Chromatid Questions: What, Why, How, 2 Sets, Homologous

[isyang94]

Is a chromosome, two chromatids bonded together by a centromere? then, what is a chromatid?

Also what is meant when they say that there are two sets of chromosomes? do they mean that there are 2 chromosomes together with four chromatids?

what also is the difference between homologous chromosomes and a regular chromosome?

Sorry for asking all these questions at once, but it is indeed urgent, considering that i have a unit test tomorrow.

Please answer as easy as possible

thank you so much

 

[Ryan_m_b]

Chromatids are string-like DNA structures. Two of them bind together to form a chromosome. Chromosome come in pairs (so yes there would be 4 chromatids)

Homologous chromosome are chromosomes with the same length, centromere position and genes in the same loci.

I'm afraid I'm sure what you mean by a regular chromosome

Some helpful links

Chromatid - http://en.wikipedia.org/wiki/Chromatid
Chromosome - http://en.wikipedia.org/wiki/Chromosome
Homologous chromosome - http://en.wikipedia.org/wiki/Homologous_chromosome
Regular chromosome -

 

[mishrashubham]

Is a chromosome, two chromatids bonded together by a centromere? then, what is a chromatid?

A chromosome is a single long molecule of DNA bound with many proteins and which exists as chromatin when the cell is not dividing and condenses into a more compact form during division. Since each Daughter cell must get the same number of chromosomes, each of it must be replicated to form a new chromosome. And these two identical copies, joined together at their centromeres are called chromatids. Each of this pair will go into one of the two daughter cells.

Chromatid is a term used only during cell division.

Also what is meant when they say that there are two sets of chromosomes? do they mean that there are 2 chromosomes together with four chromatids?

When the cell is not dividing, it has two sets of each chromosome (and each set is called a pair of homologous chromosomes). During cell division each set will result in two chromatids, so yes, you could say that in a brief period of time between prophase and anaphase you have four chromatids.

what also is the difference between homologous chromosomes and a regular chromosome?

Homologous is just a term for comparing two chromosomes. If you take two chromosomes and find that they are of the same length, have same centromere position and have the same genes at the same location, then they are homologous, that's all.

Sorry for asking all these questions at once, but it is indeed urgent, considering that i have a unit test tomorrow.

Please answer as easy as possible

thank you so much

Try studying well in advance next time. Good luck.

 

[ZealScience]

Chromatids are just replications of each other, during the synthesis phase of the inter phase, DNA would replicate. Only during metaphase, they are scatterred by spindle fibres and forms two sets of chromosomes in each daughter cell.

But a pair of chromosomes have different locus or differnt gene information involved, whereas chromatids are identical (except from miscopied ones which are mutations).

To sum it up, basically chromatids and chromosome pairs are different concepts, one chromosome can have two chromatids, but chromosomes are always present in pairs.

In addition, they are present in form of chromatins during interphase which is not arranged.

That's what it is during mitosis. But there are more concepts involved in meiosis.

 

[mishrashubham]

In addition, they are present in form of chromatins which is not arranged. That's what it is during mitosis. But there are more concepts involved in meiosis.

No, mitosis also requires the condensation of chromatin.

 

[ZealScience]

No, mitosis also requires the condensation of chromatin.

Sorry, my fault, I mean during interphase, I will correct that.