Dr Iqbal Class 02 Lec 01 Flashcards
1
Q
What is the primary goal of developmental cell biology?
A
To understand the cellular and molecular mechanisms that direct the transformation from a single cell to a multicellular organism.
2
Q
What are the four fundamental processes in animal development?
A
Cell proliferation cell-cell interaction cell specialization and cell movement.
3
Q
What does cell proliferation achieve in animal development?
A
Produces many cells from a progenitor population.
4
Q
How does cell-cell interaction function in development?
A
Coordinates the behavior of each cell with that of its neighbors.
5
Q
What is cell specialization also known as?
A
Differentiation.
6
Q
What is the outcome of cell specialization in development?
A
Creates cells with different characteristics at different positions.
7
Q
What role does cell movement play in development?
A
Rearranges cells to form structured tissues and organs.
8
Q
What are the four essential cell processes that allow a multicellular organism to be made?
A
Cell specialization cell interaction cell movement and cell proliferation.
9
Q
What is the starting point of an animal or plant’s life?
A
A single cell called a fertilized egg or zygote.
10
Q
What happens to the zygote during development?
A
It divides repeatedly to produce many different kinds of cells.
11
Q
What is the final outcome of cell division in a zygote?
A
A pattern of spectacular complexity and precision.
12
Q
What anatomical feature do epidermal cells form in animals?
A
A protective outer layer.
13
Q
What is the function of gut cells in animals?
A
Absorb nutrients from ingested food.
14
Q
What do muscle cells enable in animals?
A
Movement.
15
Q
What role do neurons and sensory cells play in animals?
A
Control behavior.
16
Q
How are diverse cell types organized in animals?
A
Into tissues and organs.
17
Q
What forms the exterior covering of an animal?
A
A sheet of skin.
18
Q
What is the role of the mouth in an animal’s anatomy?
A
Feeding.
19
Q
What does the internal gut tube do in animals?
A
Digests food.
20
Q
Where are muscles nerves and other tissues located in animals?
A
In the space between the skin and the gut tube.
21
Q
What is the antero-posterior axis in animals?
A
Mouth and brain anterior anus posterior.
22
Q
What defines the dorsoventral axis in animals?
A
Back dorsal belly ventral.
23
Q
What is the left-right axis in animals?
A
A bilateral symmetry axis.
24
Q
What is a blastula in early animal development?
A
A sheet of epithelial cells often surrounding a cavity.
25
What happens during gastrulation in animal development?
Some cells tuck into the interior to form mesoderm and endoderm.
26
Which cells remain on the outside during gastrulation?
Ectodermal cells.
27
What does the cross section of an amphibian embryo show?
A sheet of ectoderm outside a tube of endoderm inside and mesoderm between them.
28
What does the endoderm form in animal development?
The epithelial lining of the gut from mouth to anus.
29
Which structures develop from the wall of the digestive tract?
Salivary glands liver pancreas trachea and lungs.
30
What components does the endoderm form in associated structures?
The epithelial components like the lining of the gut and secretory cells.
31
What gives rise to the connective tissues in animal development?
Mesoderm.
32
What is the initial form of connective tissue in an embryo?
Mesenchyme.
33
What tissues does the mesoderm ultimately form?
Cartilage bone fibrous tissue and dermis.
34
What does the mesoderm form besides connective tissues?
Muscles vascular system kidneys and gonads.
35
What is the notochord derived from?
Mesoderm.
36
What is the role of the notochord in development?
Serves as the core of the future backbone and coordinates surrounding tissue development.
37
What does the ectoderm form in animal development?
Epidermis and epidermal appendages.
38
What are examples of epidermal appendages formed by ectoderm?
Hair sweat glands and mammary glands.
39
What does the ectoderm give rise to besides the epidermis?
The entire nervous system including neurons glia and sensory cells.
40
What is the developmental potential of blastomeres?
Can give rise to most or all cell types.
41
How does the developmental potential of cells change as development proceeds?
Becomes more restricted.
42
What influences the restriction of cell developmental potential?
Signaling molecules and gene regulatory factors.
