Shining bright like a diamond………:Explaining giant covalent structures, AS style.

diamond-5
Who knew diamond was mad out of such a dulling element like Carbon?….. Just joking, Carbon is cool!
Another allotrope of Carbon. Introducing..... Graphite!
Another allotrope of Carbon.
Introducing….. Graphite

In AS , we build up on the simple facts about covalent structures we had learnt at GCSE,but with a few key additions.I will be explaining in this blog what exactly a giant covalent lattice structure(aka macromolecular structure) is and two types that you may have heard of ; diamond and graphite.

Firstly, what is a giant  covalent structure? A giant covalent structure is simply molecules that are covalently bonded together in a regular structure that repeats over and over again.Giant covalent lattices form ‘crystals’ due to their structure.Diamond is an example of a giant covalent lattice.

People say diamond is a girls best friend and you usually see it on expensive engagement rings.As well as reflecting light so that the diamond can shine and sparkle all day long, what is so special about diamond? Well, let me tell you.

Number 1: There can never be liquid diamond! What’s that, no liquid diamond you say? YES, no liquid diamond.Unlike Gold and Platinum which you can heat, although lots of energy is needed (Gold needs 1,064 degrees and platinum needs 1,768 degrees to melt), there can never be such thing as liquid diamond.This is because the arrangement of diamond,  which I will later explain,means that diamond not only has a high melting point but  also sublimes when its melting point has been reached, meaning it turns straight from a solid to a gas , there’s no  transformation into liquid in between

Diamond is a giant covalent lattice(macromolecule) that consists only of Carbon.Each Carbon atom bonds covalently to 4 other carbon atoms, forming a tetrahedral shape out of the numerous carbon atoms.The structure of diamond explains the many properties it has.It has a high melting point because there are strong covalent bonds between the carbon atoms in diamond and lots of energy is needed to overcome the covalent bond.Because of its covalent bond, it is also insoluble in solvents because its strong covalent bonds are too strong for the polar molecules of a solvent such as water to separate apart the oppositely charged ions from the lattice structure.It is also hard and is used in diamond saws .It is also a good thermal conductor because vibrations can pass easily through the macromolecule but does not conduct electricity because it does not have any delocalised(free) electrons to carry the current.

Now, let me introduce to to graphite,which is an allotrope of Carbon.If you haven’t heard what an allotrope of Carbon is;usually when you’ve got an element, it is either in a solid, liquid or gas form.With an allotrope, you can different compound made entirely of the same element and with the same state, which in this case is solid, but just with a little arrangement in its structure.That is what graphite is.

Each Carbon atom in graphite is covalently bonded to 3 other Carbon atom, meaning that there is an extra delocalised electron from each atom found in the graphites macromolecular structure.Graphite is arranged in sheets made out of hexagonal rings of carbon.The sheets are held together by weak intermolecular(van der Waals) forces that can easily be overcome , allowing the graphite layers to slide over each other, making graphite slippery and useful as a lubricant.

It is also insoluble in solvents such as water because of its strong covalent bonds that are hard to overcome by the attraction of polar molecules that make up solvents (e.g. water) and have a high melting point because of strong covalent bonds between each Carbon atom which need lots of energy to overcome., just like Diamond.However, unlike diamond, graphite can conduct electricity as well as heat (it is, in other words, a  good thermal conductor).

Graphites density compared to diamond is also explained by the fact that because the graphite layers are further away than the length of the covalent bonds with Carbon in diamond, graphite is less dense than diamond.

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Chemistry How the time of flight mass spectrometer works

The time of flight mass spectrometer.

The mass spectrometer is a device used to find out the atomic or molecular mass of a sample.There are different types of mass spectrometers but below I will be writing about how a time of flight mass spectrometer works.The stages to find out  the atomic mass(Ar) or molecular/formula(Mr) go  like this:

1. The vaporisation stage :Here, the atoms in a sample are vaporised, turned into a gas,before being injected into a vacuum chamber through a sample inlet.The reason for having a vacuum chamber is to prevent the hindrance of the gaseous atoms, which will later became ions, from moving to one end of the vacuum chamber to the other due to air particles colliding with air particles.

