Lect 1: Gametogenesis I Flashcards Preview

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Flashcards in Lect 1: Gametogenesis I Deck (33):
1

Embryology

Study of the embryo. Descriptive and experimental (developmental bio).

2

Ontogeny

Includes all developmental processes from conception to death

3

Embryogeny

That part of ontogeny from conceptions to birth/hatching

4

Determination

Process by which a cell or part of an embryo becomes restricted to a given developmental pathway.

5

Differentiation

Complex of changes involved in progressive specialization of structure and function, often resulting in the formation of luxury molecules

6

Growth

Permanent increase in mass. Hyperplasia (increase in cell numbers) Hypertrophy (increase in cell size)

7

Morphogenesis

Generation of form or assumption of new shape.

8

Induction

An affect one embryonic tissue (inductor) has upon another (responder) such that the development course of the responding tissue is qualitatively changed from what it would have been in the absence of the inductor

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Integration

Process by which different tissues are brought together and combined to form organs and tissues

10

Phases of Gametogenesis

*Extraembryonic origin of germ cells and their migration into the gonads
*Increase in # of germ cells by mitosis
*Reduction in chromosomal # by meiosis
*Structural and functional maturation of the eggs and spermatozoa

11

Following fertilization, when do the primordial germ cells first appear?

24 days after fertilization

12

What is the migration route of the primordial germ cells?

Yolk sac -> hindgut epithelium, through dorsal mesentery, into developing gonads.

13

Teratoma

Growths from misdirected migrating primordial germ cells. Contain mixtures of highly differentiated tissues.

14

Process of gametogenesis in females and products

Oogenesis - eggs

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Process of gametogenesis in males and products

Spermatogenesis - spermatozoa

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Stages of Meiosis

Prophase I, Metaphase I, Anaphase I, Telophase I Prophase II, Metaphase II, Anaphase II, Telophase II

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Substages in Prophase I

Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis

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Prophase I - Leptotene

Chromosomes are threadlike. Each chromosome consists of 2 chromatids. Chromosomes begin to coil

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Prophase I - Zygotene

Homologous chromosomes pair (synapsis). Synaptonemal complex forms.

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Prophase I - Pachytene

Maximum coiling. Tetrads. Crossing-over begins

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Prophase I - Diplotene

Crossing over continues. Chiasmata are well defined.

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Prophase I - Diakinesis

Crossing-over is complete. Terminalization. Spindle apparatus is in place. Nuclear membrane is disrupted.

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Metaphase I

Tetrads line up along equatorial plate. Centromeres do not divide.

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Anaphase I

Homologous chromosomes move to opposite poles. Each homologue consists of 2 chromatids. Chromatids are not genetically identical b/c of crossing-over. Daughter cells will be haploid.

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Telophase I

Cytokinesis occurs (usually). Nuclear membranes reform (maybe). Spindle apparatus disassembles. Chromosomes may uncoil to varying degrees.

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Prophase II

Chromosomes again condense. Nuclear membranes disappear. Spindle apparatus reforms in each cell. Each chromosome consists of 2 chromatids. Each daughter cell has 1 complete set of chromosomes (haploid)

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Metaphase II

Chromosomes line up on equatorial plate

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Anaphase II

Centromeres divide. Chromosomes move to opposite poles. Each chromosome consists of a single chromatid.

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Telophase II

Chromosomes uncoil. Cytokinesis is complete. Nuclear membranes reform. End result is 4 genetically unique haploid daughter cells.

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Aneuploidy

Abnormal number of chromosomes. Monosomy/Trisomy

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Euploidy

Changes in number of complete sets of chromosomes. Monoploidy/Diploidy

32

Meiosis requires how many divisions and replication?

2 consecutive cell divisions but only 1 cycle of DNA replication

33

Since there are 2 divisions and 1 replication in meiosis, what are the results?

increase in cell numbers sometimes; daughter cells aren't genetically identical; they are haploid