11th Lesson- CSI DNA Identity 1

For today's lesson, we learnt about DNA and traits.

Key takeaways: 

- Most traits can't be changed -> genetic traits

- Some traits can be changed -> influenced by environment (for eg: hair colour as it can be dyed)

With the worksheet given, we assessed ourselves for some characteristics:

RH/LH	Right / Left handedness
A/a	tongue rolling
B/b	widow's peak
C/c	cheek dimple
D/d	free earlobe
E/e	curly hair

Next, we were to plot our results on the individuality chart and i found out that i was a 32e. 

In our class, there were alot of "32e". 

I was quite amazed as i did not expect everyone to be any similar at all, i guess i was wrong. From this exercise, i learnt alot because even though many of us have certain similar traits, we still look different because of our DNA.

*Moreover, i have made some assumptions beforehand (that are probably misconceptions now that i know) I thought that if we really could find someone with the same individuality number as me, that person would be my good friend or someone who had a very similar personality with me. However, i was wrong. Having similar traits does not mean that we would be exactly similar to the person. We may look totally different and behave in totally different ways. After this exercise, it cleared the question in my brain: "Would i have the same personality as someone with the same individuality number as me?" *


A graph of the traits were then collated and shown below:

The following are some of the traits i researched abit more on :) (since these are the common traits)

1.) Based on the slides went through, earlobes that hang free are detached earlobes. Earlobes that are directly attached to the side of the head are attached earlobes.
Apparently, some scientists have reported that this trait is due to a single gene for which unattached earlobes is dominant and attached earlobes is recessive. Other scientists have reported that this trait is probably due to several genes.

*However, i feel that it is sometimes hard to tell whether some people have attached or detached earlobes as personally, mine is exactly halfway between the two extremes. Thus, i am not sure whether to select yes or no for attached earlobes trait as for my earlobe, it looks as if it's detached due to a line between my ear and the skin but then up close, it actually looks attached. My earlobe isn't exactly very detached, nor isit very obviously attached. As all my life i've thought my earlobe was attached, i selected the attached earlobe option and i've only realised now that my earlobe trait is quite unclear...*

Different earlobes of cyclists :) From most detached to most attached left to right continuously for both rows!

2.) Tongue rolling ability may be due to a single gene with the ability to roll the tongue a dominant trait and the lack of tongue rolling ability a recessive trait.

CAN ROLL! 

CANNOT ROLL! 

*For me, when i was younger, like about primary 1 or 2, i couldn't roll my tongue, i practised rolling my tongue for a week and even tried to squeeze both sides of my tongue together but it still wouldn't work. However, when i went up to P4, i suddenly found out that i could roll my tongue. I haven't been practising and was quite shocked that i actually could perform this tongue rolling trick thing. xD
My question is: Is it possible that someone may be born with the tongue rolling ability but is unable to do so in her earlier stages of development or youth, but this trait only develops in the person when she grows older?*

Research has been done in 1950's and 1970's and it showed that identical twins don't always share the ability to roll their tongues.

This is because we may have the gene for a certain trait but not see any sign of it. And there is a number of reasons why we can't see the sign of that gene even though we possess it.

One reason is trigger from the environment.

I would use the analogy of juvenile diabetes to explain this reason.
There are genes that make people more likely to get this form of diabetes, But to get juvenile diabetes, there needs to be a viral infection. If you have juvenile diabetes gene(s), then the part of your pancreas that makes insulin looks a bit like a certain virus. When the virus infects you, your body mounts an attack on the virus, destroying it. Unfortunately, in a "friendly fire" incident, part of your pancreas is also destroyed and you get juvenile diabetes.

juvenile diabetes- in the pancreas

Someone never infected with the virus but who has the gene (s) for juvenile diabestes will not get this form of diabetes. But they can pass the gene(s) onto their kids. And if the child gets infected with the virus, then he or she can develop diabetes. Perhaps tongue rolling also needs some sort of environmental trigger even though it probably isn't virally related.

Another reason is not having enough of the gene. That means you need two or more different genes to see a trait and you only have one. For example: At its most basic, there are two eye colour genes, a brown-blue one called bey2 and a green-blue one called gey.

may be a combination of 

To get blue eyes, both of your bey2 and both of your gey genes need to be the blue kind. For example, if both your bey2 are blue but one of your gey is green, then you have green eyes. So to get blue eyes, both genes need  to be "right."

*Two genes, bey2 and gey, work together to make brown, green or blue eyes. Each gene comes in two versions or alleles. One form of bey2 makes of melanin-> B. The other form makes only little->b.One form of gey makes some melanin-> G. While the other makes only a little-> b.
B- brown eyes
G but no B- green eyes
only b- blue eyes.
THIS IS A TABLE OF THE COMBINATION:
*

Now imagine that to be able to roll your tongue you need two genes, A and B. For each of these genes, there is a certain dominant version that lets you roll your tongue. Now let's say that one parent has a dominant A and the other parent has a dominant B. Neither parents can roll their tongues. If one parent passed on a dominant A and the other a dominant to their child, there would be a child that could roll her tongue. Parents who cannot roll their tongue would then have a tongue roller for a child.

Another example is something called a modifier gene. A modifier gene can turn another gene on or off. For a gene to have an effect, it must be "on". On means that the instructions in the gene have been made into a protein that can do something useful.
Genes are just instructions for making proteins. They don't do anything on their own. The tongue-roller gene has to make a protein that allows the muscles of the tongue to bend in a certain way. Now imagine another gene that keeps the tongue-rolling protein from being made. We name it M. M could eliminate the tongue rolling protein in lots of different ways. For example, M could prevent the cell from reading the instructions in the tongue-rolling gene or destroy the tongue-rolling protein outright.

Thus, you can't roll your tongue because M has gotten rid of the tongue rolling protein.
If two of these people have kids and they pass on the tongue rolling gene but not M, these children would then be able to roll their tongues.

THus there are potentially alot of ways for nonrollers to have roller children. Even "simple" traits liek tongue rolling can get quite complicated!

3.) Based on my research, dimples are actually genetic defects caused by shortened facial muscles. Transfer of dimples from parents to children occurs due to just one gene. The dimple creating genes are present in the sex cells prior to the process of reproduction. Each parent provides one of these genes to the child. So, if both the parents have dimples, the children have 50-100% chances of inheriting dimple genes.

dimple

no dimple

Sometimes, a variation in penetrance may also occur. Some individuals may carry a particular gene, but they do not manifest the traits associated with it. However, they still pass on the traits to their successive generations.

Apart from variable penetrance, there may also be reduced penetrance which allows a generation to skip having dimples, although they may appear in subsequent generations.
This occurs when one person inherits certain genetic trait along with another trait that suppresses it. For example, a person may inherit genes for dimples and also other genes for small face. In this case the small face will not allow the gene for dimples to function. Such people are called passive carriers of dimple genes.