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BMS2021 > Introduction to Developmental Biology > Flashcards

Introduction to Developmental Biology Flashcards

1
Q

What three areas is modern developmental biology a combination of?

A

Embryology
Cytology
Genetics

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2
Q

What is the overarching aim of developmental biology?

A

To understand the genetic and cellular mechanims that produce a comple multi-cellular organism from a single cell

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3
Q

What does pattern formation require?

A

Differential gene expression

Signalling between cells

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4
Q

What are the 6 stages that pattern formation arises through?

A 
Cell proliferation
Cell migration
Changes in cell shape and size
Cell differentiation
Cell interaction
Apoptosis
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5
Q

What are the two major cell types in the early developing embryo?

A

Epithelial cells

Mesenchymal cells

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6
Q

What are the characteristics of epithelial cells?

A 
Polarised
Sit on a basement membrane
Cell-to-cell junctions 
Usually have motile cilia
Marker genes (i.e. cytokeratin)
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7
Q

What are the characteristics of mesenchymal cells?

A

Not polarise
Not joined to others cells (i.e. motile)
Marker genes (i.e. vimetin)
Lie within a matrix

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8
Q

A cell that is destined to become a square is relocated to amongst cells that are destined to become circles. The cell become a circle cell. What can you say about its cell fate commitment?

A

It is specified but not determined

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9
Q

A cell that is destined to become a square is relocated to amongst cells that are destined to become circles. The cell become a square cell. What can you say about its cell fate commitment?

A

It is determined

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10
Q

What is cell fate restriction governed by?

A

Cell’s genome (gene expression)
Cell’s history (factors it has been exposed to, where it has moved from)
Interaction with its neighbours

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11
Q

What are the advantages of using Drosophila and round worms to model normal and abnormal human development?

A

Easy to keep; rapid life cycle (10 days in fly, 3 days in worm)
Easy to genetically modify over multi-generations; key genes known
Fate of most or all cells known

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12
Q

What are the disadvantages of using Drosophila and round worms to model normal and abnormal human development?

A

Many aspects of development and anatomy are not conserved with humans

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13
Q

What are the advantages of using zebra fish and African clawed frog to model normal and abnormal human development?

A

Easy to keep; can add factors to the environment (water

Easy to manipulate as embryo develops outside maternal body

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14
Q

What are the disadvantages of using zebra fish and African clawed frog to model normal and abnormal human development?

A

Distant from humans; some features not shared (mammary glands)

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15
Q

What are the advantages of using chicks to model normal and abnormal human development?

A

Closer to humans
Easy to manipulate as embryo develops outside maternal body
Early embryogenesis is very similar to humans

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16
Q

What are the disadvantages of using chicks to model normal and abnormal human development?

A

Longer life cycle (4 months); transgenic strategies lag behind mice

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17
Q

What are the advantages of using mice to model normal and abnormal human development?

A

Same organ systems and many of the same diseases as humans

Relatively easy to maintain colonies; advanced transgenic available

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18
Q

What are the disadvantages of using mice to model normal and abnormal human development?

A

Embryos develop in utero
Can be expensive to generate null mutants
Models can sometimes show different phenotypes to human disease

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19
Q

Some cells of a frog embryo that would give rise to the gut are transplanted into the future head region and still develop into intestinal epithelial cells.
Which word best describes the cells at the time of transplantation?
a) they are specified
b) they are determined
c) they demonstrate fate mapping
d) they are differentiated
e) none of the above

A

b) they are determined

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20
Q

Differential gene expression occurs due to interaction between ___________ (working within a cell) and __________ (working between cells)

A

Transcription factors; signalling molecules

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21
Q

What are the regulatory elements that control gene expression?

A

Promoters
Enhancers
Inhibitors

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22
Q

What is an example of homeotic transformation?

A

Antennapedia (legs where antennae should be)

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23
Q

How are homeotic transformations caused?

A

Mutation in relevant Hox gene

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24
Q

How many Hox clusters do mammals have?

A

Four

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25
Q

What is it called when one gene can compensate for the loss of a related one?

A

Functional redundency

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26
Q

How would you determine the role of a gene found to be expressed in the brain?

