DNA RNA Protein Synthesis Chapter 9 & 10 DNA RNA Protein Synthesis

DNA DNA- deoxyribo nucleic acid Structure of DNA: DNA is a genetic molecule that contains all of the instructions to create an organism Structure of DNA: Double helix “spiral ladder” Discovered by James Watson & Francis Crick

Nucleotides Nucleotides are the basic subunits that make up DNA Nucleotides consist of 3 molecules: a phosphate group, a sugar(ribose), and a nitrogen base Diagram: 5-carbon Sugar

DNA Bases There are 4 different DNA Bases: A: Adenine T: Thymine C: Cytosine G: Guanine

DNA Base Pairs DNA bases always pair in the same way A : T - adenine pairs with thymine C : G - cytosine pairs with guanine

DNA Strand: A T - fill in the corresponding DNA bases G C T Remember: C:G

DNA Replication DNA replication is the process of copying DNA It occurs during S-phase of the cell cycle Makes 2 exact copies of a cells DNA

Steps in DNA Replication The two original DNA strands separate - the DNA-helicase enzyme separates the two DNA strands Diagram: DNA strand Helicase Enzyme

Steps in DNA Replication 2) DNA-polymerase enzyme forms two new DNA strands to match the original strand Diagram: Replication Fork! new DNA! original DNA strand new DNA!

Steps in DNA Replication 3) Two DNA molecules are formed that are identical to the original DNA molecule!!!!!! Diagram:

DNA Mutations Any change in the genetic code of an organism is a mutation Mutations may have a small, large, or no effect on an organism Mutagens: - substances that can cause mutations Ex: toxic chemicals, UV radiation, nuclear radiation, extreme heat

DNA Mutations Deletion- 1 nuclotide is left out during replication Insertion- 1 nucleotide is added during replication Point Mutation- 1 nucleotide is substituted with another during replication

Chromosome Mutations Deletion- removal of a segment of a chromosome Duplication- addition of a repeated DNA segment

Chromosome Mutations Inversion- reordering of genes on a chromosome Displacement- attachment of DNA to a different chromosome

RNA RNA – ribo nucleic acid 3 Types of RNA: rRNA - ribosomal RNA - used to make ribosomes tRNA - transfer RNA - used to make proteins mRNA - messenger RNA - used to send messages from the nucleus to the cytoplasm

RNA Bases RNA uses Uracil(U) instead of Thymine(T) RNA Base Pairs: A : U C : G AGU CAU GUG CAC UUA CAG AUC GCA

Transcription Transcription is used to make mRNA Steps: 1) DNA-Transcriptase “unzips” DNA The two DNA strands unwind & separate 2) RNA-polymerase enzyme binds to DNA 3) mRNA is made by RNA-polymerase based on the genetic code of the DNA

Transcription Diagram

mRNA Composition mRNA has distinct segments called introns and exons Introns- segments of RNA that do not code for proteins Exons- sequences that do code for proteins

Reading the Genetic Code Codons: a series of 3 nucleotides that code for an amino-acid - each codon is used to create an amino-acid

RNA Codons Codon A U G C

Translation Translation forms proteins from RNA Steps: 1) Ribosomes bind to mRNA in cytoplasm 2) tRNA carrying amino-acids attaches to the mRNA 3) Amino-acids from the tRNA begin to form a chain(polypeptide) 4) When the ribosome reaches the end of the mRNA it detaches 5) The polypeptide chain is complete, forming a protein

Translation Diagram

Overview of Protein Synthesis DNA mRNA Protein Transcription Translation

Genetic Engineering Genetic engineering is used to create organisms with specially designed genes & traits Recombinant DNA- pieces of DNA combined from 2 different organisms

Gene Splicing

Uses of Recombinant DNA Insulin- make bacteria produce insulin for human use to treat diabetes Resistance- can put recombinant DNA into plants to make them resist diseases Vaccines- can use recombinant DNA in animals to produce immunity to diseases

Cloning Cloning is the production of organisms with identical genes

END OF CHAPTER 9&10 NOTES!!!