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Gene Expression

Gene Expression. How is the information in DNA used to determine an organism’s characteristics?. An organisms trait’s are determined by proteins that are built according to the plans specified in its DNA. What are Genes?. Hold information specifying how to build particular proteins.

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Gene Expression

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  1. Gene Expression How is the information in DNA used to determine an organism’s characteristics?

  2. An organisms trait’s are determined by proteins that are built according to the plans specified in its DNA.

  3. What are Genes? • Hold information specifying how to build particular proteins. • Referring back to the gym socks what part of the sock did the gene represent?

  4. Genes are the DNA-encoded information that specifies particular proteins; each gene is made of a specific sequence of ____________??? • nucleotides

  5. Transcribe and Translate a Gene • The DNA that makes up the human genome can be subdivided into information bytes called genes. Each gene encodes a unique protein that performs a specialized function in the cell. The human genome contains more than 25,000 genes.

  6. Cells use the two-step process of transcription and translation to read each gene and produce the string of amino acids that makes up a protein. The basic rules for translating a gene into a protein are laid out in the Universal Genetic Code.

  7. How do you build a protein? • It goes through two steps. The first step is to undergo TRANSCRIPTION and make RNA!!!

  8. Transcription 1st step • In the nucleolus the cells machinery copies the gene sequence into messenger RNA (mRNA), a molecule that is similar to DNA. Like DNA, mRNA has four-nucleotide bases-but in mRNA, the base uracil (U) replaces thymine (T).

  9. Creating new strands • DNA: GGTATCGATTGG    • Complimentary: CCATAGCTAACC     • RNA GGUAUCGAUUGG  

  10. DNA Double strand 5-C sugar deoxyribose Nitrogen bases: ATCG RNA Single strand 5-C sugar ribose Nitrogen bases: AUCG Uracil is complementary to adenine DNA vs. RNA

  11. RNA polymerase • Binds to a promoter • Unwinds and breaks sequence • Builds up sequence by pairing up each nucleotide with its complementary base

  12. What is the Role of DNA in this Process?

  13. Step 1: RNA polymerase binds to gene’s promoter

  14. Step 2: The two DNA strands unwind and separate

  15. Step 3: Complementary RNA nucleotides are added

  16. Step 4

  17. Step 5

  18. Transcription

  19. Transcription copies the DNA code of a gene and converts it to messenger RNA (m RNA). The m RNA will be used at the ribosome to make polypeptides (proteins). However all of the code contained in the m RNA molecule is not needed to produce the polypeptide. The sections of m RNA which do not code for translation of polypeptide are called introns.

  20. As the m RNA readies itself to leave the nucleus, enzymes cut out and remove the introns. The remaining exons are spliced back together again by a different enzyme. This modified m RNA is what comes to the ribosome to be translated into polypeptides.

  21. RNA • 3 TYPES: messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA)

  22. mRNA • Holds the information from DNA and passes it on to create a protein • It’s an RNA copy of a gene used as a blueprint for a protein. • When a cell needs a particular protein, a specific mRNA is made.

  23. rRNA • Associates with protein to form the ribosome

  24. tRNA • Acts as an interpreter molecule, translating mRNA sequences into amino acid sequences

  25. Genetic Code • After transcription the genetic material message is ready to be translated from the language of RNA to the language of proteins. • The instructions for building a protein are written as a series of 3 nucleotide sequences called codons.

  26. Translation: 2nd Step • The protein-making machinery, called the ribosome, reads the mRNA sequence and translates it into the amino acid sequence of the protein. The ribosome starts at the sequence AUG, then reads 3 nucleotides at a time. Each 3-nucleotide codon specifies a particular amino acid. The “stop” codons (UAA, UAG, and UGA) tell the ribosome that the protein is complete.

  27. Translation

  28. Transcribe and Translate a Gene.htm

  29. Overview • DNA duplicates itself in replication. • DNA produces RNA in transcription. • RNA produces proteins in translation.

  30. DNA, RNA, and Proteins

  31. Protein builder

  32. Transcribe a DNA sequence into a protein Protein

  33. Extra Slides

  34. Transcription • Transcription is the process of creating RNA from DNA. • Transcription occurs in the cell's nucleus. • RNA polymerase is the protein molecule that reads the DNA and creates the RNA intermediary. • Transcription requires: DNA, RNA polymerase, ribonucleotides, and some ATP for energy. • Uracil (U) is substituted for thymine (T) in RNA. • Transcription initiation is the main point of regulation of gene expression.

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