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BIOL 225 > EXAM 1 Chapter 8, Principles of Development > Flashcards

EXAM 1 Chapter 8, Principles of Development Flashcards

1
Q

Epigenesis is

A

stages of development of an embryo (before, creation)

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2
Q

The stages of epigenesis are

A

gametes
fertilization
blastulation (cleavage)
gastrulation
organogenesis
growth

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3
Q

Gametes

A

these are both inherited from the male and the female

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4
Q

Fertilization

A

the two gametes come together to form the diploid zygote

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5
Q

Blastulation

A

zygote divides through mitosis and meiosis, the SIZE OF CELL DOESNT CHANGE

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6
Q

Gastrulation

A

the internal cavity start to form (which will eventually become organs)

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7
Q

Organogenesis

A

actual formation of individual organs

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8
Q

Growth

A

after all organs form, start to actually grow

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9
Q

Fertilization studied using…because…

A

sea urchin

used because it has external fertilization, male releases sperm in water, female releases egg, fertilization occurs outside the bodies so it is easily observed

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10
Q

Preformation

A

idea that within gametes, you have small version of adult

tiny baby in sperm, egg gave more genetic information, tiny baby grew then born

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11
Q

Eggs are…

A
  • much larger than sperm
  • takes more effort to make egg
  • females only produce few hundred eggs, males produce thousands of sperm
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12
Q

Must prevent

A

polyspermy

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13
Q

Polyspermy

A

when multiple sperm fertilize one egg

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14
Q

The egg contributes…and the sperm contributes…

A
  • egg = DNA and nutrients for development
  • sperm = only contributes DNA
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15
Q

Need only one….to make…

A

haploid from female and male to make diploid

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16
Q

Fraternal twins

A

dizygotic, 2 eggs and 2 sperm, share 1/2 DNA

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17
Q

Identical Twins

A

monozygotic, 1 egg, 1 sperm, splits, share all DNA

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18
Q

Semi-identical twins

A

sesquizygotic, 1 egg, 2 sperm, splits, share 3/4 DNA

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19
Q

….prevent polyspermy

A

fast and slow block

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20
Q

the fast block…

A

triggers the slow block

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21
Q

(fertilization/blocks) step 1 (A)

A
  • acrosomal process (point of sperm) contains egg recognition proteins
  • these bind with sperm-binding receptors/species specific receptors on surface of egg
  • this results in DEPOLARIZATION
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22
Q

Membrane electrical potential

A
  • when the outside out the cell is positive (Na+) and the inside of the cell is negative
  • difference of charges from outside to inside
  • electrical potential energy
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23
Q

depolarization…

A

changes electrical membrane potential across the membrane

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24
Q

When depolarization occurs…

A

it spreads across the outside of the egg and turns off all of the sperm binding/species specific receptors

this makes it so no other sperm are received

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25
Q

This depolarization is…

A

the fast block, first step, starts 2 seconds after sperm binds, lasts ~60 seconds

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26
Q

(fertilization) step 1 (B)

A
  • the depolarization also triggers release of Ca2+ from ER, which initiates step 3
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27
Q

(fertilization) step 2

A
  • once sperm membrane fuses with the egg membrane, created fertilization cone
  • this fertilization cone draw in the nucleus of the sperm
  • draws nucleus under egg membrane and eventually into the egg
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28
Q

(fertilization) step 3

A
  • Ca2+ causes cortical granules to discharge hypertonic fluid (high concentration of solute) into space between egg membrane and vitelline envelope
  • water flows in, separates two membranes and space between membranes filled with water, other sperm lifted off
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29
Q

vitelline membrane is

A

outer most membrane

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30
Q

egg membrane is

A

inner most membrane

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31
Q

(fertilization) step 4

A

the vitelline envelope hardens and is then called the fertilization membrane (prevents additional fertilization from occurring)

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32
Q

Steps 3 and 4 are

A

the slow block to polyspermy, start about 60 seconds after step #1

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33
Q

(fertilization) step 5

A

12 min after step one, fusion of egg and sperm nuclei, this forms the diploid zygote

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34
Q

(fertilization) step 6

A
  • 90 min after step 1, first cleavage
  • mitosis and cytokinesis for daughter cells
  • zygote divides into 100s of cells
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35
Q

