Mitosis and Meiosis Onion Cell Lab AP Bio

Differences in Mitosis in plants vs animals

1) Cytokinesis (not a part of Mitosis part sometimes (as in oninion cells) occurs simutaneously with Telophase) Animal cells form new cleavage furrow while plants form a new cell plate(myosin and actin vs proteins from plant's golgi app. vesicles) 2)Where it takes place (maristem vs everywhere) 3)PLANTS DON'T HAVE CENTRIOLES , well complex plants don't. They create a preprophase band of microtubules, but less complex plants do have centrioles.

Chromosome vs Chromatids

A Chromosome is a strand of chromatin that has been condensed. After replication in the S phase of Interphase, that single Chromosome gets copied. Thus, the two new twins are each SISTER chromatids. Together they are one chromosome. After replication the individual chromosomes are referred to as chromatids, so as to say that replication has already occured. After anaphase, when the two sisterchromatids separate, apart they are now chromosomes once again.

Prophase

A WHOLE LOT boi. The nuclear envelope and nucleoli break down, the centrosomes start to move to opposite poles of the cell, the asters and mitotic spindle forms, and sister chromatids connect to each other via sister chromatid cohesion and connect at their centromere. Microtubules polmerize (add tubulin). Some microtubules become kinetochore microtubules by connecting to the protein complexes called kinetochores that coat the centromeres of each sister chromatid

In general, where does mitosis occur in an animal?

Anywhere it is needed. Whenever you get cut, just to replace old cells

Based on the date in Table 3.1, what can you infer about the relative length of time an onion root tip cell spends in each stage of cell division

As with most cells (rem that each cell approximately spends 90% in interphase) the onions cells spend most of their time in interphase, in preparation for Mitosis. The spend the second most amount of time in Prophase, a lot of stuff has to occur during this phase: too many cooks, too many things to do takes a long time. The length f every other phase depends upon where in the root you inspect, it takes a while to make sure the Sister chromatids are aligned properly on the metaphase plate (rem. M checkpoint), Anaphase takes time separate, Telophase is relatively quick.

What point in the Cell Cycle is DNA replicated

Interphase, during the S phase (DNA Synthesis)

Telophase

Nuclear envelope and nucleoli reappear, chromosomes decondense.

Anaphase

The cohesins connecting the sister chromatids cleave, making it easier for the kinetochore mictrobules to separate the two. Thus the kinetochore microbules depolymerize (lose tubulin), where as the other microtubules polymerize.

In general, where does mitosis occur in a plant?

The meristem (tips of stems or at the roots)

Metaphase

The sister chromatids are aligned along the Metaphase plate by dint of the kinetochores mircotubules pulling their respective sister chromatid into place. M checkpoint at the end to make sure they are aligned properly. Centrosomes are now on opposite poles of the cell.