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Embryology
Northwestern Health Sciences Chiropractic Embryo Test 1 T2
| Question | Answer |
|---|---|
| Incidence of birth defects | 6/100 50% pregnancies unplanned |
| What disturbs pregnancy | Teratogens |
| How many weeks is Gestation | 38 weeks |
| Fertilization to birth is called | Gestation |
| How long is the pre-embryonic period | Fertilization to 3 weeks |
| How many cells and germ layers are there in the pre-embryonic period | 1 cell 3 germ layers |
| When is it classified as the Embryonic Period and what occurs | 4th to 8th week, Germ layers make all the organs and tissues |
| When is it classified as the fetal period | 9th week to birth |
| Birth defects are most likely to occur from what week to what week before risk goes down and what is the riskiest week | Fertilization to week 5. Week 5 is the riskiest before risk starts to decrease |
| What are the periods of development of an embryo | Pre-embryonic, Embryonic , Fetal |
| How many chromosomes in the human genome | 46 chomosomes (2N), 22 pairs of homologous autosomes, 1 pair of sex chromosomes |
| What are the two major periods of the cell cycle | Interphase and mitosis |
| What are the phases of interphase and what happens during each | s-phase - synthesis, G1 phase - gap before synthesis, G2 phase - gap after synthesis, |
| Cell division is called | Mitosis |
| What are the phases of Mitosis and what are the results | Prophase, Metaphase, Anaphase, Telophase, Cytokinesis Results are 2 identical daughter cells with 2n DNA |
| What happens during prophase | Nuclear envelope breaks down |
| What happens during Metaphase | Chromosomes line up in the middle (equatorial) in the cell |
| What happens during Anaphase (wittich said this was the most important phase) | Separation of the chromatids |
| What happens during Telophase | Chromatids are pulled to each side of the cell |
| What happens during Cytokinesis | Division of the cytoplasm, this is different in males and females and doesn't always happen. |
| What happens in Meiosis | Only occurs in the formation of gametes, series of 2 divisions but only one is preceded by synthesis, follows the G2 phase |
| Meiosis has 6 phases but only 3 were highlighted, what are they | Zygotene, Pachytene, Diplotene |
| What happens during the Zygotene phase of prophase I | The chromosomes, 1 from mom 1 from dad, pair up |
| What happens during the Pachytene phase of prophase 1 | Recombination occurs, little pieces of the chromosomes are traded to give genetic diversity |
| What happens during the Diplotene phase of prophase I | The newly recombined chromosomes start to pull apart but they don't finish |
| What happens during Meiosis II and what are the results | Same as mitosis except it is not preceded by an S-phase 1N DNA where each one is unique |
| What is the cause of the most common chromosomal disorders | Non-disjunction- chromosomes do not split apart Failure of the chromatids to separate or of the homologous pairs to separate |
| When do chromosomal disorders occur | Mitosis, Meiosis I, Meiosis II |
| 45 instead of 46 chromosomes Missing an Autosome (lethal), Missing a sex chromosome (missing Y is lethal) (only have 1X=turners syndrome) | Monosomy |
| 47 instead of 46 chromosomes Extra autosomes (most are lethal), | Trisomy Trisomy 21= Downs Syndrome Trisomy 22= Rare and rarely survivable |
| Process by which stable and observable difference arise- due to persistent and preferential transcription and synthesis of proteins | Differentiation |
| Period of time preceding differentiation when the "Fate is locked in but not expressed" | Determination |
| Triggering the determined cells to differentiate | Induction |
| What is a normal process controlled by the genome which must occur to keep problems from happening | Cell Death |
| In week 3 __________ differentiate in the wall of the yolk sac and migrate to the primitive gonad | Primordial germ cells |
| Development of spermatozoa formation from spermatogonia | Spermatogenesis |
| Primordial germ cells remain quiescent until puberty when they differentiate into ___________ | Spermatogonia |
| What processes are involved in Spermatogenesis | Mitosis, Meiosis, differentiation and morphologic changes |
| What is the process of Spermatogenesis | Spermatogonia------>Primary Spermatocytes----> Seconday Spermatocytes-----> Spermatids-----> Spermatozoa |
| What are the structures of Spermatozoa | Tail, Acrosome, Nucleus |
| Formation of the primary oocyte is called | OOgenesis |
| Primordial germ cells migrate to the _____________ | Primitive Ovary |
| When mitosis occurs, this gives rise to the _________ | Primary Oocyte |
| The primary oocyte enters the 1st meiotic division but is arrested in the ___________ phase of prophase I | Diplotene |
| Primordial follicles | Composed of one primary oocyte and a layer of follicular cells, Embedded in the stroma of the ovary, About 2 million formed by birth |
Created by:
Kcarder
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