Let's learn what genes, DNA & chromosomes are. Created by Mahesh Shenoy.
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- If my dad was 6'4 and my mom was 5'4, how tall will I most likely be? I am already 5'7 and I'm a girl. Will I end up being taller? And if so...my older(16 yr old) sister is 5'5. Why is it that she is shorter and I'm taller?(3 votes)
- Probably because u have your dads genes is more in number and your sister have more of your moms Genes hence the dominance differs.(4 votes)
- If this is so, then how does a person get black eyes even if both the parents eyes are brown?(1 vote)
- Recessive genes. The eyes of the grandparent may be black. Its like how the self - pollination of a tall plant gives some short plants(7 votes)
- can crossing between two different species take place? if yes what type of species do they reproduce(2 votes)
- Why do I have blue eyes if my dad has brown eyes and my mom has green eyes?(2 votes)
- blue is a recessive trait, green is a blend of blue and brown(this is a non-mendelian law), and brown is a dominant trait.Thus it can be said that you have inherited the least possible type in the phenotypical ratio.(1 vote)
- In all the videos, the dad's traits are always dominant.
why is it so?(1 vote)
- It is true that you get half of your genes from each parent, the genes from the father are more dominant. According to a study on lab mice by University of North Carolina's School of Medicine the paternal line is mostly found to govern how a person develops into an adult - especially in regards of their health
(Source : independent.co.uk)(2 votes)
- I have green eyes but my parents and grandparents don't, they have brown eyes. I asked them if my great-grandparents had green eyes but they don't either. how does that work?(1 vote)
- it's a non-mendelian law. In mendel's experiments none of the traits mixed as they were contrasting in nature.(1 vote)
- Each cell has 46 chromosomes, but then does every cell in the body have the same genetic makeup(46 chromosomes)? For example, would a hair cell's 46 chromosomes' collective gene pattern e the same as that of a skin cell's? By the way, I am referring to the 46 as a whole, not every individual chromosome being the same.(1 vote)
- @ Kaatya I think you are forgetting the part that not all 46 chromosomes play a part in reproduction. Only 2 or 3 pairs participate. These may contain organ-specific genes, like skin color, heart color (I am just giving example there is nothing called heart color).
Hope this helps
Nolan R.T :)(1 vote)
- As he said, our DNA is exact copy of our father's and mother's DNA, so we can even say that their DNA will go to my child as father's DNA?
if yes, wouldn't that lead to DNA becoming too long/big in the future generations?(1 vote)
- Well not exactly. Since humans tend to reproduce sexually, every offspring tends to have variation. Now it is not necessary for the variation to be drastic, it may not always be beneficial or harmful or visible. Minute variations occur.
SO following this sense, our DNA is NOT the exact copy of our father's and mother's DNA.
However, our DNA is the COMBINATION of our father's and mother's DNA in a unique manner. Hence, we cannot say that our DNA is the same as our father's (because we have a little bit of our mother's DNA mixed with it) and similarly it is not the same as our mother's. Our DNA is the combination of our parent's DNA and thus is unique.
So our child, would have OUR DNA (which is a mix of our father's and mother's DNA in a unique way) along with our partner's DNA (which is a mix of their father's and mother's DNA in a unique way)(1 vote)
- doesnt this mean that say blue eye after LOTS of generations should not be visible because it comes from a recessive gene and after a lot of mixing and matching there won't be anyone left who has 'pure' blue eye gene(1 vote)
- It can happen though it is really rare. It can only happen if all the people carrying that gene dies and is not inherited by successive generation.(1 vote)
- Would the DNA in any cell contain the information to build each and everything in my body?
Like could I find genes to produce insulin if I took a random human cell? If yes then how does my body know which genes to use at a specific place?(1 vote)
- Unfortunately @ Fathima Fasmin that's pretty tough to explain that way. A lot of biological processes are there which you will learn in later classes. Based on these processes the genes are present, passed on, etc.
Nolan R.T :)(1 vote)
old family photos this is where people say hey you got your eyes from your mom or something like your mouth is like your dad yeah over here I don't see any resemblance but you know what I'm talking about right that's me by the way so why do we assemble our parents well you might know the answer to this you might say hey it's the jeans man jeans are what we call the unit of inheritance basically we say that jeans gets passed along from parents to their kids and that's why we look similar to them but what exactly are these jeans let's find out to answer this question we need to look deep into a cell so let's say this is one of the cells that compose my body now the cells have a lot of stuff inside of it right it also has a nucleus that's what we are interested in if we were to look deep into the nucleus then you will find some squiggly thread-like structures you know what these thread-like structures are called these are called the DNA d.n.a and if I were to zoom into a small portion of that DNA then you might be seeing something which is familiar that you may have seen these things in movies and cartoons and everything it may be wondering what exactly is this DNA we make a big deal about it right now without getting into too much of detail DNA can be thought of as an instruction manual which is present to build me if this is my DNA it contains the instructions to build everything about me from the tip of my hair through the guts to the tip of the toes every single detail of how to build me is present in this DNA so it's a long instruction manual of how to build Mahesh similarly your DNA is an instruction manual to how to build you the DNA of a chimpanzee is an instruction manual to build a chimpanzee and did you know that about 99 percent of its DNA matches with human DNA that may not be all that surprising because I only know you might have heard of that we are very close relatives of Jim's right but what may be surprising is to learn that about 50% of a fruit flies DNA also matches with ours 50% the fact that our DNA is so common to other animals actually is an evidence for the theory of evolution but of course we'll talk more about evolution in future videos so anyways this DNA is super important but where do you think this instruction manual came from any guesses our parents that's what gets passed along from our parents to the kids and if you're wondering wait a second shouldn't we have two copies of this one from the mom and one from dad well then you are absolutely right we have two copies of this DNA set one we got from the mom and one we got from the dad in fact and this might sound a little weird but just before my dad's sperm fertilized my mom's egg this DNA was present in that sperm and this mom's DNA was present in her egg and then when the fertilization happened the two DNA came