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DAT Bio > Fertilization and Development > Flashcards

Fertilization and Development Flashcards

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Biology 101 flashcards
1
Q

polyspermy

A

When an egg gets fertilized by more than one sperm. It usually results in unsuccessful fertilization

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2
Q

What is the first step of fertilization

A

An exocytosis of digestive enzymes from the acrosome of the sperm

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3
Q

What is the acrosomal reaction

A

Exocytosis of enzymes from the acrosome occurs. The enzymes digest the jelly of the outer membrane, while actin filaments grow from the acrosomal process. The sperm binds to the egg cell membrane receptors

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4
Q

What is the fast block to polyspermy?

A

Contact and fusion of the egg and sperm occur. The egg’s membrane voltage changes (depolarization) as Na+ ion channels open and Na+ ions flood the cell membrane. This prevents any further sperm cells from fusing with the cell membrane.

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5
Q

What is the slow block to polyspermy?

A

Cortical Reaction

Ca++ ions are released from the endoplasmic reticulum. The Ca++ ions help cortical granules (special egg organelle) fuse with the plasma membrane. Sperm binding receptors are removed from the plasma membrane and a fertilization envelope forms. The forming of the fertilization envelope is termed the slow block to polyspermy

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6
Q

progesterone

A

A hormone release from the oocyte that helps with sperm motility among other functions.

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7
Q

zona pelludica

A

Extracellular egg matrix. Includes the receptors for sperm.

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8
Q

cleavage

A

Once fertilization occurs, a rapid period of mitosis, S, and M phases are carried out. The cytoplasm divides into smaller units called blastomeres.

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9
Q

Blastomere

A

The smaller units that result from rapid cell division upon fertilization

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10
Q

Morula

A

a solid ball of cells resulting from rapid cell division from fertilization.

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11
Q

blastocoel

A

A fluid filled cavity within the morula that begins to hollow out the morula.

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12
Q

Blastula

A

a hollow ball of cells (about 128 cells or 7 cleavages)

Two Poles:

  • Vegetal Pole: High in Yolk
  • Animal Pole: Low in Yolk

Yolk distribution is the most important driving factor that influences the cleavage pattern in many animals.

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13
Q

How does yolk distribution affect cleavage?

A

The heavy yolk in birds and other animals sinks to the bottom of the cell and there is less of the cytoplasm available for cleavage. Those with high yolk content end up with smaller replications and those like humans with very little yolk end up with more equal cleavages.

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14
Q

gastrula

A

We see a shape change

  • Forms from a blastula.
  • A new central cavity called the archenteron is formed that will become the primitive gut.
  • The opening of the archenteron is called the blastopore. This forms the mouth in protosomes and the anus in deuterostomes.

-Three germ layers in a dome shape with a hole at the bottom (blastopore):
Ectoderm
Mesoderm
Endoderm

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15
Q

Deuterostomes

A

chordates and echinoderms

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16
Q

Protosomes

A

Mollusks, Arthropods, and annelids

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17
Q

What is the order of fertilized cell division groups?

A

Zygote -> Morula - > Blastula -> Gastrula

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18
Q

Ectoderm

A
  • Outermost layer - Most sensitive to radiation
  • Skin
  • Nails
  • Hair
  • Sweat glands
  • Tooth enamel
  • Cornea and lens of eye
  • Adrenal medulla
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19
Q

Mesoderm

A
  • Middle layer
  • Bone
  • Muscle
  • Blood
  • Connective Tissues
  • Notochord
  • Excretory, lymphatic systems
  • dermis of skin
  • adrenal cortex
20
Q

Endoderm

A
  • Innermost layer
  • Epithelial linings of respiratory, excretory, and digestive tracts, urinary bladder, and lining of reproductive systems and urethra
  • Glands such as the thymus, thyroid, and parathyroid
  • Liver and pancreas
21
Q

