Recall that DNA is replicated during the S phase of the cell cycle. Thus during metaphase of mitosis, each chromosome (i.e., each chromatid pair) will contain two molecules of double stranded DNA (one molecule per sister chromatid).
What stage of mitosis are the chromosomes double stranded?
Chromosomes are double stranded in Prophase and metaphase and single stranded in anaphase and telophase. Identical copies of a chromosome that are connected together at the centromere.
At what stages of the cell cycle are double chromosomes present in the cell?
In the S phase (synthesis phase), DNA replication results in the formation of two identical copies of each chromosome—sister chromatids—that are firmly attached at the centromere region. At this stage, each chromosome is made of two sister chromatids and is a duplicated chromosome.
Which phases of meiosis have double stranded chromosomes?
Science – Chapter 4
|zygote||the cell formed from fertilization|
|meiosis I||same step as mitosis (prophase I, metaphase I, anaphase I, telophase I) each chromosome pair is double stranded|
|meiosis II||prophase II, metaphase II, anaphase II, telophase II|
|prohase II||double stranded chromosomes and spindle fibers reappear|
What stage is chromosome double?
So during a mitotic cell cycle, the DNA content per chromosome doubles during S phase (each chromosome starts as one chromatid, then becomes a pair of identical sister chromatids during S phase), but the chromosome number stays the same.
What are the 4 stages of the cell cycle?
In eukaryotes, the cell cycle consists of four discrete phases: G1, S, G2, and M. The S or synthesis phase is when DNA replication occurs, and the M or mitosis phase is when the cell actually divides. The other two phases — G1 and G2, the so-called gap phases — are less dramatic but equally important.
In which phase of mitosis does the number of chromosomes in a cell double quizlet?
Chromosomes are duplicated only during the S phase (“S” stands for synthesis of DNA). The phase following completion of the S phase is G2. In telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils.
What happens during G2 phase?
During the G2 phase, extra protein is often synthesized, and the organelles multiply until there are enough for two cells. Other cell materials such as lipids for the membrane may also be produced. With all this activity, the cell often grows substantially during G2.
During what stage does G1 S and G2 phase happen?
Interphase is composed of G1 phase (cell growth), followed by S phase (DNA synthesis), followed by G2 phase (cell growth). At the end of interphase comes the mitotic phase, which is made up of mitosis and cytokinesis and leads to the formation of two daughter cells.
What phase is between G1 and G2?
|1.||S phase or synthesis phase is the second sub-phase of interphase.|
|2.||It occurs in between the G1 (Gap 1) phase and G2 (Gap 2) phase.|
|3.||It is the phase of the cell cycle in which DNA replication takes place.|
When in the cell cycle do single stranded chromosomes become double stranded?
During anaphase each chromosome present in metaphase separates into two chromosomes, each with a single double-stranded DNA molecule. Therefore, during anaphase the chromosome number is temporarily doubled until the cells finish the process of cell division.
During what phase of meiosis do double stranded chromosomes move to opposite poles?
Next, during anaphase, the centromeres holding the sister chromatids together are divided and the sister chromatids are pulled apart by the spindle fibers to opposite poles of the diving cell. During the last phase of mitosis, telophase, the two sets of chromosomes reach the opposite poles of the cell.
Are chromosomes double stranded in meiosis?
During meiosis, cells deliberately form numerous DNA double-strand breaks (DSBs) in order to initiate homologous recombination, which exchanges genetic information between homologous chromosomes and promotes accurate chromosome segregation.
During which phase of the cell cycle are the chromosomes duplicated quizlet?
Chromosomes are duplicated only during the S phase (“S” stands for synthesis of DNA) of interphase of the cell cycle.
Which phases of the cell cycle will have cells with twice the amount of DNA Explain you answer?
Interphase is the longest phase of the cell cycle. Cell growth is central to the cell cycle, and this is the primary purpose for interphase. At the end of this phase, there is double the amount of DNA, centrioles have replicated, and the cell is big enough for cell division.
How many duplicated chromosomes are present at each stage of mitosis?
For humans, this means that during prophase and metaphase of mitosis, a human will have 46 chromosomes, but 92 chromatids (again, remember that there are 92 chromatids because the original 46 chromosomes were duplicated during S phase of interphase).