dna double helix

New Studyblr Introduction

Hey! In a couple months, my academics are gonna kick into high gear so I decided to make this blog for the motivation and stuff

So here’s some things about me:

•hs junior

My goals:
•career: bioinformatics research
•intending to major in biology and minor computer science
•obtain a PhD in bioinformatics

My academics:
•In the fall, I’m going to be starting a 2-year Bioscience Technologies college-prep program, which requires me to transfer to a much larger school (5x the size of my current one), though with that comes more academic opportunities
•my courses: AP US History, Honors Spanish IV, Honors English 11, and Honors Algebra II (really taking advantage of all the courses) alongside the bio program classes

•biology (molecular biology, genetics, evolution, DNA sequencing, etc.)
•computer science (analytics, programming, research)
•women’s history (suffrage, prohibition, ERA, rights of other countries, pre-suffrage, etc)
•quirky parts of history people forget to mention, kinda just history in general
•gardening and plants (succulents, vegetables, trees)
•baking, specializing in cupcakes
•reading, not just books but everything
•writing and making lists
•tea, mostly herbal
•walks and adventures
•currently have a part time jobs at a grocery store
•like background noise, music and tv shows I’ve already seen

There’s probably more I should mention, but I can’t think of anything right now.

Blogs that have inspired me:

So nice to meet you, I’m looking forward to chatting with you guys and joining the studyblr community! And feel free to talk to me whenever :)

Human DNA: A history

DNA is an important part of modern crime evidence, but it is important to know when DNA is actually used in history, and the experiments it took to actually get DNA to be the robust science it is today. Hopefully this is helpful for your writing needs!

DNA Timeline

1866 – Gregor Mendel determines the principles of genetic inheritance

1902 – Sir Archibald Edward Garrod associated Mendel’s theories with human disease alkaptonuria (black urine or black bone disease, genetic disorder where the body cannot process the amino acids phenylalanine and tyrosine)

1944 – Oswald Avery, working with MacLeod and McCarty determines DNA as the “transforming principle”, while working with Streptococcus pneumoniae (bacteria causing pneumonia), it was determined that dead/heat-killed S-strain (which is lethal) can “transform” living R-strain (which is non-lethal) into lethal bacteria

1950 - Chargaff’s rules was developed by Edwin Chargaff, it basically states that there is a 1:1 ratio of pyrimidine and purine bases, that adenine = thymine, and guanine = cytosine, an important rule for base pairings and the DNA double helix structure

1952 – Alfred Hershey and Martha Chase experimented with T2 phage and elemental isotopes; phosphorus-32 labelled DNA while sulfur-35 labelled the proteins; the progeny infected unlabelled bacteria, and since phosphorus-32 showed up, it confirmed that DNA is the genetic material

1952 – Rosalind Franklin uses X-ray crystallography to photograph DNA fibres

1953 – James Watson and Francis Crick uses Franklin’s crystallography and previous research material to determine the double helix structure of DNA

1959 – an extra chromosome 21 is linked to Down’s syndrome

1965 – Marshall Nirenberg worked with E.coli bacteria cells to determine how DNA is involved with RNA and protein expressions, he helped decipher the codons of the genetic code

1977 – Frederick Sanger develops a technique for rapid DNA sequencing, the Sanger sequencing is also known as chain termination method based on selectively incorporating chain-terminating dideoxynucleotides (ddNTPs)

1984 – Sir Alec Jeffreys developed the multi-locus RFLP probes, a method to compare the variations in DNA of different individuals, leading way to genetic fingerprinting

1986 – The first use of DNA testing in a forensic case, using Jeffreys’ multi-locus RFLP probes for DNA typing to catch Colin Pitchfork, who sexually assaulted and murdered Lunda Mann in 1983 and Dawn Ashworth in 1986

1990 – the Human Genome Project begins, with the goal of mapping all of the 3.3 billion bases of the human genome, and the genome of other organisms, this project costed about $2.7 billion (this amount wasn’t calculated for inflation) and took almost 15 years to complete, compare that to now where it will take about $1000 to sequence the human genome and it will take about a day to do so

2013 – it was discovered that identical (monozygotic) twins actually have differences in their genetic make-up, with differences/mutations called Single Nucleotide Polymorphism (SNPs)

Science Aesthetics

I was feeling inspired last night, so I decided to make this purely for fun.

To the moon and back: Cold, dark nights clutching thermos flasks of hot coffee. Machinery whirring as telescopes trace a star across the sky. Intricate, geometric drawings of the celestial sphere. A messy bun and a NASA t-shirt. Filling in the logbook while punk rock blares in the background to keep you energised and awake. Pictures of nebulae and galaxies everywhere, because pretty space pictures is half the fun. Annoyed huffs every time someone mentions their star sign.

