a buffer solution is blood.
The central dogma of molecular biology was first articulated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970:
The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information.. It states that information cannot be transferred back from protein to either protein or nucleic acid.
In other words, 'once information gets into protein, it can't flow back to nucleic acid.'
The dogma is a framework for understanding the transfer of sequence information between sequential information-carrying biopolymers , in the most common or general case, in living organisms . There are 3 major classes of such biopolymers: DNA and RNA (both nucleic acids ), and protein . There are 3×3 = 9 conceivable direct transfers of information that can occur between these The dogma classes these into 3 groups of 3: 3 general transfers (believed to occur normally in most cells), 3 special transfers (known to occur, but only under specific conditions in case of some viruses or in a laboratory), and 3 unknown transfers (believed never to occur). The general transfers describe the normal flow of biological information: DNA can be copied to DNA ( DNA replication ), DNA information can be copied into mRNA , ( transcription ), and proteins can be synthesized using the information in mRNA as a template ( translation ).
Crawling around me...
Sleepless eyes...
Your hands, they haunt me...
finger tipping down my spine.
Heaven forbid, well aware of your sins.
In the wake I'll be just like the rest.
Tell the sun don't fall, so we'll never forget.
Heaven forbid, well aware of your sins.
In the wake I'll be just like the rest.
Past praying for.
Always kept quiet...
Clenching my teeth.
Find me fighting the floor.
Raise me from my bones once more.
You're way past praying for.
I wouldn't want to wake you from yourself.
...doesn't sit in your stomach just quite right.
Toying with time...
Lascivious stares and a dangerous rhyme
Which of following reaction do not produce the NADH as adding product at Krebs Circle? a. Isocytrate → Oxalosuccinate b. Alpha ketoglu...
Wanita adalah mahluk ciptaan tuhan yang tahan banting, kesabarannya jauh di atas lelaki. Dia akan menjadi setia jika dia merasa nyaman...
Sebuah cerita... Ini Kisah anak berumur 5 tahun bernama Anisa. Di sore hari yg cerah, Anisa dan ibunya berbelanja di supermarket tepatnya d...