how many dna replications are there is mitosis?? what about meiosis??

Question

please explain

lol omg this is so confusing!! thats why im asking, i dont understand if a dna replication means just one of the chromosomes, so therefore there would be 2 replications, or if it is just talking about the S phase is the only time that dna is replicated!!! ugh, thanks for helping guys...lol

Answer 1

One and only one DNA replication event each. All the rest is manipulations of the chromosomes.

Answer 2

only 1 period of dna replication in both. G1 phase is for growing the cell the first time. S phase is for synthsizing proteins and dna replication and G2 phase is the second period of growth. Mitosis and meiosis are the exact same up until the second spliting. instead of having 2 cells with identical dna and 46 chromosomes each, they split again to have 4 cells with 23 chromosomes each. Meiosis only occurs in sex cells and the final products are gametes

Answer 3

Mitosis replicates each pair of chromosome once.

In miosis, I believe that each is also replicated once, but the two chromatids in the pair are seperated into different cells (sperm or egg)

Answer 4

In mitosis there is one replication per each D.N.A. strand. Which equals two in total. Mitosis is the splitting of one cell into two daughter cells.D.N.A. in each cell nuclease somes in a double strand for all higher organisms. (i.e. eukaryotes). It is a different matter in more primitive organisms. (prokaryotes). Euklkaryotes usually underfo sexual reproduction at some pont in the organisms life. Thke germ ceoos, sperm cells and egg cells, have single sranded D.N.A. until they are fertilised. in other words the single strand D.N.A. of the sperm cell upon fertilisation joins the single strands oif D.N.A. of the egg cell and a double strand of D.N.A. results. Sexual reproduction must have a reduction dividion of the D.N.A. in order to produce that single strand of D.N.A. that combines with the other set from your partner's germ cell in order to form the double stranded chromosome of the fertilised germ cell (the egg cell). This occurs when the D.N.A double strand of the sperm or the egg cell splits into two sets and the single strands of each set are copied. The resulting four sets of singlet D.N.A. each get packaged into one of four resulting germ cells. (e.g. sperm cells).
In order to make the assortment of two sets of chromosomes in mitosis and initially in meiosis (redution division). D.N.A. condences to form chromosomes. Similar chromosome strrands line up side by side into pairs before al the chromosomes split into two groups. The linig up in is not orderly. The chromatids ooriginally derived from your father do not line up on one side (& those of your mother line up on the other side. The lining up is independent for each chromosome. Each group of chromosomes that split have some mother derived chromatids and some other father derived chromatids. This is a great source of genetic change. Another great process of change happens when the chromatid pairs are lined up as chromosomes. they undergo a process of crossing over of portions of one chromosome strand (= chromatid) are swapped with the corresponding portion on the other chromatid. The pairs of single D.N.A. chromatids are each copied in meiosis and the two groups split again. Each set (= 4) ends up in a germ cell.
It's easier to visualise the process.
If I have not been clear google a genetics text for pictures.
Dan.