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Nucleic Acids

Nucleic acids are the “genetic software” of the cell, allowing organisms to pass on their complex components to the next generation. You might know them better as DNA (deoxyribonucleic acid) or RNA (ribonucleic acid): the macromolecules responsible for storing and transmitting hereditary information. They’re the reason you have blonde hair, or long fingers, or a gigantic nose. Without them, no organism could produce offspring, so they’re essential for all life.

Nucleic acids are made up of a chain of monomers called nucleotides, which are in turn made up of five-carbon sugars, a nitrogenous base, and one or more phosphate groups. That might seem like an extra level of complication, but we need to know this to understand their structure.

Consider, for example, a DNA molecule:

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The two strands running down on either side are called the molecule’s “sugar phosphate backbone”, which are connected in the middle by nitrogenous bases that pair up to the adjacent strand.There are four kinds of bases: Adenine and Guanine, which are purines, and Cytosine and Thymine, which are pyrimidines. In RNA, Thymine is replaced with Uracil (a pyrimidine). Purines have two rings and pyrimidines have one ring, so the groupings just refer to structure.

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(Source)

The bases are almost always shortened to A, G, C, T & U. Their order determines how life is built—they encode a sequence of amino acids, which instruct how proteins are built. We’ll learn more about later.

Nitrogenous bases are hydrophobic, meaning they hate water. This is crucial to the structure of the DNA, because the strands are oriented so the bases face each other rather than the outside world, protecting them from water. The bases pair together using hydrogen bonds—purines always pair with pyrimidines, so A pairs with T (U in RNA), and C with G.  In any given DNA molecule, the amount of A equals the amount of T, and the amount of C equals the amount of G. This is important because it maintains a uniform diameter for the helix of DNA.

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The person who realised this equality was Austrian biochemist Erwin Chargaff, and he was a contemporary of American biologist James Watson and English physicist Francis Crick, who you might have heard of. In 1953, they were the first to publish the spiralling, double-helix structure of DNA. (See my article on Rosalind Franklin for the reason I’m not a fan of Watson and Crick.)

DNA strands have a polarity, meaning they have a direction—strands are always synthesised from the 5’ (said “five prime”) end to the 3’ end. I’ll talk a whole lot more about how this happens later on. The important thing to know now is that when two strands are connected in a DNA molecule, they run antiparallel, like this:

So, what about an RNA molecule?

For starters, DNA is located in a different place to RNA:

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RNA only has a single strand, and it’s made from a different sugar: ribose instead of deoxyribose. Basically, this means it has one more OH group). RNA also has a completely different function. While DNA is the blueprint for life, RNA is the guy who actually gets things done. Different types of RNA are specialised for different functons: mRNA (messenger RNA) carries the blueprints between DNA and ribosomes in order to make proteins; rRNA (ribosomal RNA) essentially makes up the ribosomes; and tRNA (transfer RNA) carries amino acids into the ribosome for synthesis into proteins.

In summary: nucleic acids are made up sugars, phosphate groups, and nitrogenous bases, and their function is to encode, transmit, and express hereditary information. Next article, we’ll take a look at how scientists learned that nucleic acids are the genetic material of life.

Body images sourced from Wikimedia Commons

Further resources: Structure of Nucleic Acids at Educationportal

Esta manera de escribir es diferente.

Fantasmas. Eso son. O así me gustaría imaginarlos porque no tengo otra conceptualización de lo que siento y me persigue. 

Lamento si voy muy rápido, necesito música y no sé que pueda acompañarme hoy después de que algo de trova atropelló mis sentidos (no estaba lista para ello). No suelo escribir “por día” porque entonces lo que escribo se convierte en material obsoleto, pero necesito a alguien y mi único recurso es algo. Lo que significa… no, no desconfianza… no, tampoco soledad… ¿incertidumbre? eso está más próximo… quizás solo es una enorme colisión de emociones mezcladas que no pueden definir quienes son ni a quien pertenecen (si es que pudiesen hacerlo).

Siento que mis dedos vuelan en el teclado y me espanta no poder ahondar en mis emociones, claramente no están definidas y por eso no puedo escribir o un texto sombrío o algo puramente inspirador; la situación (si es que así se le puede llamar) es que mi mente va más rápido que mi habilidad para concretar y plasmar las ideas. ME ABRUMA, completamente. Días sintiéndome así y canalizando cada una de las reacciones que conlleva ese estado pero no concluyen en nada, no se liberan ni desaparecen ni NADA. 

Eso! Nada. Es lo que hay, hay tanto vacío dentro que, cuando se llena, provoca un estruendo (mis sentir, mi confusión, mi estado constante) justo como un trueno. Exactamente como ese sonido aplastante que se origina cuando un relámpago desplaza el aire y cuando se llena ese vacío es cielo se estremece… cuando alguien ha encontrado mi vacío, me alarma, me espanta, me atormenta, me confunde, me acobardo… tengo miedo.

Miedo y no es intriga, no lo es. Es miedo, de terror. 

Me sentía más que esto. Yo era más que esto… era. 

Susceptibilidad. 

Es un hecho. Me encanta cuando una buena voz toca la parte perceptiva artística de mi cerebro y hace que se me erice la piel… como la armonía de los instrumentos me hacen liberar tensión es una descarga sensorial de cada neurona. (Christina Perri - Human)

Es que ¿Por qué? ¿Por qué de esta manera? ¿No pudo haber sido más sencillo? Aseguro que heridas de guerra tengo bastantes y refugiarme ya no resulta ser funcional porque pasa ESTO y no me gusta sentirme así. Paz interior, ejercicios de manejo de ira, explotación física diaria, tardes, noches y madrugadas de series para agotar el tiempo, llamadas de mil minutos, terapias de música instrumental, lecturas interminables de personas que dicen entenderte, oraciones y plegarias incesables… pero no. No puedo ignorar el dolor de los cristales en mis pies, ¿en qué estaba pensando cuando supuse que podría ponerme de pie sobre los escombros? Tomé lo que pude, lo guardé y hasta ahora estoy trabajando en ello, pero me olvidé de todo lo que no pude desaparecer. Y cuando lo hago, cuando recuerdo que el dolor es terapia y que de allí nacen los más fuertes, es cuando me desprendo de mi y continúo, con temor.

Este es el punto donde el ciclo se repite… en el temor.

It’s not fair. Sometimes it is just not fair the way you are falling for someone. Not because it is a tragedy, not because you define yourself like solid rock after picking up all your pieces, or you don’t want to get hurt, but the way you cannot understand what is happening because of how awesomely different he is.

Now I understand what they mean with “be the girl you are when you write”.

sealsong:

'Famously Scarred'
I’m black as the proof that is on my face, I’m a soldier.
"My scars like tattoos with a different edge,
they’re my soul they’re my story.
Co’s there’s a million different people …
living inside of me.
I’m like a million different people ..
living inside of me”
(from my forthcoming album 7)
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sealsong:

'Famously Scarred'

I’m black as the proof that is on my face, I’m a soldier.

"My scars like tattoos with a different edge,

they’re my soul they’re my story.

Co’s there’s a million different people …

living inside of me.

I’m like a million different people ..

living inside of me”

(from my forthcoming album 7)

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