A

Knockout the gene and observe the phenotype

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27
Q

How would you determine the role of a gene found to be expressed in the brain when it is also expressed in several other sites?

A

Conditional knockout

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28
Q

What are the main type of paracrine signalling molecules?

A

Fibroblast growth factors (FGFs)
Hedgehog
Wnt
Transforming growth factor-β (TGF-β)

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29
Q

What is a change in cell fate due to signals sent from other cells called?

A

Induction

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30
Q

What factors determine how a cell will respond to morphogens?

A 
Other signals it is currently receiving
Cell memory (past signals it has received)
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31
Q

What type of inhibition is the Notch signaling pathway?

A

Lateral inhibition

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32
Q

How does the Notch signalling pathway occur?

A

Direct interaction between the cell surface receptor (Notch) on the receiving cell and a ligand (Delta, Jagged or Serrate) on the signalling cell. When the receptor is activated, a protease cleaves part of the receptor that enters the nucleus and promotes the transcription of a particular gene

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33
Q

What are the three types of signalling?

A

Autocrine
Paracrine
Endocrine

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34
Q

What are the two type of receptors that paracrine factors activate and how do they induce phosphorylation?

A
  1. Those with intrinsic protein kinase activity (phosphorylates downstream factors)
  2. Those that use a second messenger system to activate cytoplasmic kinases
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35
Q

What type of recepor does fibroblast growth factors (FGFs) activate?

A

Receptor tyrosine kinases (RTK)

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36
Q

What functions of FGFs play in development?

A

Cell proliferation
Promotion of angiogenesis
Activation/suppression of other pathways

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37
Q

What is the mechanism by which FGFs activate/supress gene transcription?

A

FGFs bind to the receptor tyrosine kinase which activates a G-protein which activates RAS which activates RAF which activates a MAP kinase which activates ERK which phsophorylates a transcription f1actor

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38
Q

Where is Fgf8 mRNA expressed in a chicken embryo?

A

Outer epithelial of limb bud

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39
Q

What happens when a bead carrying Fgf8 is implanted into the embryo?

A

An extra limb can form

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40
Q

Which of the following is an example of a morphogen?

a) a transcription factor that can bind more than one target gene
b) an endocrine signal that can influence how cells behave
c) a diffusible protein that influences cell fate
d) a cell that induces its neighbours to follow a developmental fate

A

c) a diffusible protein that influences cell fate

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41
Q

What receptor does transforming growth factor-β (TGF-β) use?

A

Serine/theronine kinase receptor

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42
Q

How does TGF-β influence the transcription of a gene?

A

Activation of the receptor leads to activation of Smad proteins that combine to form a dimer which then combines with a cofactor in the nucleus and interacting with the DNA

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43
Q

What function does TGF-β play in development?

A

Cell specification
Regulating extracellular matrix formation
Cell division
Cell death

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44
Q

What can make TGF-β functionally redundant?

A

Bone Morphogenetic Proteins (BMPs)

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45
Q

What are essential regulators of chondrogenesis (cartilage formation)?

A

Bone Morphogenetic Proteins (BMPs)

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46
Q

Which signalling pathway is essential for gastrulation?

A

Wnt signalling pathway

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47
Q

How does the Wnt pathway influence gastrulation?

A

It defines that dorsal side of the embryo; assists with neural tube formation, cells proliferation, polarity and differentiation

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48
Q

How does Hedgehog activate transcription?

A

Hedgehog binds to a patched (PTC) receptor, preventing it from inhibiting SMO meaning that SMO can prevent the phosphorylation and deactivation of the transcription factor Gli. Gli can then enter the nucleus and promote transcription

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49
Q

What are the two important drivers of morphogenesis?

A

Direct cell-to-cell adhesion

Cell migrationl

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50
Q

How can boundaries between cells be created?

A

Cells having different types and different amounts of cell surface molecules called cell adhesion molecules

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51
Q

What type of cadherin is found on most early embryonic cells and later in epithelial tissues?

A

E-cadherins

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52
Q

What type of cadherin is found on neural cells?

A

N-cadherins

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53
Q

What type of cadherin is found on placental cells?

