Author Archives: sallyarj
Carbohydrates Part 2
Carbohydrates part 2
Well we know the simplest forms of carbohydrates are the monosaccharides (glucose, fructose, galactose etc.) , however these monosaccharides are mere building blocks and they combined to form disaccharides as well as polysaccharides. But how do they combine and why? Well its simply most monosaccharides are highly reactive as reducing agents and they are very soluble, thus they cannot be kept in the body in that form since they have the potential to cause damage and can cause many problems associated with the internal osmotic condition. It is also very difficult to store reactive single molecules since they may take up space. These are all reasons why monosaccharides are converted or exist as complex sugars.
Glycosidic Bonds
Monosaccharides combine via condensation reactions and form glycosidic bonds. During the condensation reaction molecules align and an HO group is removed from one of the sugars and an H from the other, this forms a H2O(water) molecule. The new bond that is formed holds the molecules together and is known as a glycosidic bond. The following is a diagram of the reaction bonding 2 glucose molecules.
As you can see the OH on C1 of one molecule reacts with the OH on C4 of the other molecule. The Carbon atoms that react define the type of bond formed as we will see below.
NOTE: This reaction is reversible by hydrolysis
The 3 most common disaccharides are Maltose, Lactose and Sucrose.
Formation of Maltose, Lactose and Sucrose
Maltose
Maltose is form by the combination of 2 α glucose molecules. The C1 of one molecule reacts with the C4 this form an alpha 1-4 glycosidic bond as seen below. The name of the bond is derived from the fact that both are alpha glucose that are reacting and from the carbons which take part in the reaction.
Maltose can be found in malt and can be obtained by mixing gain with water. Maltose can be found in beer as well as cereal and pasta. During fermentation with yeast maltose can be converted carbon dioxide and ethanol which is used to make many alcohols and beers. In our body maltose is broken down by the enzyme maltase and two glucose molecules are derived.
Lactose
Lactose is a very common sugar and yes I said sugar and as its name suggests is the sugar contained in milk. Lactose if formed by combining an beta galactose and glucose molecule and forms a β-1→4 glycosidic bond.
Lactose can be found in most milk and all dairy products in the body lactose is broken down by lactase. It is normal for many adults to stop producing lactase beyond puberty however most people belonging to European, Indian and east African ancestry tend to maintain lactase production well into adulthood. The lack or reduced production of lactase leads to a case called lactose intolerance.
Sucrose
Sucrose is probably the most common disaccharide as it is found in almost all fruits and table sugar. Sucrose is made of a beta fructose and an alpha glucose resulting in an α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside bond.
Polysaccharides
These are polymers of monosaccharides they are formed via condensation reactions forming glycosidic bonds between each monomer unit. These form long chains of up to thousands of monomers. This forms a macro molecule and the most common are starch, glycogen and cellulose all of which are made up of glucose and its forms.
Starch
A molecule found in plants it is made up of amylose as well as amylopectin. Starch acts as a storage component in plants and allows the sugars created in via photosynthesis to be safely transported to other parts of the plant for storage and use. Amylose is made up of a alpha glucose molecules joined by a 1-4 linage. It is not branched but exists as a straight chain amylopectin is made up of alpha glucose and is joind by both 1-4 and 1-6 lineages. This molecule is branched and both amylose and amylopecting combined forms starch. The branching allows for a smaller storage space as well folding of the molecule.
Branching occurs every 24 residues.
Glycogen
Essentially glycogen is made of the same structure as starch however it is very important to note that the branching occurs more frequently such as every 10 residues. The major difference is that glycogen is found in animals and acts as an easy way to store and access glucose when the body needs it.
When we eat the glucose is absorbed in our blood and raises the concentration in our blood (hyperglycaemia) if this is left unchecked it can cause water in our cells to move out via osmosis which will leave our cells dehydrated and thus die. However our body contains a hormone called insulin which allows cells to accept glucose more readily and accelerate reparation or to be taken to the liver and stored as glycogen. When glucose levels run low (if we miss a meal) and the consternation of glucose in our blood decreases (hypoglycaemia) this can cause us to die as our body doesn’t have the glucose it need to perform reparation. Thankfully we have another hormone called glucagon which converts the glycogen into glucose which is then transferred into the blood. This glycogen is very important to us and since it is used as a fast and easy means of the glucose the branching serves as an easy way to store more glucose as well as can easily be broken off and converted to glucose.
