Download DNA Replication

DNA REPLICATION
• means the “copying of
DNA’
• It happens during
Interphase
• semi-conservative:
each new DNA helix
formed is made of one
old strand and one
new strand.
STEP 1:
•
Original DNA strand is pulled apart by the enzyme
DNA helicase. It breaks the hydrogen bonds.
STEP 2:
•
Another enzyme, DNA polymerase, adds new
nucleotides to each strand which produces two
new, identical DNA strands.
STEP 3:
•
The strands wrap back up and the cell is ready to
divide (mitosis!!!)
DNA REPLICATION
• http://www.youtube.com/watch?v=yqESR7E4b_8
CLONING
• The production of identical copies of
molecules, genes, cells or even entire
organisms.
• Dolly the sheep was cloned by Ian Wilmut
(Scottish scientist) in 1997.
WILMUT’S EXPERIMENT
• He took an egg cell from one
adult female sheep and
removed its nucleus.
• He replaced the nucleus with
one from a mammary gland
cell from a different adult
female sheep.
• The egg cell with the new
nucleus was implanted into
the uterus of a surrogate
mother sheep.
• It began to divide and form
an embryo.
WILMUT’S RESULTS
• 5 months later Dolly was born. (She lived for
8 years)
• She was an exact copy of her “mother” –
the cell that provided the nucleus.
• It took many failed attempts and
experiments before this technique of cloning
finally succeeded.
DOLLY THE SHEEP
• http://www.youtube.com/watch?v=YoEWYJHf0kU
USEFUL APPLICATION OF CLONING
• Cloning is used in agriculture to produce
many copies of high-quality crop plants.
• In medicine
• to produce identical strands of bacteria
for research.
• to try to replace damaged cells, tissues,
and possibly organs.
• GENE cloning is more common than cloning
of whole organisms.
GENE CLONING
• Scientists cut out a gene of interest.
• Insert gene into bacterial cell genome.
• As the bacteria cells divide and replicate,
the new gene is copied along with their own
DNA.
• The bacteria start to make the protein that
the gene codes for. Ex. Insulin
• Similar process also used in GMO’s.
ISSUES WITH CLONING
• Read the assigned case study
• Write down the ethical problem specific to the
scenario
• Brainstorm 3-5 possible solutions or alternative
actions to the problem
• Be prepared to discuss your opinions with the class