A

P-cadherins

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54
Q

True or False:

Both epithelial and mesenchymal cells migrate

A

True

Epithelial as sheets or tubes

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55
Q

How do epithelial cells migrate?

A

The polarity of the cell changes due to signals. Actin filaments assemble at the leading edge of the cell and provide mechanical force. The cell interacts with extracellular matrix, particularly integrins which pull the cell along. Myosin also provides motile force along the actin filaments

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56
Q

Which experiment below shows that Fgf4 is sufficient for limb development in the chicken embryo?

a) Implant a bead expressing Fgf4 and observe an extra limb forming
b) Knock out the gene and note loss of limb during development
c) Show that Fgf4 is expressed in the forming limb using in situ hybridisation
d) All of the above

A

a) Implant a bead expressing Fgf4 and observe an extra limb forming
b) is incorrect because it shows that it is required not sufficient

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57
Q

What are the four types of cell potency?

A

Totipotent
Pluripotent
Multipotent
Unipotent

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58
Q

What are individual cells called during the cleavage stage?

A

Blastomeres

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59
Q

What cadherin mediates compaction at the 8-cell stage of cleavage?

A

E-cadherins

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60
Q

What is the compacted ball of cells called during cleavage?

A

Morula

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61
Q

When the inner cells move to one side of the morula, creating a cavity, what is the ball of cells called?

A

Blastocyst

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62
Q

Which part of the blastocyst is ES cells found?

A

Inner cell mass

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63
Q

The cells that move to one side of the morula are called what?

A

Inner cell mass

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64
Q

The cells on the outside of the blastocyst are called what?

A

Trophoblast

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65
Q

What pluripotency factors do cells in the inner cell mass express?

A

Oct4, Nanog and Sox2

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66
Q

A blastomere exposed to Oct4 will become what?

A

Inner cell mass

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67
Q

A blastomere exposed to Cdx2 will become what?

A

Trophoblast

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68
Q

An inner cell mass cell exposed to Nanog` will become what?

A

Epiblast

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69
Q

An inner cell mass cell exposed to Gata 6` will become what?

A

Hypoblast

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70
Q

What must a blastomere be exposed to in order to become an epiblast cell?

A

Oct4 and then Nanog

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71
Q

The first cells to migrate through the primitive streak and displace the hypoblast become what?

A

Endoderm

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72
Q

The second cells to migrate through the primitive streak and displace the hypoblast become what?

A

Mesoderm

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73
Q

Where is the primitive streak found?

A

The caudal (tail) end of the embryo

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74
Q

What are the two key organisers that develop in the early mammalian blastocyst?

A
  1. A specialised group of cells in the hypoblast (Anterior Visceral Endoderm (AVE) in mice)
  2. Primitive streak
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75
Q

What is the primitive node?

A

A dynamic mass of cells at the anterior tip of the primitive streak

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76
Q

Which signalling molecules are responsible for the positioning of the primitive streak?

A

Nodal, FGFs and Wnts

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77
Q

What signalling molecules are highest at the posterior?

A

Wnts, BMPs and FGFs

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78
Q

What signalling molecules are highest at the anterior?

A

BMP and Wnt antagonists

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79
Q

From which structure in the late blastocyst does the entire embryo develop?

A

Epiblast

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80
Q

What parts of the body does the ectoderm differentiate into?

A 
Skin and its derivatives
Nerves and sensory systems
Pituitary gland and adrenal medulla
Jaw and teeth
Neural crest cells
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81
Q

What parts of the body does the mesoderm differentiate into?

A 
Skeleton and muscles
Circulatory and lymphatic systems
Excretory and reproductive systems (not germ cells)
Dermis
Adrenal cortex
82
Q

What parts of the body does the endoderm differentiate into?

A

Epithelial lining of the digestive tract and associated organs
Epithelial lining of respiratory, excretory and reproductive tracts
Thymus, thyroid and parathyroid glands

83
Q

What are the four main tissue types?

A

Epithelium
Connective tissue
Muscle
Nerves

84
Q

Which two key structure form towards the end of gastrulation?

A

Notochord and neural tube

85
Q

Which signalling molecule induces neurulation?