Cellulose
Cellulose is made of beta glucose and is joined via a beta 1-4 linage. Cellulose is found in plant cell walls and acts as a structural building agent. This can be done because of the nature of cellulose, cellulose is has very strong inter and intra hydrogen bonding and hold the molecule together. It has a very high tensile strength which allows plant cell walls to expand and contract with ease.
Within the structure each every odd molecule is flipped in order to perform the bonding required. Thus it exist as a straight chain.
Reflection on carbohydrate
This was a very fun topic and the concepts were easy to understand once you grasp the idea. I never knew there was such a thing as D and L configuration but it made me understand a lot more and filled made gaps for me. Most of the topic I did in secondary school but just crammed it off now I can honestly say I understand how carbohydrates operate, what are their functions and properties and why they are important.
The next topic is amino acids and proteins so please stay tuned 🙂
Sugar rush
These are just some fun facts about carbohydrates before we get to part 2.
WHY DO WE YEARN FOR THAT CHOCOLATE CAKE OR CANDY BAR??
Well after doing some research (not too much) I have one theory on why we prefer sweets. It is a primitive action where you brain perceives things that are sweet as good since carbohydrates are used for respiration and thus energy. When we were hunters and gathers carbohydrates did not come in abundance as it does today in fact it was very few only found in fruits and honey (natural sources) and up until the discovery of making sugar from sucrose stored in plants this was our only means of carbohydrates. Thus our bodies are programmed to love sweets since these people would need to eat as much as possible and keep it stored as glycogen since most time they had no idea where the next carbohydrate rich meal came from.
CATS DON’T HAVE A SWEET TOOTH??
Cats are among the few animals that lack taste receptors for sweet, this is because cats, loins tigers etc. lack the Tas1r2 and Tas1r3 which code for sweet receptors. They only have preferences for proteins. No wonder they are so angry it is because they cannot enjoy the pleasure of sweet goodness …
DID CARBOHYDRATES CHANGE THE CARIBBEAN???
When Europeans rediscovered ways to make sugar (sugar was first made in ancient Egypt and China) and went literally crazy for its sweet taste they searched for ways make it in a large scale. Sugar care was first experimented in our region in 1700’s with Portuguese planters in Brazil, It was then brought to the Dutch colonies in the Caribbean and well let’s just say the French, Spanish and British soon followed establishing large plantations.
Where did they get labour for these plantations? Of course through slavery, this was the era when slavery became extensive; slaves were used as the main source of labour for sugar plantations until emancipation. After that Indentured labourers from India and China were contracted on large scales to work in the plantations…. it was the darkest time in our history all to produce this carbohydrate ….ohh and trade it for money.
Imagine if it wasn’t for human’s insatiable appetite for the sweet taste of simple carbohydrates most of us wouldn’t be here today …. I wonder if that’s a good thing or a bad thing 
WHAT IS THE SWEETEST THING ON EARTH???
You might say …. sucrose because table sugar is made from that and its pretty sweet ….
If you said sucrose your are WRONG !!! the sweetest compound on this planet thus far is actually a protein … yes a protein called Thaumatin which measures approximately 2000 on the sweetness charts :O
Sucrose is only 1 and fructose is 1.75 !!!!!!
This is the table below :
Thaumatin is a protein found in the katemfe fruit of the Thaumatococcus daniellii Bennett plant of west Africa. This is what it looks like:
Honestly I think it looks like suhari leaves or something we can find growing wild here in trini…
http://www.scientificamerican.com/article.cfm?id=strange-but-true-cats-cannot-taste-sweets
Green C (1999). “Thaumatin: a natural flavour ingredient”. World Rev Nutr Diet. World Review of Nutrition and Dietetics 85: 129–32
http://books.google.tt/books?id=hIyM_o4YFZ4C&pg=PA274&dq=%22same+concentration+(1M)%22&hl=en&ei=6yqRTIz4Ho-evQOM4dnBCw&sa=X&oi=book_result&ct=result&redir_esc=y#v=onepage&q=%22same%20concentration%20(1M)%22&f=false
Carbohydrates 1
weeks 2 and 3
Carbohydrates 1
This week’s topic for study was carbohydrates which simply meant a hydrated carbon :O it never occurred to me that it was simply a C with an H2O group attached hence the name . I am so simple minded this was amazing for me to think about. The general formula is (CH2O)n. How amazing it is if you think about it for glucose its 6 C + 12H + 6O which literally translate to 6 (H2O) to 6C.
