The DNA Connection

Chromosomes are made of DNA

The DNA Code

Each chromosome contains thousands of genes.

The sequence of bases in a gene forms a code

Every 3 Letters is called a CODON

Code = protein

DNA carries the codes

DNA

Deoxyribonucleic Acid (DNA)

Double Stranded

DNA BasesPurines:1. Adenine (A)2. Guanine (G)

Pyridimines1. Cytosine (C)2. Thymine (T)

DNA Base Pairing A=T

G C

RNA Base Pairing A=U *Uracil There is NO “T” in RNA

G C

Transcription

The process by which RNA is made from DNA

Occurs in the Nucleus

Since DNA is too big to fit through the nuclear pores, messenger RNA is used to “read” DNA

RNASingle StrandedSame bases as DNA EXCEPT instead of T RNA contains U

After transcription mRNA leaves the nucleus and attaches onto a ribosome

Translation

The message is translated into an amino acid sequence

Occurs on ribosomes

Every 3 Letters is called a CODON

Code = protein

Requires tRNA to translate the code

tRNA can only read 3 mRNA codes at one time (codon)

The Genetic Code

The Codon codes for which amino acid is to be made

Amino Acids – the building blocks of proteins

mRNA codonUACTranslated Code

Tyr

DNA Sequence:A T G C A A T G C

U A C G U U A C G

RNA Sequence:UAC GUU ACGAmino Acids Produced:Tyr – Val – Thr

DNA Mutations

Substitution

Deletion

Addition