A

Hedgehog

86
Q

What is the name given to the decendants of epiblast cells that do not pass through the primitive streak?

A

Ectoderm

87
Q

An early mouse embryo dies very early in development and is found to have a swollen brain, skin, but stumps instead of limbs, and no eidence of a skeleton. This could be due to an early developmental defect in an aspect of:

a) Ectoderm specification
b) Endoderm specification
c) Mesoderm specification
d) Cleavage

A

c) Mesoderm specification

88
Q

What are the two broad types of stem cells?

A

Embryonic stem cells (ES cells)

Adult stem cells

89
Q

What are the three main potential uses of stem cells?

A

Regenerative medicine
Modelling and treating human disease
Understanding and treating birth defects

90
Q

Where is Oct4 expressed?

A

Inner cell mass

91
Q

What are potential problems with ES cells?

A

Heterogenous cell populations are often produced
The transplanted cells may not behave normally
Tumourigenic potential
Immunological rejection
Ethical concerns

92
Q

You have isolated what you believe to be pancreatic beta stem cells. What evidence would you need that they are pancreatic stem cells?

A
  1. Self renew in culture
  2. Express pancreatic cell markers in culture
  3. Can behave as beta cells in vivo (e.g. insulin production in mice)
93
Q

What is the difference between embryonic and adult stem cells?

A 
Embryonic:
Pluripotent
Immune rejection possible
Tumour potential
Ethical concerns
Adult:
Multipotent
Immune rejection unlikely
Less likely to form tumours
Less ethical concerns
94
Q

Which four factors are required to create iPS cells?

A

Oct4, Sox2, c-Myc and Klf4

95
Q

What does Oct4 and Sox2 do in the creation of iPS cells?

A

Activate Nanog to establish pluripotency and block differentiation

96
Q

What does c-Myc do in the creation of iPS cells?

A

Opens chromatin; makes genes accessible to Sox2, Oct4 and Nanog

97
Q

What does c-Klf4 do in the creation of iPS cells?

A

Prevents cells death

98
Q

What are the advantages of using iPS cells instead of ES cells?

A
  1. They are patient specific (no immune rejection)

2. No ethical concern

99
Q

Which statement is true?

a) iPS cells are derived from the inner cell mass
b) The Tamanaka reprogramming factors are growth factors
c) Therapeutic cloning typically involves transplanting an embryo into a recipient female host
d) iPS cells are totipotent
e) None of the above

A

e) None of the above

100
Q

What is an adult stem cell?

A

a multipotent stem cell derived from mature organs that play a role in homeostasis. They are found in regulated microenvironments called stem cell niches

101
Q

What is angiogenesis?

A

the growth of new blood vessels that tumours need to grow. This process is caused by the release of chemicals by the tumour and by the host cells near the tumour

102
Q

What is the anterior visceral endoderm (ACE)?

A

a key signalling centre in the late blastocyst that establishes the anterior-posterior axis and dictates where the primitive streak will form

103
Q

What does autocrine mean?

A

a type of signalling where a substance is secreted by a cell and acting on surface receptors of the same cell

104
Q

Define bilaminar disc

A

an embryonic structure that appears as a disc composed of epiblast and hypoblast. These two layers are sandwiched between two balloons: the primitive yolk sac and the amniotic cavity

105
Q

Define bone morphogenetic proteins (BMP)

A

a member of a superfamily of proteins that promote the formation of bone and the skeleton and help mend broken bones.

106
Q

Define blastocyst

A

a thin-walled hollow structure in early embryonic development that contains a cluster of cells called the inner cell mass from which the embryo arises. The outer layer of cells gives rise to the placenta and other supporting tissues needed for fetal development within the uterus while the inner cell mass cells gives rise to the tissues of the body

107
Q

Define cadherins

A

calcium-dependent adhesion molecules that are essential for establishing and maintaining intracellular connections. They play a crucial role in spatial segregation of cell types and morphogenesis

108
Q

Define cell fate

A

the developmental destination of a cells if left undisturbed in the embryo

109
Q

Define cell fate commitment

A

the commitment of cells to specific cell fates and their capacity to differentiate into particular kinds of cells

