13-2 Manipulating DNA - BiologyJunction

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12 Δεκ 2012 (πριν από 4 χρόνια και 10 μήνες)

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Biology

Biology

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Manipulating DNA

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Manipulating DNA

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The Tools of Molecular Biology

How do scientists make changes to DNA?

The Tools of Molecular Biology

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Manipulating DNA

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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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Manipulating 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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Manipulating DNA

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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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Manipulating DNA

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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
Eco
R 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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Manipulating DNA

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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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Manipulating DNA

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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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Manipulating DNA

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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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Manipulating DNA

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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 cycles

DNA 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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Restriction enzymes are used to


a.
extract DNA.


b.
cut DNA.


c.
separate DNA.


d.
replicate DNA.


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

a.
more slowly it moves.


b.
heavier it is.


c.
more quickly it moves.


d.
darker it stains.


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

a.
genetic engineering.


b.
the importance of biodiversity to
biotechnology.


c.
the polymerase chain reaction.


d.
selective breeding.

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A particular restriction enzyme is used to


a.
cut up DNA in random locations.


b.
cut DNA at a specific nucleotide sequence.


c.
extract DNA from cells.


d.
separate negatively charged DNA
molecules.


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During gel electrophoresis, DNA fragments
become separated because


a.
multiple copies of DNA are made.


b.
recombinant DNA is formed.


c.
DNA molecules are negatively charged.


d.
smaller DNA molecules move faster than
larger fragments.

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