24 Şubat 2015 Salı
23 Şubat 2015 Pazartesi
PROTEİNLER
Proteins are large molecules.
They are not really soluble, rather they form colloids
- colloids are about 500nm, which is larger than particles in solution, but smaller than particles in suspension
- colloids exist in a "sol-gel state", whereby sometimes they appear to be liquid and at other times they are jelly-like (much of the material in cytoplasm is colloid)
Proteins contain: C, H, O and N, sometimes S and P
There are an almost limitless number of proteins, which vary between species and are often species-specific (fajlagosok). They determine the characteristics of a species.
Types of Proteins
a. Structural proteins - these form the organism. eg. hair, nails, feathers, etc.
b. Physiological proteins - these carry out functions, examples include:
-enzymes (biocatalysts)
-carrier molecules (szállítómolekulák)
- pigments (eg. various colour molecules in skin and eyes, haemoglobin in red blood cells)
- hormones (chemical messengers)
- contractile material in muscles
- antibodies (disease protection)
** Proteins are rarely stored (only in seeds and eggs). Proteins are only broken down for energy if a living organism is starving.
PROTEIN STRUCTURE
- a protein is a polymer. Its monomers are called amino acids.
Image from http://api.ning.com/files/xO6ybWgUbfFlk7GUXm9d8dfR--U-fUdPOJEtDzVGgDY_/aminoacidstruc.jpg
- some amino acids are basic, others are neutral - this depends on the variable group
- some amino acids are polar and others are apolar - this depends on the variable group
-amino acids are soluble in water, where they form dipolar ions (zwitterion = ikerion), this means they have BOTH acid-base properties, so they have good buffering capacity.
Synthesis of polypeptides
- amino acids attach to each other by condensation to form covalent peptide bonds
2 amino acids condense to form a dipeptide, 3 form a tripeptide and many joined together form a polypeptide.
- if more than 100 amino acids attach together it is considered a protein
- polypeptides (and proteins) are broken down by hydrolysis
*both condensation and hydrolysis require enzymes to occur.
Structure
Primary structure: this is the number and sequence of the amino acids.
*Insulin was the first protein to have its primary structure determined by a researcher named Fred Sanger
Secondary structure: This type of structure is created by H-bonds forming between amino acid monomers
Alpha helix (eg. keratin - a major component of hair and skin)
Image from http://www.bio.miami.edu/~cmallery/150/protein/alpha-helix.jpg
Beta-pleated sheet (eg. silk protein)
Image from http://student.ccbcmd.edu/courses/bio141/lecguide/unit3/viruses/images/betasheet.jpg
-both structures can be found in a single protein.
Tertiary structure: This is the secondary structure folded in 3-dimensional space.
-usually forms globular shapes
-bonded by S-bridges (requires the amino acid cysteine), ionic bonds, H-bonds and van der Waals forces
Image from http://lectures.molgen.mpg.de/ProteinStructure/Levels/tertiary.gif
Quaternary structure: A protein has quaternary structure if it is formed of 2 or more subunits (polypeptides). They are held together by various forces including hydrophobic interactions, H-bonds and ionic bonds.
eg. Haemoglobin
Image from http://www.theironfiles.co.uk/images/Haemoglobin_Structure.jpg
Proteins can further be catagorized as simple or complex. A simple protein contains only amino acids, complex proteins often include other elements, such as the iron containing haeme molecule found in haemoglobin (above).
Protein Stability and Denaturation
A protein will be stable (maintain its shape and function) if the environment it is in is appropriate. The most common environmental factors that will cause a protein to denature (lose its shape and/or function) are temperature and pH levels. Some proteins have a wide range of tolerance (can function at 4C and at 40C), while others have a very narrow range. This is a protein-specific characteristic. An example of protein denaturation is when we cook an egg. The white of the egg is almost entirely made of the protein albumin. At room temperature it is a clear liquid. If we increase the temperature, the protein starts to denature (lose its shape and therefore function too) and it become solid and white. Denaturation occurs because the bonds between the amino acids are broken.
