CELL INTERACTION

I am a motor neuron attached to a muscle in the leg of the Xenopus Laevis.

Screenshot_101713_061844_AM

I have a cell body containing nucleus, cytoplasm, and cell organelles all surrounded by dendrons that conduct impulses to the cell body. At the end of the dendrons there are dendrites which are nerve endings. I have one long nerve fiber called an axon which transmits impulses away from the cell body. At the end of the axon I have axon terminal ends which are the nerve endings. Along the axon there are several myelinated sheets. Separating the myelin sheets are nodes of Ranvier.

neuron.png[1]

Next to my dendrites there is another nerve cell that transmits nerve impulses to me and at the end of my axon terminals there are muscle cells to which I transfer nerve impulses.

When a nerve impulse reaches the end of the axon terminal of the neuron next to me, the impulse triggers the opening of ion pores in that axon terminal which allows calcium ions to enter. This causes the movement of small membrane bounded packets of neurotransmitter chemicals, called vesicles to move to the cell membrane, where the vesicles fuse into the cell membrane, thus releasing the neurotransmitters, into the synaptic cleft between the axon terminal and my dendrite.
I have many structures each of which are like a combination of a “well” which is a receptor for the neurotransmitter chemical which travels by diffusion and enters that well, it affects the shape of the companion tunnel ion pore, such that the ion pore opens, thus allowing sodium ions to enter the my cell at a dendrite.

Screenshot_101713_055710_AM

This sodium ion then travels along my axon from one node of Ranvir to the next depolarizing the nodes as it passes. This action takes milliseconds and causes the release of acetylcholine from my axon terminals. This causes the depolarization of the membrane of the adjacent muscle cell. Depolarization triggers the release of calcium ions from the sarcoplasmic reticulum inside the muscle cell. In the presence of ATP, the high calcium level causes the myosin heads to bend, dragging actin filaments towards the middle of the unit of contraction of the muscle in the leg of the Xenopus Laevis.

Screenshot_101713_060115_AM

My Model Organism

A model organism is an organism (other than a human) that is studied because of a particular trait. These organisms are also studied as they relate to advancement in medical research.
My model organism is the Xenopus Laevis also known as the African clawed frog.
I am an ectodermal cell in the embryo of the African clawed frog.

Xenopus_laevis_by_Xenopuslaevisfan

The fertilization of an egg by a sperm lead to the formation of an embryo. Fertilization causes the creation of the molecules necessary to begin cell cleavage and development. I developed in the center of the embryo in the yolk ectoderm. I am to be developed into a cell in the epidermis or a nerve cell and later on in the life cycle of this frog I am going to become a peripheral neuron.

te-151-1

During my development a signal is sent from a rod of the mesodermal cells from the most dorsal position that tells me that I am going to become the nervous system. Elongation, stretching and folding of the ectodermal cell neural precursor this becomes the neural tube which undergoes mitosis and forms cells of the face, cartilage and peripheral neurons of the embryo. The embryo develops even further as it becomes a tadpole and later develops into a frog.

Electron Trannsport Chain and ATP Synthesis

This video helps with understanding the mechanisms involved and what is meant by the movement of electrons. In this video the electron transport chain is said to have 3 protein complexes and one other protein complex that carries out ATP synthesis. This is only partially accurate.

The 3 complexes seen in this video are the only three complexes that pump protons into the intermembrane as seen in the diagram bellow.

etc

Image taken from “Lehninger Principles of Biochemistry (5E 2008 ISBN 9780716771081) David L. Nelson, Michael M. Cox”

There are 4 protein complexes that make up the electron transport chain. They are:

Complex I : NADH Dehydrogenase

Complex II : Succinate Dehydrogenase

Complex III : Cytochrome b-c1

Complex IV : Cytochrome Oxidase

This together with Complex V : ATP Synthase

carry out aerobic respiration as seen in the diagram bellow

etc

Image taken from “Lehninger Principles of Biochemistry (5E 2008 ISBN 9780716771081) David L. Nelson, Michael M. Cox”

The next video shows the production of ATP via the concentration gradient created by the electron transport chain.

