Lect 1: Gametogenesis I

Question 1

Embryology

Answer 1

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

Question 2

Ontogeny

Answer 2

Includes all developmental processes from conception to death

Question 3

Embryogeny

Answer 3

That part of ontogeny from conceptions to birth/hatching

Question 4

Determination

Answer 4

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

Question 5

Differentiation

Answer 5

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

Question 6

Growth

Answer 6

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

Question 7

Morphogenesis

Answer 7

Generation of form or assumption of new shape.

Question 8

Induction

Answer 8

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

Question 9

Integration

Answer 9

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

Question 10

Phases of Gametogenesis

Answer 10

• 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

Question 11

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

Answer 11

24 days after fertilization

Question 12

What is the migration route of the primordial germ cells?

Answer 12

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

Question 13

Teratoma

Answer 13

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

Question 14

Process of gametogenesis in females and products

Answer 14

Oogenesis - eggs

Question 15

Process of gametogenesis in males and products

Answer 15

Spermatogenesis - spermatozoa

Question 16

Stages of Meiosis

Answer 16

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

Question 17

Substages in Prophase I

Answer 17

Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis

Question 18

Prophase I - Leptotene

Answer 18

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

Question 19

Prophase I - Zygotene

Answer 19

Homologous chromosomes pair (synapsis). Synaptonemal complex forms.

Question 20

Prophase I - Pachytene

Answer 20

Maximum coiling. Tetrads. Crossing-over begins

Question 21

Prophase I - Diplotene

Answer 21

Crossing over continues. Chiasmata are well defined.

Question 22

Prophase I - Diakinesis

Answer 22

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

Question 23

Metaphase I

Answer 23

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

Question 24

Anaphase I

Answer 24

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.

Question 25

Telophase I

Answer 25

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

Question 26

Prophase II

Answer 26

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)

Question 27

Metaphase II

Answer 27

Chromosomes line up on equatorial plate

Question 28

Anaphase II

Answer 28

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

Question 29

Telophase II

Answer 29

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

Question 30

Aneuploidy

Answer 30

Abnormal number of chromosomes. Monosomy/Trisomy

Question 31

Euploidy

Answer 31

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

Question 32

Meiosis requires how many divisions and replication?

Answer 32

2 consecutive cell divisions but only 1 cycle of DNA replication

Question 33

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

Answer 33

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