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MMD1045: Module 2 > Embryo Molec 1 > Flashcards

Embryo Molec 1 Flashcards

1
Q

Rôle des proto et anti oncogènes?

A

Anti-oncogene: Stops the progression of cancers

Contrôler la prolifération cellulaire dans les tissus sains de l’embryon et de l’adulte

There are many proto-oncogenes and anti-oncogenes that together control cell proliferation in the healthy tissues of embryos and adults. The activation and inactivation of these genes are usually very precisely regulated to trigger cell proliferation where and when needed, and also to stop it at the right time. During the first 4 weeks post-conception, the number of cells doubles every 2 to 4 days, and this cell proliferation is largely controlled by these genes.

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2
Q

Par quoi s’explique la prolifération différente d’une région à l’autre?

A

L’expression différente des proto/anti oncogène d’une région à l’autre

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3
Q

Conséquences d’une absence d’apoptose au niveau des mains?

A

Doigts palmés

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4
Q

Décrit le syndrome de Piebaldisme.

A

examples are maladie de Crete Neurale.

Migration incomplète des mélanocytes de la crête neurale, qui migrent de la ligne dorsale sur toute la surface de l’ectoblasme

Peau non pigmentée aux endroits les plus médians de la ligne médiale dorsale

https://www.notion.so/Embryologie-Molecular-1-73901d6dc72c4d36a58f02d14a56ad42?pvs=4#ad02e31fea5449158ae046471444beee

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5
Q

Décrit la linea nigra.

A

Sécrétion de MSH durant la grossesse
Double le nb de mélanocyte de chaque côté de la ligne médiane

La grossesse occasionne une sécrétion de l’hormone stimulatrice des mélanocytes (MSH), et rend cette
ligne plus proéminente: la Linea nigra (line in the middle that is much more prominent on the mother).

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6
Q

Décrit la mutation inactivatrice de C-KIT.

A

Fillette et souris ayant une mutation inactivatrice du proto-oncogène C-KIT. Cette carence
diminue l’aptitude des mélanocytes à proliférer, d’où l’hypopigmentation

Diminue l’amplitude des mélanocytes à proliférer

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7
Q

Décrit la surexpression de C-KIT

A

C-KIT opposite brother: Overexpression of C-KIT

sur-expression stimule les mélanocytes à proliférer, résultant en un cancer de ces cellules.

Message: Low C-KIT= white area, Too much C-KIT = Cancer

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8
Q

What is Imatinib?

A

Médicament pour gérer la mutation de C-KIT sur les mélanocytes

Inactivator of C-KIT.

Prevents the progression of cancer.

The beauty of this treatment is that it is very precise targeting directly what is affected leading to less side effects.

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9
Q

True or False

The molecular mechanisms controlling embryonic apoptosis are still almost completely unknown.

A

True

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10
Q

True or False

Apoptosis is oxygen dependent

A

True

Oxygen is also needed for glucose usage so need oxygen for apoptosis.

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11
Q

Relation to diabetes and apoptosis

A
  • Diabetes can stimulate apoptosis. We saw this in the syndrome de dysplasie caudale
  • Baby where the tail disappeared to quickly and so the legs are grown together

1

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12
Q

What is cell polarization

A
  1. In certain types of cells, the axis along which cell division occurs plays a significant role in maintaining the “stem” state and in the differentiation of these cells.
    1. This is called polarization. If it divides in one axis vs the other it might differentiate or not. Remember this in immune cell genesis.
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13
Q

Explain the Renouvellement des cellules souches dans les cryptes de l’intestin grêle.

A
  1. Cells proliferating rapidly become increasingly differentiated during their journey from the base of the crypts to the top of the villi (a path resembling that of an escalator), from “slow” stem cells to cell death at the apex.
  2. Apoptotic cells detach from the basal membrane and “fall” into the light.
  3. The contact between a proliferating stem cell and a Paneth cell constitutes the “stem factor” that controls whether mitotic division is symmetrical or not.
    1. If the cells divide in another axis and not touch the Paneth cells, well there is no stem cell stimulation.
  4. In the small intestine, the contact of a stem cell with a Paneth cell acts as a “pink factor”.
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14
Q

PIT-1 vs Octamére

A

PIT-1 est un gène contrôleur maître exprimé seulement dans l’hypophyse.

Octamére:
Facteur de transmission activated in lymphocyte B

Les séquences d’ADN reconnaissant PIT-1 et Octamére ne different que de 2 nucléotides.

PIT-1 can stimulate prolactin expression in hypophyse cells but octamer cannot do this in hypophyse or in the b-cells.

However, if we take B-lymphocytes and change the promotor region so that octamer can recognize it, well then the Bcells will produce prolactin under octamer transcription factor but not under PIT-1. This shows an example where the cell is simply listening to signals without asking questions

If we have the right promotor and the right facteur then gene will be transcribed no matter what.

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15
Q

True or False

l’effet des gènes contrôleur maitres est souvent irréversible

A

True

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16
Q

Qu’active PAX dans le développement musculaire?

A

MYOD

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17
Q
A
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18
Q

Vrai ou faux? MYOD est un gène contrôleur maitre.

A

Vrai

19
Q

Effets de MYOD?

A

Facteur de transcription qui se lie aux promoteurs de la fonction musculaire
S’auto-active et cause differentiation

20
Q

Explique la double assurance concernant MYOD.

