question 1. are sister chromatids present in all or part of this phase? 2. is the dna condensed in all or part of this phase? 3. does the cell contain twice as much dna in this phase as it did in the g₁ phase? g₁ s g₂ beginning of m (prophase→ early anaphase) (late anaphase→ telophase) end of m

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Accepted Answer

# Brief Explanations:
- **For $G_1$ phase**:
    - Sister chromatids are formed after DNA replication in the S - phase. Since $G_1$ occurs before S - phase, sister chromatids are not present. So, the answer to "Are sister chromatids present in all or part of this phase?" is "no".
    - DNA condensation (into chromosomes) mainly occurs during mitosis (M - phase). In $G_1$, DNA is in a less - condensed form (chromatin), so the answer to "Is the DNA condensed in all or part of this phase?" is "no".
    - $G_1$ has the same amount of DNA as the cell in $G_0$ (a non - dividing state). It has not yet replicated its DNA (which happens in S - phase), so it does not have twice as much DNA as in $G_1$ (it has the same amount), and the answer to "Does the cell contain twice as much DNA in this phase as it did in the $G_1$ phase?" is "no".
 - **For S phase**:
    - Sister chromatids are formed during S - phase as DNA replication occurs (each chromosome now has two sister chromatids attached at the centromere). So, the answer to "Are sister chromatids present in all or part of this phase?" is "yes".
    - DNA is in a relatively un - condensed form (chromatin) during S - phase (condensation occurs in M - phase), so the answer to "Is the DNA condensed in all or part of this phase?" is "no".
    - S - phase is the period of DNA replication. By the end of S - phase, the cell has twice as much DNA as it did in $G_1$. So, the answer to "Does the cell contain twice as much DNA in this phase as it did in the $G_1$ phase?" is "yes" (by the end of S - phase).
 - **For $G_2$ phase**:
    - Sister chromatids, which were formed in S - phase, are still present in $G_2$ (as the cell prepares for mitosis). So, the answer to "Are sister chromatids present in all or part of this phase?" is "yes".
    - DNA is in chromatin form (un - condensed compared to mitotic chromosomes) in $G_2$, so the answer to "Is the DNA condensed in all or part of this phase?" is "no".
    - $G_2$ occurs after S - phase, so the cell has already replicated its DNA. It has twice as much DNA as it did in $G_1$, so the answer to "Does the cell contain twice as much DNA in this phase as it did in the $G_1$ phase?" is "yes".
 - **For (prophase - early anaphase)**:
    - Sister chromatids are present from prophase (where chromosomes, each with two sister chromatids, are visible) until anaphase (where sister chromatids separate). So, the answer to "Are sister chromatids present in all or part of this phase?" is "yes".
    - DNA is condensed into chromosomes during prophase (a key event of mitosis), so the answer to "Is the DNA condensed in all or part of this phase?" is "yes".
    - The cell has already replicated its DNA in S - phase. In (prophase - early anaphase), the cell has twice as much DNA as in $G_1$ (until cytokinesis occurs). So, the answer to "Does the cell contain twice as much DNA in this phase as it did in the $G_1$ phase?" is "yes".
 - **For (late anaphase - telophase)**:
    - In late anaphase, sister chromatids have separated (they are now individual chromosomes). So, sister chromatids are not present in late anaphase - telophase. The answer to "Are sister chromatids present in all or part of this phase?" is "no".
    - DNA starts to de - condense in telophase (after being condensed during mitosis). But during anaphase (even late anaphase), chromosomes (condensed DNA) are still present. However, as the cell moves into telophase, the condensation state changes. But overall,  in (late anaphase - telophase), we can consider that the main event related to condensation is de - condensation (telophase), but anaphase still has condensed chromosomes. But if we consider the whole (late anaphase - telophase) period,  the answer to "Is the DNA condensed in all or part of this phase?" is "no" (because telophase is part of this phase and DNA de - condenses).
    - The cell has already replicated its DNA in S - phase. In (late anaphase - telophase),  before cytokinesis, the cell still has twice as much DNA as in $G_1$. So, the answer to "Does the cell contain twice as much DNA in this phase as it did in the $G_1$ phase?" is "yes" (before cytokinesis).

# Answer:
| Phase | Are sister chromatids present in all or part of this phase? | Is the DNA condensed in all or part of this phase? | Does the cell contain twice as much DNA in this phase as it did in the $G_1$ phase? |
|---|---|---|---|
| $G_1$ | no | no | no |
| S | yes | no | yes |
| $G_2$ | yes | no | yes |
| (prophase - early anaphase) | yes | yes | yes |
| (late anaphase - telophase) | no | no | yes |

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Explanation:

Answer:

Phase	Are sister chromatids present in all or part of this phase?	Is the DNA condensed in all or part of this phase?	Does the cell contain twice as much DNA in this phase as it did in the \(G_1\) phase?
S	yes	no	yes
\(G_2\)	yes	no	yes
(prophase - early anaphase)	yes	yes	yes
(late anaphase - telophase)	no	no	yes