 The central concept in biology is:  DNA determines what protein is made  RNA takes instructions from DNA  RNA programs the production of protein synthesis  Proteins determine the phenotype of the organism

 Proteins are made into two main stages  Transcription- the transfer on genetic info from DNA to RNA molecule  Translation- transfer of info in the RNA into a protein

 What is a protein?  What protein have you eaten today and/or yesterday?  What role do proteins play in your bodily functions?

mRNA Codon Chart

 Genes are located on molecules of DNA  The language of DNA is the order (sequence) of nucleotides  Ex: AAGCTT  The order of the nucleotides determine which genes are made Transcription & Translation of codons

 DNA’s instructions are based on 3 nucleotides (triplet code)  The 3 nucleotide sequence (codon) are the genetic instructions from DNA to make amino acids; which together make polypeptide chains (proteins)

 Each codon specifies for an amino acid

A close-up view of transcription

 During transcription: 1. RNA polymerase (an enzyme)binds to DNA on the promoter region & separates the DNA strands.

 Promoter- Region of DNA (a codon) that allows transcription to begin  Terminator- Region of DNA that signals the end of a gene & transcription stops.

There are 3 main types of RNA: Messenger RNA (mRNA)– carry copies instructions from genes for putting together amino acids into proteins. Carry “messages” from DNA to the rest of the cell. 

Ribosomal RNA (rRNA)- makes up a major part of the ribosome (proteins are put together here) True shape of a functioning ribosome

Transfer RNA (tRNA)- transfers each amino acid to the ribosome as it is specified by coded messages in mRNA.

When RNA molecules are formed, introns and exons are copied from DNA. Introns- DNA sequences of nucleotides that do not code for a protein Exons- sequences that does code for a protein The introns are cut out of RNA molecules. The exons are then spliced together to form mRNA.

Takes place on the ribosomes Translation- the decoding of an mRNA message into a polypeptide chain (protein) 1. Translation begins when an mRNA molecule attaches to a ribosome. 2. As each codon of the mRNA molecule moves through the ribosome, the proper amino acid is brought into the ribosome by tRNA. 3. In the ribosome, the amino acid is transferred to the growing polypeptide chain.

In the process anticodons are formed Anticodon- 3 unpaired bases of tRNA that are complementary to mRNA

 Are made of rRNA  Have a binding site for mRNA and three binding sites for tRNA molecules  The P site holds the tRNA carrying the growing polypeptide chain  The A site carries the tRNA with the next amino acid  tRNAs leave the ribosome at the E site

1) Initiation brings together mRNA, with tRNA Special initiator tRNA carries and attaches to the start codon

2) Elongation adds amino acids according to the mRNA codons  Peptide bond formation b/w a.a’s  During translocation, the ribosome moves the tRNA with the attached polypeptide from the A site to the P site  Elongation continues codon by codon to add amino acids until the polypeptide chain is completed

3) Termination occurs when one of the three stop codons reaches the A site

 Errors can occur during DNA replication, DNA repair, or DNA recombination  These can lead to base-pair substitutions, insertions, or deletions  Can lead to frame shifts, which move the reading frame over slightly and change the primary structure of the polypeptide

 Are chemical or physical agents that interact with DNA to cause mutations  Physical agents include high-energy radiation like X-rays and ultraviolet light  Chemical agents include carcinogens cause cancer