Human Biology
Sylvia S. Mader
Michael Windelspecht
Chapter 21
DNA Biology
and Technology
Lecture Outline
Part 3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
21.2 Gene Expression
Regulation of gene expression
5 levels
1. ____________________ (nucleus)
• e.g., chromatin density and DNA accessibility
2. Transcriptional control (nucleus)
• e.g., transcription factors
3. Posttranscriptional control (nucleus)
• e.g., mRNA processing
4. Translational control (cytoplasm)
• e.g., differential ability of mRNA to bind
ribosomes
5. Posttranslational control (cytoplasm)
• e.g., changes to the protein to make it
functional
2
21.2 Gene Expression
Regulation of gene expression
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cytoplasm
signal
Nucleus
nucleosome
chromatin
packing
DNA unpacking
DNA
DNA transcription
intron
exon
primary mRNA
mRNA processing
maturem RNA
mRNA translation
nuclear
envelope
nuclear
pore
polypeptide
Prosttranslational control
functional
protein
degraded
protein
Figure 21.13 Control of gene expression in eukaryotic cells.
3
21.3 DNA Technology
DNA technology
1.
2.
3.
4.
Gene cloning through recombinant DNA
Polymerase chain reaction (PCR)
DNA fingerprinting
Biotechnology products from bacteria,
plants, and animals
4
21.3 DNA Technology
DNA technology terms
• ______________________ – altering DNA in
bacteria, viruses, plants, and animal cells
through recombinant DNA technology
• Recombinant DNA – contains DNA from 2 or
more different sources
• Transgenic organisms – organisms that have a
________ gene inserted into them
• Biotechnology – using natural biological
systems to create a product or to achieve an
end desired by humans
5
21.3 DNA Technology
DNA Sequencing
• The order of nucleotides in a DNA sequence is
determined
• 1970s: performed manually using dye-terminator
substances
• Now performed using dyes attached to
nucleotides, with a laser and computerized
machine to determine sequence
6
21.3 DNA Technology
Automated DNA sequencer and
an electropherogram
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Figure 21.14 Automated
DNA sequencer and an
electropherogram.
Small section of a genome
(sequencer): © Lawrence Berkeley Nat’l Lab/Roy Kaltschmidt, photographer
7
21.3 DNA Technology
Polymerase chain reaction (PCR)
•
•
Polymerase chain reaction is used to
_______ small pieces of DNA.
It is important for amplifying DNA for
analysis such as in DNA fingerprinting.
8
21.3 DNA Technology
Polymerase chain reaction (PCR)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1. Sample is first
heated to
denature DNA.
2. DNA is cooled to a
lower temperature
to allow annealing
of primers.
DNA strand
DNA segment
to be amplified
5´
3´
DNA is denatured
Into single strands
3´ 5´
5´
3. DNA is heated to
72°C, the optimal
temperature for
Taq DNA
polymerase to
extend primers.
3´
3´
Primers anneal to DNA
5´ 3´
5´
3´
5´
5´
3´
3´
5´
3´
3´
5´
5´
3´
5´
3´
5´
3´
3´
5´
5´
3´
3´
5´
3´
5´
3´
5´
5´
3´
3´
5´
Cycle 2:
4 copies
Taq DNA polymerase
3´
5´
3´
5´
Cycle 3:
8 copies
5´
5´
3´
3´
5´
5´
3´
5´
3´
5´
3´
3´
5´
5´
3´
3´
5´
3´
5´
3´
5´
5´
3´
3´
5´
Figure 21.15 The polymerase chain reaction.
9
21.3 DNA Technology
DNA fingerprinting
•
Figure 21.16 PCR and electrophoresis used for DNA fingerprinting.
Collect
DNA
marker
Crime
scene
Suspect A
16 repeats
suspect
B
12 repeats
12 repeats
Perform
PCR on
repeats
suspect
A
12 repeats
crime scene
evidence
16 repeats
•
Fragments are
separated by their
charge/size ratios
Results in a _______
_______ for each
individual
Often used for paternity
testing, or to identify an
individual at a crime
scene or unknown body
remains
12 repeats
•
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Suspect B
Use gel electrophoresis to identify criminals
10
21.3 DNA Technology
Gene cloning
•
Recombinant DNA – contains DNA from 2 or
more different sources that allows genes to be
cloned
•
Bacteria used to clone the human insulin gene
–
–
–
Restriction enzyme is used to cut the vector
(plasmid) and the human DNA with the insulin
gene.
DNA ligase seals together the insulin gene and
the plasmid.
Bacterial cells take up plasmid, the gene is
copied, and the product can be made.
11
21.3 DNA Technology
Visualizing gene cloning
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
human DNA
plasmid
(vector)
bacterium
human cell
insulin gene
1
2
Restriction enzyme
cleaves DNA.
DNA ligase seals
the insulin gene
into the plasmid.
recombinant DNA
3
4a
Figure 21.17 Cloning of a human gene.
Host cell takes up
recombined plasmid.
Gene cloning occurs.
4b
Bacteria produce a product.
insulin
12
21.3 DNA Technology
Biotechnology products: Transgenic organisms
• Important uses
– Production of:
•
•
•
•
•
Insulin
Human growth hormone (HGH)
Clotting factor VIII
Tissue plasminogen activator (t-PA)
Hepatitis B vaccine
– Naturally-occurring oil-degrading bacteria
can be made more effective through
genetic engineering
13
21.3 DNA Technology
Biotechnology products: Transgenic organisms
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a.
b.
c.
d.
a: © Maximilian Stock Ltd./Photo Researchers; b: Courtesy Robert H. Devlin, Fisheries and Oceans Canada;
c: © Richard Shade; d: © Jerry Mason/Photo Researchers
Figure 21.18 Transgenic organisms.
14