* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download U - West Windsor-Plainsboro Regional School District
Community fingerprinting wikipedia , lookup
Protein adsorption wikipedia , lookup
Bottromycin wikipedia , lookup
List of types of proteins wikipedia , lookup
Cre-Lox recombination wikipedia , lookup
RNA interference wikipedia , lookup
Promoter (genetics) wikipedia , lookup
RNA silencing wikipedia , lookup
Non-coding DNA wikipedia , lookup
Polyadenylation wikipedia , lookup
Molecular evolution wikipedia , lookup
RNA polymerase II holoenzyme wikipedia , lookup
Biochemistry wikipedia , lookup
Eukaryotic transcription wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Silencer (genetics) wikipedia , lookup
Point mutation wikipedia , lookup
Transcriptional regulation wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Messenger RNA wikipedia , lookup
Non-coding RNA wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Expanded genetic code wikipedia , lookup
Gene expression wikipedia , lookup
Chapter 11.4 – 11. 6 Gene Action and Expression Central Dogma DNA is the genetic material within the nucleus. Replication The process of replication creates new copies of DNA. The process of transcription creates an RNA using DNA information. DNA Transcription RNA Nucleus The process of translation creates a protein using RNA information. Translation Protein Cytoplasm Two types of nucleic acids # of strands kind of sugar bases used Two types of nucleic acids • RNA • Usually single-stranded • Has uracil as a base • Ribose as the sugar • Carries protein-encoding information • Can be catalytic • DNA • Usually double-stranded • Has thymine as a base • Deoxyribose as the sugar • Carries RNA-encoding information • Not catalytic Types of RNA function mRNA Messenger RNA carries DNA’s info to ribosomes rRNA Ribosomal RNA part of ribosome, used to translate mRNA into protein tRNA Transfer RNA brings amino acid to ribosome rRNA is part of ribosome, used to translate mRNA into protein tRNA is a connection between anticodon and amino acid The genetic code The genetic code • 3 RNA nucleotides for every one amino acid • The three nucleotides used to encode one amino acid are called a codon. • The genetic code refers to which codons encode which amino acids. The genetic code is nonoverlapping The genetic code is universal • All known organisms use the same genetic code. • (Rare organisms use one codon for an additional amino acid.) The genetic code is degenerate Some codons encode the same amino acid. e.g. GGU, GGC, GGA, and GGG all encode glycine Degeneracy is mostly at the third base of the codon. Some codons have additional functions AUG encodes methionine. Methionine can be used within a protein sequence and is often the first amino acid cueing the beginning of translation. UAA, UAG, and UGA do not encode an amino acid These codons signal termination of the protein. Transcription • Occurs in three steps: Initiation RNA Polymerase finds the Promotor site on DNA and begins transcription Elongation RNA polymerase adds nucleotides to growing RNA. Termination Sequences in the DNA prompt the RNA polymerase to fall off ending the transcript. Transcription • Only one DNA strand is used as a template for making RNA • Ribonucleotides make H bonds using complementary DNA base pair rules. 5’ • A pairs with U G T C A T T C G G • G pairs with C 3’• Enzyme RNA polymerase. 3’ C A G T A A G C C 5’ Transcription DNA coding strand 5’ DNA G T C A T T C G G 3’ 3’ C A G T A A G C C DNA template strand 5’ Transcription • The new RNA molecule is formed by incorporating • nucleotides that are complementary to the template • strand. DNA coding strand 5’ 3’ DNA G T C A T T C G G 3’ G U C A U U C G G 3’ C A G T A A G C C 5’ DNA template strand 5’ RNA RNA processing • mRNA transcripts are modified before use as a • template for translation: •Addition of capping nucleotide at the 5’ end •Addition of polyA tail to 3’ end Important for moving transcript out of nucleus And for regulating when translation occurs •Splicing occurs removing internal sequences introns are sequences removed exons are sequences remaining RNA processing • RNA Processing • tRNA • Folds to the clover shape • Activates by attaching to a specific amino acid on the attachment site • rRNA • Joins with proteins to make a large subunit and a small subunit • Both subunits will join to make the working “unit” of ribosome Gene Expression • Together transcription and translation are called gene expression. • The genetic information encoded in the DNA of an embryo includes all of the genes needed to develop and maintain the organism. • Different cell types express different subsets of genes. • Differential gene expression during development establishes the role of a cell within the body. • Translation The process of reading the RNA sequence of an mRNA and creating the amino acid sequence of a protein is called translation. DNA template DNA Transcription T T C A G T C A G A A G U C A G U C strand Messenger RNA mRNA Codon Codon Codon Translation Protein Lysine Serine Valine Polypeptide (amino acid sequence) Translation is composed of three steps • Initiation translation begins at start codon (AUG=methionine) Elongation the ribosome uses the tRNA anticodon to match codons to amino acids and adds those amino acids to the growing peptide chain Termination translation ends at the stop codon UAA, UAG or UGA Initiation Leader sequence Small ribosomal subunit 5’ 3’ mRNA mRNA U U C G U C A U G G G A U G U A A G C G A A U A C Assembling to begin translation Initiator tRNA Met Translation Elongation Ribosome 5’ 3’ mRNA A U G G G A U G U A A G C G A U A C C C U tRNA Amino acid Met Gly Large ribosomal subunit Translation Elongation 5’ 3’ mRNA A U G G G A U G U A A G C G A U A C C C U Met Gly Translation Elongation 5’ 3’ mRNA A U G G G A U G U A A G C G A C C U A C A Gly Cys Translation Elongation 5’ 3’ mRNA A U G G G A U G U A A G C G A C C U A C A Gly Cys Translation Elongation 5’ 3’ mRNA A U G G G A U G U A A G C G A A C A U U C Cys Lengthening polypeptide (amino acid chain) Lys Translation Elongation 5’ 3’ mRNA A U G G G A U G U A A G C G A A C A U U C Cys Lys Translation Elongation 5’ 3’ mRNA A U G G G A U G U A A G C G A A C A U U C Cys Lys Translation Elongation Stop codon 5’ mRNA A U G G G A U G U A A G C G A U A A U U C Lys Release factor Translation Termination Stop codon Ribosome reaches stop codon 5’ mRNA A U G G G A U G U A A G C G A U A A Release factor Translation Termination Once stop codon is reached, elements disassemble. Release factor Translation: multiple copies of a protein are made simultaneously Levels of protein structure Primary structure sequence of amino acids Secondary structure shapes formed with regions of the protein (helices, coil, sheets) Tertiary structure shape of entire folded protein due to interactions between particular peptides Quaternary structure structures formed by interaction of several proteins together e.g. Functional hemoglobin is two alpha-hemoglobin proteins and two beta-hemoglobin proteins form a heterotetramer Levels of protein structure Human Genome • 3.2 million DNA base pairs • 1.5% encode proteins < = > 98.5% not protein encoding • ~ 31,000 genes encoding 100,000 - 200,000 proteins • How are 100,000 to 200,000 proteins produced from 31,000 genes?