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GENE

GENE. EXPRESSION. What is DNA Replication?. DNA Replication – the process of creating copies of DNA molecules Why is DNA Repliction SEMI CONSERVATIVE? DNA Replication is SEMI-CONSERVATIVE (each strand of the original DNA molecule serves as a template for the two new DNA molecules). One ring.

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GENE

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  1. GENE EXPRESSION

  2. What is DNA Replication? • DNA Replication – the process of creating copies of DNA molecules Why is DNA Repliction SEMI CONSERVATIVE? • DNA Replication is SEMI-CONSERVATIVE (each strand of the original DNA molecule serves as a template for the two new DNA molecules)

  3. One ring • Thymine and cytosine each have one ring

  4. Two rings • Adenine and guanine each have two rings

  5. Hydrogen Bonds • When making hydrogen bonds, a double ring always pairs with a single ring • A – T • C – G

  6. DNA Replication: Simplified DNA Replication = 3 steps

  7. What are the 3 steps of DNA Replication? DNA Replication = 3 steps • Unzip DNA • Add free nucleotides • Re-zip new strands to old strands

  8. Enzymes Play an Important Role! • Many enzymes help DNA replicate • Enzymes are proteins • Enzyme #1 = helicase (unwinds DNA)

  9. Enzymes Play an Important Role! • Many enzymes help DNA replicate • Enzymes are proteins • Enzyme #2 = DNA Polymerase (add new nucleotides, “proofreads” for mistakes

  10. So...exactly HOW do we use our DNA? • Our DNA sequences serve as a code! • ACTGGGACTACCATTGA • We take this information and make RNA molecules, which help us to make proteins!

  11. DNA Review:Try to fill in the blanks: 1. A nucleotide is made of three parts: ______________ , __________________, and one of the _______ pairs. 2. The nucleotides are combined together to create a __________ acid, and ______ is an example of this.

  12. Review: 1. A nucleotide is made of three parts: DEOXYRIBOSE SUGAR__ , _PHOSPHATE_, and one of the __BASE _ pairs. 2. The nucleotides are combined together to create a _NUCLEIC_ acid, and _DNA_ is an example of this.

  13. More about Nucleic Acids! • We’ve already learned about one important nucleic acid, DNA. Today, we’ll explore the second nucleic acid… • RNA!!

  14. RNA NOTES

  15. How is RNA different from DNA? • Three differences from DNA: • RNA = one strand (DNA = two strands) • RNA has the sugar ribose (DNA has the sugar deoxyribose) • RNA uses uracil [U] instead of thymine (DNA = A, T, G, C RNA = A, U, G, C )

  16. DNA vs. RNA Deoxyribose Sugar Ribose Sugar Double Stranded Single Stranded (usually) (usually) THYMINE base URACIL base 1 type of DNA 3 types of RNA (mRNA, rRNA, tRNA) Examples of Nucleic Acids Made of Nucleotides Code for Information

  17. DNA RNA

  18. What are the 3 types of RNA? • 3 types of RNA: • Messenger RNA (mRNA) carries the genetic message • Transfer RNA (tRNA) transfers amino acids • Ribosomal RNA (rRNA) makes ribosomes

  19. D N A Transcription

  20. What is Transcription? transcribe = “to copy” The genetic code on DNA is copied to RNA in the nucleus Why does it happen in the nucleus? Original DNA cannot pass through the nuclear membrane, so a smaller copy is made and transported

  21. Where in the cell does transcription happen? • The nucleus! • Why does it happen in the nucleus? • Original DNA cannot pass through the nuclear membrane, so a smaller copy is made and transported

  22. How does Transcription happen? 1. RNA polymerase unwinds DNA 2. RNA polymerase adds RNA nucleotides (A  U, G  C) 3. mRNA is formed! DNA reforms a double helix

  23. Transcription recap… • RNA polymerase makes RNA using DNA sequence • RNA leaves the nucleus for the cytoplasm

  24. Translation Where does it go from there? Into the great beyond?

  25. To a ribosome! (Floating in cytoplasm)

  26. At this point you only knew ribosome's as little dots in the cell… now you will learn their big purpose! Turning RNA into the proteins that make up your hair, skin, muscles, nails etc!

  27. What is translation? • Ribosomes translate mRNA into an amino acid sequence • Amino acids form proteins

  28. What is a Codon? Codons = 3 nucleotides in a row How are codons used? Ribosome recognizes a codon on mRNA and matches to the aniticodon on tRNA amino acid anticodon A C G

  29. How do tRNA and anticodons work together? Transfer RNA transfersamino acids from the cytoplasm to a ribosome amino acid Anticodon = 3 nucleotides on one end of a tRNA anticodon A C G Anticodons base pair with complementary bases on mRNA

  30. Codons Codon triplets code for 1 of 20 amino acids

  31. Codons 1 “start” codon 3 “stop” codons

  32. Steps of Translation • mRNA attaches to ribosome mRNA

  33. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

  34. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

  35. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

  36. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

  37. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

  38. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

  39. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

  40. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

  41. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

  42. Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA

  43. Steps of Translation • 3. Protein is released from ribosomes! Protein chain Stop codon

  44. Steps of Translation • 3. Protein is released from ribosomes! Protein chain

  45. What process turns DNA into RNA? • Transcription!!

  46. What process turns RNA into PROTEIN? • Translation!!

  47. What do amino acids build? • Protein!!

  48. Summary DNA (Transcription) RNA (Translation) PROTEIN

  49. Gene Expression Practice • DNA sequence: AAC TGA CTG ATT GCA TGC • What is the complementary DNA sequence? • What is the complementary RNA sequence? • What are the amino acids for this sequence? • 2. • DNA sequence: TAG CAT TGG GCA TCA CGA • What is the complementary DNA sequence? • What is the complementary RNA sequence? • What are the amino acids for this sequence? TTG ACT GAC TAA CGT ACG UUG ACU GAC UAA CGU ACG ATC GTA ACC CGT AGT GCT AUC GUA ACC CGU AGU GCU

  50. EXIT QUIZ Determine the amino acids for this strand of mRNA: AUG GCA AGU UCU UGA Met – Ala – Ser – Ser – STOP (Use genetic code table on page 186-Turtle or p. 526)

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