1. DNA, RNA & Genetics Notes
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DNA, RNA & Genetics Notes

2. DNA The basic substance of heredity
DNA is short for Deoxyribonucleic Acid
The basic substance of heredity
DNA organized into chromosomes which
are found in the nucleus of cells
Stores and passes on genetic information
from one generation to the next.

3. DNA’s Structure Discovered by Watson and Crick in 1953
Finding the structure of DNA allowed
scientists to crack the genetic code.

4. Double Helix structure which looks like a
twisted ladder
The sides are sugar molecules and
phosphate groups.
The steps or rungs are nitrogen bases
There are 100s to
1000s of steps or
rungs per DNA chain.

5. 4 Nitrogen Bases Adenine – A Cytosine – C Guanine – G Thymine – T
Arranged in base pairs.
Chargraff’s Rule tells us…
Adenine must always pair with Thymine
Guanine must always pair with Cytosine

6. Proteins The main function of chromosomes is to
control the production of proteins.
Proteins help to determine the size, shape,
color and many other traits of an organism.
Proteins are made of amino acids
Each set of 3 DNA base codes code for a
certain amino acid.
This 3 letter code is called a codon
There are 64 codons; 61 that code for amino
acids and 3 stop codons.
Proteins are produced on ribosomes in the
cytoplasm of cells.

7. So how does the DNA inside the nucleus get its genetic information to the ribosomes in the cytoplasm?

8. RNA RNA is short for Ribonucleic Acid RNA is made of Adenine,
Guanine, Cytosine and Uracil
RNA has only one strand
Messenger RNA (mRNA) copies the message from the DNA in the nucleus and carries it to the ribosomes in the cytoplasm.
transfer RNA (tRNA) reads the genetic code from the mRNA and makes protein chains.

9. DNA Facts and Information
There are ≈ 3.4 billion base pairs in the human genome.
There are 20,000 to 25,000 genes in the human genome.
The diameter of a human DNA strand is ≈2nm. It would take 12,500 DNA strands to approximate the size of a human hair.
The length of human DNA (all 46 chromosomes) stretched end-to-end is 6 feet.
The length of all the DNA in the body would be over 113 billion miles (or the distance to the sun and back 610 times)
Humans are 99.8% genetically identical – the remaining 0.2% accounts for the variation seen in the human population.