The cells that the zygote divides into (the individual cells) are called

A

blastomeres

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36
Q

The cluster of cells (that is the same size as original zygote) is called

A

blastula

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37
Q

_________ on surface of cell….

A

contractile proteins

start to contract an pull together and this causes single cell to split into two

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38
Q

Mitosis is….Cytokinesis is…

A

Mitosis is duplication of DNA, one copy in each of the cells

Cytokinesis is equal splitting of cytoplasm

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39
Q

zygote through blastula stage is

A

cleavage and early development

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40
Q

yoke made up of…and is…

A

proteins and lipids

is food source

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41
Q

yolk effect is

A

because it is thicker than cytoplasm, there is an effect on the size of the cells that are formed, the more yolk that is present the bigger the cells that are formed are because it is harder for them to split/cleave into smaller cells

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42
Q

two main categories of yolk cleavage are

A

HOLOBLASTIC, MEROBLASTIC

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43
Q

Under holoblastic are…

A

isolecithal, mesolecithal

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44
Q

under meroblastic are…

A

telolecithal

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45
Q

holoblastic means

A

entire cell cleaves

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46
Q

meroblastic means

A

partial cleavage (too much yolk, only part of the cell cleaves)

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47
Q

isolecithal

A

sparse yolk, evenly distributed

all blastomeres have same amount of yolk, whole yolk divides into 2, then 4, then 8, etc.

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48
Q

example of isolecithal cleavage occurs in

A

sea stars, seas urchins

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49
Q

mesolecithal

A

moderate amount of yolk at one end of egg

the top half cleaves faster than bottom half

  • animal pole cleaves fast, not much yolk present
  • all yolk goes to bottom in vegetal pole, this cleaves at a slower rate
  • smaller cells in animal pole, large cells in vegetal pole
  • BUT whole yolk still dividing, so still holoblastic
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50
Q

example of mesolecithal is

A

a frog

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51
Q

telolecithal

A

a lot of yolk at one end of egg

so much yolk present that it does not divide, stays as solid yolk form

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52
Q

telolecithal is meroblastic because

A

there is only cleavage of part of the cell, only animal pole, vegetal pole does NOT divide

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53
Q

Example of telolecithal is

A

a chick

54
Q

The chick develops

A

in just the part where the cells are cleaving

55
Q

Holoblastic cleavages are

A

RADIAL

56
Q

Meroblastic cleavages are

A

DISCOIDAL because develops like a disc

57
Q

During frog development which is….the…

A

mesolecithal, the animal pole shifts a bit to form a little window, called grey crescent

58
Q

during frog development polarization occurs which is…

A

determination of dorsal and ventral even at single stage development

59
Q

cortex is

A

outer most layer

60
Q

medulla is

A

inner most layer

61
Q

sperm entry point is

A

only in animal pole

62
Q

the yolk…

A

is very dense because it has all the nutrients so it gravitates to bottom of egg

63
Q

after sperm binds during development…

A

the animal cortex rotates around the surface of the egg, as well as the vegetal pole

64
Q

when the animal cortex shifts the inner contents…

A

of the egg do NOT shift, they remain level

65
Q

this results in

A

the vegetal cortex is now over some of the less dense inner cytoplasm part of the inside of the egg

creates lighter little window

66
Q

the grey crescent is

A

this part where the vegetal pole is over less dense lighter cytoplasm

67
Q

the gray crescent region becomes

A

dorsal side of animal

68
Q

…..is found is this grey crescent region and is important because…

A

beta catenin

very important to the development of nervous system in an organism

69
Q

inner cytoplasm creates cavity called

A

blastocoel

70
Q

beta catenin is

A

cell to cell signaling molecule

necessary for cells to communicate with one another and initiate response to one another

this is why it is present in nerve tissue

71
Q

originally, before fertilization (locations of b-catenin, GSK-3, and GSK-3 Inhibitor)

A

beta catenin distributed equally throughout cell

cell contains GSK-3 enzyme that breaks down beta catenin (INACTIVE until fertilization)

GSK-3 inhibitor is ONLY IN VEGETAL POLE

72
Q

as soon as fertilization happens (sperm nucleus transported)…

A
  • GSK-3 inhibitor transported from vegetal pole to grey crescent region
  • GSK 3 is now active and can break down beta catenin
73
Q

so in grey crescent region

A

although GSK3 is activated because cell fertilized and break down beta catenin everywhere else, it does NOT break down beta catenin is gray crescent region because of the GSK-3 inhibitor