43
What is an example of a highly specialized cell type derived from endoderm?
Pancreatic β-islet cells.
44
What underlies the complex outcomes of development?
Cell memory.
45
What determines a cell's gene expression and behavior?
Its past and present circumstances.
46
How do specialized cells maintain their characters?
Through a record of extracellular signals received during development.
47
Do specialized cells have different genomes?
No they retain the same complete genome as the zygote.
48
What causes differences between specialized cells?
Differential gene expression.
49
What is largely responsible for differences between organs and animal species?
Regulatory DNA.
50
How does regulatory DNA influence gene expression?
By defining patterns through transcription regulators binding to gene regulatory elements.
51
What happens in skin cells regarding gene expression?
Transcription regulators activate gene 1.
52
What happens in muscle cells regarding gene expression?
Transcription regulators activate gene 3.
53
Which gene is active in both skin and muscle cells?
Gene 2.
54
What coordinates spatial patterning in development?
Small numbers of conserved cell-cell signaling pathways.
55
What is inductive signaling in development?
A process where signals from one cell influence the fate of another.
56
What is combinatorial signaling in development?
The effect of a signal depends on other signals received simultaneously.
57
How does cell memory affect signal response?
Previous signals leave a lasting trace that alters the response to current signals.
58
What are morphogens in development?
Short-range inductive signals that exert graded effects.
59
How do morphogens form gradients?
By localized production and diffusion away from the source.
60
What induces different gene expression patterns in morphogen gradients?
Different concentrations or durations of exposure.
61
What is the typical range of morphogen action?
1 mm or less.
62
What happens to a morphogen as it diffuses?
It undergoes degradation.
63
What is the typical half-life of a morphogen in the example provided?
170 minutes.
64
What is the effective diffusion constant of a morphogen in extracellular tissues?
1 μm²/sec.
65
How quickly does a morphogen gradient reach steady state?
Within an hour.
66
How does the morphogen concentration change with distance?
Falls off exponentially.
67
What happens if the diffusion constant of a morphogen increases threefold?
Extends its range but lowers concentration near the source.
68
What happens if the morphogen half-life increases threefold?
Increases concentration throughout the tissue.
69
How do target cells respond to morphogens?
By integrating responses over time.
70
What is lateral inhibition in cell patterning?
One cell produces a substance that inhibits the same substance in a neighboring cell.
71
What creates a runaway instability in lateral inhibition?
Positive feedback increasing the substance in one cell while decreasing it in another.
72
What is the outcome of lateral inhibition?
Two cells become radically different.
73
What represents memory in lateral inhibition?
The final stable state chosen.
74
What generates complex cellular patterns?
Short-range activation and long-range inhibition.
75
What is the role of a short-range activator in pattern generation?
Stimulates its own production in one cell.
76
What does a long-range inhibitor do in pattern generation?
Blocks activator production in neighboring cells.
77
What types of patterns can reaction-diffusion systems create?
Spots stripes or single clusters of specialized cells.
78
What is asymmetric cell division?
Sister cells are born different.
79
What is symmetric cell division?
Sister cells become different due to influences after birth.
80
How does sequential induction generate cell types?
Through a series of inductive interactions starting from a few cell types.
81
What is the incorrect historical view of development?
The homunculus theory where the entire body is preformed in the sperm.
82
What is the modern understanding of development?
A progression from simple to complex through gradual refinement.
83
What triggers dorsoventral asymmetry in a frog egg?
Fertilization and rotation of the egg cortex.
84
What determines the direction of egg cortex rotation in a frog?
The site of sperm entry.
85
What molecule defines the dorsoventral polarity in a frog embryo?
Wnt11 mRNA.
86
What does vegetally localized VegT induce?
Endoderm and mesoderm.
87
What is the basic structure of a blastula in a frog?
A sheet of epithelial cells surrounding a cavity.
88
What are the three germ layers formed during gastrulation?
Ectoderm mesoderm and endoderm.
89
What is the role of mesoderm in the vascular system?
Forms the heart blood vessels and blood cells.
90
What does the ectoderm form in the nervous system?