It’s amazing to note also that plants create carbohydrates via photosynthesis and we use these carbohydrates formed to produce our own energy via respiration the following is an equation to demonstrate that:
Anyways today everyone seems to be dieting especially with Carnival round the corner and valentines on the horizon everyone is trying to cut down on “carbs” this left me to wonder do we know what “carbs” are? Do we fully understand what them and how important they are and do we even know the foods that contains carbs and if so what type?
Important Roles of Carbohydrates
Carbohydrates act as:
Storage
Example: Glycogen in animals in which excess glucose is stored as in the liver.
Starch in plants.
Source of Energy
Example: glucose which through processes of glycolysis break down to release energy in the form of ATP.
Structure
Example: Cellulose in plants which account for the cell walls in plant cells. Chitin in insects.
Dietry Fiber
Cellulose since it cannot be broken down by our body it passes through us.
Used to make more complex Bio molecules
Example: lipids and proteins even DNA
Classes of Carbohydrates
First we have the monosaccharides these are the simple sugars we all know about glucose but do we know about fructose, galactose, xylose and ribose. Essentially they are the building block for all complex carbohydrates weather it by disaccharides or polysaccharides.
Monosacchrides can be classified by the number of C atoms : diose (2) triose (3) tetrose (4), pentose (5), hexose (6), heptose (7)
Types of monosacchrides :
There are also 2 types of sugars; aldoses and ketoses.
By the name we can tell that the difference is based on the carbonyl group attached. Aldos sugars contain the adehyde group while ketos sugars have the ketone group attached. The carbon this group is attached to is called the anomeric carbon.
Chirality of Carbohydrates:
Basically a chiral carbon is one with 4 different groups attached. They form non-super imposable molecules meaning mirrored molecules. This allows the molecule to form isomers which is a very important component when dealing with carbohydrates since different isomers exhibit different prosperities and affect bonding.
Carbohydrates have many chiral carbons and these chiral carbons thus allow carbohydrates to have many isomers. To count the amount of stereoisomer that can be formed we use the formula n2 where n is the number of chiral carbons.
Example: glucose has 4 chiral carbons thus using the formula 42 gives 16 different isomers that can be formed.
Epimers:
Epimers are carbohydrates that differ in configuration around ONE carbon.
Common epimers are mannose (differ around C2) and galactose (differ around C4)as seen below :
D and L Configuration:
This is based on the isomers form by the single asymmetric carbon in glyceraldehydes C3H6O3. When the OH group is on the right side it’s a D an if its in the left its L.
However when dealing with a larger monosaccharide with more than one chiral centre such as glucose the flowing applies:
The chiral carbon furthest away from the anomeric carbon (the carbon attached to the carbonyl group) is used to determine the D or l configuration and the same rule applies:
OH on left L
OH on right D
NOTE: THE MOST FREQUENTLY OCCURRING FORM IS THE “D” FORM.
This is because enzymes react readily with D isomers not the L.
Hemiacetal and Hemiketal
This is where an adehyde group reacts with the alcohol group to form a hemiacetal. In carbohydrates this reaction accounts for the formation of ringed forms of the molecules.
Example : In glucose the adehyde group on C1 reacts with the alcohol group on C5 to form the pyrunose ring.
For Hemiketals the ketose group reacts with an alcohol group to form the hemiketals.
Example: In fructose the ketone group C2 reacts with alcohol group on C4 to form the fruranose ring.
Based on this formation of the cyclised molecules we can get the alpha and beta forms of glucose.
