Mattie, 18, huge nerd, science fiction geek, skeptic, aspiring science journalist, self-sustaining cycle of chemical reactions. My mission is to spread knowledge, information and teach critical thinking skills while not being utterly boring. Follow for articles, news, pictures, science jokes and more. I write original posts and answer questions addressed to the science side of tumblr. All I want to do is learn. Question everything, and stay curious.
You should never feel ashamed for any sort of mental illness you may have or the medication you need to take to help you function. “Normal” people rely on the same stuff, yours just happens to be store bought.
Based off this post. I have both depression and anxiety so that quote made me feel a little better about the fact that my brain is wired differently. I hope it might help other people as well.
Find it in the shop: [link]
Please do not repost, reblog instead and leave all artists comments intact, thank you!
I kinda abandoned this blog because it seems like no one is interested in what I post, especially the original stuff. So just to be sure: if you like this blog and enjoyed my original stuff or anything here, let me know. Like this post or leave a reply or send me an ask or something like that. If you are still interested, I'll be active here again.
These are real plants, called Albuca sp. Although we can’t say why it looks so weird, it’s thought leaves like this could be an advantage in hot climates, where having a spiral leaf reduces surface area that is exposed to the sun. 😮 📷: plantpropaganda http://ift.tt/2dhJngQ
A small-ish guide to the complex lives of the simplest eukaryotes
Our classification of life on Earth became rather more complicated since the invention of electron microscopes and genetic sequencing, since we moved away from grouping species by common morphology and started grouping them by common ancestry. We used to think that all living things could be divided into two groups: single-celled and multiple-celled organisms. Then we found out the single-celled creatures aren’t as similar as we thought, and some of them are actually more closely related to animals or plants than to each other. Now we divide all species into two giant categories: prokaryotes and eukaryotes. Eukaryotes, which make up the domain “Eukaryota”, have a membrane-bound cell nucleus, semi-autonomous organelles such as mitochondria and plastids, and DNA in a form of chromosomes. Prokaryotes don’t have all those things.
Of course we didn’t stop there, and advanced our classification further. We recognize that there are two distinct domains of prokaryotes – bacteria and archea, and archea are closer relatives to eukaryotes than bacteria. And when it comes to unicellular eukaryotes, protists… well, their relation bonds are much more complex than we previously thought, which is not surprising since organisms that we’d probably classify as protists gave rise to three different kingdoms: plants, fungi and animals. As a result, putting them in one group seems like a simplification of truth, so scientists are currently considering an alternative approach to protist taxonomy. But for now, they comprise a single kingdom “Protista”, and that’s what I’m going to write about today.
Protists: what are they, exactly?
Like I’ve said in the introduction, as a polyphyletic group (meaning they aren’t all twigs on one branch of the tree of life) protists don’t have that much in common. Apart from having the standard eukaryotic traits like a membrane bound nucleus and DNA in a form in chromosomes and all that stuff, they don’t share many morphological or genetic characteristics. Scientists usually group them together based on the other eukaryotic kingdoms they resemble: animal-like protists, or protozoa, plant-like protists, or algae, and fungi-like protists, which include slime molds. However this classification doesn’t actually represent their evolutionary heritage. For example most of the protists that we call protozoa separated from the protists that likely evolved into animals (choanozoa) before they diverged into different phyla.
Protists vary from one another in many ways. They can be heterotrophic (consuming other organisms, like us) or autotrophic (deriving energy from sunlight, like plants, or from chemicals, like bacteria), or combine both metabolic types (for example euglenozoa are mixotrophic). They can reproduce asexually like bacteria and archea, or have different sexes like most animals. They can live on their own or be parasites or symbiotes in the bodies of other organisms. They can have various organelles used for locomotion (like flagella and cilia), feeding, excreting waste and other functions. And they have incredibly diverse anatomy, physiology and life cycles.
