Courtney C.

Wiki Post #1- March 25/13


Inhereting Eye Color


How do we inherit eye color? Is it possible for a person with blue eyes and a person with brown eyes to make a child with green eyes?



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The genes in our DNA make up who we are; they are how our physical and personal traits are passed down to us through our parents. Eye color is one of the traits that we inherit from our parents.

Different eye colors are produced from different patterns and amounts of pigment in the iris or your eye. The amount of pigment and the pattern of it are determined from your genetic makeup.

Things called alleles are found in genes and they are what determine the appearance of any characteristic. For each trait inherited, there are two alleles. If these two alleles are the same they will be called homozygous and if they differ they will be called heterozygous. In heterozygous alleles, there is a recessive and a dominant allele. The dominant allele is the one that will be expressed, and the recessive one will not.

There are three known gene pairs that control eye color, the bey one and two genes on chromosome 15 and the gey gene on chromosome pair nineteen.
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Chart predicts the likelihood of a baby's eye color


A green allele will be dominant over a blue allele, and a brown allele will be dominant over both blue and green alleles. On either chromosome pair, the brown allele is still the dominant allele. If there is a brown allele on either of the chromosomes, the person will have brown eyes. A green eyed person must have a green allele on chromosome pair nineteen and all or some other blue alleles. To create blue eyes, both parents must have blue eyes, and therefore all alleles must be blue.
Melanin, which is a pigment found in the skin is what produces the eye color that is specified by the genes. Melanin is a dark brown pigment that is placed in the iris. To put it simply, the more melanin in the iris, the darker the eye will be. Genes are what tell the enzymes how much melanin to deposit in the iris. At the time of a baby’s birth, melanin production has not yet started. A newborns eyes may appear blue but can darken over the years. It is said that you cannot determine the true eye color of a child until they are around three years old.
















This video explains why most babies are born with blue eyes


In an albino person, the eyes will appear pink because there is a lack of any pigment throughout the eye and the pink color is a reflection of the blood vessels in the back of the eye. It is also possible for a person to have two different colored eyes. This is called heterochromia. There are two types of this, if a person has always had two different colored eyes it is called congenital heterochromia and is quite rare but nothing to have a medical concern over. Heterochromia developing later in life is believed to be caused by something affecting the melanin synthesis in the eye. This could be from a disease of the eye or a side effect of certain types of medicine. 6369021807_915f85831e_z.jpg




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Heterochromia
Albino Eyes



Child born with Heterochromia

PS. No, it is not possible for a person with blue eyes and a person with brown eyes to make a child with green eyes. The brown allele is dominant over both the green and blue allele, therefore the eyes will be brown.

Extra Links!! + Sources
The Genetics of Eye Color
Eye Color Inheritance Chart
Eye Color as a Clue to Paternity
Genetics of Eye Color


Wiki Post #2- April 12/13


Fragile X Syndrome


What is Fragile X Syndrome? How is it inherited? Why is it more common in boys than girls?


Fragile X Syndrome is a hereditary nero-developmental disorder passed on in a family by individuals showing no signs or symptoms themselves. Fragile X Syndrome is the most common form of mental retardation in males, and is also a significant cause of mental disability in females. Fragile X Syndrome affects approximately 1/4000 males and 1/8000 females. One of the ways that it is recognized is by the child having a larger than average head circumference, a long face, a prominent forehead and chin and protruding ears.


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Fragile X Syndrome is caused most often by an expansion of a DNA section called the CGG triple repeat in the FMR1 gene. Generally this sequence would be repeated around 5-40 times, but it people with Fragile X Syndrome it is repeated up to 200+ times. This expansion causes the FMR1 gene to be deactivated which prevents the gene from performing its function, which is to produce a protein called the Fragile X Mental Retardation protein. The loss of this protein is what leads to the signs and symptoms of this condition.



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Fragile X Syndrome can affect both boys and girls, but since boys are lacking an extra X chromosome they have a much higher chance of being affected, and more severely.

This video, which is a newscast showing an interview with a family trying to raise more awareness about Fragile X Syndrome states that 1 in every 130 women is a carrier for Fragile X which means that they have a 50% chance of having a child with that disability.








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Another condition that is associated quite often with Fragile X is autism. Affected boys may also experience hyper activity, hand flapping and temper tantrums. Girls with this condition generally only experience mild mental retardation. Both genders will also have problems with tremors and poor coordination.

There are no real treatments for Fragile X Syndrome other than special education and early intervention. In some cases medication may be used to assist with some behavioral problems although no specific one has chosen to be significantly helpful.


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Trailer for a documentary called Living with Fragile X



Sources!!

Fragile X Syndrome
National Fragile X Foundation
Fragile X- Wikipedia

Extra Reading!!
Fragile X- Genetics Home Reference
Fragile X Canada




Wiki Post #3- May 17/2013

Evolution of the Horse


Over the last 50 million years, horses have gone from the small, fox sized Eohippus to the modern Equus caballus that we know today.

Horses belong to the order Perissodactila, which are all animals that share hooved feet and an odd number of toes on each foot. They all have mobile upper lips as well. Horses share a common ancestry with rhinos and tapirs.