Sometimes denaturation is permanent (like cooking an egg), other times it can be reversible.http://bilingualbiology11a.blogspot.com.es/2010/09/lesson-4-chemistry-of-life-proteins.html
They are not really soluble, rather they form colloids
- colloids are about 500nm, which is larger than particles in solution, but smaller than particles in suspension
- colloids exist in a "sol-gel state", whereby sometimes they appear to be liquid and at other times they are jelly-like (much of the material in cytoplasm is colloid)
Proteins contain: C, H, O and N, sometimes S and P
There are an almost limitless number of proteins, which vary between species and are often species-specific (fajlagosok). They determine the characteristics of a species.
Types of Proteins
a. Structural proteins - these form the organism. eg. hair, nails, feathers, etc.
b. Physiological proteins - these carry out functions, examples include:
-enzymes (biocatalysts)
-carrier molecules (szállítómolekulák)
- pigments (eg. various colour molecules in skin and eyes, haemoglobin in red blood cells)
- hormones (chemical messengers)
- contractile material in muscles
- antibodies (disease protection)
** Proteins are rarely stored (only in seeds and eggs). Proteins are only broken down for energy if a living organism is starving.
PROTEIN STRUCTURE
- a protein is a polymer. Its monomers are called amino acids.
Image from http://api.ning.com/files/xO6ybWgUbfFlk7GUXm9d8dfR--U-fUdPOJEtDzVGgDY_/aminoacidstruc.jpg
- some amino acids are basic, others are neutral - this depends on the variable group
- some amino acids are polar and others are apolar - this depends on the variable group
-amino acids are soluble in water, where they form dipolar ions (zwitterion = ikerion), this means they have BOTH acid-base properties, so they have good buffering capacity.
Synthesis of polypeptides
- amino acids attach to each other by condensation to form covalent peptide bonds
2 amino acids condense to form a dipeptide, 3 form a tripeptide and many joined together form a polypeptide.
Formation of a dipeptide
Image from http://www.mrothery.co.uk/images/Image46.gif- if more than 100 amino acids attach together it is considered a protein
- polypeptides (and proteins) are broken down by hydrolysis
*both condensation and hydrolysis require enzymes to occur.
Structure
Primary structure: this is the number and sequence of the amino acids.
*Insulin was the first protein to have its primary structure determined by a researcher named Fred Sanger
Secondary structure: This type of structure is created by H-bonds forming between amino acid monomers
Alpha helix (eg. keratin - a major component of hair and skin)
Image from http://www.bio.miami.edu/~cmallery/150/protein/alpha-helix.jpg
Beta-pleated sheet (eg. silk protein)
Image from http://student.ccbcmd.edu/courses/bio141/lecguide/unit3/viruses/images/betasheet.jpg
-both structures can be found in a single protein.
Tertiary structure: This is the secondary structure folded in 3-dimensional space.
-usually forms globular shapes
-bonded by S-bridges (requires the amino acid cysteine), ionic bonds, H-bonds and van der Waals forces
Image from http://lectures.molgen.mpg.de/ProteinStructure/Levels/tertiary.gif
Quaternary structure: A protein has quaternary structure if it is formed of 2 or more subunits (polypeptides). They are held together by various forces including hydrophobic interactions, H-bonds and ionic bonds.
eg. Haemoglobin
Image from http://www.theironfiles.co.uk/images/Haemoglobin_Structure.jpg
Proteins can further be catagorized as simple or complex. A simple protein contains only amino acids, complex proteins often include other elements, such as the iron containing haeme molecule found in haemoglobin (above).
Protein Stability and Denaturation
A protein will be stable (maintain its shape and function) if the environment it is in is appropriate. The most common environmental factors that will cause a protein to denature (lose its shape and/or function) are temperature and pH levels. Some proteins have a wide range of tolerance (can function at 4C and at 40C), while others have a very narrow range. This is a protein-specific characteristic. An example of protein denaturation is when we cook an egg. The white of the egg is almost entirely made of the protein albumin. At room temperature it is a clear liquid. If we increase the temperature, the protein starts to denature (lose its shape and therefore function too) and it become solid and white. Denaturation occurs because the bonds between the amino acids are broken.