2. Ionisation: The gaseous atoms reach the ionisation area where a beam of high energy electrons from a heated filament  bombards the gaseous atoms , knocking an electron from each of the gaseous atoms and forming gaseous ions with +1 positive charge (The high energy electrons ionise them).

3. The gaseous ions from the sample enter the acceleration area where they are accelerate to the same kinetic energy by an electric field.

4. The gaseous ions, now all with the same kinetic energy, travel through the drift region .At this point, the mass of the ions are measured by how long it takes to travel the known distance of the drift region(called the flight path) to the ion detector at the end.Because kinetic energy= 1/2 mv squared, this means larger ions take longer to reach the ion detector while lighter ions reach the detector in less time.

5. The ions reach the detector which transfers the information received to produce a mass spectrum with the relative abundance of the gaseous ions of atoms and molecules that had reached the detector and their relative masses.

Nuclear reactions are taking place above you, wise men.

Christmas-Star

Since it’s nearly Christmas day(the 25th), I wanted to talk about stars, in particular how energy is released from stars like the sun using bare nuclei that had been separated from their electrons ,which are unbound , and either fusing these nuclei together or splitting them apart.

Nuclear fission and fusion are two nuclear reaction processes that take place at  extremely high temperatures, one of these places which have high temperatures are at the stars such as the sun.

These nuclear reactions i’m writing about are reactions which involve changes to the nucleus .This is different from chemical reactions which you may have heard of time and time again in your chemistry lessons for GCSE , A level and other studies.Chemical reactions are simply reactions where the outer electrons are involved and rearranged.This includes losing  one or more electrons to form a cation(positively charged ion) or gaining one or more electrons to form an anion(negatively charged ion).Nuclear reactions involve the nuclei and  their rearrangement.This includes fusing nuclei together to form a larger nucleus (nuclear fusion) and splitting up a large nucleus into two smaller nuclei (nuclear fission), these two concepts of which I will be explaining below:

Nuclear fission: The splitting up of a larger nucleus into smaller nuclei.This 'larger' nucleus can be a  plutonium or uranium nucleus.It does not take place in the sun because the Hydrogen and Helium molecules are not large enough to be broken down. Fission produces less energy than fusion.
Nuclear fission:
The splitting up of a larger nucleus into smaller nuclei.This ‘larger’ nucleus can be a plutonium or uranium nucleus.It does not take place in the sun because the Hydrogen and Helium molecules are not large enough to be broken down. Fission produces less energy than fusion.

Firstly, let me introduce nuclear fission.It is simply the splitting up of a large nuclei into 2 smaller nuclei. To start off the ‘splitting’, a nucleus is knocked into  the large  plutonium or uranium atoms .The large nucleus absorbs the neutron, causing the large nucleus to split into 2 smaller nuclei. The process of  nuclear fission releases neutrons and energy in the form of radiation as well as kinetic energy being provided to the neutrons ,to move, and to the nuclei formed by the fission reaction.

As good as the process of nuclear fission is and the fact that it releases a lot of energy, it does produce reactive waste which must be disposed of safely and which is expensive to dispose of.

The second type of nuclear  reaction is nuclear fusion.This is where two smaller nuclei fuse to form a larger nucleus.This process releases energy  but only if the relative atomic mass (the mass number) of the nucleus formed is more than 55 ,in other words, if the nucleus formed is the nucleus of the atomic mass of Iron in the Periodic table onwards.If the mass number of the nucleus formed is more than 55 , energy will not be released in the nuclear fusion reaction.This process releases energy and does not produce  radioactive waste products like in nuclear fission does and releases a lot of energy.For the smaller nuclei to fuse, they must fuse at high speed and high kinetic energy to overcome the repulsive forces between the positively charged nuclei.

Nuclear fusion takes place in the sun which is hot enough for the nuclei ,suspended in a plasma of bare nuclei and unbound electrons , to fuse together and overcome forces of repulsion between positively charged nuclei.
Nuclear fusion takes place in the sun which is hot enough for the nuclei ,suspended in a plasma of bare nuclei and unbound electrons , to fuse together and overcome forces of repulsion between positively charged nuclei.

The heart and the cardiac cycle.

