Transcription Using DNA to make RNA

Transcription An enzyme called RNA polymerase finds the beginning of a gene RNA Polymerase DNA Molecule Gene

Transcription RNA polymerase moves down the gene and… Unwinds the DNA molecule into 2 temporarily separated strands “Reads” one of the strands of DNA and pairs free floating nucleotides to it forming a new single strand of mRNA Direction of Movement New single strand of mRNA

Transcription RNA polymerase reaches end of gene RNA polymerase detaches New strand of RNA detaches from DNA template RNA Polymerase DNA Molecule Completed new strand of mRNA

Practice: If RNA polymerase were to find a gene, move down the gene unwinding the double stranded DNA, read the template strands to be this: A G G C T A T T G C A what would the sequence of the new strand of RNA be?

Practice: If RNA polymerase were to find a gene, move down the gene unwinding the double stranded DNA, read the template strands to be this: A G G C T A T T G C A what would the sequence of the new strand of RNA be? U C C G A U A A C G U

Using RNA to make Protein Translation Using RNA to make Protein

Kinds of RNA Before we talk about translation, you should know: There are 3 types of RNA involved in the process of making protein mRNA: messenger RNA carries the message of how to make a protein (this is the one we talked about in transcription!) tRNA: transfer RNA transfers amino acids to the ribosome during translation rRNA: ribosomal RNA is one small piece making up the ribosome

Kinds of RNA mRNA

Kinds of RNA tRNA Amino Acid Folded RNA Strand Anticodon (complementary to the mRNA codon)

Kinds of RNA rRNA Ribosomal RNA Ribosome

The Genetic Code On the mRNA molecule, bases are read 3 at a time A group of 3 bases in a row is called a codon There are 64 possible different codons that code for the 20 different amino acids codon for methionine (Met) leucine (Leu)

The Genetic Code How do you know which codons code for which amino acids? Use the sheet I will pass out now!!!

The Genetic Code AUG is the start codon UAA, UAG, UGA are stop codons This is where translation will begin UAA, UAG, UGA are stop codons This is where translation will end

Practice translating codons: Codon=3 nucleotides that are read together If this is the strand of mRNA: UCGCACGGU The codons are:

Practice translating codons: Codon=3 nucleotides that are read together If this is the strand of mRNA: UCGCACGGU The codons are: UCG-CAC-GGU

Practice translating codons: Codon=3 nucleotides that are read together If this is the strand of mRNA: UCGCACGGU The codons are: UCG-CAC-GGU How many codons are there?

Practice translating codons: Codon=3 nucleotides that are read together If this is the strand of mRNA: UCGCACGGU The codons are: UCG-CAC-GGU How many codons are there? 3

Practice translating codons: Codon=3 nucleotides that are read together If this is the strand of mRNA: UCGCACGGU The codons are: UCG-CAC-GGU How many codons are there? 3 What amino acids are coded for?

Practice translating codons: Codon=3 nucleotides that are read together If this is the strand of mRNA: UCGCACGGU The codons are: UCG-CAC-GGU How many codons are there? 3 What amino acids are coded for? Serine, Histadine, Glycine

The Process mRNA molecule leaves nucleus and binds with ribosome Beginning at the start codon, ribosome binds tRNA molecules with mRNA molecules according to correct codon—anticodon pairing So for example, if the codon GAC is on the mRNA molecule, a tRNA molecule with the anticodon CUG will bind to it The tRNA molecule brings its amino acid, which the ribsosome will bind to other amino acids being brought in to make a polypeptide chain (protein)