LAST MEETING:

IN THE WOMB

Identical Twins

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?

LECTURE 3:

ASEXUAL

REPRODUCTION Erika Marie Alvero-Bascos

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)

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

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

ASEXUAL REPRODUCTION:

CLONING

All by myself.

What is cloning?

the creation of an exact

genetic replica of a small

segment of DNA, a cell or

a whole organism

Natural Cloning Cloning is

widespread in nature.

Prokaryotes like bacteria propagate by binary fission

Natural Cloning

Eukaryotic protozoa such as Paramecium also propagate through binary fission

Natural Cloning

Some animals, like Hydra undergo budding

www.saburchill.com/ans02/chapters/chap051.html

Hydra

Natural Cloning

http://www.saburchill.com/ans02/chapters/chap051.html

Some organisms undergo fragmentation

Starfish Filamentous algae

Natural Cloning

Some plants also undergo asexual reproduction

Stolons in grasses

Natural Cloning

Clones (plantlets) grow along leaf margins of Katakataka

Identical twins

From one zygote

(same DNA)

Natural Cloning

CLONING TECHNOLOGY

Artificial Cloning

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

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.

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

Traditional Reproduction and Cloning

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

Artificial Cloning Procedures

Cell or tissue culture (in

plants)

Embryo splitting

Nuclear transfer

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)

ANIMALS CAN BE CLONED

BY SEVERAL METHODS

Embryo splitting

Nuclear transfer

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.

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.

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.

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:

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

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).

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.

Benefits of Human Cloning

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

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

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

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

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.

Threat to Family

In the cloning process the basic relationships of the

human person are perverted: filiation, consanguinity,

kinship, parenthood.

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.

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.

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

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).

"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

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