Since it’s nearly Christmas time and soon after the New Year, you’re probably feeling a little bit excited and your heart is probably beating with excitement.Because of this, I’ve decided to blog about the cardiac cycle.This includes the words ‘filling’, ‘volume’, ‘pressure and more. At least if you wake up on the 25th , raring to open your presents and enjoy the festivities and wonders of Christmas, and you find yourself getting excited , you’ll know that it’s your heart beating that little bit faster and you’ll also know what is going on in your heart .

The Heart!

The Cardiac cycle:

The cardiac cycle starts when the ventricles relax and the atria (both left and right)fill up with blood.This decreases the volume of blood available in the atria and increases the pressure inside the atria.This causes the pressure in the atria to be higher than the pressure inside the ventricles .This high pressure causes the atrioventriclar (mitral/bicuspid and tricuspid) valves to open, causing blood to flow into the ventricles.The atria then contract, forcing the remaining blood out of the atria and into the ventricles .

While the atria contract, the ventricles fill up with blood.This causes the volume in the ventricles to decrease and the pressure inside the ventricles to increase.The pressure in the ventricles is higher than the pressure in the atria ,causing the atrioventricular valves to shut.The pressure is also higher than the pressure inside the pulmonary artery and aorta, causing the semilunar (pulmonary and aortic) valves to open.The ventricles then contract, forcing blood out of the heart through the pulmonary artery and aorta.

The ventricles and the aorta both relax as blood leaves the heart.Then the atria fill up again and the whole cardiac cycle restarts due to the pressure at the pulmonary vein and vena cava being higher than the pressure of the atria.

During the cardiac cycle, the valves mentioned keep blood flowing in one direction only and prevents backflow into other areas of the heart.

A really good animation explains the cardiac cycle is found by clicking the link below:

http://bcs.whfreeman.com/thelifewire/content/chp49/49020.html

Homeostasis and diabetes.

* If you have any questions on this article, please do not hesitate to ask through the comments box so that I may answer you through my next blog ‘bite’ (a mini blog post).

‘More than 3 million people in England live with diabetes. Another 850,000 have diabetes but don’t know it.’

                                                                ~ Quote taken  from the NHS website.

sugar cartoonLast week on the 14th December 2015 was the International day of diabetes!

Obviously it’s not as well-known as holidays such as Easter and the Christmas holidays that are coming up soon but diabetes is a topic to be aware of, especially due to the rise in the number of recorded cases of diabetes since 2010 and which, according to the NHS, is predicted to rise to 4.6 million, 90 percent of these people suffering from type 2 diabetes (type 2 diabetes caused by unhealthy lifestyle. I’ll explain diabetes later). There are many people in the UK who also have blood sugar levels high above the normal range but not high enough to be labelled as diabetes .This level of blood sugar which is in between higher-than-normal blood sugar levels and diabetes is called ‘prediabetes’.This means that although there are millions of people in the UK who have diabetes, many thousands, at least, may be on the brink towards diabetes.

There are many misconceptions that you may have heard of such as diabetes being caused by a person eating ‘too many sweets’ but this is not actually the case.

For the sake of wiping away the misconceptions of diabetes, in this blog I’ll be recapping what you’ve probably heard of in GCSE biology ‘hormones’ and as briefly describing what homeostasis is , both of these things  helping you to  also help understand a bit more about how diabetes work.

Before I explain what diabetes is and the types of diabetes, let me explain homeostasis, specifically the regulation of blood sugars as a part of homeostasis.

Homeostasis is the regulation of internal conditions in the body. In other words, homeostasis is controlling conditions inside the body so that they are constant or within a certain range. These conditions include body temperature, water content in the blood and the concentration of glucose in the blood also. If the temperature, glucose and water levels and waster products such as carbon dioxide etc. are either too high or too low, it will cause damage to your cells which therefore may lead to death!

One of the internal conditions that must be controlled is the levels of glucose. The levels of glucose must be constant. This is because glucose enters the cells of your body by diffusing from the blood. Due to diffusion, if there is a high level of sugar I the blood, there would also be a higher concentration of sugar in the blood than in the body cells. This means the water potential of the body cell will be higher than the water potential of the solution in the blood, causing lots of water to leave our body cells, shrink and shrivel up and for us to die as a result.