Sometimes denaturation is permanent (like cooking an egg), other times it can be reversible.http://bilingualbiology11a.blogspot.com.es/2010/09/lesson-4-chemistry-of-life-proteins.html
HÜCRE DÖNGÜSÜ, REPLİKASYON, MİTOZ VE MAYOZ
Topic 11: Cell cycle, DNA replication, mitosis and meiosis
DNA is found in the nucleus. It carries the genetic information in all eukaryotes.
How is DNA organized?
-its basic structure is the double helix
-this is then wound around proteins (called histones) to form chromatin. Under an electron microscope, it looks like beads on a chain. This is the form that DNA is stored in between cell divisions
-during cell division the DNA winds up more tightly and the chromatin coils on itself, looping and coiling to form thick rods called chromosomes, which are visible under the light microscope
Image from: http://themedicalbiochemistrypage.org/dna.html
What happens?
DNA is copied when it is uncondensed, then it condenses into chromosomes that have 2 halves (each a copy of the other). Each half is called a chromatid. Sister chromatids are identical. The point at which the DNA narrows and the chromatids are connected is called the centromere. Each chromosome has many genes, each gene defines a single characteristic.
The number and shape of chromosomes are species-specific. eg. Humans = 46 chromosomes, dogs = 78, pea = 14, fruit fly = 8
All sexually reproducing organisms have 2 sets of chromosomes, one from each parent (this is the diploid state). In humans a diploid cell has 46 chromosomes, half from the mother and half from the father (23). The chromosomes which carry the same kind of information are called homologous chromosomes.
Cell division
There are 2 types:
- mitosis (számtartó sejtosztodás): purpose is growth and repair, 2 identical daughter cells are produced
- meiosis (számfelező sejtosztodás): purpose is to produce gametes (sex cells) for reproduction, 4 genetically different cells are produced
The cell cycle describes the typical cycle of a somatic (body) cell that will go through mitosis:
Image from: http://www.cdli.ca/courses/biol3201/unit02/unit02_org01_ilo02/b_activity.html
During the first growth phase, the cell simply grows and carries out its normal functions. At a certain point, the cell enters the synthesis phase, where the DNA is replicated.
DNA replication refers to the creation of another DNA double helix using the first helix as a template. In order for this to occur:
Once DNA replication has occured, the nucleus then has 2 copies of all of its DNA and will continue to grow and carry out some normal functions, but it will also prepare for cell division, which is either mitosis or meiosis, depending on whether or not it is a cell that will simply copy itself, or a cell that is designed to produce gametes (eggs or sperm).
Mitosis is divided into 4 phases:
Prophase:
-chromatin condenses to chromosome
-nuclear envelope disintegrates and disappears
-spindle (magorsó) forms
Metaphase:
-chromosomes line up at the equator
Anaphase:
-chromatids are pulled to opposite poles of the cell
Telophase:
-cell plasma divides
-nuclear envelope reappears
(don't worry about the extra stages in the image below!!)
Image from: https://www.msu.edu/~robiemat/science.htm
Image from : http://imcurious.wikispaces.com/Midterm+Exam+2010+Review+P1
Meiosis occurs to produce haploid cells that will be gametes (sperm and eggs).