74
Q

the end result is

A

gray crescent region contains beta catenin, inhibitor, and GSK 3

ONLY GSK3 found everywhere else

75
Q

Other patterns of cleavage (in addition to holoblastic and meroblastic) include

A

radial cleavage
(regulative development)

spiral cleavage
(mosaic development)

76
Q

radial cleavage

A

new cells form directly on top of each other, form layers

77
Q

another term that is generally related to radial cleavage is

A

regulative development

78
Q

regulative development is

A

if blastomeres separate early, each can become own whole organism, arent dependent on others

identical genetic copy of each other

79
Q

spiral cleavage

A

new cells form in furrows in between the individual blastomeres (pack tight)

almost twisted as they form

80
Q

spiral cleavage related to

A

mosaic development

81
Q

mosaic development

A

if blastomeres separate early, each does not become whole organism, fate dependent on others

82
Q

(SECOND STEP AFTER FERT) blastulation is

A

separation of single cell into multiple cells , takes mitosis and cytokinesis

formation of blastula, cluster of blastomeres

develops fluid filled cavity called blastocoel

SAME SIZE as original zygote

no cell differentiation yet (cells may still need each other to develop properly)(mosaic development)

83
Q

cleavage and blastocyst formation in humans is as follows…

A

1.) zona pellucida - protein coat that prevent implantation; morula “hatches” from this, then implants
2.) Morula (mulberry fruit) - solid ball of cells
3.) Blastocyst in mammals same as blastula in others
4.) inner cell mass becomes baby; trophoblast forms placenta

84
Q

gastrulation (STEP AFTER BLASTULATION 3RD STEP)

A

formation of inner cavity and results in formation of germ layers

85
Q

germ layers are

A

endoderm - inner most layer
ectoderm - outer most layer
mesoderm - middle layer

86
Q

gastrulation will looks different in different organisms because of

A

yolk effect on cell size

87
Q

sea star gastrulation

A

sea star is isolecithal

invagination (cells migrating) forms archenteron

bottle cells on outer layer pinch inward and pull outermost layers inward

new cavity formed by pinching is the archenteron

88
Q

ectoderm becomes

A

epidermis and nervous system

89
Q

endoderm becomes

A

lining of digestive and respiratory systems

90
Q

mesoderm becomes

A

muscular, skeletal, cardiovascular, urogenital systems

91
Q

frog gastrulation different because

A

mesolecithal, big cells with yolk in vegetal pole

blastocoel not as big

92
Q

step 1 frog gastrulation

A
  • on dorsal lip of blastopore bottle cells pinch inward and pull the animal cells inward creating new tissue and layers
93
Q

when it gets pulled inward

A
  • bottle cells pull inward
  • animal pole spread outward coming around the other side, this displaces blastocoel and creates new cavity called archenteron
94
Q

derm layers at this point

A

ectoderm - animal pol cells
endoderm - lines archenteron
mesoderm - in between ecto and endoderm

95
Q

after ectoderm wraps all around…

A

have little area where yolk is still present called yolk plug

96
Q

after gastrulation

A

more division of cells occurs and a bit of a fold occurs in animal cortex develops into neural fold which becomes neural plate and brain stem

97
Q

notocord comes from

A

mesoderm

98
Q

nervous system comes from

A

ectoderm

99
Q

dorsal and ventral lip of blastopore create cavity that becomes

A

anus

100
Q

another part of gastrulation is

A

formation of coelom (body cavity with organs) (from archenteron)

the gut and hollow part of body forms

100
Q

two ways that the coelom can form

A

schizocoelous and enterocoelous

101
Q

both ways have the

A

same result

102
Q

schizocoelous

A

-cells at lip of the blastopore split and break off of the lip area and mirgrate toward middle of body forming the pockets
- once cavity is formed, the outer most layers fuse together creating new complete structure
- cells that split off fuse together and form organs of the gut

103
Q

peritoneum

A

MESODERMALLY DERIVED tissue that covers the lining of your body

104
Q

enterocoelous

A
  • piece of archenteron pinches off (near the top part of arch)
  • instead of little pieces breaking off, you have pockets that form and pinch together and separate from that main cavity
  • the pouches fuse and separate into actual development body cavity of organism
105
Q

bilateral

A

one place of symmetry, if want equal halves need to take one split down the middle

only 1 longitudinal plane creates equivalent right and left halves

106
Q

coelom

A

fluid filled (in some animals) space around gut (cavity)

