🧬 DNA and Protein Synthesis (Edexcel)


DNA structure

What are the strands made of?

DNA replication

The genetic code

mRNA

mRNA / DNA

tRNA (Transfer RNA)

Protein synthesis

Transcription

Splicing

Translation

Cause of Mutations

The Effects of Mutations


Β 

DNA structure

DNA (deoxyribonucleic acid) is a large molecule which carries the genetic information, or blueprint, of all life on Earth. Mutations arising in the DNA code account for the diversity upon which evolution by natural selection can work. Therefore, it is not far-fetched to say that DNA is one of the central, most important molecules in living organisms.

For such an important molecule, it sure looks beautiful:

Β 

What are the strands made of?

The strands are made of repeating units consisting of a deoxyribose (sugar) molecule with a phosphate molecule attached to it; hence, it is called a sugar-phosphate backbone.

DNA is a double helix i.e. two individual strands running along each other in an anti-parallel way, connected to one another by relatively weak hydrogen bonds. DNA’s structure can be learned easily by thinking about the strands and the β€œstuff in-between” separately.

Phosphodiester bonds between nucleotides (above) create the backbone:

What is the centre made of?

Attached to the sugar molecules in the backbone are a different type of molecule called nitrogenous base. There are 4 bases in DNA: adenine, thymine, cytosine and guanine. These are abbreviated by their initials: A, T, C and G….