It is a division that reduces the chromosome number by half. It is divided into meiosis I and meiosis II
Meiosis I
Prophase I
-chromatin condenses to chromosomes
-chromosomes "find" their homologous pairs and crossing over occurs
Metaphase I
--nuclear membrane disappears
-homologous chromosomes line up at the equator and attach to spindle fibres
Anaphase I
- chromosomes pairs are split as they are pulled to opposite poles
Telophase I
- cell plasma divides
- nuclear membrane reforms
Short interphase, with no DNA replication
Meiosis II
Prophase II
-chromosomes condense
- nuclear membrane disappears
-spindle forms
Metaphase II
-chromosomes line up at the equator
Anaphase II
-chromatids are pulled to opposite poles of the cell
Telophase II
-cell plasma divides
-nuclear membrane forms
Image from: http://commons.wikimedia.org/wiki/File:Meiosis_diagram.jpg
So mitosis and meiosis share some characteristics, but are also unique in many ways. The following diagram presents a comparison of the two. Be sure to consider how they are similar and how they are different.
Image from: http://bioactive.mrkirkscience.com/09/ch9summary.html
How is DNA organized?
-its basic structure is the double helix
-this is then wound around proteins (called histones) to form chromatin. Under an electron microscope, it looks like beads on a chain. This is the form that DNA is stored in between cell divisions
-during cell division the DNA winds up more tightly and the chromatin coils on itself, looping and coiling to form thick rods called chromosomes, which are visible under the light microscope
What happens?
DNA is copied when it is uncondensed, then it condenses into chromosomes that have 2 halves (each a copy of the other). Each half is called a chromatid. Sister chromatids are identical. The point at which the DNA narrows and the chromatids are connected is called the centromere. Each chromosome has many genes, each gene defines a single characteristic.
The number and shape of chromosomes are species-specific. eg. Humans = 46 chromosomes, dogs = 78, pea = 14, fruit fly = 8
All sexually reproducing organisms have 2 sets of chromosomes, one from each parent (this is the diploid state). In humans a diploid cell has 46 chromosomes, half from the mother and half from the father (23). The chromosomes which carry the same kind of information are called homologous chromosomes.
Cell division
There are 2 types:
- mitosis (számtartó sejtosztodás): purpose is growth and repair, 2 identical daughter cells are produced
- meiosis (számfelező sejtosztodás): purpose is to produce gametes (sex cells) for reproduction, 4 genetically different cells are produced
The cell cycle describes the typical cycle of a somatic (body) cell that will go through mitosis:
During the first growth phase, the cell simply grows and carries out its normal functions. At a certain point, the cell enters the synthesis phase, where the DNA is replicated.
DNA replication refers to the creation of another DNA double helix using the first helix as a template. In order for this to occur:
1. The DNA double helix begins to unwind or unzip at one end to form a replication fork. Unwinding requires the help of an enzyme called a helicase.
2. Enzymes called DNA polymerases bind to the single strands of DNA. They then proceed to "read" the template strand (in the 5' to 3' direction) and add complementary nucleotides. Since the polymerase only travels in one direction, it will move more quickly along the leading strand, but on the lagging strand it will attach at the fork and move toward the end, until it meets up with a previously formed DNA strand fragment, then it will detach and reattach at the continuously unwinding replication fork. The fragments that are created in this way are called Okazaki fragments. They are "glued" together with the help of enzymes called ligases.
The end result is two semi-conservative daughter double helixes- meaning that each double helix contains one strand from the original and one strand that is new.
If you want to see a video: http://www.youtube.com/watch?v=teV62zrm2P0
Once DNA replication has occured, the nucleus then has 2 copies of all of its DNA and will continue to grow and carry out some normal functions, but it will also prepare for cell division, which is either mitosis or meiosis, depending on whether or not it is a cell that will simply copy itself, or a cell that is designed to produce gametes (eggs or sperm).
Mitosis is divided into 4 phases:
Prophase:
-chromatin condenses to chromosome
-nuclear envelope disintegrates and disappears
-spindle (magorsó) forms
Metaphase:
-chromosomes line up at the equator
Anaphase:
-chromatids are pulled to opposite poles of the cell
Telophase:
-cell plasma divides
-nuclear envelope reappears
(don't worry about the extra stages in the image below!!)
