I was watching an animation video about Meiosis and this is what the video shows (pics attached.) It shows that before synthesis, each chromosome exists as single chromatid and then after replication, it has a sister chromatid. I am confused because germ cells are diploid, so shouldn't the S phase look like this? It should start with 23 chromosomes (46 different DNA's) and then replicated to 46 chromosomes (92 different DNA) which then get assorted into 4 different cells?
In terms of chromosome number
During meiosis, the meiocyte is a diploid cell ( 46 chromosomes for human). So during the S-phase , the meiocyte would contain 46 chromosomes.
At the end of meiosis I, the divided meiocyte contains 23 chromosomes so it's called the reductional division
At the end of meiosis II each cell contains 23 chromosomes.
In terms of chromatid number and number of DNA molecules
Meiocyte in S phase contains 2 chromatid so the number of DNA molecules is doubled (if you consider that each chromatid is composed of a pair of DNA strands like in Watson Crick Model, then each chromosome of S phase contains 4 strands... So 46×4 strands of DNA is present. Often each helix / duplex is considered one DNA molecule , so in that case you have 46×2 molecules. So you have to be careful with the terminology mentioned.
After meiosis I there are 23 chromosomes in each divided cell with 2 chromatids in each chromosome...So there are 23×2 DNA molecules.
After meiosis II there are 23 chromosomes with 1 chromatid...So they contain only 23 DNA molecules.