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RNA & Transcription

RNA & Transcription. Chapter 12- p.300-301. What are the two types of nucleic acids?. DNA- Codes to make a protein. Codes= bases (CTGA) Made up of nucleotides. 2 strands to a DNA molecule RNA- Disposable copy of DNA Made up of nucleotides. 1 strand to a RNA molecule.

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RNA & Transcription

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  1. RNA & Transcription Chapter 12- p.300-301

  2. What are the two types of nucleic acids? DNA- Codes to make a protein. Codes= bases (CTGA) Made up of nucleotides. 2 strands to a DNA molecule RNA- Disposable copy of DNA Made up of nucleotides. 1 strand to a RNA molecule

  3. What is a chromosome? • Very large DNA molecule • 100, 000’s of base pairs What is a gene? • Segment of base pairs that are codes to make a protein and thus determines a trait. • 1000’s of base pairs

  4. What is the role of a gene? • Sequence of base pairs containing instructions for making a protein. • Examples of proteins • Cell membranes (protein channels) • Organelles • Enzymes • Hormones • Muscle, tendons, ligaments • Skin, hair and nails

  5. RNA- (Ribonucleic acid) • Single stranded • Nucleotides • Ribose sugar • Phosphate group • Bases (A, U, G, C) U= uracil, A= adenine, G=guanine, C= cytosine

  6. mRNA • Several types of RNA – one is mRNA (messenger RNA) • mRNA is a copy of the code for a gene • “Messenger” RNA because it carries the instructions out of the nucleus to … Ribosomes!

  7. Transcription • The process of making a mRNA molecule using one strand of DNA as a template • Only one geneis transcribed at a time Nucleosome Chromosome DNA double helix Coils Supercoils Histones

  8. Promoter(RNA polymerase binding site) DNA strand Stop transcription Start transcription • Step 1:RNA polymerase binds to a DNA molecule at a specific sequence called a promoter

  9. Step 2: RNA polymerase unwinds & unzips the two strands of DNA • Step 3: RNA nucleotides follow the rules of base pairing (A-U, G-C) using one strand of DNA as a template • Step 4: RNA polymerase bonds the RNA nucleotides together into a mRNA molecule

  10. Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNApolymerase DNA mRNA

  11. Step 5:The mRNA molecule is edited: • Introns are removed • Exons are spliced back together • Protective caps are added to each end Cap Tail

  12. Step 6: The mRNA molecule exits the nucleus and travels to a ribosome for protein synthesis Nucleus Messenger RNA is transcribed in the nucleus. mRNA

  13. NucleicAcids Single-stranded (usually) Double-stranded Each strand is a chain of nucleotides A chain of nucleotides Deoxyribose (sugar) Ribose (sugar) A, U, G, C (bases) U = uracil A, T, G, C (bases)

  14. Animations- transcription • Animation • Animation for review • Animation for review • Transcription game

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