Image from: https://www.msu.edu/~robiemat/science.htm
Image from : http://imcurious.wikispaces.com/Midterm+Exam+2010+Review+P1
Meiosis occurs to produce haploid cells that will be gametes (sperm and eggs).
It is a division that reduces the chromosome number by half. It is divided into meiosis I and meiosis II
Meiosis I
Prophase I
-chromatin condenses to chromosomes
-chromosomes "find" their homologous pairs and crossing over occurs
Metaphase I
--nuclear membrane disappears
-homologous chromosomes line up at the equator and attach to spindle fibres
Anaphase I
- chromosomes pairs are split as they are pulled to opposite poles
Telophase I
- cell plasma divides
- nuclear membrane reforms
Short interphase, with no DNA replication
Meiosis II
Prophase II
-chromosomes condense
- nuclear membrane disappears
-spindle forms
Metaphase II
-chromosomes line up at the equator
Anaphase II
-chromatids are pulled to opposite poles of the cell
Telophase II
-cell plasma divides
-nuclear membrane forms
Image from: http://commons.wikimedia.org/wiki/File:Meiosis_diagram.jpg
So mitosis and meiosis share some characteristics, but are also unique in many ways. The following diagram presents a comparison of the two. Be sure to consider how they are similar and how they are different.
Image from: http://bioactive.mrkirkscience.com/09/ch9summary.html
İNSAN DNA' SI HAKKINDA BİLMEDİĞİNİZ 10 ŞEY
http://io9.com/5907275/ten-things-you-probably-didnt-know-about-dnaIt may be the basis of all life on Earth, but we're betting there's still a lot you don't know about deoxyribonucleic acid. Who discovered it? What makes it "right-handed"? And what does it have to do with LSD? Find out after the jump.
10. James Watson and Francis Crick did not discover DNA
Neither did Rosalind Franklin or Maurice Wilkins, for that matter. In actuality, the credit for discovering DNA goes to one Friedrich Miescher. In 1869, the Swiss biochemist was inspecting the pus on used surgical bandages (yay, science!) when a substance he didn't recognize passed into his microscope's field of view. He called the substance "nuclein," because, he noted, it was located within the nuclei of cells.
Neither did Rosalind Franklin or Maurice Wilkins, for that matter. In actuality, the credit for discovering DNA goes to one Friedrich Miescher. In 1869, the Swiss biochemist was inspecting the pus on used surgical bandages (yay, science!) when a substance he didn't recognize passed into his microscope's field of view. He called the substance "nuclein," because, he noted, it was located within the nuclei of cells.
9. Good Call, Miescher
Which is funny, because you can actually find a fair bit of DNA in mitochondria, as well. What's interesting, though, is that out of all your DNA, it's the stuff in your nuclei that play the most important role from a hereditary standpoint; remarkably, Miescher would later speculate in a letter to his uncle that this mysterious "nuclein" might actually play a role in heredity.
Which is funny, because you can actually find a fair bit of DNA in mitochondria, as well. What's interesting, though, is that out of all your DNA, it's the stuff in your nuclei that play the most important role from a hereditary standpoint; remarkably, Miescher would later speculate in a letter to his uncle that this mysterious "nuclein" might actually play a role in heredity.
8. It took decades to prove Miescher's hunch was right
Miescher's insight was years, if not decades, ahead of its time. By the turn of the 20th century, scientists had begun to strongly suspect that chromosomes — densely packed structures of DNA and protein — were involved in the transmission of traits from one generation to the next, but it wasn't until researcher Thomas Hunt Morgan showed that molecular differences in chromosomes actually corresponded to heritable physical characteristics in fruit flies that anybody truly appreciated the fundamental role of said chromosomes in the transfer of genetic information.
Miescher's insight was years, if not decades, ahead of its time. By the turn of the 20th century, scientists had begun to strongly suspect that chromosomes — densely packed structures of DNA and protein — were involved in the transmission of traits from one generation to the next, but it wasn't until researcher Thomas Hunt Morgan showed that molecular differences in chromosomes actually corresponded to heritable physical characteristics in fruit flies that anybody truly appreciated the fundamental role of said chromosomes in the transfer of genetic information.
