Term
| Each of the two sister chromatids of a replicated chromosome has a ___(a)_____, a structure of proteins associated with specfic sections of chromosomal DNA at the centromere. |
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Definition
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Term
| An _(a)__, a radial array of short microtubules, extends from each centromere. |
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Definition
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Term
| The two centrosomes move apart during ___(a)___ , and ___(b)___ , of mitosis as spindle microtubules grow out from them. |
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Definition
(a): prophase (b): prometaphase |
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Term
| During ___(a)___ , in animal cells, the single centrosome replicates, forming two centrosomes, which remain together near the nucleus. |
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Definition
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Term
| In animal cells, the assembly of spindle microtubules starts at the ___(a)___, a subcellular region containing material that functions throughout the cell cycle to organize the cell's microtubules. |
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Definition
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Term
| Many events of mitosis depend on the ___(a)___. |
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Definition
| (a) mitotic spindle, which begins to form in the cytoplasm during prophase. |
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Term
| Mitosis, __(define)__, is usually followed immediately by __(b)__, the division of the cytoplasm. |
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Definition
(definition): the division of the nucleus (b): cytokinesis |
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Term
| The two chromatids, each containing an identical DNA molecule. are initially attatched all along their lengths by adhesive protein complexes called ___(a)___. |
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Definition
| (a):cohesion; this attatchment is known as sister chromatid cohesion. |
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Term
| Each duplicated chromosome has two __(a)__. |
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Definition
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Term
| Eukaryotic chromosoms are made of ___(a)___. |
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Definition
| (a) chromatin, a complex of DNA and assiciater protein molecules. |
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Term
| Reproductive cells are otherwise known as ___(a)___. |
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Definition
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Term
| Somatic cells are defined as __(a)__. |
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Definition
| (a): all body cells except the reproductive cells. |
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Term
| The replication and distribution of so much DNA is mangeable because the DNA molecules are packaged into ___(a)___. |
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Definition
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Term
| Prokaryotic genome is usually a __(a)__ long DNA molecule, eukaryotic genomes usually consist of a __(b)__ of DNA molecule(s). |
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Definition
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Term
| What are the 5 stages of mitosis? |
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Definition
1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase ** Overlapping with the latter stages of mitosis, cytokinesis completes the mitotic phase.** |
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Term
What happens during each phase of interphase? |
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Definition
G1 = cell grows S= continues to grow as it copies its chromosomes G2 = grows more as it completes preparations for cell division. M = divides |
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Term
| Interphase can be divided into which stages? |
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Definition
G1 ("1st gap"), S ("synthesis"), G2 (2nd gap"), M (division). **Chromosomes are only duplicated during the 'S' phase.** |
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Term
| It is during __(a)__ that the cell grows and copies its chromosomes. |
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Definition
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Term
| The__(a)__ phase usually alternates with the __(b)__ phase, which accounts for about 90% of the cycle. |
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Definition
(a): mitotic (M) (b): interphase |
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Term
| The __(a)__ phase is usually the shortest part of the cell cycle. (Includes both mitosis and cytokinesis.) |
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Definition
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Term
| The continuity of life is based on the reproduction of cells or __(a)__. |
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Definition
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Term
| Some things that cell division enables are: |
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Definition
1. sexually reproducing organisms to develope from a single cell -- the fertilized egg, or zygote. 2. The renewal / repair of cells that die from normal wear, accidents, or tear. |
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Term
| The cell division process is an integral part of the __(a)__, the life of a cell from the time it is first formed from a dividing parent cell until its own division into two cells. |
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Definition
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Term
| Passing __(a)__ to a cellular offspring is a crucial part of cell division. |
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Definition
| (a): identical genetic material |
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Term
| A dividing cell duplicates its DNA, allocates 2 copies to opposite ends of the cell, and only then splits into __(a)__. |
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Definition
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Term
| A cells endowment of DNA, its genetic information, is called its __(a)__ . |
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Definition
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Term
| A cells endowment of DNA, its genetic information, is called its ___(a)___. |
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Definition
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Term
| During prometaphase, what are the spindle microtubules that attach to the kinetochores are called? |
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Definition
| Kinetochore microtubules (the number of microtubules attatched to a kinetochore varies among species). |
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Term
| What is the plane (midway between the opposite ends of the cell) that the chromosome attatched to the kinetochore microtubule settles on? |
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Definition
| The metaphase plate (of the cell). |
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Term
What occurs during the G2 phase of Interphase? |
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Definition
- A nuclear envelope bounds the nucleus.