Here are the main types of protists I will describe:
Amoebozoa
Helioza
Retaria (radiolaria and formanifera)
Cercozoa
Excavata (metamonada-->parabasalia)
Choanozoa
Alveolata: Dinoflagellata, Apicomplexa and Ciliophora
Phylum: Amoebozoa
Subphyla: lobosa, conosa
Description:
Most of Amoebozoa have rather crude, finger-like pseudopodia (specifically names lobopodia) that help them move around in water and can also be useful for feeding via phagocytosis. Some have an organelle called uroid, which is used to store and expel waste that accumulates in the cell. They vary greatly in size, and some can actually form colonies consisting of many cells (cause some slime molds are in this phylum). Usually they are ‘naked’, but some possess a hard shell or miniature scales on their membrane (for example made from carbohydrates). These protists don’t have plastids and are heterotrophs. Their mitochondria have characteristically tubular branching cristae. However in one group called archamoebae, mitochondria have been lost.
Notable species:
Entamoeba histolytica: anaerobic intestinal parasite that can infect humans and even lead to death.
Pelomyxa polustris: a giant protist with a highly complex lifecycle that have multiple nuclei (up to several thousands).
Order: Heliozoa
Description:
This is a diverse group of protists including species from various phylums and classes that share some similar qualities. They have axopodias: long, arm-like pseudopodia that radiate away from their body and are used for feeding, sensing and moving around. The structures are made from microtubules, which is a common feature in cell anatomy. They are related to radiolaria, but differ from them in skeletal cell anatomy. And they are rather pretty, resembling a tiny unicellular dandelion.
Phylum: Retaria
Subphylum: Radiolaria
Description:
These protists are commonly found in zooplankton in seas and oceans, and are famous for the intricate structure of their cell skeleton. Made from inorganic minerals, their sophisticated shells are much less brittle than organic membranes, which is why radiolaria fossils are possible to find and study. They have pseudopodia (axopodia and filopodia) radiating from their bodies, and making up diverse and rather beautiful structures. And they have been around since the Cambrian period.
Subphylum: Foraminifera
Description:
Relatives of radiolaria and one of the oldest protists on Earth, these creatures have a rigid shell made from CaCO3 (also known as chalk) that contains several individual cells. The shells have small openings through which pseudopodia can reach out and be used for locomotion and finding food. They prefer to live deep in seas, often in warm-water tropical ones. And they have a really complicated lifecycle, which includes haploid and diploid forms, rounds of mitosis and meiosis, zygotes, megaspheres and possible asexual reproduction. Looking at the scheme of their reproduction cycles makes me appreciate the simplicity of vertebrate reproduction.
Supergroup: Excavata
Phyla: metamonada, euglenozoa
Description:
This is a diverse group of protists that includes several phyla and is classified together due to similar flagella structure. They have a lot of variations in their mitochondria, which gets so different in some species, they are actually referred to as ‘amitochondriate’, meaning ‘lacking mitochondria’ (although they do have similar structures). The group contains famous and dangerous parasites of humans.
Notable species:
Trypanosoma brucei: the culprit behind African sleeping sickness; have an unusual organelle called ‘kinetoplast’ and have complex parasitic lifecycles including infestations of several species.
Euglena viridis: part of the genus ‘euglena’, these protists can derive energy both from sunlight, using chloroplasts, and other animals, via osmotrophy (which makes them both autotrophs and heterotrophs). They have flagella, photosensitive structures called ‘stigma’ and they store energy in a form of carbohydrates.
Phylum: Metamonada
Description:
Another diverse group of protists containing anaerobic organisms that mostly live in bodies of other animals: either as symbiotes or as parasites. Due to their dependence on other creatures, they have lost mitochondria. They are grouped together because they all possess flagella in groups of four. You can find some of them in intestines of animals, doing something good (like digesting cellulose) or something bad (like causing infectious disease).
Notable species:
Giardia lamblia: parasites that live in human small intestines and cause giardiasis.
