BLG 400 Lecture Notes - Lecture 7: Oogonium, Cell Division, Chromosome Segregation

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violetfish575

5 Mar 2016

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Telophase ii: chromosomes begin to uncoil, nuclear envelopes and nucleoli re-form. Cytokinesis: cytoplasm divides forming 4 haploid cells. Meiosis contributes to genetic diversity in 2 ways: Independent assortment of non-homologues creates different combinations of alleles. Crossing over between homologues creates different combinations of alleles within each chromosome. Meiosis: occurs in germ cells as part of the sexual cycle, two rounds of division (meiosis i and ii, only diploid cells undergo meiosis, occurs after mitosis. None are identical to eachother or the original cell. Germ-line: specialized diploid cells set aside during embryogenesis. Oogonia: diploid germ cells in ovaries of female embryos. Divide by mitosis and enter meiosis i to become primary oocytes. Primary oocytes arrest in diplotene stage of meiosis i until after birth. At puberty, one oocyte per month resumes meiosis. At ovulation, completion of meiosis i produces a secondary oocyte and first polar body. Secondary oocyte arrests in metaphase of meiosis ii.

Related Questions

31.????? interphase A. cytoplasm divided between the two daughter cells

32.????? chromosomenumber B. final phase of mitosis; daughter nuclei form

33.????? chromatid C. sum total of chromosomes in all cells of a given

type

34.????? cytokinesis D. chromosomes condense and mitotic spindle

begins to form

35.????? metaphase E. chromosomes line up at spindle equator

36.????? alleles F. sister chromatids separate, move to opposite

spindle poles now

37.????? prophase G. none between meiosis I and II

38.????? telophase H. half of a chromosome in prophase

39. ????? anaphase I. different molecular forms of the same gene

Matching

ultramarineporpoise990

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.

Question 3 (5 points)

Match the terms to the definitions provided.

Question 3 options:

	telophase II
	meiosis II
	telophase I
	anaphase I
	anaphase II

1.	Division, beginning without DNA replication, that resembles and produces four haploid cell.s
2.	Phase of meiosis when chiasmata are broken as spindle fibers shorten and homologous pairs are pulled apart.
3.	Phase of meiosis when sister chromatids are pulled to opposite poles of the cells.
4.	Phase of meiosis in which homologues cluster at the poles of the cells and the nuclear envelope reforms.
5.	Phase of meiosis in which four different haploid cells are present.

Question 4 (7 points)

Match the terms to the definitions provided.

Question 4 options:

	G0
	telophase
	G2
	mitosis
	cytokinesis
	cell cycle
	S

1.	The phase in which the cell synthesizes a replica of its genome
2.	The overall process of genome duplication
3.	The phase in the cell cycle during which mitochondria and other organelles replicate.
4.	The phase in mitosis when chromosomes are clustered at opposite poles and the spindle apparatus disappears
5.	A resting state that cells often enter before resuming cell division.
6.	The phase in the cell cycle when the cytoplasm divides creating two daughter cells.
7.	The phase in the cell cycle in which the spindle apparatus assembles and sister chromatids move apart.

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Question 5 (6 points)

Put the events of a MAP kinase cascade in the correct order.

Question 5 options:

	MAPKKK phosphorylates and activates another kinase
	MAPKK phosphorylates and activates MAPK
	Binding of MAPKKK to Ras
	External signal binds to membrane receptor and activates receptor kinase.
	MAPK phosphorylates an inactive response protein and activates it.
	Phosphorylation of receptor kinase and interaction with RAS

BLG 400 Lecture Notes - Lecture 7: Oogonium, Cell Division, Chromosome Segregation

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