7. Wait... what genetic information?
What's interesting about the phrase "genetic information" is that even as late as 1933, the year Morgan received a Nobel Prize for his groundbreaking work on chromosomes, many scientists still doubted the existence of so-called "genes" — information, presumably housed within chromosomes, that gave rise to the physical traits Morgan had observed in his experiments. At the time, Morgan wrote that there was no consensus "as to what the genes are — whether they are real or purely fictitious."
What's interesting about the phrase "genetic information" is that even as late as 1933, the year Morgan received a Nobel Prize for his groundbreaking work on chromosomes, many scientists still doubted the existence of so-called "genes" — information, presumably housed within chromosomes, that gave rise to the physical traits Morgan had observed in his experiments. At the time, Morgan wrote that there was no consensus "as to what the genes are — whether they are real or purely fictitious."
The concept of genes only really found its footing in 1944, when molecular biologistOswald Avery (pictured here) showed thatgenes were not only real, but that they were composed of DNA (and not, for example, proteins, which — also being contained in chromosomes — many scientists had assumed comprised our true "genetic" blueprint).
6. LSD May have played a role in the discovery of DNA's structure
Just nine years after Avery's discovery, James Watson and Francis Crick published an article inNature describing the double helical structure of DNA — a structure which, according to some accounts, Crick claims to have perceived while high on LSD.
Just nine years after Avery's discovery, James Watson and Francis Crick published an article inNature describing the double helical structure of DNA — a structure which, according to some accounts, Crick claims to have perceived while high on LSD.
5. Why is it Watson and Crick and not Crick and Watson?
Joe Hanson actually posed this excellent question last week on It's Okay to be Smart:
Joe Hanson actually posed this excellent question last week on It's Okay to be Smart:
How did they decide whose name would come first on their paper? That's where we get the comfortable meter of their paired and classic name pairing from. I mean, did they flip a coin? It was a fairly even collaboration, and I don't know why their names weren't on the paper in alphabetical order.I mean, just think of that. What if it had been Crick & Watson? A huge part of the biological lexicon would be changed:"Well Steve, you can clearly see the canonical Crick & Watson base-pairing there in the hairpin."
It turns out they did just flip a coin, though to hear James Watson tell it, it sounds like he felt he deserved to be first author, anyway.
4. DNA is Right-Handed
When you see DNA depicted as a double helix, you can clearly see that its structure is twisted. That twist makes DNA a "chiral" molecule, meaning it is asymmetric in such a way that a DNA molecule and its mirror image are not superimposable. Examples of chirality are everywhere. Take your hands, for example. For all intents and purposes, your left hand and right hand are mirror images of one another, but no matter how you twist or position either hand, you'll find that it is impossible to orient the two of them in exactly the same way. Chirality is the reason you can't shake a person's right hand with your left, or wear your left shoe on your right foot.
When you see DNA depicted as a double helix, you can clearly see that its structure is twisted. That twist makes DNA a "chiral" molecule, meaning it is asymmetric in such a way that a DNA molecule and its mirror image are not superimposable. Examples of chirality are everywhere. Take your hands, for example. For all intents and purposes, your left hand and right hand are mirror images of one another, but no matter how you twist or position either hand, you'll find that it is impossible to orient the two of them in exactly the same way. Chirality is the reason you can't shake a person's right hand with your left, or wear your left shoe on your right foot.
Chiral molecules are said to possess "handedness," and in DNA, that handedness is characterized by the direction of its twisting strands. DNA's right-handedness can be identified by a simple trick involving your hands. Take your right hand and, with your thumb pointing upward, imagine grasping the spiral pictured here (in this diagram there is only one helix... in DNA there are two, but this rule still applies). Now imagine your hand twisting around the outside of the spiral, tracing its grooves in the direction that your fingertips are pointing. Your hand should rotate upward along the helix. If you try this trick with your left hand, again grasping the helix with your thumb pointing up, you'll notice that following the rotation of the helix in the direction your fingertips are pointing will cause your hand to move downward.