into one cell and then that single cell started dividing and every time it divided a copy of this DNA was made which makes sense right you don't want to lose things like these and so as the cell kept on dividing and dividing and dividing I started growing and growing and growing and using this very instruction manual I was built and this might sound silly but this is the reason why human babies grow into humans and dog babies grow into dogs anyways before we talk about genes let me tell you one thing over here whenever a cell gets divided I said that the DNA needs to get copied right it turns out copying DNA like this when the DNA is in this form is very difficult so when the cell is ready to divide the DNA's start getting coiled up in a very tightly condensed condensed coil okay and this coil of DNA tight coil of DNA and a bunch of stuff gets attached to it to make this coil happen but anyways this kind of DNA is what we call chromosomes grow more tsums okay so chromosomes are think of them as basically coiled up versions of the DNA and this is why most of the time we use the word chromosomes and DNA interchangeably okay anyways now let's talk about genes what exactly are genes genes are portions of DNA not the entire DNA but these are portions of DNA which carry instructions to make a specific action basically it carries instruction to make a specific protein for example what I mean is let's say this section of DNA contains the recipe or contains the instructions to build a protein which eventually makes the eye color then we will say this is the eye color gene this is the eye color gene and let's say some other portion of the DNA this portion of DNA contains the instructions to make a protein which say makes up our hair so then we'll call this as the hair shape gene now I'm making these names up okay in reality the names of the teams are pretty boring and so you see genes are basically portions of DNA that contain instruction to build a specific protein it's these proteins eventually that end up building you remember your body is mostly made of water fat and proteins and the instruction to build these proteins are given by these genes I like to think of this as a robot building kit which might include a long instruction manual to tell you how to build this robot exactly then this instruction manual the DNA but well if you open it let's say each page gives you specific instructions of how to build a specific part of that robot maybe one page tells you how to build the lens of the eye that makes up the robot another page might tell you what you know how to build a particular screw something like that then each page we will call as a gene so the whole book is like the DNA the pages which contain the instructions for specific things are like the genes anyways remember that genes contain instructions to build proteins and we have two copies of them one we have dads copy and one we have mom's copy so this might bring another question if we have two set of instructions then what does our body do well this is where the concept of dominance and recessive Ness comes into the picture that we may have learnt off from Mendel's experiment so for example let's say the dads copy of the gene makes up a protein which gives us brown color of the eye and let's say mom's copy would give us blue color of the eye then what color will our I get brown or blue well it turns out that brown is the dominant version of that gene and so it will be brown but I always wondered how does this a dominance and recessive Ness work well I'm going to oversimplify it over here okay just to get the idea so let's say that dad's eye color dad's gene gives a protein which makes our eyes brown brown pigment then mom's gene doesn't give blue pigment what does mom's gene do you know it creates a protein that doesn't do anything think of them as a broken protein it doesn't give any pigment to the eye and when your eyes receive no pigment surprisingly they look blue and if you're wondering why why don't they just look transparent why do they look blue if they have no pigment that's a little bit of physics actually it's called a scattering of light it's the same reason why sky which is made of no color looks blue okay but anyways here is that some physics anyways so if your eyes is you know pigments it'll look blue now think about this your dad's gene is gonna make this protein and your mom's gene is gonna make these proteins both the proteins do get built but because brown color goes to the eye your eye will end up looking brown and so now how do you see that if you just have one of this gene which gives you brown pigment then regardless of what the other is your eyes will end up looking brown that's the reason we say brown is a dominant version of that gene and so this means if you want your eyes to look blue in color then both the version of the genes must be like this they must make broken proteins which do not give you any pigment only then they will look blue but remember I have definitely or simplified things over here okay for example one thing I didn't tell you earlier is that all your instructions are not found on one single strand of DNA in fact in humans it turns out that your instructions to build your body is spread out over 23 such different strands and so your cells contain 23 DNA strands from your dad 23 from your mom giving your total 46 DNA strands or you can also say you will have 46 chromosomes different animals can have different numbers okay secondly I've drawn these threads to be pretty short over here but in reality if you take this entire DNA strand and lay them out it turns out it can be about 2 to 3 meters long containing about 20 to 25,000 genes so yeah they are highly coiled up inside our cells another thing is in most cases a single gene is not responsible for how any part of you looks for example when it comes to eye color it's decided by about 16 genes which are spread over different different chromosomes or different different DNA strands so yeah things are really pretty complicated but at least it gives us some sense of why we assemble our parents now right because the instruction manual the DNA to build our body directly is a copy of our parents DNA but then why don't we look exactly like any of our parents well that's because we have two set of them so some part of our body is built from the instructions of dad's genes dominant ones and some other parts of our body are built from the instructions of our mom's a dominant genes and so it's this combo that makes us resemble our parents but not exactly like them we are unique so we can thank sexual reproduction for this uniqueness I mean think about it in asexual reproduction there is only one parent and so the kid will just get one copy of this DNA so the kid will look exactly like his parent so sexual reproduction makes us unique all right so that's pretty much it okay so let's see if we can summarize and recall what we learned so here are some questions for you can you recall what a DNA is and where is it found exactly inside a cell what are chromosomes how many chromosomes do human cells have what are genes and finally what is the main advantage of sexual reproduction over asexual reproduction if you have difficulty in answering any of these don't worry just go back and revisit the video