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x_NeuroGenetics Review > Embryology > Flashcards

Embryology Flashcards

1
Q

When do dermal ridges form on the palms and soles of the fetus?

A

Weeks 13-19

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2
Q

Define induction

A

The process whereby one group of cells or tissues causes another set of cells or tissues to change their fate.

  • Important for embryologic formation of organs
  • Happens mostly through cell-cell signaling through either secreted molecules (paracrine) or direct cell-cell interactions (juxtacrine)
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3
Q

Name 4 classes of GDFs (growth and differentiation factors) that are important for cell-cell signaling during embryologic development.

A

Secreted, diffusible molecules involved in cell-cell signaling

  1. Fibroblast growth factors (FGFs)
  2. WNT
  3. Hedgehog
  4. Transforming Factor Beta (TGFB)
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4
Q

Define fibroblast growth factors

A

=family of proteins that are involved in cell-cell signaling during development

  • secreted proteins that bind to fibroblast growth factor receptors on various cells to activate various pathways
  • 25 genes with hundreds of different isoform FGF proteins generated by alternative RNA splicing
  • Can act on different pathways for different specific developmental events
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5
Q

Name the 3 hedgehog genes

A
  1. Desert
  2. Indian
  3. Sonic hedgehog (SHH)

These are secreted proteins that are involved in cell-cell signaling. SHH binds to a receptor called Patched which binds to a protein (smoothened or SMO). Once SHH binds, inhibition on SMO released and SHH signal transduced

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6
Q

Name 3 embryologic roles of FGFs.

A

Not limited to but includes:

  1. angiogenesis
  2. Axon growth
  3. mesoderm differentiation
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7
Q

Name 4 embryologic roles of SHH

A
  1. limb patterning
  2. neural tube induction and patterning
  3. somite differentiation
  4. gut regionalizations
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8
Q

The receptors of the WNT proteins are in the _______ family of proteins.

A

frizzled

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9
Q

Name 4 embryologic roles of WNT proteins.

A
  1. regulating limb patterning
  2. midbrain development
  3. somite differentiation
  4. urogenital differentiation
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10
Q

What 3 classes of proteins are all a part of the TGF Beta superfamily?

A
  1. TGFBs
  2. bone morphogenic proteins
  3. Mullerian inhibiting facor
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11
Q

The period between two successive mitoses is called _________.

A

=interphase

  • cell spends most of its life here.
  • made up of G1, S, and G2 phases
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12
Q

What is the stage that cells are in immediately after mitosis?

A

=G1

  • 1 diploid copy of the genome
  • no DNA synthesis
  • Amount of time a cell spends in this part of the cycle varies by the type of cell and whether or not there is damage to the cell
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13
Q

What are the 4 phases of the cell cycle?

A

1-3=interphases

  1. G1
  2. S
  3. G2
  4. M (mitosis)
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14
Q

What happens during S phase of the cell cycle?

A

S=synthesis

-Replication of each chromosome ->form 2 sister chromatids connected by a centromere

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15
Q

Name the 5 stages of mitosis

A
  1. Prophase
  2. Prometaphase
  3. Metaphase
  4. Anaphase
  5. Telophase
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16
Q

What is prophase?

A

=first step in mitosis

  • condensation of the chromosomes
  • formation of mitotic spindle
  • formation of centrosomes
17
Q

What is prometaphase?

A

=second step in mitosis

  • nuclear envelope dissolves
  • chromosomes attach to mitotic spindle
18
Q

What is metaphase?

A

=3rd step in mitosis

  • state where chromosomes are maximally condensed
  • chromosomes line up at equatorial plane of the cell
19
Q

What is anaphase?

A

=4th step in mitosis

  • sister chromatids separate -> 2 independent daughter chromosomes
  • daughter chromosomes move to opposite poles of the cell after they separate
20
Q

What is telophase?

A

=5th and final step in mitosis

  • 2 separate sets of daughter chromosomes, one at each pole of the cell
  • chromosomes decondense
  • nuclear membrane reforms
  • cleavage of the cytoplasm into 2 daughter cells
21
Q

What happens in meiosis I?

A
  • number of chromosomes in each daughter cell is reduced by half because the homologous chromosomes are split up and one homologue in each pair goes into a different daughter cell
  • genetic recombination also occur
22
Q

What is meiotic crossing over? When does it occur?

A

=homologous segments of DNA are swapped between the chromosome pair

  • ensures that none of the gametes will be identical to one another
  • occurs during Meiosis I
23
Q

True or false: the original sets of maternal and paternal chromosomes are maintained after meiosis.

A

False: the 23 pairs of homologous chromosomes assort independently into a random combination
-there are 2^23 different configurations of chromosome pairs

24
Q

When does meiotic crossing over occur?

A

Meiosis I

25
Q

How many gametes are generated at the end of meiosis I & II?

A

4 haploid gametes

26
Q

True or false: the 4 haploid gametes generated are identical to one another.

A

=False
-because of meiotic crossing over (meiosis I) and random sorting of chromosomes from the original pair into daughter cells, each gamete is unique

27
Q

What cells undergo meiosis?

A
  1. Primary oocytes or primary spermatocytes
28
Q

True or false: male and female gametes have different patterns of gene expression, marked by their developmental origins (either from an XY or XX embryo).

A

true

29
Q

What is the difference between male and female meiosis?

A

In females meiosis is initiated once, during early fetal life, in a limited number of primary oocytes

In males, meiosis is initiated continuously in many cells from a dividing populations throughout the adult life of a male

30
Q

Describe the processes of meiosis that take place in an oocyte around the time of ovulation

A
  • primary oocytes are generated from oogonia (primordial germ cells) beginning in the 3rd month of fetal life
  • primary oocytes are suspended in prophase I of meiosis I until sexual maturity
  • At the time of ovulation, the oocyte completes meiosis 1. One of the 2 daughter cells becomes the secondary oocyte (egg), the other becomes the first polar body
  • Meiosis II starts and proceeds to metaphase during ovulation, arrests and meiosis II only completes if fertilization occurs (and generates a second polar body)

x_NeuroGenetics Review (38 decks)

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