Class: Parabasalia
Description:
Like other members of their phylum, most parabasalia are symbiotes of other animals, and some contain symbiotic bacteria, which explains their ability to break down cellulose. They have basal bodies which in combination with parabasal fibers and Golgi apparatus make up their primary shared characteristic. They also have an axostyle – a system of microtubules that runs across the cells and is also distinctive to the group.
Notable species:
Trichomonas vaginalis: parasite that causes a sexually transmitted disease called trichomoniasis. According to WHO, 160 million cases of the infection are acquired worldwide every year. Nasty.
Phylum: Choanozoa
Description:
Closest living relatives of metozoa – multicellular animals. Genetic evidence suggests that all eukaryotes separated into two branches, where one contains most of protists and all plants, and the other has fungi, animals and choanozoa. A particular class of this phylum, Choanoflagellata, appears to be the most closely related to the kingdom Animalia. These protists have a single flagella at the base of their body and they mostly feed on bacteria that they capture in water. Some species in the phylum are capable of forming colonies, which might have been the first step towards truly multicellular animals.
Phylum: Cercozoa
Description:
The members of this phylum lack shared morphological traits and are grouped together based on similar rRNA and actin structures. Most of the species also share a type of pseudopodia – filopodia, and their common heritage is confirmed by genetic studies.
An interesting group inside the phylum is chlorarachniophytes. Like euglena viridis, they are mixotrophic, so they derive energy from both digesting other organisms and photosynthesis. However their chloroplasts have four membranes instead of two, which confused scientists for some time, until they figured out that it was the result of endosymbiosis II.
As some of you already know, plastids and mitochondria were acquired by endosymbiosis I, during which a type of bacteria (alpha-proteobacteria for mitochondria and cyanobacteria for plastids) were captured but not digested by early eukaryotes, and later became semi-autonomous organelles. With organisms like chlorarachniophytes, the process must have occurred a second time, when a heterotrophic protist captured a photosynthetic protist. As a result they have two cell nuclei, one fully functioning, the other more of a non-functional relic that is referred to as nucleomorph.
Note: in some protists, endosymbiosis actually occurred a third time, which is why they have organelles bound by six or five membranes. However that is pretty rare.
Group: Alveolata
A group of protists that includes phyla dinoflagellata, apicomplexa and ciliophora. They share a cellular structure, cortical alveoli, which consists of flattened vesicles running along the membrane and helping support it. It might take different forms in different species, but it has some obviously similar structures, which points at mutual ancestry.
Phylum: Dinoflagellata
Description:
One of the largest phyla of protists that contains many different species, with most of them being autotrophic, photosynthetic algae living in seas and oceans as a part of plankton. Other individuals are mixotrophic, also deriving nutrients from phagocytosis of other organisms, while some lost their photosynthetic pigments and completely rely on capturing prey or on their host as parasites. Certain dinoflagellata species are responsible for water blooming, which can be a serious problem since they can breed to enormous numbers and corrupt all the nutrients in the water.
Their plastids are bound by three membranes, suggesting another case of Endosymbiosis II. They have two flagella, one longer than the other, producing characteristic circular movement. The flagella lie in grooves that run along their body, which is another distinguishing trait of the phylum. Some individuals are capable of bioluminescence, producing a colorful glow on the surface of water, which can be quite a spectacle.
Phylum: Apicomplexa
Description:
A phylum that by large consists of obligate parasites, with an exception of Nephromyces, a symbiont of marine animals. All species have a specialized structure called an apical complex, and a modified plastid – apicoplast. The apical complex is used to penetrate the cell wall of the host, while apicoplast produces chemicals that dissolve and digest the organic material. They also have a typical parasitic lifecycle, including the formation of gametes, spores and schizogones.
Notable species:
Genus Plasmodium: parasites that cause malaria, a disease that has killed more humans than all of the wars put together. Transmitted by mosquitos, which makes them the deadliest animal on Earth (at least for humans).
