Have you ever been told that you look exactly like your mum, or your dad? Or your grandma??
Well, the reason that you look like someone from your family is down to genes and genetics. What is this genes and genetics jargon then? I’m glad you ask.
A gene is a unit of inheritance, through which parents pass traits on to their kids. I know I know!! This jargon isn’t any better either. So let’s simplify it further. Think about a very very odd family heirloom – maybe your great grandma’s denim jeans that get passed down your family from generation to generation. So from your great grandma, to your grandma, to your mum, to you – and then for you to give to your daughter.
Genetics work in a similar fashion. A trait is passed down from generation to generation, sometimes it may skip generations, and sometimes it may become more and more prominent with every coming generation.
Now that you know that genetics means the passing of hereditary information (i.e. passing down of your great grandma’s very very odd heirloom denim jeans) – let’s break it down (with metaphors, as always) and get into the nitty gritty of it all.
So… your high waist skinny jeans as a whole – that’s your chromosome. What is it made of? Denim. That denim cloth – that’s your singular gene. Denim is stitched together in all kinds of fancy ways to make your high waist skinny jeans. Similarly, a whole load of genes come together to make the chromosome. Eventually, you know that denim breaks down further into thread – this metaphorically, is your DNA. Again, a lot of “thread” (DNA) comes together to make small sections of genes (i.e. denim cloth, which is stitched together to make your high waisted skinny jeans or chromosomes). The DNA and chromosomes are compacted and stored in the nucleus of the cell.
The style of these jeans; that’s the phenotype of the jeans. You can have various phenotypes (i.e. styles) – so straight cut, boot legged, skinny jeans, mom jeans, ripped jeans etc. A common example for different phenotypes is eye colour – black, brown, green, grey, blue, hazel: etc. Another phenotype is blood group, of which again are various types.
The collection of all your genes together, is your genotype. All your genes written together, make you who you are. All humans have the same genes arranged in the same order. 99.9% of our DNA is the same – it’s the variations in the 0.1% that makes each one of us so unique.
So now we know what genes are, but what do they do?
Genes are a set of instructions provided to your body to tell it how to work. These instructions tell your cell which proteins to make, and how to make them.
Think of these instructions as directions to go from London to Manchester for instance. In a healthy person, the instructions will be good and you will have a hassle free journey to Manchester. In a scenario like this, your body is able to make the functional proteins without any problems.
Sometimes you could be borderline, and get lost on the way only for your navigation system to “recalculate” – and eventually take you to Manchester about 30 mins later: still safe and sound. In this case, your body may require some more time to make the same amount of protein or to conduct the same task. This is what happens in Asian Flush Syndrome – the body is able to make the protein required to break the alcohol, but it takes the body some extra time to break it due to a protein deficiency.
It can also sometimes happen that your navigation system is broken and you need to go old-school and ask around for directions. Here, your body requires a little encouragement with drugs perhaps, to be able to make the protein.
If you’re extremely unlucky, your navigation system breaks down and there’s no one around to ask for directions. In this final scenario, your body is not able to make the proteins (as can be in the case of producing insulin in a person with Type I Diabetes).
There is still another case where in some diseases, the gene is translated into a protein, but this protein does not function correctly. This is because there is some variation within the gene. Variations in genes are normal, however, variations in some particularly important genes can be fatal or cause disease. This is called a mutation because the variation is in a very important gene. Although it should be noted that not all mutations cause disease.
Since some diseases have genetic causes – this is often a preferable target in drug therapies. Other therapies look at making ethically-challenged life-changing manipulations to DNA and this is an often contended topic. Gene editing technologies allow scientists to make changes in the DNA of a certain cell. When changes are made in germ cells, or embryonic cells – these changes can be very potent, and are capable of changing the phenotype of an organism. Have you ever heard of designer babies?
Designer babies are babies that are genetically modified. Usually this would be limited to removing genes associated with disease, or adding genes to prevent disease. However, this is quite often challenged as the limits to “design” babies need to be defined. Should you be allowed to genetically select for blue eyes? Or brown hair? Or a small nose? Or plump lips? Due to this possibility for selection, this is a highly contended topic within bioethics.
Comment below on your thoughts about designer babies, and genetic engineering in general. I would love to know your thoughts.