WARNING: If you know nothing about water potential, please check my blog from the 13th December on osmosis and water potential, which you can search in this websites search box)!

diabetes-glucose-regulation.gif pic

Diabetes and its symptoms have been recorded since approximately the 1500 BC and when first investigating this strange thing many of years ago, they found that the sufferers of diabetes would display common symptoms such as massive weight loss, frequent urination and this urine which they had frequently produced was sugary in taste (and yes, doctors would have a taste of a patients urine!). Death for diabetics was inevitable. There was no cure, neither is there one today, nor was there any effective treatment, although people had tried bloodletting and herbal remedies. Now we know how blood sugar levels are controlled in people without diabetes and this has led to scientists finding a treatment to control the levels of glucose in the body; by using manmade insulin.

In non-diabetics, when the blood sugar is too low, insulin is not secreted. This causes a decrease in uptake of the cells. If the cells do not take in as mush glucose as before, this means the levels of glucose in the blood can increase, returning the blood glucose levels to a constant, ‘normal’ level.

In people without diabetes, a hormone called insulin is involved in the control of blood sugar (glucose) in the blood. If the blood sugar in an individual is too high, the hormone insulin is produced and secreted by the pancreas, which allows the cells to absorb more glucose  from the blood(increases glucose uptake), thus reducing the levels of glucose in the blood .If there is still excess sugar, the release of insulin causes glucose to be converted into glycogen to be stored in the muscles and liver also, so if you eat quite a few sweets in one go, it doesn’t mean you will get diabetes straight away; anyway, diabetes is due to many factors such as genetic factors and your lifestyle.

In type 2 diabetics, not enough insulin is produced meaning that less glucose can be removed out of the blood and into respiring cells, muscles and liver cells for storage. This causes the blood glucose levels to remain dangerously high. The blood containing extra glucose could be filtered in the kidneys and detected to check if a person has high levels of blood sugar and diabetes. In type 2 diabetes, the cells could also not react to insulin, which is why type 2 diabetes is also known as insulin-resistant diabetes.

If you would like more information on diabetes, please follow the links below:

http://www.nhs.uk/Conditions/Diabetes/Pages/Diabetes.aspx#close

http://www.google.co.uk/url?sa=t&rct=j&q=youtube%20clip%20on%20diabete&source=web&cd=1&cad=rja&uact=8&ved=0CCMQtwIwAA&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DMHlWM8_iqfA&ei=X8SSVJ3rHNDZatm6gbAH&usg=AFQjCNGxJaDFWvty3vj1o6pX7nU43bVMvw&bvm=bv.82001339,d.d2s

… And also a link on why foot care in diabetes is important:

http://www.diabeticlivingonline.com/complications/feet/why-good-foot-care-important-diabetes

blood-glucose-levels

Ginger and tonic, hypertonic, hypotonic and isotonic…Weird names for drinks, huh?

* If you have any questions on this particular blog post, please send me any questions through commenting so I can answer them for you.

osmosis cartoon strip!
What would you answer to this students question?

cellsToday I’ll be writing about solutions and how water molecules can move from one place to another by osmosis. I will also be discussing how water moves from one area to another when there is a difference in water potential (gradient) of different solutions which are together.

Firstly, let’s talk osmosis. Here is the definition:

Osmosis is the movement of water from an area of low water potential (concentration of water) to an area of high water potential  down a concentration gradient .Water moves across a partially permeable membrane.

In simple terms, water moves from where there are lots of water molecules to an area where there are less of them. The movement from an area of high to low concentration gradient is called moving ‘down’ the concentration gradient. Osmosis is a passive process, meaning energy is not required for osmosis to take place.

Now that we’ve consolidated the definition of osmosis, now I’ll talk to you about three different types of solutions; Isotonic, hypertonic and hypotonic solutions.

These solutions describe the movement of water from one area to another when there are 2 different types of solutions present together.

618px-Turgor_pressure_on_plant_cells_diagram_svg

Hypertonic solutions- Hypotonic solutions are solutions where the water potential of the solution outside the cell is lower than the water potential of the solution inside the cell. There is a concentration gradient (difference in concentration) which causes water to move from an area of high water potential, which is in the cell, to an area of high water potential, which is outside the cell, down a concentration gradient. The net movement of water out of the cell could result in 2 things happening, depending on the type of cell from which water were moving out from.