Phylum: Ciliophora
Description:
This group of protists is characterized by the presence of flagella-like organelles called cilia, which gives them their name. Cilia are similar to flagella in structure but are generally shorter and cover their entire membrane. They are used for locomotion, sensation, catching prey and other purposes. They live in pretty much any body of water, whether saline or not. Many species are symbiotic with other organisms, while other are obligate or opportunistic parasites. They have two cellular nuclei, one used for reproduction, and the other used for general cell regulation.
These protists don’t just have a cell mouth like some other unicellular eukaryotes, they actually have a cell anus, cytopyge, which is where the waste products of metabolism are expelled. That’s impressive, considering that some multicellular organisms (such as jellyfishes and hydras) have just one orifice for both purposes. Ciliophora reproduce asexually, but the micronuclei (which is used for reproduction) can undergo meiosis and be exchanged with another cell during conjugation. After conjugation the cells might stay fused, or separate and continue on with their life on their own.
Notable species:
Balantidium coli: the only species of ciliophora that is known to infect humans and cause a disease called balantidiasis.
Resources used: my university study notes and the Internet.
This post was written by me in order to prepare for a test, so feel free to use it for studying.
Hey I'm sorry I neglected this blog for so long. I was busy moving to another country and on Tuesday I'm starting university. But I will try to pay more attention to this blog and do science side of tumblr again. With essays/lectures and "logical fallacy of the week" though... those segments never get more than 2-3 notes so I'm assuming none of you are interested in them. If you are, please let me know! I don't want to write and post those if there's no audience for them, but if you do enjoy them (just don't want to like/share for any reason) I'll keep doing them.
It’s a fact of human nature that we are all titillated on some level by the mere notion of sex, and chances are many of us spend a good portion of our free time either having sex or thinking about it.
Because of this, it’s only natural to be curious about how the whole process takes place in other creatures. And if my research in animal sex biology has taught me anything, it’s that, on the whole, human sex is pretty uneventful compared to most of our wild counterparts.
Here are some astounding facts about sex in the animal kingdom:
It was Wednesday 16 February 2011, and Goldman was at a hotel in Hamburg, Germany, talking with some of his fellow bioinformaticists about how they could afford to store the reams of genome sequences and other data the world was throwing at them. He remembers the scientists getting so frustrated by the expense and limitations of conventional computing technology that they started kidding about sci-fi alternatives. “We thought, ‘What’s to stop us using DNA to store information?'”
Then the laughter stopped. “It was a lightbulb moment,” says Goldman, a group leader at the European Bioinformatics Institute (EBI) in Hinxton, UK. True, DNA storage would be pathetically slow compared with the microsecond timescales for reading or writing bits in a silicon memory chip. It would take hours to encode data by synthesizing DNA strings with a specific pattern of bases, and still more hours to recover that information using a sequencing machine. But with DNA, a whole human genome fits into a cell that is invisible to the naked eye. For sheer density of information storage, DNA could be orders of magnitude beyond silicon — perfect for long-term archiving.
If you put that ball on that machine while it wasn’t spinning, it would just roll straight down the lower sides.
The raised edges would keep it in the middle line, but it’s only controlled in one direction. By spinning it, you constantly alternate the position of the tall sides, meaning that the ball is held in the middle, never able to fall off.
Particle accelerators control particles in the same way. Magnetic or electric fields can only direct particles in one plane at a time, so to keep a beam of particles rushing down a particle accelerator in one focused stream, the current gradient must constantly oscillate. This means the particles are constantly held in place, never able to shoot off in one direction.
Here’s the same principle in action: these are tiny pollen grains being held in place by an oscillating field. Rods in the four corners of the beam establish a field that oscillates many times a second to keep the pollen trapped. If it didn’t constantly switch, the pollen would all fly off in one direction.
Watch the full film with Dr Suzie Sheehy for more.
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