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CHANGING THE LIVING WORLD. How we change the living world… Selective breeding: crossing organisms with desired traits to produce the next generation.

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Presentation on theme: "CHANGING THE LIVING WORLD. How we change the living world… Selective breeding: crossing organisms with desired traits to produce the next generation."— Presentation transcript:

1 CHANGING THE LIVING WORLD

2 How we change the living world… Selective breeding: crossing organisms with desired traits to produce the next generation.

3 How we change the living world… Hybridization: crossing dissimilar organisms to get the best of both.

4 How we change the living world… Inbreeding: continually breeding individuals with similar characteristics.

5 GENETIC ENGINEERING

6 Genetic engineering vocab – Recombinant DNA- nucleotide sequences from two different sources to form a single DNA molecule. – Transgenic organism – contains a gene from another organism, typically a different species – Genetically modified organisms (GMOs)- organisms that have acquired one or more genes by artificial means.

7 Figure 12.1

8 Genetic Engineering Genetic engineering: The process of manipulating genes for practical purposes. Genetic engineering may involve building recombinant DNA DNA made from two or more different organisms.

9 Steps in a Genetic Engineering Experiment Step 1 Isolate Target DNA and plasmid and cut with restriction enzymes Step 2 Recombinant DNA is produced. Step 3 Gene cloning: the process by which many copies of the gene of interest are made each time the host cell reproduces. Step 4 Cells undergo selection and then are screened.

10 Steps in a Genetic Engineering Experiment Step 1 The DNA from the organism containing the gene of interest and the vector are cut by restriction enzymes. A vector is an agent that is used to carry the gene of interest into another cell Commonly used vectors: viruses, yeast, and plasmids. circular bacterial DNA

11 Plasmids Bacterial chromosome Remnant of bacterium Colorized TEM Figure 12.7

12 Plasmid Bacterial cell Isolate plasmids. Figure

13 Plasmid Bacterial cell Isolate plasmids. DNA Isolate DNA. Cell containing the gene of interest Figure

14 Plasmid Bacterial cell Isolate plasmids. DNA Isolate DNA. DNA fragments from cell Cut both DNAs with same enzyme. Gene of interest Other genes Cell containing the gene of interest Figure

15 Plasmid Bacterial cell Isolate plasmids. Gene of interest Recombinant DNA plasmids DNA Isolate DNA. DNA fragments from cell Cut both DNAs with same enzyme. Gene of interest Other genes Mix the DNAs and join them together. Cell containing the gene of interest Figure

16 Plasmid Bacterial cell Isolate plasmids. Recombinant bacteria Gene of interest Recombinant DNA plasmids Bacteria take up recombinant plasmids. DNA Isolate DNA. DNA fragments from cell Cut both DNAs with same enzyme. Gene of interest Other genes Mix the DNAs and join them together. Cell containing the gene of interest Figure

17 Plasmid Bacterial cell Isolate plasmids. Clone the bacteria. Recombinant bacteria Bacterial clone Gene of interest Recombinant DNA plasmids Bacteria take up recombinant plasmids. DNA Isolate DNA. DNA fragments from cell Cut both DNAs with same enzyme. Gene of interest Other genes Mix the DNAs and join them together. Cell containing the gene of interest Figure

18 Plasmid Bacterial cell Isolate plasmids. Find the clone with the gene of interest. Clone the bacteria. Recombinant bacteria Bacterial clone Gene of interest Recombinant DNA plasmids Bacteria take up recombinant plasmids. DNA Isolate DNA. DNA fragments from cell Cut both DNAs with same enzyme. Gene of interest Other genes Mix the DNAs and join them together. Cell containing the gene of interest Figure

