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III Manipulating DNA

III Manipulating DNA

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III Manipulating DNA. The Tools of Molecular Biology How do scientists make changes to DNA?. The Tools of Molecular Biology. The Tools of Molecular Biology. Scientists use different techniques to: extract DNA from cells cut DNA into smaller pieces - PowerPoint PPT Presentation

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Page 1: III  Manipulating DNA

III Manipulating DNA

Page 2: III  Manipulating DNA

The Tools of Molecular Biology

How do scientists make changes to DNA?

The Tools of Molecular Biology

Page 3: III  Manipulating DNA

The Tools of Molecular Biology

Scientists use different techniques to:

• extract DNA from cells

• cut DNA into smaller pieces

• identify the sequence of bases in a DNA molecule

• make unlimited copies of DNA

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The Tools of Molecular Biology

In genetic engineering, biologists make changes in the DNA code of a living organism.

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The Tools of Molecular Biology

DNA Extraction

DNA can be extracted from most cells by a simple chemical procedure.

The cells are opened and the DNA is separated from the other cell parts.

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The Tools of Molecular Biology

Cutting DNA 

Most DNA molecules are too large to be analyzed, so biologists cut them into smaller fragments using restriction enzymes.

Which type of molecule is an enzyme?

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The Tools of Molecular Biology

Each restriction enzyme cuts DNA at a specific sequence of nucleotides.

Recognition sequences

DNA sequence

Restriction enzyme EcoR I cuts the DNA into fragments

Sticky end

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The Tools of Molecular Biology

Separating DNA  

In gel electrophoresis, DNA fragments are placed at one end of a porous gel, and an electric voltage is applied to the gel.

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The Tools of Molecular Biology

DNA plus restriction enzyme

Mixture of DNA fragments

Gel

Power source

Gel Electrophoresis

Longer fragments

Shorter fragments

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The Tools of Molecular Biology

First, restriction enzymes cut DNA into fragments.

The DNA fragments are poured into wells on a gel.

DNA plus restriction enzyme

Mixture of DNA fragments

Gel

Gel Electrophoresis

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The Tools of Molecular Biology

An electric voltage is applied to the gel.

The smaller the DNA fragment, the faster and farther it will move across the gel.

Power source

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The Tools of Molecular Biology

Longer fragments

Shorter fragments

Gel Electrophoresis

Power source

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Using the DNA Sequence

Making Copies 

Polymerase chain reaction (PCR) is a technique that allows biologists to make copies of genes.

Small amounts of DNA can be multiplied making it easier to analyze.

Made possible by an enzyme found in a bacterium living in hot springs in Yellow Stone National Park.

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Using the DNA Sequence

DNA heated to separate strands

PCR cyclesDNA copies

1 2 3 4 5 etc.1 2 4 8 16 etc.

Polymerase Chain Reaction (PCR)

DNA polymerase adds complementary strand

DNA fragment to be copied

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Quiz

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Restriction enzymes are used to• extract DNA.• cut DNA.• separate DNA.• replicate DNA.

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During gel electrophoresis, the smaller the DNA fragment is, the

• more slowly it moves.• heavier it is.• more quickly it moves.• darker it stains.

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The DNA polymerase enzyme found in bacteria living in the hot springs of Yellowstone National Park illustrates

• genetic engineering.• the importance of biodiversity to biotechnology.• the polymerase chain reaction.• selective breeding.

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A particular restriction enzyme is used to• cut up DNA in random locations.• cut DNA at a specific nucleotide sequence.• extract DNA from cells.• separate negatively charged DNA molecules.

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During gel electrophoresis, DNA fragments become separated because

• multiple copies of DNA are made.• recombinant DNA is formed.• DNA molecules are negatively charged.• smaller DNA molecules move faster than larger

fragments.

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END OF SECTION