BIOL 202 Lecture Notes - Polytene Chromosome, Salivary Gland, Petri Dish

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ceruleanprairie-dog589

21 May 2012

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As we know dna is not naked in the cell; genes are part of a bigger genome, which is wrapped up into a chromosome. Any modification in the shape and/or number of chromosomes in a cell will have drastic effects. Visualizing chromosomes can be done most easily by taking a blood sample, centrifuging it, and isolating the wbcs, which are the only blood cells with nuclei. They are placed on a petri dish and left to divide in culture; cell division is stopped with certain drugs by disabling the mitotic spindle. A hypotonic solution is then used to swell the cells up, at which point they are squished onto a slide and stained using a fluorescent or radioactive dye/probe (e. g. biotin, which we have seen before) Stopping the cells in division is necessary because in the cell"s cycle, only 1/24 of it is spent in mitosis.

Related Questions

1.Briefly describe three functions of cell division.

2.Compare and contrast cell division in bacteria, plant cells, and animal cells.

3.Define and recognize examples of the following terms: genome, chromatin, sister chromatids, centromere, chromosome arm, duplicated chromosome, unduplicated chromosome, kinetochore, kinetochore microtubule, non-kinetochore microtubule, centrosome, aster, mitotic spindle, metaphase plate.

4.Compare and contrast chromatin with chromosomes.

Describe, draw, or label a diagram of the structure of a duplicated or unduplicated eukaryotic chromosome

1). Explain the significance of the fact that gametes contain half of the chromosome complement of somatic cells. Tell me something about variation, if you have a sibling (if you don't imagine you do) - how is your sibling's genetic make-up similar and/or different from yours? What about your mom and dad?

2). Explain the terms reductional division and equational division. What is reduced or kept equal? To which nuclear divisions do these terms refer?

3). What is the diploid number (2n = ?) of an organism if it has
a) 12 chromosomes at Anaphase of Mitosis?
b) 12 chromosomes at Anaphase I of Meiosis?
c) 12 chromosomes at Anaphase II of Meiosis?

4). Compare/contrast Metaphase I of Meiosis with Metaphase of Mitosis.

5). What are the two mechanisms of variation in Meiosis, and during which stage(s) does each occur?

6). Draw a diagram of a bivalent and label the following parts: centromere, sister chromatids, non-sister chromatids, homologous chromosomes, chiasma.

7). A diploid cell has 1 pair of acrocentric chromosomes (Chromosome 1) and 1 pair of submetacentric chromosomes (Chromosome 2).
Â· Gene X is on Chromosome 1. Gene Y is on the short arm of Chromosome 2 and Gene Z is on the long arm of Chromosome 2.
Â· The maternal chromosomes have the X, y, z alleles, whereas the paternal chromosomes have the x, Y, Z alleles.
Draw these chromosomes, labeling ALL alleles, as they might appear in Metaphase I of Meiosis.

Complete the table below by calculating the number of chromosomes indicated by each letter (A-F) in the table. Explain how you arrived at your answers.

	Polar Bear	Rattlesnake Fern
n	A.	92
Number of chromosomes before mitosis	74	D.
Number of chromosomes after mitosis	B.	184
Number of chromosomes before meiosis	C.	E.
Number of chromosomes after meiosis	37	F.

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BIOL 202 Lecture Notes - Polytene Chromosome, Salivary Gland, Petri Dish

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