Compare and Contrast: DNA and RNA Bell Ringer Compare and Contrast: DNA and RNA

Bell Ringer What organelle is responsible for protein synthesis (making proteins)? What types of cells have this organelle? Where in the cell can this organelle be found?

What are the 3 types of RNA? What is the function of each type? Bell Ringer (1) What are the 3 types of RNA? What is the function of each type?

Protein Synthesis: An Overview Day 5 Unit 5 Goal: Students will be able to describe the processes of transcription and translation.

Protein Synthesis Foldable Transcription Translation Where? What molecules are involved? What is produced? Where does it go? What happens? Where? What molecules are involved? What is produced? Where does it go? What happens?

Back of Foldable Amino Acids & Nucleotides Central Dogma Types of RNA Codons Start = Stop =

copyright cmassengale Structure of RNA Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded. copyright cmassengale

Pathway to Making a Protein DNA mRNA tRNA (ribosomes) Protein copyright cmassengale

copyright cmassengale DNA  RNA  Protein Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein Eukaryotic Cell copyright cmassengale

Types of RNA Messenger RNA (mRNA) makes a copy of DNA Transfer RNA (tRNA) decodes mRNA and transfers amino acids to the ribosome Ribosomal RNA (rRNA) build the protein by bonding amino acids together. Ribosomes are made of rRNA.

Protein Synthesis 2 Steps Transcription Translation Protein synthesis uses the information in genes to make proteins. 2 Steps Transcription Translation

Transcription: Where? mRNA is made in the NUCLEUS mRNA will leave the nucleus through the pores in the nuclear membrane (DNA does NOT leave the nucleus)

Transcription: Involved Molecules DNA (instructions for making the protein) mRNA (copy of the instructions) RNA polymerase (enzyme that builds mRNA)

RNA Polymerase = The Enzyme responsible for Transcription copyright cmassengale

Transcription: Produces? mRNA (messenger RNA) Long Straight chain of Nucleotides Made in the Nucleus Copies DNA & leaves through nuclear pores Contains the Nitrogen Bases A, G, C, U ( no T ) copyright cmassengale

Remember the Complementary Bases On DNA: A-T C-G On RNA: A-U copyright cmassengale

Transcription: What Happens? Big Idea: DNA is copied into a complementary sequence of mRNA. RNA polymerase is the enzyme that is responsible for transcription DNA = GCCATT mRNA = CGGUAA

RNA polymerase DNA RNA Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only)

Transcription: Goes to? mRNA leaves the nucleus through the pores in the nuclear membrane and goes to the cytoplasm & ribosomes copyright cmassengale

copyright cmassengale The Genetic Code Each gene on a strand of DNA is read in 3 base sequences called codons A codon designates an amino acid An amino acid may have more than one codon There are 20 amino acids, but 64 possible codons Some codons tell the ribosome to stop translating copyright cmassengale

copyright cmassengale The Genetic Code Use the code by reading from the center to the outside Example: AUG codes for Methionine copyright cmassengale

copyright cmassengale Name the Amino Acids GGG? UCA? CAU? GCA? AAA? copyright cmassengale

Start/Stop Codons There will always be a “Start” codon (AUG) at the beginning. It is like capitalizing the 1st letter of a sentence. There will always be a “Stop” codon (UGA, UAA, UAG) at the end. It is like a period at the end of a sentence.

Translation

Translation: Where? Ribosome Free floating ribosome in cytoplasm (makes proteins for that cell) OR attached ribosome on the Rough ER (makes proteins to be exported to other cells)

Translation: Involved Molecules mRNA (copy of the instructions) tRNA (translates the instructions) rRNA (builds the protein)

copyright cmassengale Transfer RNA amino acid attachment site U A C anticodon Decodes (translates) the mRNA Transfers amino acids to the ribosome copyright cmassengale

copyright cmassengale Codons and Anticodons The 3 bases of an anticodon are complementary to the 3 bases of a codon Ex: Anticodon UGA Codon ACU UGA ACU copyright cmassengale

copyright cmassengale Ribosomal RNA (rRNA) rRNA is a single strand 100 to 3000 nucleotides long Globular in shape Made inside the nucleus (nucleolus) of a cell Associates with proteins to form ribosomes Site of protein Synthesis copyright cmassengale

Translation: Produces? Chain of amino acids Polypeptide (protein)

Translation: What Happens? tRNA translates the mRNA using “anticodons.” (complementary to the codon) Each tRNA molecule has an anticodon on one end and an amino acid on the other. tRNA transfers the amino acids to the ribosome in the correct sequence. rRNA forms peptide bonds between the amino acids. This links them together to build the protein.

Translation: Where does it go? The protein will do one of 2 things Stay inside the cell to carry out functions for that cell OR Be exported to other cells Rough ER  Golgi  Exocytosis

mRNA Nucleus Messenger RNA Lysine Phenylalanine tRNA Transfer RNA Messenger RNA is transcribed in the nucleus. Transfer RNA The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon. mRNA Start codon Ribosome Methionine Phenylalanine tRNA Lysine Nucleus

The Polypeptide “Assembly Line” The ribosome joins the two amino acids—methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids. mRNA Ribosome Translation direction Lysine tRNA Growing polypeptide chain Completing the Polypeptide The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain.

Mutations Gene Mutations — result from a change in a single gene Chromosomal Mutations — the whole chromosome is changed

Gene Mutations: result from a change in a single gene Point Mutations = affect 1 nucleotide; switches one nucleotide for another This only affects 1 amino acid in the protein sequence May also be called Substitution Example THE CAT ATE THE RAT (normal) THE CAT ARE THE RAT (mutation)

Gene Mutations: result from a change in a single gene Frameshift mutations affect how the entire gene is read. Insertion or Deletion—a nucleotide is inserted or deleted from the sequence This changes the codons FROM THAT POINT ON! All the remaining amino acids will be affected. Example THE ACA TAT ETH ERA T. (insertion mutation) THE CAT ATE THE RAT. (normal) THC ATA TET HER AT. (deletion mutation)

Protein Synthesis Activity Step 1: Transcription Copy the “gene” into the complementary sequence of mRNA. This must be done in the “Nucleus.” Step 2: Translation Translate the mRNA using the “tRNA cards” posted around the room. The codon should match up with a word. If you have done this correctly, your sentence should make sense!!! Don’t forget the punctuation (Start/Stop codons)!!

What happens during transcription? What happens during translation? QOD (1) What happens during transcription? What happens during translation?