110
Q

Define cell fate determination

A

a process involved in cell fate commitment. Once determination has taken place, a cell becomes committed to differentiate down a particular pathway regardless of its environment

111
Q

Define cell fate specification

A

a form of embryonic specification in which a developing cell is able to differentiate (become a cell carrying out a specialised function) without receiving external signals

112
Q

Define cell differentiation

A

the expression of a developmental fate where a cell adopts its final phenotype allowing it to express proteins that allow it to perform its function

113
Q

Define cell migration

A

a central process in the development and maintenance of multicellular organisms. Tissue formation during embryonic development, wound healing and immune responses all require the orchestrated movement ofcellsin particular directions to specific locations

114
Q

Define cell proliferation

A

the process that results in an increase of the number ofcells, and is defined by the balance betweencelldivisions andcellloss throughcelldeath or differentiation

115
Q

Define cell-to-cell adhesion

A

the process by which cells interact and attach to neighbouring cells through specialised molecules of the cell surface. This process can occur either through direct contact between cell surfaces or indirect interaction, where cells attach to surroundingextracellular matrix, a gel-like structure containing molecules released by cells into spaces between them

116
Q

Define cleavage

A

the repeated division of a fertilizedovum, producing a cluster ofcellswith the same size as the originalzygote

117
Q

Define combinatorial signalling

A

the effect of multiple signalling molecules on cellular function

118
Q

Define conditional knockout

A

a technique used to eliminate a specific gene in a certain tissue, such as the brain. This technique is useful to study the role of individual genes in living organisms

119
Q

Define congenital birth defects

A

a condition that is present at birth due to structural deformities in the development of a fetus. Common examples of congenital birth defects include congenital heart disease, neural tube defects and Down syndrome

120
Q

Define cytology

A

the branches of biology and medicine concerned with the structure and function of plant and animal cells

121
Q

Define developmental biology

A

the study of how organisms grow and develop

122
Q

Define DNA-binding proteins

A

proteins that have DNA-binding domains and this have a specific or general affinity for sing- or double-stranded DNA

123
Q

Define ectoderm

A

the outermost of the three germ layers, or masses of cells, which appears early in the development of ananimalembryo. In vertebrates, ectoderm subsequently gives rise to hair, skin, nails or hooves, and the lens of the eye; the epithelia of sense organs, the nasal cavity, the sinuses, the mouth , and the anal canal; and nervous tissue, including the pituitary body and chromaffin tissue

124
Q

Define epithelial cells

A

any one of several cells arranged in one or more layers that form part of a covering or lining of a body surface. The cells usually adhere to one other along their edges and surfaces. One surface is free, and the other rests on a noncellular basement membrane

125
Q

Define epithelial to mesenchymal (EMT)

A

a process by whichepithelial cells lose theircell polarityand cell-cell adhesion, and gain migratory and invasive properties to becomemesenchymal stem cells; these aremultipotent stromal cellsthat can differentiate into a variety of cell types. EMT is essential for numerous developmental processes includingmesodermformation andneural tubeformation

126
Q

Define embryogenesis

A

the process by which the embryo forms and develops

127
Q

Define embryoid bodies

A

three-dimensional aggregates of pluripotent stem cells. The pluripotent cell types that compriseembryoid bodiesinclude embryonic stem cells (ESCs) derived from the blastocyst stage of embryos from mouse (mESC), primate, and human (hESC) sources

128
Q

Define embryonic induction

A

theembryonic process in which one group of cells, the inducing tissue, directs the development of another group of cells, the responding tissue.Inductiondirects the development of various tissues and organs in most animalembryos; for example, the eye lens and the heart

129
Q

Define embryonic stem cells

A

a pluripotent stem cell derived from inner cell mass that has wide differentiation potential

130
Q

Define endocrine

A

the secretion of molecules that are distributed in the body by way of the bloodstream

131
Q

Define endoderm

A

the innermost of the three primary germ layers of an embryo that is the source of the epithelium of the digestive tract and its derivatives and of the lower respiratory tract

132
Q

Define epiblast

A

one of two distinct layers arising from the inner cell mass in the mammalian blastocyst that gives rise to the three primary germ layers (ectoderm, definitive endoderm, and mesoderm)