Natural Philosopher: Long, intellectual debates in coffee shops about mathematics, physics, philosophy. Chalkboards covered with equations and calculations in a precise, curving handwriting. That Eureka moment while deep in thought, expressed only with a small smile and a scribbled proof on the back of a serviette. Chaotic desks in front of bookshelves groaning with old textbooks. Antique lab equipment as functional decor.

Trust Me, I’m a Scientist”: Large computer screens running freshly-typed code. Neat lab books and PDFs of journal articles. The smell of whiteboard markers. Polished new equipment in a tangle of cables, hooked up to a digital oscilloscope. Exact amounts of chemicals in rows in metal shelves. Resting your feet up on the bench after a long day in the lab. The satisfying hum of your colleagues as they work on their experiments around you.   

Science Expedition: Dirt under your nails and a loosely-bound collection of field notes. Plant clippings carefully taken to be analysed back in the lab. Soft fur on tough, wild animals. The bitter smoke from eco-friendly firewood while you roast marshmallows and listen to a supervisor’s witty stories. Free-handing diagrams while looking through a microscope. Sketching flowers and that gorgeous ocean view from your last field trip. Reading Darwin on the bus home but falling asleep on your lab partner’s shoulder out of sheer exhaustion after the first three pages.

Life is a Science: Scrolling past an anti-vax facebook post and resisting the urge to burn down the internet. Shiny dissection kits and the sharp smell of formaldehyde. Making time to work out and pack a healthy lunch because your mind is sharpest when your body is well. Debunking the latest superfood fad with peer-reviewed journal articles. Making friends with some of the nicer med school kids in anatomy class. Colour-coded, neatly labelled diagrams and a thousand different terms memorised. Getting a double-helix DNA sculpture for your desk.      

What they show on TV isn’t real hacking: Rubbing your eyes after staring at a screen for five hours straight. Having a blank keyboard because all the letters are rubbed off already. Energy drinks in strange colours at strange hours. Being fluent in four different coding languages. Circuit boards and printouts. Ones and zeroes. Running jokes about turning everything off and on again. Rage-quitting when you realise you forgot a comma or a colon somewhere. Black screens with brightly coloured lines. The comforting click-click of fingertips tapping keys. Applying to intern at Google every three months because maybe they’ll take you this time. Writing a piece of code to do something simple just because.

Anti-cancer drugs - DNA targeting

Include alkylating agents, intercalating agents, and chain cutters.

Alkylating agents

  • Highly electrophilic species, looking for nucleophilic sites to attack, and forming covalent bonds to bases in DNA 
  • Prevent replication and transcription 
  • Toxic side effects (e.g. alkylation of proteins) 
  • Bind in the major groove of DNA
  • Both types cross-link DNA by covalently bonding to nitrogen of base pairs.
  • Binding of nucleic acid bases results in miscoding and distortion. 
  • Distortion of DNA prevents excision by HMG proteinspermanent damage. 
  • Transcription and replication prevented, tumour growth slows. 

Two electrophilic sites on an anticancer drug can cause interstrand and intrastrand cross-linking.

  • Preference for 1,2-GG or 1,2-GC linkage sites, with interstrand or intrastrand linkage, is dictated by drug chemical structure 
  • Other linkage adducts are possible. Eg 1,3-GCG, 1,2-GA. 
  • Monofunctional adducts are also possible 

Chlormethine (a nitrogen mustard)

  •  Chlormethine is highly reactive, toxic side effects. 
  • Lead compound for many less toxic mustard derivatives. 
  • Methyl (CH3 ) group has positive inductive effect – promotes loss of chloride – see mechanism 

Less toxic chlormethine analogues:

  • Melphalan:  e- withdrawing ring lowers Nu strength of N, less reactive drug, less side effects, less toxic. Mimics PhAla, carried into cells by transport proteins. 
  • Uracil mustard:  Uracil ring is e-withdrawing, less reactive alkylating agent. Mimics a nucleic acid base, concentrates in fast growing cells.
  • Cyclophosphamide:  Most commonly used alkylating agent, Non-toxic, orally active prodrug. Acrolein associated with toxicity.
  • Busulfan: Causes interstrand cross-linking. Sulphonate group withdraws electrons, adjacent carbon subject to Nu attack by DNA bases. 
  • Dacarbazine – A diazine:  Prodrug activated by oxidation in liver, decomposes to form methyldiazonium ion. Alkylates guanine groups 


 Aminoacridines eg Proflavine

Antibiotics - Dactinomycin

  • Extra binding to sugar phosphate backbone by cyclic peptide 
  • Intercalates via minor groove of DNA double helix 
  • Prevents unwinding of DNA double helix 
  • Blocks transcription, blocks DNA-dependent RNA polymerase 

Anthracyclines eg Doxorubicin (adriamycin) 

  •  Extra binding to sugar phosphate backbone by NH3 Planar rings and Anthracyclines eg Doxorubicin (adriamycin) 
  • Intercalates via major groove of DNA double helix 
  •  A topoisomerase poison - blocks action of topoisomerase II by stabilising DNA-enzyme complex 


Calicheamicin g1 I antitumour agent 

  •  Nucleophilic attack on trisulphide chain starts a rearrangement process. 
  • This interacts with DNA to generate a DNA diradical, which reacts with oxygen, resulting in chain cutting.

