Question

Journey From DNA to Protein Tutorial
Creator of Tutorial: Somy

Answer 1

There are 2 main steps
-Transcription – DNA → mRNA
-Translation – mRNA → Polypeptide/Protein

But, beforehand, the structure of DNA and RNA must be understood.

What is DNA made of?
DNA is a polymer consisting of nucleotide monomer units joined together
Nucleotide consists of:
- Phosphate backbone
- \(\sf \color{green}{Deoxyribose ~sugar }\)
- Nitrogenous bases
• Adenine
• \(\sf \color{red}{Thymine}\)
• Guanine
• Cytosine

What is mRNA made of?
mRNA is a polymer consisting of nucleotide monomer units joined together just like of DNA, BUT:
Nucleotide consists of:
- Phosphate backbone
- \(\sf \color{green}{Ribose ~sugar }\)
- Nitrogenous bases
• Adenine
• \(\sf \color {red}{Uracil}\)
• Guanine
• Cytosine

***Notice the difference
DNA has Deoxyribose sugar: deoxy- means oxygen is missing in this ribose sugar
You can see it here:

Answer 2

Another difference is Thymine & Uracil
While DNA has Thymine as one its nitrogenous bases,
mRNA has this nitrogenous base replaced by Uracil

These two, are main differences to distinguish between DNA and mRNA
BUT there are yet more differences coming up!

Answer 3

*view http://prntscr.com/dff05j if you are having troubles reading the text*

Answer 4

So next up these nucleotides join together by \(\sf \color{blue}{Phosphodiester~ bond}\) between OH of sugar of one nucleotide and phosphate backbone of another nucleotide

DNA

*view http://prnt.sc/dff0j0 if you are having troubles reading the text*

RNA
http://image.prntscr.com/image/f88a41dc25ff401cb836610475e6ad9b.png
*view http://prnt.sc/dff164 if you are having troubles reading the text*

Answer 5

And finally a long polynucleotide strand is formed

*view http://prnt.sc/dff2p2 if you are having troubles reading the text*

Answer 6

As you can see in the picture
\(\sf \color{purple}{RNA}\) is \(\sf \color{purple}{single~ helix}\)
while \(\sf \color{orange}{DNA}\) is \(\sf \color{orange}{double~ helix}\)

Answer 7

This is yet another difference
*** Please note that this explanation is of basic highschool level, & RNA also has a double helix but it is parallel helix. You can search for more details to get a better idea.

Answer 8

So moving on to DNA double helix
Take a close look at it and you will see that the strands are \(\sf \color{brown}{antiparallel}\) meaning one strand is in 3 to 5 prime direction while the other is in 5 to 3 prime direction

*view http://prnt.sc/dff3gw if you are having troubles redding the text*

Answer 9

This is yet another difference as you can see

Answer 10

Next
there is Hydrogen bonds between the nitrogenous bases of the two strands
Before we go on with Hydrogen bonds
Lets talk about word that you might have already heard of
' \(\sf \color{deeppink}{Complementary}\) '
Yes, nitrogenous bases are complementary to each other
\(\sf \color{lightsalmon}{Adenine}\) always pairs with \(\sf \color{pink}{Thymine}\)
\(\sf \color{palegreen}{Guanine}\) always pairs with \(\sf \color{seagreen}{Cytosine}\)

Single letter code
Adenine = A
Thymine = T
Guanine = G
Cytosine = C

now Here is where hydrogen bonds are forming
\(\sf \color{red}{2}\) hydrogen bonds between A and T
\(\sf \color{red}{3}\) hydrogen bonds between G and C

Answer 11

So
if we see \(\sf \color{red}{A}\) on one strand of DNA, its complementary base pair on antiparallel strand would be \(\sf \color{red}{T}\)
if we see \(\sf \color{red}{T}\) on one strand of DNA, its complementary base pair on antiparallel strand would be \(\sf \color{red}{A}\)
if we see \(\sf \color{red}{G}\) on one strand of DNA, its complementary base pair on antiparallel strand would be \(\sf \color{red}{C}\)
if we see \(\sf \color{red}{C}\) on one strand of DNA, its complementary base pair on antiparallel strand would be \(\sf \color{red}{G}\)