Organogenesis

A

We see a big shape change

  • Condensing of the mesoderm gives rise to the notochord. This is a rod of stiffened tissue that gives structure to all chordates
  • Neural plate forms from the ectoderm and rolls into the neural tube which becomes the CNS (brain and spinal chord)
  • Somites are formed, they represent blocks of mesoderm that give rise to vertebrae and muscle. Somites are arranged along the notochord
22
Q

Amniotes

A

Bird, reptiles, and mammals

All contain a fluid like sac called the amnion

23
Q

Extraembryonic membranes

A

Think everything surrounding the embryo, amniotic fluid, part of the placenta, etc

  • Located outside the embryo:
  • Yolk Sac: Encloses the yolk, provides needed nutrients
  • Amnion: Absorbs shocks, keeps embryo from drying out
  • Chorion: Gas exchange, forms part of the placenta
  • Allantois: Disposes of nitrogen waste and gas exchange. In humans it does not store wastes, but is involved in O2 and nutrient transport.
  • Visibly found in most shelled eggs
24
Q

Yolk Sac

A

Encloses the yolk, provides needed nutrients

25
Q

Amnion

A

Absorbs shocks, keeps embryo from drying out

26
Q

Chorion

A

Gas exchange, forms part of the placenta

27
Q

Allantois

A

Disposes of nitrogen waste and gas exchange. In humans it does not store wastes, but is involved in O2 and nutrient transport.

28
Q

Totipotent

A
  • Capable of developing into all different cell types

- A zygote is Totipotent plus the next three cell divisions to a Morula

29
Q

Pluripotent

A
  • Capable of developing into many different cell types, but NOT extraembryonic tissues.
  • Stem Cells
  • Blastocyst inner mass cells are pluripotent
30
Q

Unipotent

A

Normal organ cells that create clones of themselves

31
Q

Implantation

A
  • Occurs in the Endometrium and occurs before the end of the first week
  • It’s the blastocyst that adheres to the endometrium. (blastocyst is the mammalian version of the blastula)
32
Q

blastocyst

A

Mammalian version of the blastula

33
Q

Human yolk sac

A

Plays a role in developing the digestive tract. Does not provide nourishment like egg laying animals

34
Q

Umbilical cord

A
  • Connects the human embryo to parts of the yolk sac, allantois, and amnion
  • Well endowed with blood vessels.
35
Q

Chorion development

A

Develops around the embryo and secretes chorion gonadotropin hormone that helps maintain the corpus leutum

36
Q

Corpus Leutum

A

Secretes progesterone during the first three months of pregnancy (trimester I)

After the first three months the placenta takes over to produce progesterone and estrogen (steroid hormones)

37
Q

Trimester 1

A
  • Most growth and differentiation occurs here
  • Most sensitive to radiation and drug toxicity
  • Main period for organogenesis
  • After eight weeks the embryo is called a fetus
  • Outer layer of the blastocyst called the trophoblast grows within the endometrium to form the placenta
38
Q

Trimester 2

A
  • All major organs formed
  • Pregnancy is obvious
  • Corpus luteum deteriorates as levels of hCG decrease.
  • The placenta takes over the role of making progesterone and estrogen
39
Q

Trimester 3

A
  • Further development

- Fetus can generally survive at 8 months

40
Q

viviparous

A

young are born alive after nourishment in the uterus from the placenta

41
Q

oviparous

A

Young hatch from eggs laid outside the mother

42
Q

trophoblast

A

The outer layer of the blastocyst that attaches to the endometrium and helps form the placenta

43
Q

Fraternal vs identical twins

A

Fraternal: Two eggs drop and are fertilized
Identical: The cell divides after fertilization

44
Q

Summary of human development

A

zygote -> Morula -> blastocyst -> embryo -> fetus - > baby

45
Q

Homeotic gene

A

A gene that regulates the placement and spatial organization of body parts in animals, plants, and even fungi

These control the development and the fate of many cell groups

A homeotic mutation in an insect could result in a leg being placed where an antenna should be.

DAT Bio (46 decks)

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