Bleomycins (BLM)

  • Highly active head, neck, testicular cancer (Hodgkin lymphoma) 
  • Single and double-strand cleavage of DNA with several reduced metal ions and O2 , Fe(II) highest in vivo activity. 
  • Three regions - 
  • bithiazole DNA binding domain (DBD) locks BLM into the minor groove, 
  • carbohydrate domain (CHD) H-bonds BLM to sugar phosphate of DNA 
  • metal binding domain (MBD) bonds to Fe(II)    


  • A reaction with hydrogen peroxide gives Fe(III) and hydroxyl radicals which abstract H atoms and cut the DNA chain. 
  • Fe2+ + H2O2 Fe3+ + OH. + OH− Fenton mechanism 

Lungs and skin have low levels of BLM hydrolase - higher sensitivity and toxicity. Pneumonitis occurs in about 10% of patients, progresses to pulmonary fibrosis. Over-expressed in malignant cells, resistance to bleomycin    

Summary of Anti-Tumour Specificity for DNA 

Major groove alkylators 

  • GG interstrand - N-mustards, nitrosoureas. 
  • GG intrastrand - methanesulphonates. 
  • GC-interstrand - nitrosoureas, triazines. 

Minor groove intercalators 

  • GG interstrand – anthracyclines. 
  • GC-interstrand – actinomycins, acridines. 

Minor groove chain cutters 

  • GC or GT intrastrand – bleomycins 



Video reveals UFO sighting in Toronto, where lighted craft ( ? ) form as DNA , strange yet interesting, fake or real it doesn’t matter, the truth of universal truths is within the spiral , the ladder to heaven, kundalini, serpent rising, spiritual etheric electromagnetic fields composing both physical and nonphysical matter- a matter that science is confused about at this time, simply because they haven’t expanded their consciousness - the topic of superconductive fractals, hypercubes and crystalline structure is a real technology that is already in motion within our earths grid networks and within the universal galactic existence - A Reality you must face within yourself, within your own illuminated pituitary gland - with the brightness of your heart the truth comes alive in Vision, the fear no longer exists- the initiation into the true art starts with yourself and Nature. All around you - the signs are, the signs are revealing - and the signs are in the geometric nature of existence - This video was formed to remind humanity that we are being upgraded and updated by Forces of light-
All that is required is the meditative art and the inward sight, for if Eye is One , Body shall be full of light -
The Oneness is a real experience where there is only One consciousness guiding, healing, restructuring and adjusting the Earths System. We are One with this.
Ehani is One with the Family Of Light who CARE for all life, and want Life to flower and blossom in the times to come.
One Light and One Love to All who visit this channel and this video-
There is only Peace, Wisdom, Truth and Art here - Creativity from the Heart-Minds of Many, Collaborating over the course of many years to form a Galactic Database of Universal Communion. 

Felicity Smoak Legacy Speculation

@marytagus and @cinfos asked where is Felicity’s story going?

I was almost sure Helix and their timely presentation into Felicity’s life - at a time when she needed information on Walker to support John was not coincidental and that Alena- Kojo Sledgehammer was working with Adrian - Prometheus; under a bigger big bad who I thought could be Talia. That Alena’s convenient presentation at the time must have been related to Adrian’s play on Oliver. The Talia/big bad speculation burned and crashed!  LOL! 

So I am reconsidering Alena and Helix on a purely separate basis from Prometheus. Still bad but not related bad!

I have long thought Alena bore a physical resemblance to Brie Larvan - the bug-eyed bandit; Felicity’s nemesis - the bee lady.  Brie is of genius level intellect; and an evil hacker; who last wanted Felicitys chip in 4.17 because she had spinal cancer.  It lead Felicity to a conversation with Thea where she wanted to do some good outside the team. So maybe Alena and Helix where there; watching and waiting?  Maybe they’d been sitting there lurking waiting for an opening with Felicity and the search for the Walker files on the dark web raised a coincidental flag?

Aside: What is a helix?  Our DNA has a double helix.. its a code.. GATC.. a sequence of 4 different molecules.  Every person’s DNA is different unless you have a twin; because of the difference sequence each one of us carries.. Hence the initiative to map the human DNA- and since I am not a comic book fan; I would not waste a name like Helix on an organization that didn’t have medical applications in their repertoire!