If water moves out of an animal cell, the cell shrivels and shrinks (animal cell shrinking due to water movement out of the cell is called crenation).

If this took place in a plant cell, the plant cell would not shrink but the cell membrane and the cytoplasm move away from the cell wall; this process of moving away from the cell wall is called plasmolysis. It causes the cell to be flaccid (limp) and the plant cell to wilt.

Hypotonic solutions- Hypotonic solutions are solutions where the water potential (concentration) of the solution inside the cell is lower than the water potential outside the cell. Because water moves from an area of high water potential to an area of low water potential, down a concentration gradient, water moves into the cell from an area of high water potential outside the cell to an area of low water potential inside the cell. The net (overall) movement is into the cell.

In animal cells, the large movement of water into the cell causes the cell to swell up and burst (lysis). In plant cells, the movement of water into plant cells causes the plant cell to swell up (become turgid) and the cell membrane and cytoplasm to push against the cell wall. The plant cell does not burst because the rigid cell wall surrounds the cell, resisting pressure and preventing the cell from bursting.

Think of ‘hypo’ and ‘low’ to remember it if you’re confuse d between hypotonic and hypertonic solutions. Hypotonic solutions have a lower water potential.

Isotonic solutions– Isotonic solutions are solutions where the water potential of the solution inside the cell is the same as the water potential outside the cell. Because the water potential inside and outside of the cell is the same, there is no change in the concentration gradient meaning there is there is no net (overall) movement of particles either into or out of a cell. Water diffuses into and out of the cell by osmosis but there is still no net (overall) movement of particles into and out of the cell.

Isotonic, hypotonic and hypertonic solutions; now you know that they are not drinks and that they describe osmosis when you’ve got 2 different solutions together!

THE END.

DR. MITOSIS’ PMAT CERTIFICATE ! (Explaining mitosis).

DR. MITOSIS’ PMAT CERTIFICATE !(Explaining mitosis).

chromosome_graphic
Mitosis is a process which takes place in multicellular organisms such as animals and plants for growth to take place.
The reason why I had written PMAT in this title is because PMAT is a good way to remember the stages of the process of mitosis.
Mitosis is part of the cell cycle, starting with a cell produced by cell division and ending with 2 daughter cells that are genetically identical to each other.
Interphase is the first part of the cell cycle and takes up most of it. Interphase is the process before mitosis where the cell grows, unravelling and replicating it’s DNA, replicating organelles and is where the cell checks itself for errors in the copied genetic material. If there are errors detected, the cell kills itself as the lysosomes, containing digestive enzymes, break down causing the cells destruction. If the cell does not end up being destroyed, the cell starts to divide in the process called mitosis. Like I have hinted at, there are several stages of the process mitosis, although the process is much shorter than the process of Interphase. Below, I will be describing to you Interphase and mitosis.
During Interphase, the cells organelles duplicate, creating extra organelles and the DNA (deoxyribonucleic acid) unravels and replicates, doubling the amount of genetic material in the cells. The centrioles move to opposite sides of the cell, forming protein fibres (or strings) called spindles, across the cell. While Interphase takes place, the cell also carries out normal functions of the body. That’s multi-tasking for you!
Now, for PMAT…

P-Prophase: After the replication of organelles and the DNA, the nuclear envelope (the membrane surrounding the nucleus) breaks down so that all the contents of the nucleus, including the chromosomes, lie freely in the cytoplasm.
M-Metaphase: is the second stage of mitosis and is where prophase ends. During metaphase, the chromosomes of the cell line up at the centre of the cell and are connected the spindle fibres by its centromeres (see the image below of the centromere):

mchromatids-chromosomes_eng

(The green dot= the centromere.It’s basically the region of the centre of the chromosome).
A-Anaphase: Anaphase is the third process of mitosis where the chromosomes, each containing 2 sister chromatids are separated. This is done by the centromere splitting into 2 which separates the chromatids from each other. The spindle fibres attached to the centromeres contract, moving the chromatids to opposite sides of the cell, centromeres first.
T-Telophase: Anaphase is the final stage of mitosis (cell division) where the groups of chromatids separate opposite poles of the cells. A nuclear envelope surrounds the group of chromatids, forming 2 nuclei and the cytoplasm in the middle divides, forming two cells which are genetically identical.
The cells produced by mitosis then undergo the cell cycle again, replicating the cells (interphase) in preparation for another round of mitosis (cell division).

