bio 1 lec3_erika
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Bio 1 PowerpointTRANSCRIPT
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LAST MEETING:
IN THE WOMB
Identical Twins
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IN THE WOMB: IDENTICAL TWINS
How do identical twins and fraternal
twins come about?
Do identical twins really possess
identical DNA?
Which has a greater influence on
health, personality and sexual
preferencegenes or environment?
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LECTURE 3:
ASEXUAL
REPRODUCTION Erika Marie Alvero-Bascos
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Two Modes of Reproduction Asexual Reproduction
Inferior form of reproduction (less energy required)
Requires 1 parent
No involvement of gametes
Offspring identical to their parent
Mitotic chromosome division (Binary fission)
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Sexual Reproduction
Requires 2 parents
Involves gametes that fuse during fertilization
Meiotic chromosome division
Reshuffling of parental genes
Offspring not identical to their parents
Two Modes of Reproduction
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Asexual Sexual
No. of parents
involved
1 2 (or 1 if parent is a
viable hermaphrodite)
Genetic composition of
offspring
Genetically identical
to parent CLONE Genetically different to
either parent
VARIATION
Relative speed by
which offspring are
produced
Gametes involved? No Yes
Faster
All members can
produce viable
offspring
Slower
Only one sex
(female) can produce
viable offspring
Modes of Reproduction
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ASEXUAL REPRODUCTION:
CLONING
All by myself.
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What is cloning?
the creation of an exact
genetic replica of a small
segment of DNA, a cell or
a whole organism
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Natural Cloning Cloning is
widespread in nature.
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Prokaryotes like bacteria propagate by binary fission
Natural Cloning
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Eukaryotic protozoa such as Paramecium also propagate through binary fission
Natural Cloning
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Some animals, like Hydra undergo budding
www.saburchill.com/ans02/chapters/chap051.html
Hydra
Natural Cloning
http://www.saburchill.com/ans02/chapters/chap051.html
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Some organisms undergo fragmentation
Starfish Filamentous algae
Natural Cloning
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Some plants also undergo asexual reproduction
Stolons in grasses
Natural Cloning
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Clones (plantlets) grow along leaf margins of Katakataka
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Identical twins
From one zygote
(same DNA)
Natural Cloning
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CLONING TECHNOLOGY
Artificial Cloning
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Types of Cloning
1. Recombinant DNA Cloning Recombinant DNA cloning or gene
cloning refers to the process by which a fragment of DNA is transferred from one organism to a self-replicating genetic element such as a bacterial plasmid or a virus.
Gene cloning is also important for
the development of drugs and
treatments such as in
pharmacogenetics and gene therapy
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Applications of DNA Cloning 1. Genetic components (whole genes or parts of genes)
can be reconstructed into unique combinations not easily achieved by natural selection, or synthetic genes can be constructed-Recombinant DNA.
2. Recombinant DNA can be introduced or reintroduced into bacteria, plants, or animals.
3. If an organism integrates recombinant DNA into their genome or genetic make-up, they are transgenic.
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2.Reproductive Cloning refers to the process by which
an animal is created which had
the same nuclear DNA as a
previously existing animal.
The purpose is to produce a
genetic duplicate of an existing
or previously existing
organism.
Types of Cloning
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Traditional Reproduction and Cloning
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3. Therapeutic Cloning Therapeutic cloning, or embryo
cloning refers to the production
of human embryos for research
purposes.
The goal of this is not to create
cloned babies but to harvest the
stem cells of the embryo that
have the potential to develop
into almost any cell in the body
Types of Cloning
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Artificial Cloning Procedures
Cell or tissue culture (in
plants)
Embryo splitting
Nuclear transfer
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PLANTS CAN BE CLONED FROM
SINGLE CELLS
1950s: Charles Steward grew individual carrot cells in the laboratory by using special nutrients
Single cells grew and divided to form a ball of undifferentiated cells (callus)
Calli transferred to a different medium grew into full-size carrots (clones)
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ANIMALS CAN BE CLONED
BY SEVERAL METHODS
Embryo splitting
Nuclear transfer
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Embryo Splitting
Embryo splitting involves bisecting the multicellular embryo at an
early stage of development to generate "twins".
The (two) embryos from the splitting are in the same stage of
development, exactly the same age as the undivided embryo would
have been and genetically completely identical.
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Nuclear Transfer
Transfer of the whole nucleus (which contains all the genes) from a
donor cell into to an unfertilized egg cell whose nucleus has
previously been removed.
This technique basically offers the possibility of replicating an adult
individual and their complete genetic make-up.
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History of Cloning: 1952 Robert Briggs and Thomas King of the Institute for
Cancer Research, developed the first major technique, Somatic Cell Nuclear Transfer (SCNT)
1966 John Gurdon of Oxford University created an adult frog clone using a tadpole somatic cell.
1980 Embryo splitting, developed for livestock breeding.
1980 1996 Various research groups cloned frogs, mice, and cattle.
1996 Ian Wilmut and colleagues of Roslin Institute in Scotland created the first clone of an adult mammal using adult somatic cells and SCNT. Dolly, the famous cloned sheep is born.
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1997 Ian Wilmut and colleagues cloned two other sheep, Molly and Polly.
1998 Univ. of Hawaii announced the creation of 50 mice clones using adult cells.
2000 PPL Therapeutics, Inc. cloned pigs from adult female pig body cells.
2001 PPL Therapeutics, Inc. applied genetic engineering to pig cloning, so that the pigs contain a jellyfish gene.
2004 South Korean scientists achieved the first successful human somatic cell nuclear transfer.
History of Cloning:
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Meet Dolly!!!! Dolly (5 July 1996 14 February 2003)
First mammal to cloned using a nucleus from an adult cell (mammary
gland cell)
Cloners: Ian Wilmut, Keith Campbell and colleagues (Scotland)
Why was she named dolly?
