Can someone briefly tell me in both Mitosis & Meiosis when chromosomes (at what stages) chromosomes are single

Question

stranded and what stages are they haploid or diploid?

Answer 1

Mitosis
Chromosomes become double-stranded during the S stage of interphase; still double in prophase and metaphase; split apart in anaphase to become single; still single in telophase. In mitosis of an organism whose cells are diploid, every stage is diploid - never haploid.

Meiosis:
Again, chromosomes become double-stranded during the S stage of interphase.
Double-stranded in--
prophase I (
metaphase I
anaphase I
telophase I
prophase II
metaphase II

That's when they split apart and become single stranded:
anaphase II
telophase II

During meiosis, the cells are diploid from interphase through prophase I, metaphase I.
Anaphase I separates the homologous pairs from each other, so from anaphase I through the end of all of meiosis the cells are haploid.

Answer 2

Ok first, let's sort out the terminology. When two DNA molecules are joined together, each molecule is called a chromatid and the two of the molecules are called a duplicated chromosome. When a DNA molecule(and proteins) is not attached to another one then that single molecule of DNA is not a chromatid but an unduplicated chromosome. 2 chromatids which are joined together at the centromere only exist after Prophase, that is, after DNA replication has been undergone to produce another identical copy of the starting chromosome. In total, we have 46 chromosomes, however, these 46 chromosomes include homologous pairs, which when joined together, form 23 PAIRS of homologous chromosomes. They are NOT a duplicated copy of each other. I don't know if you know what being "homologous" means. Basically, 2 chromosomes that code for the same characteristics are said to be "homologous". In the locus of eye colour for example, a chromosome which codes for blue eyes and another which codes for brown eyes are BOTH homologous to each other. I hope you get what I mean.