 

“Diabetes is only for the elderly”: A statement that is as popular as it is inaccurate.

imagesCANRNAOL

There are 350 million people worldwide living with diabetes. 90% of these people have type 2 diabetes. Type 2 diabetes occurs when weight increases and the stress of weight on the body. This stress decreases the body’s ability to regulate glucose levels in the blood. Type 1 occurs in childhood and can be controlled by daily doses of insulin. Some research shows that the incidence of type 1 diabetes has increased drastically over the years. Such an increase can not be explained by genetic mutations over such a short time period.

Diabetes, both types 1 and 2, is the inability to secrete insulin into the blood to prevent glucose levels from rising too high. Type 1, also known as juvenile diabetes is an autosomal disease. This means that the body attacks the pancreatic cells that are responsible for the production of  insulin thus these cells are unable to function. Type 2, also known as adult-onset diabetes is the tissues that are designed to absorb glucose when insulin is produced becomes resistant to the presence of insulin. This causes the a buildup of glucose in the blood and the pancreas if forced to create more and more insulin. This overproduction causes the cells to become damaged and eventually they stop working.

Research showed that the incidence of type 1 diabetes is on the rise as well as the range of ages in which it first affects infants is expanding. It was calculated that by the year 2020 the incidence of type 1 diabetes would increase by 100%. Some hypotheses put forward to try to explain the increase in type 1 cases. These included studies related to the effect of a diet of too much processed foods. Some of these hypotheses included contamination with fungi and even contagious infections via bacteria, viruses and parasites. All these hypotheses were later disregarded.

As of late, investigations have been lead back to obesity and overweight aas the number on suspect in these trends. A hypothesis called the accelerator overdrive hypothesis is now being considered. This is where the body is being forced to produce insulin in excess and this build up of insulin burns out the insulin producing cells of the pancreas. It is these cells that develop type 1 diabetes. After all the research it was found that being overweight is the main cause of type 2 diabetes and it is now causing type 1 diabetes also. Prevention methods are still being deliberated but it goes back to diet, exercise and maintaining a healthy body weight.

Article taken from: Scientific American 2012. “Diabetes Mystery: Why Are Type 1 Cases Surging?”. Accessed April 9, 2013. http://www.scientificamerican.com/article.cfm?id=a-diabetes-cliffhanger

How do you take your eggs?

 

B0002100 Human egg with coronal cells - gold

A new recipe for progeny; to one packet of egg powder add water and sperm then implant.

Conventionally women aim to preserve their fertility by storing their eggs in liquid nitrogen. Before this is done the egg undergoes a process known as vitrification where the eggs then become solid and glasslike. The egg is then stored in liquid nitrogen until needed.

The storage of oocytes in liquid nitrogen can cause damage to cellular membrane by the formation of ice crystals. There is procedure being tested by Dr. Amir Arav the leading scientist in the field of cryobiology. This procedure aims to coat oocytes in a cryo-protective solution that displaces water almost instantaneously thus reducing cold damage to the cell.

The protective solution contains sugar terhalose, known for its ability to allow some smaller animals to survive dehydration or freezing. This way the eggs can be stored in a vacuum without air or water so that no damage is caused. This technique allows for the eggs to be stored potentially forever at room temperature which costs less than storage and may be safer and should be as simple as adding water to revive cell followed by sperm to fertilize the embryo can then be implanted.

This mechanism is still in the testing stages but has been demonstrated in cow eggs. Red blood cells and mononuclear cells blood cells from umbilical cord has been converted to powder and revived. Studies are currently being done to investigate the effectiveness of fertilization of these eggs rejuvenated from powder form. If fertilization does occur tests are to be carried out to observe if the embryo will be implanted into the womb and will result in growth of a healthy baby.

 

Article taken from: NewScientist 2013. “Powder woman’s eggs for home storage”. Accessed April 9, 2013. http://www.newscientist.com/article/mg21829115.100-powder-womens-eggs-for-home-storage.html

 

This post is strictly a review of scientific research and in no way reflects the opinion or beliefs of the author at basicbiochem.