Deoxyribonucleic Acid ( DNA )

The heredity molecule controlling the

activities on the cell.

The DNA Line-up

What’s So Special About DNA?

DNA is one of the most boring macromolecules imaginable - its made of only four building blocks and has a perfectly monotonous structure.

Worse yet, DNA just sits there - it doesn’t catalyze reactions or build the cell or organism.

So, what’s so good about DNA?

The answer lies in DNA’s ability to store and copy information.

Structure

• The double helix structure of DNA was first described in 1953 by James Watson & Francis Crick.

• This was marked one of the most significant discovers of the twentieth century.

Winners of the Race to Learn DNA’s Structure – Watson and Crick 50 Years Ago

NucliotideThe building block of the DNA ladder

• Composed of:• Phosphate

• Deoxyribose sugar

• Nitrogen base

Building DNA Building Blocks

There are Four kinds of Nitrogen Bases

• Purines Pyrimidines• Adenine-----------------Thymine• Guanine-----------------Cytosine

• (Hydrogen bonds)• A always pairs with T• G always pairs with C

• Made of Two Rings Made of One Ring

Matching DNA Nitrogen Bases

G

Matching DNA Nitrogen Bases

A AC TT C G AAT CC CC C

G

G GG TT A

Matching DNA Nitrogen Bases

A AC TT C G AA

AA TTT T

T CC CC C

G GG GGGG

G GG TT

C C CA A A

A

GC T

Key words of DNA shape

• Double stranded ladder shape sides of sugar and phosphate rings of bases coil into (double helix)

Replication

Making an exact copy of a DNA molecule (self doubling)

DNA Replication

DNA perfectly illustrates the relationship between structure and function.

Simple As It Is in Principle, DNA Replication Requires Many Enzymes That Work Coordinately

First and foremost are the DNA polymerases

Protein Synthesis• The Process of making proteins

• Transcription – The process of copying the DNA pattern into messenger RNA

• Messenger RNA – Brings coded information from DNA to the ribosomes

• Ribosomes – The protein factories in the cell

Protein Synthesis

• Translation – The process of changing the information of messenger RNA into proteins

• Transfer RNA – The TNA that carries the amino acids to the ribosomes and pairs them with mRNA

• Codon – Combination of 3 bases on mRNA that determines the order of amino acids

RNA Differences

• Ribose sugar

• Uricil instead of Thymine

• Single stranded helix

• mRNA, tRNA, rRNA

• Found in nucleus and in the cytoplasm

• Smaller in size

ACGTGTGAGTCGTAGCTGGTA

and label the codon with its appropriate Amino Acid.

Transcribe the following strand of DNA to a strand of mRNA:

How Do Genes Work?

The answer is the purview of molecular genetics.