Neurons glia and sensory cells of sense organs.
91
What is the mesenchyme in an embryo?
A loose mesh of cells that becomes connective tissue.
92
What are the kidney and gonad components formed by mesoderm?
Tubules ducts and supporting tissues.
93
What is the pancreas's epithelial component derived from?
Endoderm.
94
What is the dermis in animal anatomy?
The inner layer of the skin formed by mesoderm.
95
What is the primary function of the notochord?
Coordinates the development of surrounding tissues.
96
What is the role of epidermal cells in animal anatomy?
Form a protective outer layer.
97
What is the antero-posterior axis characterized by?
Mouth and brain at the anterior anus at the posterior.
98
What is the dorsoventral axis defined by?
Back at dorsal belly at ventral.
99
What is the blastula's role in early development?
Forms a sheet of epithelial cells often surrounding a cavity.
100
What happens to ectodermal cells during gastrulation?
Remain on the outside of the embryo.
101
What does the endoderm contribute to the salivary glands?
The epithelial components.
102
What does the mesoderm form in the kidneys?
Tubules ducts and supporting tissues.
103
What is the ectoderm's contribution to sensory organs?
Forms sensory cells of the nose ear and eye.
104
What is the developmental potential of early blastomeres?
Can give rise to most or all cell types.
105
How do cells become specialized during development?
Through signaling molecules and gene regulatory factors.
106
What is the significance of cell memory in development?
Maintains specialized cell characters based on past signals.
107
What is the genome status in specialized cells?
Retains the same complete genome as the zygote.
108
What drives differences in gene expression between cell types?
Regulatory DNA and transcription regulators.
109
What is the role of transcription regulators in skin cells?
Bind to and activate gene 1.
110
What is the role of transcription regulators in muscle cells?
Bind to and activate gene 3.
111
What is the common gene activated in skin and muscle cells?
Gene 2.
112
What is the purpose of inductive signaling in development?
One cell's signal influences another's fate.
113
What is the effect of combinatorial signaling?
Signal outcome depends on simultaneous signals.
114
How does cell memory alter signal responses?
Past signals leave traces that modify current signal effects.
115
What forms a morphogen gradient?
Localized production and diffusion of a signaling molecule.
116
What determines cell fates in a morphogen gradient?
Concentration or exposure duration.
117
What is the maximum effective range of morphogens?
1 mm.
118
What happens to morphogen concentration as it diffuses?
Decreases due to degradation.
119
What is the steady-state form of a morphogen gradient?
Reached within an hour.
120
What is the concentration profile of a morphogen at steady state?
Exponential decrease with distance.
121
What effect does increasing morphogen diffusion constant have?
Extends range but reduces concentration near source.
122
What effect does increasing morphogen half-life have?
Increases concentration throughout tissue.
123
How do cells integrate morphogen signals?
Over time to determine response.
124
What is the mechanism of lateral inhibition?
One cell inhibits the production of a substance in another.
125
What amplifies asymmetry in lateral inhibition?
Positive feedback in one cell.
126
What is the final state in lateral inhibition?
Two cells in opposite stable states.
127
What does short-range activation do in pattern generation?
Promotes activator production in a cell.
128
What does long-range inhibition prevent in pattern generation?
Activator production in neighboring cells.
129
What patterns can result from reaction-diffusion systems?
Spots stripes or single cell clusters.
130
What distinguishes asymmetric cell division?
Sister cells are inherently different at birth.
131
What characterizes symmetric cell division?
Sister cells differentiate due to post-birth influences.
132
What is the process of sequential induction?
Generates multiple cell types through successive interactions.
133
What was the homunculus theory?
Believed the entire body was preformed in the sperm.
134
What is the modern view of developmental progression?
From simple to complex through gradual refinement.
135
What initiates dorsoventral polarity in frog eggs?
Egg cortex rotation triggered by fertilization.
136
What role does sperm entry play in frog egg development?
Determines the direction of egg cortex rotation.
137
What molecule is concentrated dorsally in frog eggs?
Wnt11 mRNA.