133
Q

Define fate map

A

a diagram that maps adult tissues or structure to regions of the embryo that gives rise to that structure

134
Q

Define fibroblast growth factors (FGFs)

A

a family ofcell signallingproteinsthat are involved in a wide variety of processes, most notably as crucial elements for normal development

135
Q

Define functional redundancy

A

when one gene can compensate for the loss of a related one

136
Q

Define gastrula

A

an embryo at the stage following the blastula, when it is a hollow cup-shaped structure having three layers of cells (endoderm, mesoderm and ectoderm)

137
Q

Define gastrulation

A

a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a multilayered structure known as the gastrula

138
Q

Define growth factors

A

molecules that typically act as signaling molecules between cells. Examples are cytokines and hormonesthat bind to specific receptors on the surface of their target cells. They often promote cell differentiation and maturation, which varies between growth factors

139
Q

Define hedgehog

A

a type of morphogen that specifies anterior-posterior patterning in the limbs. It acts as a ligand in asignaling pathwaythat transmits information toembryoniccells required for propercell differentiation

140
Q

Define histology

A

the study of the microscopic structure of tissues

141
Q

Define homeodomain

A

the part of the protein that attaches (binds) to specific regulatory regions of the target genes. Genes in the homeobox family are involved in a wide range of critical activities during development

142
Q

Define homeotic transformation

A

when a body part develops as a different body part (i.e. a body part is in the wrong location)

143
Q

Define hox cluster

A

a series of four clusters of Homeobox genes in mammals that play a key role in patterning the head-to -tail segmentation of the body

144
Q

Define hox genes

A

a subset of homeoticgenes, are a group of relatedgenesthat control the body plan of an embryo along the head-tail axis

145
Q

Define hypoblast

A

a tissue type that forms from the inner cell mass. It lies beneath the epiblast and consists of small cuboidal cells. Extraembryonic endoderm (including Yolk sac) is derived fromhypoblastcells.

146
Q

Define immunofluorescence

A

a technique is used for light microscopy with a fluorescence microscope and is used primarily on microbiological sample. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specific biomolecule targets within a cell, and therefore allows visualization of the distribution of the target molecule through the sample

147
Q

Define induced pluripotent stem cells

A

cells derived from differentiated adult cells that have been induced back to stem cells by reprogramming with certain factors

148
Q

Define induction

A

a change in cell fate due to signals sent from other cells

149
Q

Define in situ hybridisation

A

a type ofhybridizationthat uses a labeled complementary DNA, RNA or modified nucleic acids strand (i.e., probe) to localize a specific DNA or RNA sequence in a portion or section of tissue (in situ)

150
Q

Define inner cell mass

A

a group of cells on one side of the blastocyst that will eventually give rise to the definitive structure of the foetus

151
Q

Define inside-out hypothesis

A

states that the location of the cell in the morula determines its location and hence function in the blastocyst

152
Q

Define lateral inhibition

A

when cells send inhibitory signals to neighbouring cells that alters their behaviour

153
Q

Define lineage tracing

A

labelling a group of cells and seeing where they end up

154
Q

Define mesenchymal cells

A

fusiform or stellate cells located between the ectoderm and endoderm of young embryos; the shape of the cells in fixed material is indicative of the fact that in life they were moving from their place of origin to areas where they would become reaggregated and specialized

155
Q

Define mesenchymal stem cells (MSCs)

A

a type of multipotent adult stem cell that is found in various adult tissues that is linked to normal growth and repair in the body. It can differentiate into bone, cartilage or muscle depending on cues

156
Q

Define mesoderm

A

the middle of the three germ layers, or masses of cells (lying between the ectoderm and endoderm), which appears early in the development of an animal embryo.