19 Plasmid Bacterial cell Isolate plasmids. Some uses of genes Gene for pest resistance Gene for toxic-cleanup bacteria Genes may be inserted into other organisms. Find the clone with the gene of interest. The gene and protein of interest are isolated from the bacteria. Clone the bacteria. Recombinant bacteria Bacterial clone Gene of interest Recombinant DNA plasmids Bacteria take up recombinant plasmids. Harvested proteins may be used directly. Some uses of proteins Protein for “stone-washing” jeans DNA Cell containing the gene of interest Protein for dissolving clots Isolate DNA. DNA fragments from cell Cut both DNAs with same enzyme. Gene of interest Other genes Mix the DNAs and join them together. Figure

20 RESTRICTION ENZYMES molecular scissors

21 A Closer Look: Cutting and Pasting DNA with Restriction Enzymes – Recombinant DNA is produced by combining two ingredients: A bacterial plasmid The gene of interest How do we cut them? Using restriction enzymes: bacterial enzymes which cut DNA at specific nucleotide sequences produce pieces of DNA called restriction fragments. Why do you think bacteria contain restriction enzymes?

22 Restriction Enzymes are palindromes: the same forward as backwards, like RACECAR. Examples: GAATTCCCCGGGAAGCTT CTTAAGGGGCCCTTCGAA G AATTCCCC GGGA AGCTT CTTAA GGGG CCCTTCGA A Sticky Ends Blunt End

23 Recognition sequence for a restriction enzyme Restriction enzyme Sticky end Sticky end DNA A restriction enzyme cuts the DNA into fragments. Figure

24 Recognition sequence for a restriction enzyme Restriction enzyme Sticky end Sticky end DNA A DNA fragment is added from another source. A restriction enzyme cuts the DNA into fragments. Figure

25 Recognition sequence for a restriction enzyme Restriction enzyme Sticky end Sticky end DNA A DNA fragment is added from another source. A restriction enzyme cuts the DNA into fragments. Fragments stick together by base pairing. Figure

26 DNA LIGASE – DNA ligase connects the DNA fragments into one continuous strand (DNA Glue or tape)

27 Recognition sequence for a restriction enzyme Restriction enzyme Sticky end Sticky end DNA ligase Recombinant DNA molecule A DNA fragment is added from another source. A restriction enzyme cuts the DNA into fragments. Fragments stick together by base pairing. DNA ligase joins the fragments into strands. Figure

28 Recognition sequences DNA sequence Restriction enzyme EcoR I cuts the DNA into fragments. Sticky end

29 Your turn to try!!

30 – Plasmids: Can easily incorporate foreign DNA Are readily taken up by bacterial cells Can act as vectors, DNA carriers that move genes from one cell to another Are ideal for gene cloning, the production of multiple identical copies of a gene-carrying piece of DNA

31 Bacterial cells don’t edit the RNA, so how can they make the correct protein? Genetic Engineers can eliminate the introns from mRNA and reverse the process, producing a DNA strand that is only the instructions for the protein. Use Reverse Transcriptase

32 Cell nucleus DNA of eukaryotic gene Test tube Transcription Exon Intron Exon Intron Figure

33 Cell nucleus DNA of eukaryotic gene RNA transcript mRNA Test tube Transcription Introns removed and exons spliced together Exon Intron Exon Intron Figure

34 Cell nucleus DNA of eukaryotic gene RNA transcript mRNA Test tube Reverse transcriptase Transcription Introns removed and exons spliced together Isolation of mRNA from cell and addition of reverse transcriptase Exon Intron Exon Intron Figure

35 Cell nucleus DNA of eukaryotic gene RNA transcript mRNA Test tube Reverse transcriptase cDNA strand being synthesized Transcription Introns removed and exons spliced together Isolation of mRNA from cell and addition of reverse transcriptase Synthesis of cDNA strand Exon Intron Exon Intron Figure

36 Cell nucleus DNA of eukaryotic gene RNA transcript mRNA Test tube cDNA of gene without introns Reverse transcriptase cDNA strand being synthesized Transcription Introns removed and exons spliced together Isolation of mRNA from cell and addition of reverse transcriptase Synthesis of cDNA strand Synthesis of second DNA strand by DNA polymerase Exon Intron Exon Intron Figure


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