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Tag: Biology

Micropropagation/Tissue Culture

If you already have an animal or plant with all the characteristics you want, then it would be ideal just to make loads and loads of identical copies of it. That is what cloning is making; genetically identical copies of organisms. This is done naturally in nature by organisms that do asexual reproduction by mitosis that produce exactly identical organisms.

Only one parent; there are no gametes involved, there is no mix in genetic information and all. The ostrich Ashley identical to each other so that is a type of cloning. Asexual reproduction; another type of cloning that done very easily is taking cuttings from plants has been done for hundreds of years. Gardeners take a separ cut off a stem from a plant that they particularly like and they stick that stem of the plant in the ground and it will grow into the same as their parent.

Plants though can be cloned now in a much more commercial scale by a more scientific process called tissue culture. Now, this is a sophisticated scientific technique which can produce thousands of clones in a short space of time and it’s known as micro propagation. The way you do it is; you find the plant you want with the desired characteristics. First growers can then just take a few plant cells from the tips of the shoots or the roots. We call these ex plants then they sterilize them to clean a micron ism’s and they place them in a little petri dish containing nutrient medium. They say they are grown in vitro. What we mean by that is in a lab outside the normal biological context, this nutrient medium contains all the growth hormones and the nutrients for the shoots and the roots to start growing.

So, just from a few tiny cells, you can start to get these tiny little plants. Growing the shoots are then removed from those initial ex plants. Once they get going and you can then move those to another Petrich and keep repeating it and repeating and repeating or repeating it. So, from one original plant you can end up getting thousands of ex plants which then will grow under optimal conditions into full size plants which can then be transferred into compost and into greenhouses to develop fully. They will all be identical to the original plant. Again, this is done all the way around the world in order to maximize the yield of certain crops such as bananas.

Now, there’s some good things about cloning plants. You get large quantities of plants very quickly. You can grow plant all year round. You can clone a bit rare or endangered plants to increase populations. New plants grown in sterile conditions so they’re pests and disease free.

If you did genetic engineering on a plant first and then cloned it, you would enough to do genetic engineering again. Because you’ve only had to do that complex process once and then you just clone that one of those at times. However, all the offspring are identical genetically and that means they are very vulnerable to diseases. You also need sterile lab facilities and they’re also really vulnerable to pests.

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Cloning will generate more human organs

The ability to create a clone used to be science fiction. Dr. Ian Wilmut’s group changed that in 1997 with the creation of Dolly the sheep. Since then, the debate on applying the technique to clone human beings has been ongoing.

Based on all the discussion, it may sound like cloning, human or otherwise, is an easy process.  

Simply put, clones are organisms that have identical genetic material. In other words, the sequence of bases in their DNA is exactly the same. Long before the birth of Dolly the sheep, clones had been observed in both nature and in the laboratory. When a couple has identical twins (or identical triplets, etc.), the children are clones of one another. A plant cutting can also be used to generate a clone.

Prior to 1996, it was thought that cloning an entire animal could only be done with embryonic cells; cells present in the early stages of an organism’s development. In the 1950s, scientists generated entire frogs from embryonic frog cells. After a small number of cell divisions, embryonic cells start to change into the different types of cells that an organism needs, ┬áincluding cells that form muscle, blood, liver, etc. This process is called differentiation.

Although each of these cells has the same genetic material, each cell can only access the genes needed for its particular function. Before the experiment at the Roslin Institute, it was thought that once cells differentiated, they could not be used to generate an entire organism. For instance, in a sheep, udder cells could generate other udder cells, but not an entire sheep. The scientists at the Roslin Institute solved this problem by growing sheep udder cells under starvation conditions. This put the cells in a state similar to embryonic cells. This is called the G0 state.

An egg cell was taken from another sheep. The nucleus, which contains the genetic material, was removed from the egg cell using a very fine needle. They then used electric shock to fuse one starved udder cell with one nucleus-free egg cell. They made 277 of these fused cells. Although the egg cell came from a black-faced sheep, notice that the nucleus with the genetic material came from the white-faced sheep. These fused egg cells were then inserted into several different sheep. These surrogate mothers were also black-faced. Of the 277 fused cells, only one progressed to form a developed lamb.

Dolly was born on July 5, 1996. Scientists found that Dolly had the same DNA as the udder cells she came from. She is a clone of these udder cells. Dolly has given birth to a lamb named Bonnie, produced the natural way. Other lambs have been born at the Roslin Institute through their cloning process; some carry genes that will produce usable human drugs. A laboratory in Hawaii run by Dr. Ryuzo Yanagimachi was the second group to successfully clone an animal from an adult cell. They cloned mice using cumulus cells, a cell type found in the ovaries. The cloning method used by the lab in Hawaii was different in two ways from the method used to clone Dolly.

First, the cells used to clone the mice were not grown in culture, but instead were used immediately. Second the nucleus was removed from the cumulus cell and then directly injected into the egg cell. This egg cell’s nucleus had already been removed. The Yanagimachi lab used coat color to track genetic heritage. The cumulus cell comes from an agouti (brown) mouse, and the egg cell comes from a black mouse. The egg cell now had the same genetic information as the nucleus donor mouse. The egg cell was then activated and implanted into a white host mother.

On October 3, 1997, the host mouse gave birth to Cumulina, named after the cumulus cells she was cloned from. Cumulina is the same color as the mouse that donated the nucleus. DNA fingerprinting confirmed that Cumulina had the same DNA as the nucleus donor. The scientists have taken cells from Cumulina to make more clones. They have successfully made several generations of clones and all mice seem normal.

Dolly the sheep died at the age of six. Since the world said hello to Dolly, several other animals have also been cloned. Both Dolly and Cumulina were cloned from cells in the female reproductive system; cows have also been cloned using ovary and cumulus cells with the same method that was used to clone Dolly. Pigs have been added to the cloned animal menagerie.

Scientists hope to use cloned pigs to grow organs that can be transplanted into humans.

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Biology IGCSE Edexcel Paper 1

Hi, everyone. The video below will give you a quick review of the Edexcel Biology IGCSE Paper 1 syllabus.

Lesson centered on:

  • Characteristics of living organisms
  • Variety of living organisms
  • Level of organisation
  • Cell structure
  • Biological molecules
  • Movement of substances into and out of cells
  • Nutrition
  • Respiration
  • Gas exchange
  • Transport
  • Excretion
  • Co-ordination and response
  • Reproduction
  • Inheritance
  • The organism in the environment
  • Feeding relationships
  • Cycles within ecosystems
  • Human influences on the environmen

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