From Nucleotide Sequence to Amino Acid Sequence The

From Nucleotide Sequence to Amino Acid Sequence • The language of nucleic acids will be translated into the language of amino acids

• What is the language of nucleic acids? DNA molecule Gene 1 Gene 2 Gene 3 DNA strand Transcription RNA Translation Codon Polypeptide Amino acid

• When DNA is transcribed the result is an RNA molecule • RNA is then translated into a sequence of amino acids in a polypeptide • Triplets of bases – are called codons and they specify all the amino acids

The Genetic Code – our translating dictionary • The genetic code is the set of rules translating nucleotide sequence to amino acid sequence

• The genetic code is shared by all organisms

Transcription: From DNA to RNA • In transcription – genetic information is copied from DNA to RNA – RNA molecule is transcribed from a DNA template

RNA nucleotides RNA polymerase Newly made RNA (a) A close-up view of transcription Direction of transcription Template strand of DNA

Three Phases of Transcription • The “start transcribing” signal is a nucleotide sequence called a promoter • The first phase of transcription is Initiation • The second phase of transcription is Elongation • The third phase of transcription is Termination

Translation: The Players • Translation – conversion from the nucleic acid language to the protein language

Messenger RNA (m. RNA) • m. RNA – message sent from the DNA in the nucleus out into the cytoplasm, to the ribosomes

Transfer RNA (t. RNA) • t. RNA – carries amino acids – matches codons with anticodons Amino acid attachment site Hydrogen bond RNA polynucleotide chain Anticodon

Ribosomes • Ribosomes – organelles that make proteins – made of two protein subunits t. RNA binding sites Large subunit m. RNA binding site Small subunit (a) P site P A site A

Translation: The Process • Translation is divided into three phases – Initiation – Elongation – Termination

• A fully assembled ribosome holds t. RNA and m. RNA for use in translation Next amino acid to be added to polypeptide Growing polypeptide t. RNA m. RNA

Review: DNA RNA Protein • The flow of genetic information in a cell

CHAPTER 11 – DNA TECHNOLOGY • The DNA of two people of the same sex is over 99% identical • Animals, plants, and bacteria can be genetically modified to produce human proteins

BIOLOGY AND SOCIETY: HUNTING FOR GENES • DNA technology has created many advances – Genetically Modified (GM) food – DNA fingerprinting – Human Genome Project

RECOMBINANT DNA TECHNOLOGY • Recombinant DNA is combining genes from different sources; GM organism

From Medicine to Food • Put a gene into a bacterium and its proteins can be produced in large quantities

Making Humulin • Humulin, 1982

• DNA technology develops vaccines – a vaccine is a harmless version of a pathogen

Genetically Modified (GM) Foods • DNA technology replaces plant-breeding programs – half of American crops of soybeans and corn are GM

• GM corn; insects

• “Golden rice” has been genetically modified to contain beta-carotene; Vitamin A

“Pharm” Animals • GM animals are less common; sheep with a human blood protein for cystic fibrosis

Recombinant DNA Techniques • Bacteria are the workhorses • Biologists use bacterial plasmids – small, circular DNA molecules

• Plasmids easily incorporate foreign DNA – they act as vectors, carriers that move genes

Cell containing gene of interest Host cell 1 DNA Recombinant DNA (host DNA plus gene of interest) 2 Gene of interest Cell multiplies and produces protein 3 Genes may be inserted into another organism Protein may be harvested OR Gene for pest resistance inserted into plants Protein dissolves blood clots in heart attack therapy