CHcloseupNote:Spindle fibres are protein fibres called microtubules.These mirotubules are made of the protein called tubulin.

It’s all about the cells…(Eukaryotic cells).

It’s all about the cells…(Eukaryotic cells )

eukaryotic cells

Eukaryotic cells (pron. You-carry-oh-tick), like prokaryotic cells, are a different category of cells that are bigger and more complex than prokaryotes. They make up organisms that are multicellular organisms such as animals and plants .Just like prokaryotes, they contain genetic material, a plasma(cell surface)membrane and are living cells but there are a few things which make a eukaryotic cell what is and not a prokaryotic cell.

Firstly, eukaryotic cells have a nucleus while prokaryotic cells(aka. Prokaryotes) do not .The clue is actually in it’s name as eukaryotic means ‘having a true nucleus’, and it’s true, eukaryotic cells do have a nucleus which you can observe simply using a light microscope.

Apart from the presence of a nucleus in eukaryotes, they are much bigger than prokaryotes. They are about 20-200 micrometres in diameter compared to the prokaryotes that are less than 2 micrometres in diameter.

Eukaryotic cells surrounded by cell walls are also made of different types of polysaccharide(carbohydrate) chains from prokaryotes. While prokaryotes’ cell walls are made of murein (aka peptidoglycan), eukaryotic cells are either made of chitin ,in fungi, or cellulose in the cell walls of plant cells.

Eukaryotic cells have genetic material(DNA) contained in a nucleus rather than floating freely in it’s cytoplasm in an area of circular DNA called the nucleoid. This genetic material is also linear rather than circular .

They have larger (80s ) ribosomes compared to the smaller prokaryotic ribosomes , contain more organelles and contain mitochondria while prokaryotes do not contain mitochondria.

Eukaryotic organisms are made up of eukaryotic cells and these eukaryotic organisms include plant and animal cells. The organelles contained in these eukaryotic cells are listed below:

For animal cells: The nucleus, mitochondria, Golgi apparatus(Golgi body), SER( Smooth endoplasmic reticulum), RER(Rough endoplasmic reticulum),lysosomes, ribosomes, the cytosol(cytoplasm), plasma(cell surface) membrane and the centrioles.

For plant cells the organelles contained there are also the same as the organelles contained in the animal cells but with a few little additions; The nucleus, cytoplasm(cytosol), RER, SER, ribosomes, lysosomes, the plasma(cell surface) membrane, Golgi body(Golgi apparatus), mitochondria , centrioles, the cell wall, the plasmodesmata , the chloroplasts and the vacuole. Unlike animal cells, plant cells do miss an organelle. This organelle is called the lysosome.

Lysosomes are special organelles involved in processes such as phagocytosis and the destruction of a cell during interphase(the production of identical organelles before the division of a cell) if the cell detects an error after copying the organelles. They are involved in such processes because they have powerful digestive enzymes used to break down work out organelles and to digest invading cells(i.e. white blood cells  of the immune system engulfing and digesting bacteria and viruses ).

This is an extremely important enzyme because it prevents a cell form being damaged by pathogen and therefore, the organism to which the cell belongs to, to acquire a disease or infection.

Plant cells can also get diseases , like organisms can get while the white blood cells take their time to destroy pathogens and make you feel better, but are there no lysosomes or similar mechanisms that have the same function as lysosomes do?

Plant cells have the amazing vacuoles and are considered to contain(hydrolytic) enzymes which have the same function as the lysosome in an animal cell. Hydrolytic enzymes are enzymes that break down substances in the cells but in an environment where there is water, hence why it is in a vacuole that contains cell sap(which is a solution of salts ,sugars, etc.).

It’s all about the cells…(Prokaryotic cells).

*If you have any questions based on this post, please send me a comment on this website, along with your question(s).

It’s all about the cells….(Prokaryotic cells)

Cells make up living organisms such as plant and animal cells .This includes your pet dog, your mums and dads and yourself. In AS Level we talk about two types of cells in particular in which all cells that make up the things around you are categorised. These cells are called prokaryotic and eukaryotic cells.

