DNA: the blueprint of life

Where do you get your DNA? DNA is passed from parent to offspring. Where do we find DNA? DNA is in the nucleus of every cell. DNA makes up our chromosomes. Humans have 46 (23 pairs).

What is DNA? DNA is the genetic code. DNA is called the “blueprint” for living things. What does the code “code for”? DNA codes for the building of PROTEINS. DNA Protein Traits Gene – enough DNA to make 1 protein

Important Note All cells carry out protein synthesis, each making their own proteins. Each organism makes its own specific proteins, those proteins make an organism different from other organisms.

The “NA” in DNA stands for ? Nucleic Acid Deoxyribonucleic Acid D N A

What is a nucleic acid? What is a nucleotide? Nucleic acids are made of nucleotides. Nucleic acids are polymers made up of chains of many nucleotides. What is a nucleotide? A three part unit composed of: a sugar a phosphate a base

Nucleic acids are named for the type of sugar that they contain Nucleic acids are named for the type of sugar that they contain. DNA – Deoxyribose sugar RNA (which we will discuss later) – Ribose sugar

DNA’s shape? A double helix It looks like a twisted ladder or spiral staircase ** The structure of DNA was discovered by James Watson and Francis Crick

If DNA is compared to a twisted ladder, the sides of the ladder are . . . sugars and phosphates The rungs (or steps) are . . . the bases There are 4 bases . . .

4 Base Nucleotides Thymine – T Adenine - A Guanine - G Cytosine - C

Each base can only pair with one other base Thymine – T Adenine - A Guanine - G Cytosine - C

*** The order of these bases codes for different proteins / traits. The base pairing is: C A T G Why? Bases will always pair this way because: Size (number of rings) Number of bonds *** The order of these bases codes for different proteins / traits.

Classes of Bases Bases are grouped into 2 categories based on their size and shape. 2 categories are: 1) Purines Adenine & Guanine Saying to remember this: Purines Are Good 2) Pyrimidines Cytosine & Thymine (and Uracil for RNA) Purines (A & G) bind to Pyrimidines (C & T)