- The nucleus contains one or more nucleoli (singular, nucleolus).
- Two centrosomes have formed by replication of a single centrosome.
- In animal cells, eachcentrosome features two centrioles/
- Chromosomes, duplicated during the S-phase, cannot be seen individually because they have not yer condensed.
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Term
| What happens during Prophase? |
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Definition
- The chromatin fibers become more tightly coiled, condensing into discrete chromosomes observable with a light microscope.
- The nucleoli disappear.
- Each duplicated chromosome appears as two identical sister chromatids joined together at their centromeres and all along their arms by cohesins (sister chromatid cohesion).
- The mitotic spindle (named for its shape) begins to form. It is composed ot the centrosomes and the microtubules that extend from them. The radial arrays of shorter microtubules that extend from the centrosomes are called asters ("stars").
- The centrosomes move away from each other, apparently propelle by the lengthening microtubules between them.
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Term
| What happens during prometaphase? |
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Definition
- The nuclear envelope fragments.
- The microtubules extending from each centrosome can now invade the nuclear area.
- The chromosomes have become even more condensed.
- Each of the two chromatids of eachchromosome now has a kinetochore, a specialized protein structure located at the centromere.
- Some of the microtubules attatch to the kinechores becoming "kinetechore microtubules"; these jerk the chromosomes back and forth.
- Nonkinetochore microtubules interact with those from the opposite pole of the spindle.
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Term
| What happens during metaphase? |
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Definition
- Metaphase is the longest stage of mitosis, often lasting about 20 minutes.
- The centrosomes are now at now at opposite poles of the cell.
- The chromosomes convene on the metaphase plate, an imaginary plane that is equidistance between the spindles two poles. THe chromosomes centromeres lie on the metaphase plate.
- For each chromosome, the kinetochores of the sister chromatids are attatched to kinetochore microtubules comming from opposite poles.
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Term
| What happens during Anaphase? |
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Definition
- Anaphase is the shortest stage of mitosis often lasting only a few minutes.
- Anaphase begins when the cohesin proteins are cleaved, this allows the two sister chromatids of each pair to part suddenly. Each chromatid this becomes a full-fledged chromosome.
- The two liberated chromosomes begin moving twoards opp. ends of the cell, as their kinetochore mictorubules shorten. Because these microtubules are attatched at the centromere region, the chromoses move centromere first.
- The cell elongates as the nonkinetochore microtubules lengthen.
- By the end of Anaphase, the two ends of the cell have equivalent - and complete - collections of chromosomes.
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Term
| What happens during telophase? |
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Definition
- Two daughter nuclei form in the cell.
- Nuclear envelopes arise from the fragments of the parent cell's nuclear envelope and other portions of the endomembrane system.
- The chromosomes become less condensed. Mitosis - the division of one nucleus into two, genetically identical nuclei, is now complete.
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Term
| What happens during Cytokinesis? |
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Definition
- The division of the cytoplasm is usually well underway by late telophase, so the two daughter cells appear cells appear shortly after the end of mitosis.
- In animal cells, cytokinesis involves the formation of a cleavage furrow, which pinches the cell in two.
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Term
| By ___(a)____, the microtubules of the asters have also grown and are in contact with the plasma membrane. The spindle is now complete. |
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Definition
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Term
| What is the function of the nonkinetochore microtubules? |
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Definition
| In a dividing animal cell, these microtubules are responsoble for elongating the whole cell during anaphase. |
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Term
| During anaphase, the region of overlap is reduced as ___(a)___ attatched to teh microtubules walk them away from one another, using energy from ATP. |
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Definition
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Term
On the cytoplasmic side of the furrow is a contractile ring of actin microfilaments associated with molecules of the protein myosin. What "furrow" is this referring to? |
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Definition
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