That means that if you're reading an article online or in a magazine and it features a picture of a left-handed double helix, that picture is wrong, wrong, wrong.
3. Except when it isn't
Yes, most DNA is right-handed. The DNA molecule that Watson and Crick described, for example, was right-handed. But DNA can actually exist in a variety of biologically active helical conformations. The one most people are familiar with is called B-DNA (depicted at center in the image shown here). On the far left is another conformation of DNA, (called A-DNA) that is also right-handed, but more tightly wound than B-DNA. On the far right, however, is a left-handed conformation, known (awesomely) as Z-DNA. So before you go on a pedantic rampage about left- and right-handed DNA, make sure you're not getting all bent out of shape over some Z-DNA (or a plot point in the upcoming Spider-Man movie... watch for the left-handed helices around 1:30).
Yes, most DNA is right-handed. The DNA molecule that Watson and Crick described, for example, was right-handed. But DNA can actually exist in a variety of biologically active helical conformations. The one most people are familiar with is called B-DNA (depicted at center in the image shown here). On the far left is another conformation of DNA, (called A-DNA) that is also right-handed, but more tightly wound than B-DNA. On the far right, however, is a left-handed conformation, known (awesomely) as Z-DNA. So before you go on a pedantic rampage about left- and right-handed DNA, make sure you're not getting all bent out of shape over some Z-DNA (or a plot point in the upcoming Spider-Man movie... watch for the left-handed helices around 1:30).
2. DNA can exist in a variety of bizarre and unfamiliar forms
You want a triple helix? You got it. A transient, four-stranded super-molecule (that just happens to be the lynchpin step in the process of genetic recombination)?Coming right up. How about a smiley face, a map of the Americas, or a nanodrug-carrying box, complete with lock and key? Yeah, we've got those, too. For years, DNA has been growing in popularity as a nano-scale building material for applications in everything from medicine to technology. And we've only just begun to appreciate what these DNA nanomachines are capable of. [DNA tetrahedronvia]
You want a triple helix? You got it. A transient, four-stranded super-molecule (that just happens to be the lynchpin step in the process of genetic recombination)?Coming right up. How about a smiley face, a map of the Americas, or a nanodrug-carrying box, complete with lock and key? Yeah, we've got those, too. For years, DNA has been growing in popularity as a nano-scale building material for applications in everything from medicine to technology. And we've only just begun to appreciate what these DNA nanomachines are capable of. [DNA tetrahedronvia]
1. We can make synthetic DNA
Strands of DNA and RNA are formed by stringing together long chains of molecules called nucleotides. A nucleotide is made up of three chemical components: a phosphate (labeled here in red), a five-carbon sugar group (labeled here in yellow, this can be either a deoxyribose sugar - which gives us the "D" in DNA - or a ribose sugar - hence the "R" in RNA), and one of five standard bases (adenine, guanine, cytosine, thymine or uracil, labeled in blue).
Strands of DNA and RNA are formed by stringing together long chains of molecules called nucleotides. A nucleotide is made up of three chemical components: a phosphate (labeled here in red), a five-carbon sugar group (labeled here in yellow, this can be either a deoxyribose sugar - which gives us the "D" in DNA - or a ribose sugar - hence the "R" in RNA), and one of five standard bases (adenine, guanine, cytosine, thymine or uracil, labeled in blue).
By swapping out artificial molecules in place of any of these chemical components, researchers can actually make synthetic DNA. One of the most commonly created forms of synthetic DNA is XNA, which swaps out the sugar group for any number of artificially produced molecules. Just last month, researchers succeeded in creating a genetic system that allowed this XNA to replicate and evolve. And to top it all off, this "alien" XNA is actually stronger than the real thing.
Top image and XNA via Shutterstock; all other images via Wikimedia commons unless otherwise indicated
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