major confusion >.< plz help (1 Viewer)

[Michiru]

hi hi

is it just me or is the genetics option really really confusing?
could anyone please help me answer some baffling questions?

is trisomy the same as triploid? if not, what's the difference
between the two?


also, what's the difference between crossing over and translocation?

and is recombinant DNA the same thing as gene cloning?

thanks

 

[jessied]

i do genetics and i find it confusing/boring.. but i think i can help you with some of those questions...

im pretty sure trisomy is the inheritance of an extra chromosome (eg down's syndrome, the interitance of 3 copies of chromosome 21) whereas triploid is the inheritance of a whole extra set of chromosomes (this happens during the 1st stage of meiosis) so that the organism has 3n chromosomes instead of the usual 2n

crossing over occurs between sister chromatids (the same chromosome) during meiosis where im pretty sure translocation can occur between any 2 chromosomes..

hope that helps.. (and makes sense)

 

[Survivor39]

1. jessied got it right for the trosomy/triploidy.

2. jessied didn't exactly got it correct. Crossing over is where two homologous chromatids exchange genetic materials, NOT sister chromatids. For example, the chromatids of chromosome 1 and a chromatids of chromosome 2 swap some part of their "arms" or segment of DNA. Sister chromatids on the same chromosome do not exchange DNA because they are the exact copy of each other. (Note: do not get confused with homologous chromosomes and chromatids)

Translocation is a type of mutation where a segment of DNA move from one chromosome to another non-chromosome. e.g a piece of DNA move from chromsome 1 to chromosome 2.


3. Recombinant DNA is just a term that describe a DNA that is made by joining DNA from different organisms.

Gene cloning is a technique to try and make more copies of this gene you want. All you do is insert this whatever gene into a plasmid and insert it into a bacterium and it will divide etc and many copy of the gene can be made. Or use PCR (Polymerase Chain Reaction) and make multiple copies of this gene.

I hope this help. Genetics is a great topic. Just don't get too technical with these terms and just understand the basic and you'll be fine.

 

[Michiru]

hey jessied and Survivor39, thanks a lot for the help! ^-^v

um..i still have some questions....

just to clarify, crossing over has to do with chromatids, whereas transloation is about chromosomes, right?

and sorry... i'm still slightly confused over the recombinant DNA vs gene cloning... Survivor39, isn't what you described in the gene cloning process also the the process to produce recombinant DNA?

 

[tristan88]

Crossing over occurs between chromatids during meiosis when they touch (chiasma).

Certain genes are isolated and are cut using restriction enzymes. They are joined using ligase to form a plasmid. They are inserted into bacterium as plasmids (circular double-helix DNA). Insertion can occur under certain conditions. For example, the cell membrane is denatured to produce holes (heated) and is then quickly cooled to seal. When binary fission occurs they reproduce and the genes inserted are expressed, that is if they were successful in penetrating the cell membrane.

PCR is another form of replication of genes. Primers, nucleotides and DNA polymerase are used. They can produce larger quantities of certain genes which is one of the reasons whys it is used in biotechnology today. The process can be repeated by heating and cooling. The disadvantage is that you have to know the DNA code for the information for which you are repeating, and what that is.

 

[Survivor39]

Yes, crossing over involves chromatids and translocation involves the movement of DNA from one chromosome to another.

Recombinant DNA is only a part of gene cloning. The term recombinant DNA is a loose term which just simply means a DNA that is made up from different organism. But in gene cloning, you can either create a recombinant DNA and make many many copies of this DNA (hence the term cloning) OR you can just put this gene into a machine and the machine will just make many many copies of it. Therefore, both terms are different. Remember, you don't have to produce a recombinant DNA for gene cloning.

 

[jessied]

sorry about getting the crossing over thing wrong.. i was just relaying what my teacher had said (which is obviously wrong)...