I\'ve read the text but I\'m having a lot of trouble with this section, can some

Question

I've read the text but I'm having a lot of trouble with this section, can someone please help me understand this material?

1. The eukaryotic cell cycle is entirely composed (or would be correctly described) as mitotic cell division and meiosis.

True / False ?



2. During mitosis, the sister chromatids line up along the metaphase plate with ____________________, while in meiosis I, metaphase I, the sister chromatids line up along the metaphase plate ______________________.
Answer
A. tetrads, bivalent
B. tetrads, single row of sister chromatids
C. single row, double row (bivalents)
D. none of the above


3. Mitosis includes the G1, S, and G2 phases, while meiosis does not.
True / False


4. The normal number of chromosomes in a human gamete is 23, while the number of chromosomes in a human germ-line cell is 46 chromosomes.
True / False


5. After the DNA synthesis phase in a normal eukaryotic cell, which preceeds mitosis or meiosis, but before cell division, you have essentially how many chromosomes (chromatids)?
__________

6. Imagine that during prometaphase II and metaphase II of meiosis II, you have a problem with the spindle and the microtubule attachment to a pair of sister chromatids. As a result, instead of proper sister chromatid separation during anaphase II, you have a situation where chromatids do not separate and instead both move to one of the two poles (call it A) in one of the four resulting gametes. This is termed non-disjunction.
How many chromosomes would the abnormal gamete (in a female human) cell which had the sister chromatids move toward it (A) contain? Assume this event was the only error in this particular case.
__________

7. Consider the previous question describing a single meiosis event. The probability that the gamete (in this case of a female human) containing the abnormally high chromosome number would be the one that takes part in a fertilization event by a sperm cell is 25% (1/4).
True / False


8. During meiosis, sister chromatids separate during the first division creating two daughter cells.
True / False


9. There is evidence from recent scientific publications on the process of cell division that_________________________.

A. Nuclear membrane dissociation is related to the nuclear lamin protein breakdown and to some extent the direct influence of the microtubules of the mitotic spindle beginning during prophase.
B. Nuclear membrane dissociation is related to nuclear lamin protein breakdown and to some extent the direct influence of the endoplasmic reticulum, whose membrane is continuous with the nuclear membrane.
C. Nuclear membrane dissociation is directly affected by protein signalling during the G1 phase checkpoint.
D. Nuclear membrane dissociation is related to the nuclear lamin protein breakdown and to some extent the direct influence of actin and other cytoskeletal elements during telophase.


10. Chromosome number can naturally vary widely between species, and usually more narrowly with a species, depending on environmental effects as well abnormalities in relation to inherited disorders. For example, a normal labrador retriever has approximateley ______ chromosomes in a somatic cell, while a fruit fly has ______. Abnormalities also occur, for example ____% of human fertilized eggs result in an embryo with too many or two few chromosomes, and about ____% of all spontaneous abortions (i.e. miscarriages) are due to abnormal chromosome number.

A 39, 4, 5-10%, 25%
B 78, 8, 5-10%, 50%
C 39, 4, 10-20%, 75%
D 78, 8, 5-10%, 25%


11. The procedure to view human chromosomes and create a karyotype is performed __________________________________.

A. by examining chromatin during the G1 or G0 phase under a light microcope.
B. by examining uncondensed DNA double helices under an electron microscope.
C.
by examining a cell during the M phase when genetic material is condensed.
D. by examining representative cells during the S phase of the cell cycle using a light microscope.


12. In 1971, a checkpoint during the cell cycle was discovered in leopard frog eggs, (Rana pipiens). This checkpoint was called a maturation promoting factor, and the checkpoint's purpose is to prevent cell division from occuring unless the DNA is normal and fully replicated, and unless there is an adequate amount of particular proteins transcribed and translated which are needed during cell division. About two decades after in the late 1980's it was discovered that the MPF factor is composed of cyclins and cyclin-dependent kinases.
True / False


13. A chromosome that has completed the S phase consists of

A. four homologous chromosomes held together at the kinetochore
B. two homologous chromosomes held together at the centromere
C. four sister chromatids held together at the centromere
D. two sister chromatids held together at the centromere


14. A difference between mitosis and meiosis is that in meiosis, homologous chromosomes synapse while during mitosis they do not.
True / False

Thank you so much in advance!

Explanation / Answer

1 false A. tetrads, bivalent False False 46 23 any number other than 23 False B. Nuclear membrane dissociation is related to nuclear lamin protein breakdown and to some extent the direct influence of the endoplasmic reticulum, whose membrane is continuous with the nuclear membrane. C 39, 4, 10-20%, 75% C. by examining a cell during the M phase when genetic material is condensed. False D. two sister chromatids held together at the centromere True

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