The promo pictures posted for 5.16 show Felicity with Alena at Helix -headquarters; it looks like they have awesome technology; it also looks like they are in process for developing something. Felicity is looking up at something smiling.  What could it be?  Obviously not Oliver on the Salmon ladder!   I think the favor they ask of Felicity is related to Palmer Technology; whether its the blue print to her spinal chip or help with coding; but I really think this is where the paralysis and the chip will finally come into play.

3.17 was when Felicity presented Ray with the chip that got the Atom suite to work; and 4.17 was when Brie wanted Felicity’s chip. 

My hopeful speculation is that despite Alena and Helix’s villainous motivations; Felicity manages to outsmart them and uses their resources to complete her hopes of getting the chip to the masses and eventually by the end of the season deciding to start-up her own biomedical technology firm as either Smoak Technologies or Queen Inc, *wink, wink*

Tagging the happy bubble!

@hope-for-olicity @nalla-madness @vaelisamaza @scu11y22 @bindy417 @jules85 @eilowyn1 @coal000 @miriam1779 @tdgal1 @laurabelle2930 @emmaamelia95  @stygian-omada-fan @sweetdawn129 @spaztronautwriter @storyteller0311 @booklove22 @taurusclh @supersillyanddorky06 @quant-um-fizzx @dmichellewrites @quiveringbunny @cruzrogue @bringbackianto @onceuponarrow @marytagus @cinfos @ruwithmeguys @jaspertown @oliverdant @red-devilkin @memcjo @iheartarrow @alanna-the-lionheart  @somewhatinvisible @oliverfel4@lyricalarrow @reblynnh

The data tell us that the radius of the quark is smaller than 43 billion-billionths of a metre (0.43 x 10−16 cm). That’s 2000 times smaller than a proton radius, which is about 60,000 times smaller than the radius of a hydrogen atom, which is about forty times smaller than the radius of a DNA double-helix, which is about a million times smaller than a grain of sand.
—  Jon Butterworth

The Rebirth of Venus by ArtOfWarStudios 

Over 1000 Followers? When starting this tumblr, I didn’t expect this blog to become recognized, to be honest. Thank you for following, brothers and sisters!

Your genome, every human’s genome, consists of a unique DNA sequence of A’s, T’s, C’s and G’s that tell your cells how to operate. Thanks to technological advances, scientists are now able to know the sequence of letters that makes up an individual genome relatively quickly and inexpensively.

From the TED-Ed Lesson How to sequence the human genome - Mark J. Kiel

Animation by Marc Christoforidis

anonymous asked:

omg thank you so much for putting rosalind franklin in the dna history post!!

And also:

i think it is more correct to say that in 1953 Watson and Crick stole Rosalind’s picture to build their model, and when they published it, of course they didn’t gave her any credit. I think it is important for people to know that Rosalind Franklin discovered the antiparallel structure of the DNA molecule, but since her studies and researches were published after Watson and Crick’s, she didn’t get any recognition until many years later. (Sorry for the long message!)

Hello Nonnies!!

We can’t not talk about Rosalind Franklin. She is an awesome lady that is slowly getting the recognition she deserves in the scientific community.

(We also went to an all girls catholic highschool with large emphasis on science, and her name always came up in all of the science classes. It’s pretty hard to forget her name now. We are also going to hijack these asks to give a more in-depth biography for Rosalind Franklin.)

Franklin was a gifted X-ray crystallographer. She was a research associate at King’s College London in 1951, moved to Birkbeck College in 1953. She died at the early age of 37 due to ovarian cancer. Really she should have gotten the same Nobel Prize that Watson, Crick, and Wilkins shared in 1962 for the discovery of the DNA double helix, but the Nobel Committee are pricks and don’t award prizes posthumously.

Franklin’s the one to first contribute the concept of the two forms of DNA; A-DNA (dried, short and fat), and B-DNA (wet, long and thin). Photo 51 (image from Wikipedia) is the x-ray diffraction pattern developed while at King’s College that leads to the discovery of DNA double helix structure.

There has been some controversies surrounding the nature of her work being used by Watson and Crick. Allegations where made that Photo 51 was shown to Watson by her colleague Wilkins without Franklin’s permission (bad science ethics here) but we are not sure how true that allegation is. Franklin did not gain much recognition for her contribution originally, all that was mentioned was a footnote acknowledging that it was based on “general knowledge” of Franklin’s unpublished contribution.

Rosalind Franklin is a good example of sexism in science. She’s not gaining a lot of posthumous recognition for her work. I would also like to think that she’s an awesome role model for a lot of girls pursuing science as a field of study.