157
Q

Define morphogen

A

a secreted, diffusible molecule that can influence fate of a field of neighbouring cells via a concentration gradient

158
Q

Define morphogenesis

A

the organisation of form; groups of similar cells that have formed tissues organise with other tissues into specific shapes and sizes

159
Q

Define morula

A

an early stage embryo consisting of cells (called blastomeres) in a solid ball contained within the zona pellucida

160
Q

Define multipotent

A

having the ability to differentiate to a limited number of cell fates or into closely related family of cells

161
Q

Define Nanog

A

a transcription factor critically involved with self-renewal of undifferentiated embryonic stem cells

162
Q

Define neural crest

A

bilaterally paired strips of cells arising in the ectoderm at the margins of the neural tube. These cells migrate to many different locations and differentiate into many cell types within the embryo

163
Q

Define neural tube

A

the future brain and spinal cord that forms from an area of ectoderm called the neural plate by a process called neurulation

164
Q

Define neuralation

A

the folding process in vertebrate embryos, which includes the transformation of the neural plate into the neural tube. The embryo at this stage is termed the neurula

165
Q

Define Notch signalling pathway

A

a highly conserved cellsignalingsystem present in most multicellular organisms. Notch signaling promotes proliferative signaling during neurogenesis, and its activity is inhibited byNumbto promote neural differentiation. It plays a major role in the regulation of embryonic development

166
Q

Define notochord

A

a solid rod of tissue derived from mesoderm that supports the embryo. It degenerates in mammals but it does send inductive signals to neighbouring ectoderm to form the neural tube

167
Q

Define null mutants

A

A null mutation is a change in genetic sequence that can cause the complete loss of the protein encoded by the gene either by failing to transcribe it to RNA, or by an inability to translate the RNA sequence to protein

168
Q

Define Oct4

A

a transcription factors that is critically involved in the self-renewal of undifferentiated embryonic stem cells.

169
Q

Define organogenesis

A

the phase of embryonic development that starts at the end of gastrulation and goes until birth. Duringorganogenesis, the three germ layers formed from gastrulation: the ectoderm, endoderm, and mesoderm form the internal organs of the organism

170
Q

Define paracrine

A

denoting a type of hormone function in which hormone synthesized in and released from endocrine cells binds to its receptor in nearby cells and affects their function

171
Q

Define paralogues

A

either of a pair of genes that derives from the same ancestral gene

172
Q

Define pattern formation

A

the generation of complex organizations of cell fates in space and time.Pattern formationis controlled by genes

173
Q

Define pluripotent

A

capable of giving rise to several different cell types

174
Q

Define primitive streak

A

a structure that forms in theblastuladuring the early stages ofavian,reptilianandmammalianembryonic development. It forms on the dorsal (back) face of the developing embryo, toward the caudal or posterior end.

175
Q

Define qRT-PCR

A

a technique commonly used in molecular biology to qualitatively detect gene expression through the creation ofcomplementary DNA(cDNA) transcripts from RNA

176
Q

Define receptor tyrosine kinase (RTK)

A

high-affinitycell surface receptorsfor many polypeptidegrowth factors,cytokines, andhormones

177
Q

Define reproductive cloning

A

the creation of an organism who has identical nuclear genetic material (DNA) to an existing member of the species, and who is allowed to develop to term and beyond

178
Q

Define serine/threonine kinase receptor

A

a transmembrane receptor that contains serine/threonine kinase domain that recognises transforming growth factor-β

179
Q

Define Smad proteins

A

a family of structurally similarproteins that are the main signal transducers for receptors of thetransforming growth factor beta(TGF-B) superfamily, which are critically important for regulating cell development and growth

180
Q

Define somatic cell nuclear transfer (SCNT)

A

a laboratory technique for replacing the nucleus of an ovum with that from a somatic cell

181
Q

Define Sox2

A

atranscription factorthat is essential for maintaining self-renewal, orpluripotency, of undifferentiatedembryonic stem cells. Sox2 has a critical role in maintenance of embryonic andneuralstem cells

182
Q

Define spemann organiser

A

a cluster of cells in the developing embryo of an amphibian that induces development of thecentral nervous system.

183
Q

Define stem cells

A

an undifferentiated cell that can self-renew and has the ability to differentiate into tissue- or organ-specific cell types

184
Q

Define teratoma

A

a tumor made up of several different types of tissue, such as hair, muscle, or bone

185
Q

Define therapeutic cloning

A

cloningdesigned astherapyfor a disease. Intherapeutic cloning, the nucleus of a cell, typically a skin cell, is inserted into a fertilized egg whose nucleus has been removed. The nucleated egg begins to divide repeatedly to form a blastocyst.

