Transcription and Translation DNA and RNA Protein Synthesis Transcription and Translation

Comparing Nucleic Acids DNA RNA Double strand Thymine Deoxyribose Sugar In eukaryotes, inside nucleus Single strand Uracil Ribose Sugar Can travel in and out of the nucleus through nuclear pores

Three types of RNA mRNA rRNA tRNA Messenger RNA Created based on a gene on DNA rRNA Ribosomal RNA Reads mRNA and assembles materials needed to build proteins tRNA Transfer RNA “Taxi” Bring materials (amino acids) to the ribosome

Review:Chapter 12 When the cell is ready to divide! What is DNA replication? Copying the DNA in a cell! When would a cell need to replicate its DNA? When the cell is ready to divide! could be for growth, or to repair injury

Transcription and Translation Protein Synthesis Transcription and Translation What are proteins? Proteins are a large molecule important to living things They are made of CHON (carbon, hydrogen, oxygen, nitrogen) They are built from building blocks called “amino acids” How does a cell know how to build proteins? DNA carries all the instructions for a cell Proteins are an organic compound. Proteins contain Nitrogen, which is different from lipids and carbohydrates (which are just carbon and hydrogen). Proteins are built out of amino acids, and in various combinations can produce thousands of different compounds. Proteins can be acidic, basic, some are not charged. This makes them attract or repel in different ways. The interactions of various amino acids gives proteins multiple different functions. Some are structural components, some are enzymes that change the rates of reactions, regulation, chemical reactions, hormones, etc. Instructions are found on DNA, in the nucleus of cells. DNA holds information in the sequence of nucleotides. DNA is found in the nucleus. Proteins are built in the ribosomes. The problem is: how do we get DNA information to the ribosomes, while maintaining the security of the DNA?

Transcription and Translation Protein Synthesis Transcription and Translation What jobs do proteins have? proteins have many critical roles in living things Antibodies: fight off foreign particles (like virus/bacteria) Enzymes: run chemical reactions in cells Hormones: messenger proteins that travel Protein Synthesis is a 2-stage process Proteins are an organic compound. Proteins contain Nitrogen, which is different from lipids and carbohydrates (which are just carbon and hydrogen). Proteins are built out of amino acids, and in various combinations can produce thousands of different compounds. Proteins can be acidic, basic, some are not charged. This makes them attract or repel in different ways. The interactions of various amino acids gives proteins multiple different functions. Some are structural components, some are enzymes that change the rates of reactions, regulation, chemical reactions, hormones, etc. Instructions are found on DNA, in the nucleus of cells. DNA holds information in the sequence of nucleotides. DNA is found in the nucleus. Proteins are built in the ribosomes. The problem is: how do we get DNA information to the ribosomes, while maintaining the security of the DNA? Transcription: make mRNA from DNA gene Translation: read mRNA and build protein

Transcription and Translation Protein Synthesis How does DNA hold information? Information is found in the order of nitrgoen bases in DNA (the order of A,C,T, and G’s) Where is DNA located? Nucleus of a cell (eukaryotes) In which organelle do cells build proteins? Ribosomes Proteins are an organic compound. Proteins contain Nitrogen, which is different from lipids and carbohydrates (which are just carbon and hydrogen). Proteins are built out of amino acids, and in various combinations can produce thousands of different compounds. Proteins can be acidic, basic, some are not charged. This makes them attract or repel in different ways. The interactions of various amino acids gives proteins multiple different functions. Some are structural components, some are enzymes that change the rates of reactions, regulation, chemical reactions, hormones, etc. Instructions are found on DNA, in the nucleus of cells. DNA holds information in the sequence of nucleotides. DNA is found in the nucleus. Proteins are built in the ribosomes. The problem is: how do we get DNA information to the ribosomes, while maintaining the security of the DNA?

Genes Genes What is a GENE? A gene is a segment of DNA that gives instructions to build ONE specific protein. If DNA is a cookbook, each recipe is a gene. Every cell in your body has the whole cookbook, but only uses some recipes. A segment of DNA that controls the production of one specific protein.

Genes Exon: part of DNA sequence expressed Intron: long noncoding sequences

Transcription and Translation Step 1:Transcription Enzymes make an mRNA copy of a portion of DNA Occurs in the nucleus Why can mRNA leave the nucleus, but not DNA? Size of the mRNA is small enough to escape the nuclear pores

Step2:TRANSLATION Ribosomes! Made of r-RNA! Where does mRNA go after transcription? mRNA is read and the tRNA bring amino acids in order to it build proteins! Ribosomes! Made of r-RNA!

Transcription Helicase enzyme unzips the DNA RNA polymerase reads the selected gene and adds the appropriate RNA nucleotides RNA processing: the introns are cut out The mRNA strand breaks away and DNA rejoins. mRNA can now leave the nucleus and head to the ribosome Does it matter which strand the RNA polymerase copies from? ( difficult question, because the other side is the revearse (5-3 or 3-5) so the same letters are there. ALSO, the window is three bases, so your frame can shift)

Transcription - By using a codon of three letters for each There are only ___ nitrogen bases in the “language” of DNA. There are ___ different amino acids that can be used to build a protein. How can 4 bases form a code for all 20 amino acids? - By using a codon of three letters for each

TranSCRIPTion Read in groups of three letters: CODON (DNA gene) (mRNA) AAA GTG GCC ACT UUU CAC CGG UGA

Translation Read in groups of three: ANTI-CODONS (mRNA) (tRNA) t-RNA is the taxi that brings the amino acids to the Ribosome UUU CAC CGG UGA AAA GUG GCC ACU

UUU CAC CGG UGA mRNA: PHE HIST ARG stop Amino acids

Ribosome and tRNA

Review Summarize the steps of Protein Synthesis. Describe the three types of RNA. Relate chromosome, gene, sister chromatids and DNA. Cells replicate DNA so that after cell division (mitosis) each daughter cell has a complete set of instructions, and is identical to the parent cell. DNA is the nucleic acid that carries the instructions for cells to build proteins. It is the blueprint of life. First, a DNA molecule must be unwound. Helicase enzyme will unwind and then break the hydrogen bonds between nitrogen bases.