138
What does VegT localization induce in frog embryos?
Endoderm and mesoderm formation.
139
What is the composition of the amphibian embryo trunk?
Ectoderm outside endoderm inside mesoderm between.
140
What does the endoderm form in the digestive tract?
Epithelial lining from mouth to anus.
141
What are the mesoderm-derived components of the vascular system?
Heart blood vessels and blood cells.
142
What does the ectoderm contribute to the skin?
Epidermis and appendages like hair and glands.
143
What is the role of the notochord in tissue coordination?
Sends signals to coordinate surrounding tissue development.
144
What is the function of gut cells in nutrient absorption?
Absorb nutrients from ingested food.
145
What is the significance of the antero-posterior axis?
Organizes mouth and brain anteriorly anus posteriorly.
146
What defines the dorsoventral axis in animals?
Back as dorsal belly as ventral.
147
What is the blastula's structure in frog development?
A sheet of epithelial cells surrounding a cavity.
148
What happens to mesoderm during gastrulation?
Forms between ectoderm and endoderm.
149
What does the endoderm contribute to the pancreas?
Secretory cells.
150
What does the mesoderm form in connective tissues?
Cartilage bone and fibrous tissue.
151
What is the ectoderm's role in the nervous system?
Forms neurons glia and sensory cells.
152
What is the initial connective tissue in embryos?
Mesenchyme.
153
What does the mesoderm contribute to gonads?
Tubules ducts and supporting tissues.
154
What is the developmental potential of pancreatic β-islet cells?
Highly specialized to secrete insulin.
155
What maintains cell specialization in development?
Cell memory of past extracellular signals.
156
What is the genome difference between specialized cells?
None they share the zygote's genome.
157
What is the role of regulatory DNA in organ differences?
Defines gene expression patterns via transcription regulators.
158
What activates gene 1 in skin cells?
Transcription regulators specific to skin cells.
159
What activates gene 3 in muscle cells?
Transcription regulators specific to muscle cells.
160
What is the role of inductive signaling pathways?
Coordinate spatial patterning in development.
161
What is the effect of combinatorial signaling on cells?
Response depends on multiple simultaneous signals.
162
What is the role of cell memory in signal response?
Modifies responses based on past signal traces.
163
What is the source of a morphogen gradient?
Localized production of a signaling molecule.
164
What induces different cell fates in morphogen gradients?
Varying concentrations or exposure times.
165
What is the typical range of morphogen diffusion?
1 mm or less.
166
What is the degradation process of morphogens?
Occurs as they diffuse away from the source.
167
What is the time to reach a steady-state morphogen gradient?
About one hour.
168
What is the concentration gradient shape of a morphogen?
Exponential decay with distance.
169
What happens with a higher morphogen diffusion constant?
Wider range but lower source concentration.
170
What happens with a longer morphogen half-life?
Higher concentration across the tissue.
171
What is the role of lateral inhibition in patterning?
Creates differences between neighboring cells.
172
What drives the runaway instability in lateral inhibition?
Positive feedback amplifying differences.
173
What is the final outcome of lateral inhibition?
Two cells in opposite stable states.
174
What is the role of short-range activators in patterns?
Stimulate their own production locally.
175
What is the role of long-range inhibitors in patterns?
Prevent activator production in distant cells.
176
What patterns can reaction-diffusion systems produce?
Spots stripes or single specialized clusters.
177
What is the key feature of asymmetric cell division?
Sister cells are different from birth.
178
What is the key feature of symmetric cell division?
Sister cells differentiate post-birth.
179
What is the outcome of sequential induction in patterning?
Generates diverse cell types from few initial types.
180
What was the flaw in the homunculus theory?
Assumed the body was preformed in the sperm.
181
What is the correct view of developmental complexity?
Gradual refinement from simple to complex structures.
182
What triggers the reorganization in frog egg development?
Fertilization and microtubule cytoskeleton changes.
183
What determines the dorsoventral axis in frog embryos?
Wnt11 mRNA dorsal concentration.
184
What induces endoderm and mesoderm in frog embryos?
Vegetally localized VegT signals.