There are many differences between these cells, of which I will be talking about in the following paragraphs.

Prokaryotic cells (pronounced pro-carry-oh-tick) cells are small and simple cells. This word comes from the suffix ‘Pro’ meaning ‘before’ and ‘karyon’ meaning ‘nucleus’ or , if you put them together before (the nucleus).This is because scientists believe that prokaryotic cells existed before cells developed nuclei due to evolution. Prokaryotic cells such as bacteria are known for causing diseases, one of which is called MRSA(methicillin resistant staphylococcus aureus), but some are useful and are used to treat sewage and produce medicines.

Prokaryotic cells make up unicellular organisms, or in other words, prokaryotic cells are unicellular organisms. They have the ability to carry out the functions of life (MRS GREN; Movement, respiration, sensitivity, etc.). As simple cells, they do not contain many organelles and no mitochondria are found there at all! In GCSE, you may have heard of the famous mitochondria, the ‘powerhouse’ of a cell, where energy is released for functions of the cells (e.g. active transport) and, in general, for starting off vital chemical reactions in the cells but prokaryotic cells do not have this lovely double membrane bound organelle containing enzymes involved in  respiration .

The question is, though, that if prokaryotic cells are living and carry out chemical reactions which require energy such as, how they get energy for these things, do chemical reactions even take place in prokaryotic cells? Where do these simple cells get the energy for cell division and the synthesis of new organelles?

This is where I introduce you to a new organelle called the mesosome. If you haven’t heard of this organelle, don’t worry, it is just extra information and not part of the AS level specification (I assume) but it’s an interesting organelle nonetheless.

The mesosome is simply a simpler form of mitochondria. It is an infolding of the cell membrane of the prokaryotic cell and like the mitochondria, contains enzymes involved in respiration, it just doesn’t consist of a double membrane, but a single and simpler arrangement is used instead. Being simple, prokaryotic cells do not have many organelles and all the organelles which they do have are not double membrane bound.

As well as having no mitochondria, they also contain smaller ribosomes compared to eukaryotic cells, cell walls made out of polysaccharide(carbohydrates) other than chitin, found in the cell walls of fungi, and cellulose (found in the cell walls of plant cells).

Or in other words, the mesosome is the organelle labelled with the number 9 on the image below (This image is an example of a prokaryotic (unicellular) cell , bacteria.

prokaryote

Their genetic materials (DNA), unlike the eukaryotic cells, are not found in the nucleus but float freely in the cytoplasm. They are also circular; another name for circular DNA is ‘nucleoid’, by the way. They also contain 70s (very small) ribosomes while eukaryotic cells contain 80s (bigger) chromosomes.

I hope this blog post has been useful. If you have found this helpful, have a look out for my next blog post:

‘It’s all about the cells (Eukaryotic cells)’.

Adipose tissue and brown fat ! Biology post.

Fact of the day for the blog: ‘What is brown fat’ and ‘adipose tissue’?

Adipose tissue: Body fat tissue

Adipose tissue is a collection of body fat cells called adipocyte cells. What is meant =by this is that there are fat cells which exist in our body. The fat cells contain lipids(fats) and are able to expand (stretch, increase in size).They are present to cushion(protect) internal organs of the body, to avoid damage to cells, and for insulation as well as acting as an energy store if you haven’t eaten or need extra energy.

Multiple fat cells group together to form tissue. This is called adipose (fat) tissue. Adipose tissue is needed to keep you warm.

Adipose tissue is found under the skin, to provide insulation, and is found around internal organs e.g. the heart and intestines, to cushion the internal organs.

The word ‘adipose tissue’ and ‘fat tissue’ can be used interchangeably because they mean the same thing; it’s just that different wording is used.

People who are overweight or obese have adipose tissue which is extremely expanded.

Adipose tissue contains blood vessels to supply blood for the release of lipids and is found around the collarbone (aka the clavicle).

adipocytes 2

fat cells adipocytes

-> The ultrastructure of a fat (adipose) cell.

Brown fat: is A dark coloured adipose tissue, hence the name ‘brown fat’. This is found in babies. It is a special fat which burns glucose to produce energy to produce heat for warmth which makes sense because babies need warmth.

As well as there being brown fat, there’s also beige and white fat!

CAT scan adipose related