DNA replication, transcription, & translation How you go from DNA to proteins
Watson & Crick double helix In 1953, Watson & Crick discovered the structure of DNA- the… double helix
Remember DNA is in the nucleus of cells Chromosomes are made up of DNA Where is DNA? DNA is in the nucleus of cells What is made up of DNA? Chromosomes are made up of DNA
Remember as well… Before a cell divides (mitosis) it has to do what? Copy its DNA, (and grow)
DNA replication An enzyme unzips (or takes apart) the double helix Each strand acts as a template for the new strand A T C G get added to the growing strand An enzyme “proofreads” or double checks the new DNA to make sure there are no mistakes
Watch DNA replication http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf http://www.hhmi.org/biointeractive/media/DNAi_replication_vo1-lg.mov
DNA contains genes Genes are parts of the DNA that code for traits But how do we get from DNA to traits that we see?
First DNA is used to make RNA This process is called transcription RNA replaces T with U! This type of RNA= messenger RNA, or mRNA
Watch transcription http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a2.html Transcription
Review: Transcription Enzyme unzips DNA RNA polymerase starts transcription RNA bases are matched to one strand of DNA RNA strand is released
DNA is a double helix, RNA is not!
PRACTICE! Write the DNA strand: A C G G C T T A C T G G C A T T Now you figure out the RNA strand. Answer: U G C C G A A U G A C C G U A A
Messenger RNA mRNA carries the message of your genetic code It leaves the nucleus and goes into the cytoplasm where there are ribosomes
Serine-Histidine-Glycine Genetic Code Now you have mRNA carrying the genetic code You read the sequence of letters 3 bases at a time: UCG-CAC-GGU The 3 letter codes are called codons and stand for an amino acid: UCG-CAC-GGU There are 20 amino acids that make up ALL the proteins in your body! Serine-Histidine-Glycine
PRACTICE: 1. GCU 2. AAA 3. CGA 4. UUC
From RNA to protein This process is called Translation mRNA attaches to ribosome – rRNA found in ribosome acts as translator tRNA anticodons match up with mRNA codons and carry the amino acid The amino acids bond together to form a protein
Watch translation..TWICE! http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a3.html
REVIEW! DNA replication gives us: 2 copies of DNA Transcription gives us: mRNA Translation gives us: amino acid chain (protein!) Proteins give us traits!