Download Unit 13 Biotechnology

Unit 13
Biotechnology
Biotechnology
• The use of cells and biological molecules
to solve problems or make useful products
• Involves manipulation of DNA and RNA
DNA
• Building block of DNA is a nucleotide
– Deoxyribose, phosphate group, and a base
• Bases are adenine, thymine, guanine and
cytosine.
• Two strands of DNA molecules are held
together by hydrogen bonds which form
between the bases
– A-T
– G-C
Figure 11.7 Base Pairing in DNA Is Complementary
Phosphodiester bonds
link the sugar and
phosphate
Hydrogen bonds
hold strands
together by
complementary
base pairing
DNA replication
• DNA helix unwinds
• Each strand serves as a template for a
new strand
• How would you replicate this strand of
DNA?
– TTT GCC AGA
• Tutorial 11.2 (DNA replication)
Transcription
• Process of producing a messenger RNA copy using the
DNA template.
• mRNA takes the message from the nucleus to the
cytoplasm
• In RNA, there is no thymine (T)
• In RNA, sugar is ribose, not deoxyribose
• Base-pairing in RNA
– A-U
– C-G
• How would you transcribe this DNA?
– ATC GGG TTA
• Tutorial 12.1
Translation
• Messenger RNA is “translated” into protein
at the ribosome
• The 3-letter triplet codon on mRNA directs
transfer RNA to bring the correct amino
acid to the growing chain
• Fig 13.7 shows the genetic code
• What amino acids would be added to the
chain based on these codons?
• AUG CUU UGU GCG
Figure 12.5 The Universal Genetic Code
• Steps in translation are initiation,
elongation and termination
• View animation of translation and protein
synthesis
• http://www.whfreeman.com/thelifewirebrid
ge2/ tutorial 12.3
Exercise 13.1
• DNA puzzle
• Simulate DNA replication
• Simulate transcription
– Be sure to use ribose sugar instead of
deoxyribose
– Different colors for ribose and deoxyribose
• Simulate translation
Exercise 13.2
• Isolation of DNA from onion or banana
cells
• Filtrates will be prepared and students will
add the ice-cold ethanol to precipitate the
DNA.
• Observe DNA as a stringy, cottony mass.
Exercise 13.3
• Restriction enzymes
– Enzymes that recognize a particular DNA
sequence and cut there
• Example EcoRI
– Restriction site is
GAAT T C
C T TAA G
cuts
between
the G and
the A
• The enzyme EcoRI cuts DNA with the
following paired sequence:
– 5 ... GAATTC ... 3
– 3... CTTAAG ... 5
• Notice that the sequence is palindromic:
It reads the same in the 5-to-3 direction
on both strands.
Figure 16.4 Cutting and Splicing DNA
Fragments from a human source can be joined to
another source, such as a bacterium
• Some restriction enzymes cut DNA strands and
leave staggered ends of single-stranded DNA, or
“sticky” ends, that attract complementary
sequences.
• If two different DNAs are cut so each has sticky
ends, fragments with complementary sticky ends
can be recombined and sealed with the enzyme
DNA ligase.
• These simple techniques, which give scientists the
power to manipulate genetic material, have
revolutionized biological science in the past 30
years.
• Hundreds of restriction enzymes have
been purified from various organisms, and
these enzymes serve as “knives” for
genetic surgery.
• The fragments of DNA can be separated using gel
electrophoresis. DNA is negatively charged
• When DNA is placed in a semisolid gel and an electric
field is applied, the DNA molecules migrate toward the
positive pole.
• Smaller molecules can migrate more quickly through
the porous gel than larger ones.
• After a fixed time, the separated molecules can then be
stained with a fluorescent dye and examined under
ultraviolet light.
Figure 16.2 Separating Fragments of DNA by Gel Electrophoresis (Part 1)
Figure 16.2 Separating Fragments of DNA by Gel Electrophoresis (Part 2)
Figure 16.2 Separating Fragments of DNA by Gel Electrophoresis (Part 3)
Kitchen electrophoresis
• Prepared samples will be loaded onto an agarose gel by
instructor and electrophoresed.
• You will use the crime scene scenario to interpret the gel.
Which sample matches with the one taken from the
crime scene?
– Compare pattern of bands. If pattern of DNA bands from the
crime scene matches the pattern of one of the suspects, this
provides evidence that the suspect is guilty.
• Also view gels showing results of paternity testing.
– View the patterns for the mother, child and the potential fathers
to determine which is likely to be the father of the child.
Agar plate inoculation for next
week
• Prepare agar plates by swabbing with
environmental samples.
• These plates will be viewed next week.
• Draw lines on bottom of plate (not the lid)
to divide plate into 3 sectors.
• Swab 2 sectors with different
environmental samples and label.
• Leave one sector as a control.
• Tape down the lid and leave on cart.
Check-out procedures
• Demonstrate transcription and translation
using puzzle pieces
• Explain crime scene interpretation