Wilmut stated "Dolly is derived from a mammary gland cell
and we couldn't think of a more impressive pair of glands
than Dolly Partons
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Dolly, the Cloned Sheep The Egg
The unfertilized eggs are flushed out of a sheep (sheep 1) which has been induced to produce a larger than normal number of eggs.
The Cell
Previously a sample of tissue was from the udder of a six year old ewe (sheep 2) was taken.
The Fusion
The udder cell is placed beside the egg and an electric current used to fuse the couplet.
Culture
The reconstructed embryo is put into culture and grows for seven days.
Development
Embryos which grow successfully are taken and transferred to a sheep (sheep 3).
The sheep becomes pregnant and produces a lamb after 21 weeks (Dolly).
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Errors In Nuclear Cloning Technology 1st : most clones die early in gestation, and only a few
survive to birth or beyond.
2nd : cloned animals have common abnormalities regardless of the type of donor cell or the species used
3rd : these abnormalities correlate with aberrant gene expression, which most likely results from faulty genomic reprogramming.
4th : the efficiency of cloning depends on the state of differentiation of the donor cell.
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Benefits of Human Cloning
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1. Cure for heart problems:. possible to treat heart attack victims by cloning their healthy heart cells and injecting them into the areas of the heart that have been damaged.
2. Organ and tissue repair: Embryonic stem cells can be grown to produce organs or tissues to repair or replace damaged ones. Skin for burn victims, brain cells for the brain damaged, spinal cord cells for quadriplegics and paraplegics, hearts, lungs, livers, and kidneys could be produced.
3. Cure for Incurable diseases: Conditions such as Alzheimer's disease, Parkinson's disease, diabetes, heart failure, degenerative joint disease, and other problems may be made curable.
Benefits of Human Cloning
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4. Infertility: Human cloning could make it possible for infertile couples to have children .
5. Plastic, reconstructive, and cosmetic surgery: Instead of using materials foreign to the body for such procedures, doctors will be able to manufacture bone, fat, connective tissue, or cartilage that matches the patients tissues exactly.
Benefits of Human Cloning
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6.Defective genes. possible to inactivate defective genes.
7.Down's syndrome. women at high risk for Down's syndrome can avoid that risk by cloning.
8. Liver failure. possible to clone livers for liver transplants.
9. Kidney failure. possible to clone kidneys for kidney transplants.
10. Leukemia. possible to clone the bone marrow for children and adults suffering from leukemia.
Benefits of Human Cloning
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11.cancer. possible to switch cells on and off through
cloning and thus be able to cure cancer.
12.cystic fibrosis. possible to produce effective genetic
therapy against cystic fibrosis. 13.spinal cord injury. possible to grow nerves or the
spinal cord back again when they are injured.
14.testing for genetic disease. Cloning technology can be
used to test for and perhaps cure genetic diseases.
Benefits of Human Cloning
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Why does the Church oppose human cloning?
Cloning is a depersonalized way to reproduce, in which human beings are manufactured in the laboratory to preset specifications. It is not a worthy way to bring a
new human being into the world.
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Threat to Family
In the cloning process the basic relationships of the
human person are perverted: filiation, consanguinity,
kinship, parenthood.
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Threat to Life Itself A prohibition of cloning which would be limited to
preventing the birth of a cloned child, but which would still permit the cloning of an embryo-foetus, would
involve experimentation on embryos and fetuses and would require their suppression before birtha cruel,
exploitative way of treating human beings.
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Threat to Life Itself In any case, such experimentation is immoral because it involves the arbitrary use of the human body (by now
decidedly regarded as a machine composed of parts) as a mere research tool. The human body is an integral
part of every individual's dignity and personal identity, and it is not permissible to use women as a source of
eggs for conducting cloning experiments.
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The spiritual soul, which is the essential constituent of every subject belonging to the human species and is created directly by God, cannot be generated by the parents, produced by artificial fertilization or cloned.
- REFLECTIONS ON CLONING
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No one is a copy. We are all unique creations and not the result of cloning. We are the
expression of the life of an Other who is the Life: Everybody bears the seal of mystery and everyone is marked by desire for the Absolute, the trademark indicating that God created us in his own image and likeness (cf. Genesis 1:27).
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"Creating human life is God's job, and His alone"
"As a Christian, I feel that cloning is morally wrong. The only person who should grant a life is God."
"We are not the creator, only the creation."
"God is the Creator of all life. Period."
"The breath of life is given to us by God - not by scientists splicing genes in a lab."
Religious issues
Playing God
Some people believe that cloning is similar to playing God.
They believe that God should be the creator of all living and natural things.
It is believed that a human has the right for the full human development in a natural
environment and that the human embryo should be left alone
after the 14th day of fertilization.
Reverence for life
Some religious people believe that if you clone a human being it has no soul.
People believe human cloning takes away from an
Individual being unique and stresses Psychological and social development
Not Unique
No Soul
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Pros and Cons
Pros Cons
Cloned body parts can serve as backup systems for humans Solution to infertility Combat genetic diseases Replicate animals for research purposes Enable alterations of plants & animals. Produce people with desirable traits
Weaken diversity & ability of adaptation Production of undesirable traits Technical & economic barriers: cost effective? Reach the common man? Invites malpractices into society Human & animals rights at stake Ethical & moral principles Undermining human life Devalue mankind Humans acting as God