A

A mammal cannot survive without myocytes and a “double assurance” mechanism has been put in place: a second molecule, called Myogenin, is also present in the embryo. MYOD and Myogenin are activated at the same time, and their action is almost interchangeable (it is said that these two genes are redundant). Thus, the mutation of MYOD or Myogenin has almost no effect on the phenotype (hence the double assurance).

21
Q

Vrai ou faux? Un changement de 2 nucléotides est suffisant pour déterminer la spécificité des facteurs de transcriptions avec qui le promoteur réagit.

A

Vrai

Octamere vs PIT-1

22
Q

Comment les gènes contrôleur maitre assurent leur activation au sein des cellules filles?

A

Auto activation (feedback positif)

For example:
MYOD also recognizes its own promoter: it can therefore self-activate. Once MYOD is active in a cell, its self-activation ensures that this cell expresses MYOD perpetually: this cell is terminally differentiated - it and its descendants can henceforth only be myocytes.

23
Q

Les gènes contrôleurs maitres activent la __________ alors que les subalternes activent la ___________.

A

détermination
différentiation

24
Q

Localisation et rôle des CAMs?

A

Surface des cellules
Adhésion des cellules entre-elles

25
Q

Que font les cellules ayant une affinités de CAMs?

A

CAMs that are identical, will have an affinity for one another.

Keep in mind that there is a gradient.

Cells that express the same CAMs will be able to glue together. This is why skin cells don’t get pulled away so easily.

26
Q

What is the role of calcium in CAMs

A

CAMs need calcium

If removed the calcium, cells cannot stick to one another

But if you re-add calcium cells come back together.

The right cells go with the right cells → specificity in CAMs and conncetion

27
Q

Comment les cellules s’ancrent à la matrice extra-cellulaire?

A

Via les intégrines

28
Q

Comment les mouvements cellulaires sont-ils coordonnés par les cadhérines?

A
  1. The cell at the migration front sends out membrane projections to “sense” the extracellular matrix to find molecules with which its integrins have an affinity.
  2. When such molecules are found, they are bound and used as an anchor point to allow actin to pull the cell in that direction.
  3. Adjacent cells are dragged by the cells at the migration front via their binding by the CAMs (Cell Adhesion Molecules).
29
Q

CAMs migration and cancer

A
  1. mechanism is used by embryonic cells but can be used by cancer cells that metastasize.
  2. For example, due to the unique characteristics of the heart, cancer cells find it difficult to establish a foothold using CAMs, leading to the rarity of heart metastases.
30
Q

What is the concept that we take with nanos and bicoid?

A

2 Gradients (facteur de transcription) can control the expression of proteins.

Les gradients de concentration de bicoïde et de nanos vont contrôler l’expression de hunchback au niveau de chaque cellule, et le gradient de concentration de hunchback va à son tour moduler l’expression des autres gènes.

Concept:
Say for example you are trying to form the intestins. You do not need 10000 different promotion factors. Instead you need a few that generate a gradient which is read and specific expressed

In humans instead we have retinoid acid in the caudal region instead of nanos.

31
Q

True or False

Le rôle des facteurs de transcription est d’activer la transcription des gènes qu’ils contrôlent,
via le promoteur de ces gènes

A

False
The statement is not entirely false, but it doesn’t capture the full complexity of the role of transcription factors. They can both activate and repress gene transcription, and their action is not always through direct DNA-binding123.

32
Q

Que sont bicoide et nanos?

A

Facteurs de transcription
Morphogène

33
Q

Localisation de la sécrétion de bicoide?

A

Pôle céphalique

34
Q

True or False

Nanos active l’expression de hunchback, alors que
bicoide l’inhibe.

A

False
Bicoïde active l’expression de hunchback, alors que
nanos l’inhibe.

35
Q

Combien de complexe HOX pour le génome humain?

A

4

36
Q

Comment sont transcrits les HOX?

A

De manière séquentielle via le gradient de concentration de l’acide rétinoique

37
Q

Qui a un impact sur l’expression des HOX?

A

Acide rétinoique
Emplacement de ces gènes sur le complexe

38
Q

Quels HOX sont exprimés en premier? What does this mean

A

HOX1-2

This means that HOX1-2 need the smallest amount of retinoid acid and that they will be basically everywhere in the fetus

39
Q

Dans quel axe segmente HOX?

A

Caudo-céphalique

40
Q

Effet de trop et de pas assez de RET?

A

Trop: syndrome de néoplasie endocrines multiples (cancer)
Pas: Hirschsprung

41
Q

Qu’est-ce que le syndrome de dysplasie caudale?

A

Fusion complète des deux jambes avec malformations uro-génital

Mère diabétique = bébé diabétique
Hyperglycémie bébé active IGF2
Apoptose de la queue prématurée et fusion des deux bourgeons

42
Q

Vrai ou faux? Toutes les cellules souches sont polarisées.

A

True

43
Q

Un patient se présente avec un manque de pigmentation dans la région médiane du corps. Diagnostic? Cause?

A

Piedbaldisme
(sous-expression de C-KIT)

44
Q

Un patient se présente avec un mélanome malin. Quel médicament vas-tu prescrire?

A

Imatinib

MMD1045: Module 2 (11 decks)

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