Alpha and Beta β configurations
This configuration is based on the position of the OH of the anomeic Carbon on the plane and is as follows:
Beta β is when the OH is above the plane
Alpha is when OH is below the plane
This alpha and beta formation is very important when dealing with bonding of these molecules.
http://www.ncl.ac.uk/dental/oralbiol/oralenv/tutorials/polysaccharides/basics.htm
http://www.mikeblaber.org/oldwine/BCH4053/Lecture12/Lecture12.htm
First week Jitters
First week was somewhat interesting we learnt about the cell but it seemed like a revision rather than covering new ground (all stuff covered in Form 6) perhaps with the addition of some new information.
For example the meaning behind the mysterious “s” in the 70s and 80s for ribosomes in prokaryotes and eukaryotes respectfully, who would have known it’s not a measurement but rather the rate of sedimentation in centrifugation and the “s” stands for Svedberg as in a Swedish scientist named Theodor Svedberg. (Sigh* another foreign name to remember to spell 😦 ).
I never gave any thought into who discovered the cell but now I know its Robert Hooke who surprisingly worked under Robert Boyle yes… the person who created Boyle’s law. Thanks to him we were able to view life and science in a whole new light and was able to push forward the generation of new discovery and exploration . Thanks to him today we understand alot about ourselves and how we work and since then new innovative technology has been developed into learning about the mystery of the cell.
I also never gave any thought into viruses but apparently viruses are gruesome little critters consisting of DNA inside a protein coat they infect everything from bacterial cells to eukaryotic cells. They are approximately one one-hundredth the size of a normal bacterium. Once attached to a cell they literally send their DNA inside the cell where it combines with the cell’s DNA and codes for new little viruses until the cell burst open upon their maturity and they are released to infect other cells.
This is something straight out of a horror film and to think that I currently have the flu and that this is going on inside me 😥 I am factory for this flu (not a very comforting thought). The sad thing is that viruses don’t have an indefinite cure our body or rather our immune system has to develop antibodies against them. However due to the brilliance of biochemistry we now understand about them and have developed vaccines against common (non mutant) stains for many viruses along with ways to dealing with them.
However due to the fast rate of viral replication as well as the combination of 2 or more viruses in host, new and mutant viral strains are constantly being developed for example the influenza which vaccines do little to protect against since new stains develop every year.I am a living testimony to that since I get the flu each season so I’m sure by now I have developed the antibodies for the past 15 + years of influenza stain and I’m sure next flu season I will be infected again 😦 it think its because of my immune system’s stubbornness to helping me oh well….
Note to self the flu is a virus not a bacterium anti-biotics won’t work
Just something to think about there are 7 billion people in the world billions and billions of organisms prokaryotic as well and eukaryotic … now think of the possibilities there are of new viruses being developed as you read this …it is mind blowing …..as my lecturer said this is why the race is on between biochemist to find vaccines and possible cures for viruses and viruses to develop and mutate, this is a race we cannot afford to lag behind or lose……
And finally some biological art… these are glass models of these diseases causing critters made by an amazing artist Luke Jerram check out his microbiology collection @ http://www.lukejerram.com/glass/
Good bye for now week 1 : completed 🙂
Ohh no the intro
Hi, my name is Sally Arjoon, 18 years old and currently a student of the University of the West Indies, I am perusing a degree in Environmental and Natural Resource Management (ENRM) and Biology after which I plan to start my masters.
To the unsuspecting person I may seem to be an uninteresting, average university student this is mainly because I’m lazy. However my passion is art I love sketching, painting and even some photography. I have also been blessed with a curious mind that appreciates humanities: language, culture, theology and so on. Is this weird for a bio student? Maybe, but biology seems to be natural art created by God in addition to helping us understand ourselves and our beliefs better. Anyways, away from the academics I also love anime (not so secret infatuation i watch mainly everything ) and sport although I am not gifted with the physique of an athlete I love watching the skill others poses mainly football.
Biochem did pose as a major deterrent to starting this semester since I don’t have a solid back ground in it and I was told in the first lecture the failure rate is 50%. Oh what a joy that is …Thankfully the teacher is not the ordinary boring old doctor who lectures you for an hour while you sleep. He is a so called “specialist” and thus far I am coping well (thank you Lord) and I aim to continue getting nothing less than a B so hopefully I am not too intimidated and I get to my good grades 🙂
(ps .i have a major spelling problem so in my future post please ignore them)
And the journey begins stay tuned for new post as I continue through this semester
Goodbye for now ….
.
Another biochem blog 