Gene Expression: Using DNA to make proteins PHA Biology 9

Cytoplasm RNA Nucleus E.R. A Day in the Life of The Cell Ribosome Protein Ribosome RNA Released into blood stream and used as hormone or other bodily structure Golgi Apparatus (Modifies and shapes the protein) Protein being formed at Ribosome Nucleus Cytoplasm Protein could go to membrane to be released into blood stream DNA (Stores genetic information) RNA (Copies genetic from DNA and carries it to the Ribosome to make proteins) Vesicles (“bubbles” that transport proteins) (transports and packages proteins) E.R. ::Blood Stream:: Cell Membrane Ribosomes

Overview: Using DNA to Make Proteins [Turn your notebook sideways and write this in big letters in the middle of the page – take up the whole length of the page! Leave plenty of space above and below it.] DNA RNA Protein Trait Stays in the nucleus Copies itself and gets passed on to new cells Holds instructions for making proteins Used as body structures (muscle, bone, skin, hair), enzymes, transporters, hormones, etc. Made in the nucleus and goes to the cytoplasm Uses DNA instructions to make proteins Observable characteristic “Who you are”

Overview: Using DNA to Make Proteins Transcription: The process of making RNA by copying DNA Translation: The process of using info in RNA to make proteins DNA RNA Protein Trait Stays in the nucleus Copies itself and gets passed on to new cells Holds instructions for making proteins Made in the nucleus and goes to the cytoplasm Uses DNA instructions to make proteins Used as body structures (muscle, bone, skin, hair), enzymes, transporters, hormones, etc. Observable characteristic “Who you are”

Differences between DNA and RNA Deoxyribose sugar Double strand (forms a helix) Bases: A, T, G, C Ribose sugar Single strand (can form different shapes) U instead of T (A, U, G, C) Objectives for Class: Describe the major structural differences between DNA and RNA Differentiate between structure and function differences between the types of RNA

Base Pairing between DNA and RNA DNA  RNA A ------ U T ------ A C ------ G G ------ C Objectives for Class: Describe the major structural differences between DNA and RNA Differentiate between structure and function differences between the types of RNA

Transcription: Copying DNA into RNA (the red & green strands) mRNA (the orange strand) Objectives for Class: Describe the major structural differences between DNA and RNA Differentiate between structure and function differences between the types of RNA

Transcription Overview: Steps: Final Result: mRNA copy of a gene A DNA gene is copied into RNA Occurs in the nucleus Steps: RNA Polymerase separates (unzips) DNA strands RNA Polymerase makes RNA by matching complementary nucleotides with the DNA strand mRNA leaves nucleus and DNA winds back up! Final Result: mRNA copy of a gene Objectives for Class: Describe the purpose and major steps of transcription Describe the purpose and major steps of translation Objectives for Class: Describe

Three Types of RNA: Messenger RNA (mRNA) - Transfer RNA (tRNA) – Carries a copy of protein-making instructions to the ribosome Codon = 3 letters on mRNA that stand for one amino acid Transfer RNA (tRNA) – Carries amino acids to the ribosome Contains anticodons that match up with mRNA codons to put amino acids in the correct order Ribosomal RNA (rRNA) – Part of the ribosome (helps bond amino acids together)

Transfer RNA (tRNA) Structure (Draw it!) Amino Acid attached to the top Anti-codon on the bottom Objectives for Class: Describe the major structural differences between DNA and RNA Differentiate between structure and function differences between the types of RNA

Ribosomal RNA (rRNA) Acts like an enzyme to bond amino acids together into long chains (proteins!)

Translation Details Final Result: A polypeptide (protein) Overview: The gene sequence in mRNA is translated into a chain of amino acids that forms a protein Occurs at the ribosome Steps: mRNA enters the ribosome tRNA molecules bring amino acids to the ribosome tRNA anticodons match with mRNA codons to put amino acids in the right order According to the Genetic Code Ribosome connects the amino acids into a long chain Final Result: A polypeptide (protein)

Making Proteins at the Ribosome Growing Protein Amino Acid t RNA mRNA Ribosome Anticodon Codon Objectives for Class: Describe the purpose and major steps of transcription Describe the purpose and major steps of translation Objectives for Class: Describe

Translation Ribosome Growing protein chain mRNA strand Objectives for Class: Describe the purpose and major steps of transcription Describe the purpose and major steps of translation Objectives for Class: Describe

Transcription & Translation Objectives for Class: Describe

Reading The Genetic Code The letters in the wheel are mRNA codons Start in the middle! This is the first letter in the codon Move to the middle ring (2nd letter in the codon) Then go to the outer ring of letters (3rd letter in the codon) Outermost ring = amino acids!

Reading The Genetic Code: Examples Follow along with the examples on your worksheet! Example 1: CAG 1st base = C 2nd base = A 3rd base = G Therefore the amino acid is… Glutamine! Example 2: GUU Valine

Reading The Genetic Code: Longer Example Example 3: GCCAGCUAG Step 1: Break it into 3-letter sections (codons) GCC AGC UAG Step 2: Decode each codon GCC = Alanine AGC = Serine UAG = STOP (end of protein sequence) 1 3 2

Gene Mutations Activity: Part I Review What is a Genetic Mutation? A change in the base-pair sequence of DNA The three types of point mutations: substitution (switch one DNA nucleotide for another) insertion (add an extra nucleotide into the DNA sequence) deletion (leave out one nucleotide in the DNA sequence) Objectives for Class: Describe the major differences between substitution and frame-shift mutations

Genetic Mutations Activity – Substitution Mutations Original DNA Sequence Substitution Changes the Amino Acid Substitution/ Silent Mutation Does not Change the Amino Acid Objectives for Class: Describe the major differences between substitution and frame-shift mutations

Genetic Mutations Activity – Frame-Shift Mutations Original DNA Sequence Frame-Shift: Deletion of nucleotide Changes all Amino Acid after mutation Frame-Shift: Insertion/ Addition of nucleotide Changes all Amino Acid after mutation Objectives for Class: Describe the major differences between substitution and frame-shift mutations

Lab: Sickle Cell and Genetic Mutations Background Information Brainstorm Info on Sickle Cell Anemia Normal vs. Sickled Cells (shape is different) Genetic disease (get it from parents’ genes) Two copies of gene = sickle cell anemia One copy of gene = “carrier” for sickle cell anemia – protected from malaria Malaria – disease caused by mosquitoes that live in tropical places (ex: sub-Saharan Africa) People of African descent are more likely to carry the sickle cell gene b/c it protected their ancestors from malaria Symptoms of SCA: tired easily, lots of muscle pain b/c blood cells stick together and block blood flow. What anemia is How SCA came to be.

Lab: Sickle Cell and Genetic Mutations Background Information Brainstorm Info on Genes and Mutations: What a gene is What a mutation is Different types of mutations (substitution and frame-shift (deletion and insertion)) DNA  RNA  protein  trait and how a mutation would affect this. Transcription and translation.

Valine: Glutamic acid: