Can someone translate this more simply please...?

Question

Tetraploid expansions are common in plants. They can be induced with the compound colchicine which prevents segregation of chromosomes during mitosis. The cells wind up with twice as many genes in the same cell, creating the same balance on genes. During replication, they are able to segregate their genes and function. When crossed with their parent strain, they produce and infertile triploid plant which cannot segregate its chromosomes in a balanced fashion. In general, this does not occur in animals. Tetraploid cells will not develop in sequence. There are a variety of factors involved.

It should be noted that some giant protozoa use a comparable strategy. Paramecia produce copies of their reproductive nucleus (the micronucleus) that can produce enough RNA for the cell of that size from a working somatic nucleus (the macronucleus). In comparison, the giant amoeba has thousands of chromosomes, many duplicates, to support the cell.

This was an answer from novangelis but I can't understand it!

Answer 1

diploid= chromosomes are in pairs, basic set in biology

diploid cells undergo meiosis lose half the chromosomes and become haploid

diploid cells undergo mitosis and remain diploid

diploid cells undergo mitosis and fail to segregate properly=

tetraploid = chromosomes in quadruplet  

Answer 2

search it in the world wide web and pay attention when classes is going on for you to understand the lessons being teach

Answer 3

Tetraploid expansion occurs when the number of copies of the genome carried in the nucleus increases to 4 (called an autotetraploid). Many plants are diploid, however it is not uncommon for some plants to be tetraploid, or hexaploid, or even more.

Molecular evidence suggests that in plants the genomes tend to expand and contract over evolutionary time: for example a plant will expand from 2n (diploid) to 4n (tetraploid) and then there will be a series of chromosome rearrangements, deletions, etc. and eventually there will be a return to diploid status.

In many cases the genomes from two different species can combine forming an allotetraploid. One example of this is wheat, which is a hybrid of two ancestral grasses.

Being tetraploid can be problematic. During meiosis chromosomes must undergo crossing over by homologous recombination. If there are four copies of each chromosome, this can make alignment for crossover difficult, and can reduce (or eliminate) the number of viable gametes produced. This is more of a problem for autopolyploids than allopolyploids. Please note that in all polyploid species studied to date crossover is essential. Individuals who are not able to undergo crossover are invariably sterile.

The same problem exists for triploid organisms. With three copies of each chromosome present pairing for crossover is near impossible. Seedless grapes are an example of a triploid plant. They are generally larger in size than "normal" grapes, and produce no seeds because meiosis is aborted due to chromosome mispairing. The net result is no seeds.

Colchicine inhibits microtubule formation, which prevents segregation of the chromosomes during anaphase of mitosis. Cells entering mitosis (following replication) have duplicated their genomes. By treating with colchicine you prevent the cell from dividing, so you have created a tetraploid cell (which in plants can be cultured into mature individuals).

It is important to stress that the process of genome duplication does happen naturally in plants and some animals.Some reptiles also do this as well as some protozoans.

It's a complex topic, but I hope I helped.

Answer 4

That's about as simple as it gets.  If you can't understand it, you need to pay more attention in class.  You'd better hope you're not too far behind to catch up.

Answer 5

Okay, let me try to do this in a few simple words:

Normally in the cell cycle, DNA replicates and then the cell divides by mitosis, followed by cytokinesis where the cell physically splits into two.  

However, if you add colchicine at the right point, cytokinesis can't happen because it inhibits the formation of microtubules needed.  That means you've now got essentially have the DNA for two cells but in one physical cell.  So, you have twice the amount of DNA.  If the plant cell was originally diploid (2n), then now it is tetraploid (4n).

When this 4n plant goes through meiosis to make sperm or eggs, it produces gametes that are 2n (because meiosis makes s*x cells with half the DNA).  If you then fertilize a 2n egg with a regular haploid (n) sperm from a normal 2n plant, you get a zygote that is triploid (3n).  

Being triploid is a problem when it's time to make gametes because you don't have pairs of chromosomes to pair up during metaphase.  Therefore, 3n plants are generally sterile.  This is how seedless fruits are usually made.