107
Q

three different categories regarding coelom

A

acoelomate
pseudocoelomate
eucoelomate

108
Q

acoelomate

A

no body cavity
- space filled with another tissue type called parenchyma (mesoderm)
- fills and surround internal organs of body

109
Q

pseudocoelomate

A
  • cavity partially lined with mesoderm
  • false cavity, but difference between eucolemate is the innermost organs are not completely covered with mesoderm
110
Q

eucoelomate

A

true coelom fully lined with peritoneum (mesoderm)

111
Q

organogenesis (4TH AND FINAL STAGE)

A

creation of organs

112
Q

most of organ development

A

is going to be derived from mesoderm tissue

113
Q

example of this is….which is…

A

neurulation

formation of nervous system from ectoderm

114
Q

development of neural tube

A
  • ectoderm thicken to form neural plate
  • edges rise and join to form tube - enlarges anteriorly (brain), and posteriorly (spinal cord)
  • crest cells (peripheral nervous system) will migrate outwward, they are guidence molecules from neuron are target which guide neuron growth
115
Q

again this neural tube is where

A

there is high concentration of beta catenin which helps with cell to cell signaling and will help develop nervous system

116
Q

around nerve tube is development of another structure which is the……which…

A

notochord
- critical for development of nervous system
- gives support and structure during development of nervous system
- mesodermally derived
- hard rod like structure

117
Q

chordates

A

have notochord sometime in development

118
Q

there is a quote from textbook

A

essentially stating that development of nervous system is so complex that it almost appears there were predestinated destinations and they carry out a purpose

119
Q

major division in animal kingdom includes

A

protostome, deuterostome

120
Q

protostome

A
  • blastopore develops into mouth first
  • ex. annelids (earthworm)
  • spiral cleavage
  • schizocoelus
  • mosaic development
121
Q

deuterostome

A
  • blastopore becomes mouth second (anus 1st)
  • ex chordates, echinoderms (sea starts, sea urchins)
  • radial cleavage
  • entercoelous
  • regulative development

*** MOST MAMMALS ARE DEUTEROSTOMES BUT SHOW SCHIZOCOELUS FORMATION

122
Q

how did scientists figure out how information got split within the different cells, or how…

A

do you get all the different kinds of cells from one cell (liver cells, nerve cells, blood cells, etc)

123
Q

original thought was

A

as cells divide, genome divided up till piece left is what cell type is

DNA splits up until only one type of DNA is left in that one cell (for example only liver DNA so becomes liver cell)

124
Q

Experiments done by _______ disproved this original thought

A

Spermann

125
Q

His experiment was…

A

he took a very thin hair and tied it around a salamander zygote at the single cell stage and watched it develop with the hair tied around the egg

126
Q

experiment 1…conclusion of this…

A

hair splits gray crescent region

  • nucleus only on one side, as nucleus divided, at about 16 cell stage, one of the nucleus cells jumped to other side and started developing as well
  • two embryos formed

conclusion: all early cells contain same nuclear information (cell totipotent)

127
Q

experiment 2…and conclusion…

A
  • split with the nucleus on one side and the gray crescent on the other
  • as nucleus divides, and at 16 cell stage one of blastomeres goes to other side
  • ONLY cell on same side of gray crescent develops into a viable embryo
  • other part just becomes cells with no organization
  • conclusion: cytoplasm in gray crescent area has essential info for development which is beta catenin
128
Q

experiment 3 performed..

A

with another researcher so it was Spemann-Mangold

129
Q

induction

A

capacity of some cells to evoke a specific developmental response in other cells

certain cells cause other cells to develop

130
Q

experiment 3

A
  • took some cell from area away from the dorsal lip of blastopore, and then took cells from around the lip of a DIFFERENT blastopore and inserted them back into the original blastopore
  • primary neural fold begins to develop by dorsal lip, and then a secondary neural development also occurs where ells were transferred
  • two conjoined salamanders form
  • proves that there are certain properties of the cells around the dorsal lip region that induces other cell to develop properly (beta catenin)
131
Q
A

BIOL 225 (3 decks)

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