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Rhino and Tapir- Common ancestors of the horse

It appears that the first horse-like creatures were originally made to live in tropical type environments, but while their relatives the rhinos and tapirs adapted well to the jungle environment and continued to live in it, early horses evolved to become better adapted to life on drier land, and further adapted to the harsher climate of life in the Steppes, which is a dry, grassland type of environment. Around the same time as these Steppes were beginning to appear, the horses began to evolve longer limbs and change the structure of their feet so that the animals would be capable of the greater speed they needed to outrun predators.

Another change that aided in the evolution of this species would be that as more grass species started to appear, the horses diets shifted from foliage to grasses, which lead to larger and more durable teeth.

Horses evolved from the early Eohippus, which was small and approximately the size of a fox, to the forest suited Kalobatippus and from there to the Merychippus, Pliohippus, Plesippus, and finally to what we know today as Equus



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Evolution of the horse

It has been said that environment is what drove the changes. As the horses climates cooled and dried, they began to change to adapt. Losing their toes and developing longer limbs and larger teeth that were much better for grazing the grass that now made up most of their diet.
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Perhaps one of the biggest changes has been to the horses feet. Early horses had small feel with 4 toes that spread apart to help keep them from sinking in the marshy ground that was their environment, as the species evolved, they began to develop longer legs and the toes began to disappear to form what we now see as a horses hoof.

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As shown here, the main changes in the horses shape have been in the head and foot region


Journey from the first horse like species to the modern Equus

Sources!!
Evolution of Horses
Horse Evolution Over 55 Million Years
Evolution of the Horse- Wikipedia
Evolution of Horses- AMNH

More Reading!!
Amherst College- Evolution of Horses
Charles Darwin
Natural Selection
Equine Study



Wikipost #4 June 13/2013


Are Allergies Inherited or Caused by Environmental Factors?


Do you have allergies but your parents don't? Or do your parents have allergies and you don't? Or maybe both you and your parents have them? Have you ever wondered if your allergies are inherited or what causes you to have them?


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While it is more common for parents with allergies to have children with allergies, and for the children of parents with allergies to have more severe allergies, it seems that only the probability of developing allergies is inherited and not the specific allergen itself. It is believed that if children have parents with allergies they have a 1 in 3 chance of developing allergies themselves.

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nother general consensus is that if you have been diagnosed with one allergy, there is a highly increased likelihood of developing more as well.


So, if allergies are not inherited, only the probability of having them, then how are they developed?

Your immune system is actually what causes allergic reactions. When an allergen (a foreign body) enters your body, your immune system sees that as a threat and attacks them, trying to get rid of them. So rashes and scratchy throats and everything that is fun about allergies is all your own bodies fault! Wonderful right?

Also, a person can become allergic to something even if they have been in contact with that specific allergen many times before. If you are coming into contact with the allergen at a time that your body is weak, or you aren't feeling the greatest, that could be all it takes for your body to suddenly flag the allergen as an intruder and you will develop an allergy to it.

There are many different kinds of allergies, but the most common ones are food and environmental allergies. Food allergies can range from just plain old food sensitivity to a potentially lethal peanut allergy and the same goes for environmental allergies


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Unfortunately, there is no "cure" for allergies, but there are ways you can reduce the symptoms. Try taking an antihistamine, or talking to your doctor or pharmacist about it, they're there to help!





This is a video about understanding what causes allergies and ways that they can be dealt with

References! :)
Wikpedia- Allergies
Are Genetics Responsible for Allergies?
Allergy Facts and Figures
Kid's Health- All About Allergies

Extra Links! :)
What Causes Chronic Allergies?
Risk Factors of Allergies
Are Peanut Allergies Genetic?
Allergies are Gender Related





Wikipost #5 (finally!) June 13/2013


The Central Nervous System- Why it's vital



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Obviously we all know that our brain and spinal cords are pretty important, I mean, we wouldn't be alive without them, but why are they so important? What do they do?

The central nervous system is composed of the brain and spinal cord. The spinal cord receives information from the skin, joints and muscles of your body through the sensory system and then carries this information to the brain where it is processed. The spinal cord also carries the nerves that control all of your movement. Very important! Your brain also receives information directly from your ears eyes nose and mouth on top of getting imformation from everywhere else from your spinal cord. The brain is the most complicated part of your nervous system. The brain uses the information it is sent to help you think, remember, plan etc.

Inside the brain, groups of nerves make up brain centers, which control different things. The brain has a "pleasure center" that makes us feel happy or sad. The brain has a "hunger center" that tells us if we are hungry or full. It is important to remember that the brain centers send out messages to the outside nerves. The respiratory center in the brain controls breathing, and the nerves around the lungs also control breathing--both nervous systems work together. The brain centers are affected by drugs.

An example of the brain centers being affected by drugs would be cocaine. Cocaine makes the body feel as if it is not hungry and a person on cocaine can go days without eating. All drugs have an impact on the body and especially the brain, they can cause permanent damage and be incredibly dangerous. So try hugs not drugs :)


The central nervous system controls our whole body and we wouldn't be alive without it. Keeping a healthy lifestyle, staying away from drugs and doing activities that stimulate your brain on a daily basis are really good for you and can also help protect you against developing debilitating diseases later in life





5- minute overview of central nervous system

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I thought that these pictures were very interesting, they show a brain that is normal and healthy compeared to one with advanced Alzheimers Disease




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These pictures just show the parts of the brain and the functions as well as the parts of the central nervous system





REFERENCES

Nervous System
What Does the CNS Do?
What Does the Nervous System Do?
Kid's Health- Brain and Nervous System