186
Q

Define totipotent

A

capable of giving rise to any cell type or (of a blastomere) a complete embryo.

187
Q

Define tranactivation domain

A

a transcription factor scaffold domainwhich contains binding sites for other proteins such as transcription coregulators

188
Q

Define transcription factors

A

DNA-binding proteins that regulate the expression of an array of target gene that usually have transactivation domains that activate or repress genes)

189
Q

Define transforming growth factor-β

A

a multifunctional cytokine that acts as a ligand for serine/threonine kinase complex

190
Q

Define trophoblast

A

cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta

191
Q

Define unipotent

A

capable of giving rise to only one cell type

192
Q

Define western blotting

A

an important technique that detects specific proteins from a complex mixture of proteins extracted from cells. The techniques uses three elements to accomplish this task: (1) separation by size, (2) transfer to a solid support, and (3) marking target protein using a proper primary and secondary antibody to visualize

193
Q

Define Wnt

A

a diverse family of secreted lipid-modified signalling glycoproteins that act as ligands to activates the Wnt pathways via paracrine and autocrine routes

194
Q

A transcription factor protein is detectable in the nuclei of both the epithelial layer and in underlying mesenchymal cells. However, the factor only has an effect in the epithelial cells. this is best explained by:
Select one:
a. The gene is only present in the epithelial layer
b. The gene encoding the transcription factor is not expressed in mesenchymal cells
c. The factor relies on another factor for its activity that is only expressed in epithelial cells
d. The factor binds to a cell surface receptor that in only present in epithelial cells

A

c. The factor relies on another factor for its activity that is only expressed in epithelial cells

195
Q

Which of the following steps would not be part of a procedure to produce a mouse over-expressing growth hormone?
Select one:
a. breeding chimeric mice with wild type mice
b. pronuclear injection
c. culturing ES cells
d. deletion of one allele by homologous recombination

A

d. deletion of one allele by homologous recombination

196
Q

Which of the following statements is FALSE?

Select one:

a. Integrins bind a cell to the extracellular matrix
b. The epiblast is pluripotent
c. Sonic Hedgehog is an example of a morphogen
d. The trophoblast is displaced by the definitive endoderm

A

d. The trophoblast is displaced by the definitive endoderm

197
Q

Which statement is CORRECT?

Select one:

a. When Wnt binds to its cell surface receptor, it leads to degradation of beta-catenin in the cell
b. Hedgehog signaling involves the Patched Receptor
c. Delta that is secreted from the cell can bind to Notch, an example of paracrine signaling
d. BMPs signal through is a Tyrosine kinase receptor

A

b. Hedgehog signaling involves the Patched Receptor

198
Q

Vertebrate embryos show regulative ability, which means
Select one:
a. They can generate non-identical twins during embryonic development
b. They can produce normal tissues when cells are removed
c. They undergo gastrulation following blastocyst formation
d. Transcription factor genes can turn on or off their downstream targets

A

b. They can produce normal tissues when cells are removed

199
Q

Which statement is FALSE?
Select one:
a. the anterior visceral endoderm (AVE) is required for organising the anterior-posterior axis
b. Wnt and Fgf signals help establish the posterior part of the early embryo
c. the primitive streak is required for gastrulation
d. The AVE forms in the epiblast opposite the primitive streak

A

d. The AVE forms in the epiblast opposite the primitive streak

200
Q

You are given a tube of cells labeled “iPS cells”. Which of the following experiments would suggest that they are indeed iPS cells?

Select one:

a. they cannot self-renew
b. they can form a teratoma when injected into a mouse embryo
c. they can differentiate into every cell type in vitro
d. they do not express Oct4

A

b. they can form a teratoma when injected into a mouse embryo

201
Q

Which statement about adult stem cells is FALSE?
Select one:
a. they are derived from somatic cell nuclear transfer
b. they can self renew
c. they are typically multipotent
d. they are found in a stem cell niche

A

a. they are derived from somatic cell nuclear transfer

BMS2021 (6 decks)

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