Lecture 2 - Concepts in Developmental Biology Flashcards
1
Q
Concepts in Developmental Biology
A
- Genomic Equivalence
- Cell Differentiation
- Selective Gene Expression
- Morphogenesis
- Homeotic Genes
- Homeobox Genes
2
Q
directive influence that determine the course of normal development
A
preformed
3
Q
direct initial developmental stages
A
- maternal genes and
- egg cytoplasm
4
Q
direct development after cleavage
A
zygotic genes
5
Q
- products of the genes
- include the environmental factors which affect development along the way
A
progressively formed
6
Q
- each cell in the body has the same genetic material
- all the information necessary to produce a complete gene is present in each cell
A
genomic equivalence
7
Q
- the restricition of nuclear potency
- ultimate test of whether the nucleus of a differentiated cell has undergone any irreversible functional restriction is to have that nucleus generate every other type of differentiated cell in the body
A
amphibian cloning
8
Q
- total capacity of a cell to give rise to a complete embyro
- direct the entire development of the organism
- true for cells in the early stages of development
A
totipotency
9
Q
ability to give rise to several types of cell, but not all –> incomplete embryo
A
pleuripotency
10
Q
did the nuclear transfer in amphibians
A
- M. DiBerardino and
- N. Hoffner Orr.
11
Q
how was Dolly created
A
- mammary gland cell nucleus fused with an enucleated oocyte
- implanted in a surrogate mother
12
Q
- generation of cellular diversity from unicellular zygote
- the process by which a cell becomes different in structure and function
- morphological and functional expression of a portion of the genome
- a cell specialized in one or few synthetic pathways
A
cell differentiation
13
Q
what is produced due to cell differentiation
A
cell diversity
14
Q
what is the common set of genes shared by different cell types
A
common set of “housekeeping” gene products
15
Q
- why there is cell differentiation
- aka differential gene expression
- genes are activated differently dependin on time and space
- depression of certain genes at different times and in different cells
- tunr genes on/off
A
selective gene expression
16
Q
selective gene expression is aka what
A
differential gene expression
17
Q
where does the activation of genes depend on
A
- time (phase development)
- space (specific cell)
18
Q
- transient increase in the number of certain genes without mitosis
- an adaptive response for meeting the synthetic requirements of the developing egg
A
selective gene amplification
19
Q
when does selective gene amplification happen
A
during the early diplotene stage of meiosis
20
Q
what happens in selective gene amplification
A
nucleoli in germinal vesicle are active in the synthesis of ribosomal RNA
21
Q
where are the rRNA packaged into during selective gene amplification
A
about 1500 extra nucleoli beneath the nuclear membrane
22
Q
- one of the most important varieties of embryonic signal calling
- cells induce or influence adjacent cells to change its behavior
- embryonic tissue induce change to responding tissue which must posses competence to respond to the inducer
A
embryonic induction
23
Q
induce change
A
inductor (embryonic tissue)
24
Q
responds to inducer
A
responding tissue
25
what must the responding tissue posses to respong to the inducer
competence
26
induces neurulation and axis development
- notochord or
- chordamesoderm
27
a set of processes that mold the internal and external configuration of an embryo
morphogenesis
28
- spatial and temporal distribution or organization of differentiated cells
- takes place under tight genetic control
- is the laying down of the morphogenetic blueprint/body plan
- defining the main body axes
- change in form
pattern formation
29
pattern formation is what
spatial and temporal distribution or organization of differentiated cells
30
ex of pattern formation
development of arms - upper, lower and fingers
31
pattern formation takes place under what?
tight genetic control
32
pattern formation is the laying down of the what
morphogenetic blueprint/body plan
33
realization of the plan
change in form
34
examples of morphogenesis
1. limb formation
2. establishment of the fundamental axes
3. branching of ducts within the glands
4. formation of the loops and whorls of the fingers (fingerprints)
35
Six processes involved in morphogenesis
1. cell proliferation
2. cell migration
3. cell aggregation/ cell adhesion
4. secretion of extracellular substances
5. change in cell shape
6. localized cell death/apoptosis
36
cell proliferation
cleavage
37
cell migration
gastrula stage
38
ex of localized cell death
formation of fingers
39
- characterized by rapid cell divisions which results to teh increase in number of cells
- mitotic divisions
cell proliferation
40
- process wherein cells or groups of cells move from one part of the embryo to another
- may involve short migrations of individual cell or massive dislocation of groups or sheets of cells over relative great distance
cell migration
41
ex of cell migration
- invagination
- involution
42
sheet of cells bends inward
Invagination
43
tissue sheet rolls inward
involution
44
process of apoptosis or programmed cell death
1. normal cell
2. cell shrinkage, chromatin condensation
3. membrane blebbing
4. nuclear collapse, continued blebbing
5. apoptotic body formation
6. lysis of apoptotic bodies
45
process where a cell's plasma membrane bulges outward and forms bubbles or protrusions
Blebbing
46
examples of apoptosis
1. resorption of the tadpole tail
2. separation of the digits in the embryonic hand and feet
3. selective cell death of neurons that leave specialized connections
47
- set of genes that specify the antero-posterior axis and segment idneityt during the early stages of metazoan development
- critical for the proper placement of certain embryonic structures like legs, antennae and eye
homeotic genes
48
- sequence of 180 base pairs which defines the homeotic genes
- codes for the 61 amino acid protein known as homeodomain
homeobox genes
49
no. of base pairs in homeobox genes
180 base paris
50
61 amino acid protein the homeobox codes
homeodomain
51
where are homeobox genes expressed
highly specific sites and stages of development
52
- an example of a homeobox gene complex
- are expressed along the craniocaudal axis of the body in the same way as they were arranged in the chromosome
hox genes
53
where are hox genes expressed
along the craniocaudal axis of teh body in the same was as they are arranged in the chromosome
54
no of clusters of hox genes in mammals
4 (A-D)
55
within a given cluster of hox genes, how many subfamilies are there
13 subfamilies or paralogous group of genes
56
- arranged in strict order along their respective chromosomes
- transcribed in the same order from the 5' end to the 3' end
paralogous chromosomes
57
the homeobox gene is known as what of developmental biology?
Rosetta Stone
58
- interpret the positional information along the antero-posterior body axis
- both vertebrates and invertebrates have similar types, order of genes in chrom. and pattern of expression
hox genes
59
diversity of body forms in animals may be due to what?
1. verts have 4 hox gene clusters, inverts have 1
2. way they interpret the expression differ (time/space)
3. gene underwent duplication and divergence which lead to different functions of proteins
4. neural crest cells absent in inverts
60
occurs through discrete and interacting modules
- organisms are contructed of units that are parts of larger units
modularity
61
allows the formation of redundant structures
duplication
62
allows the structure to assume a new role
divergence
63
involves heterochrony and allometry
dissociation
64
retention of larval traits due
heterochrony
65
heterochrony is due to what?
- heterochronic expression of certain genes and
- gene mutation in the induction competence system
66
- different parts of the organism grow at different rates
- may involve altering a target cell's sensitivity to growth factors or altering the amount of GF produced
allometry
67
- distinguish between verts from protochordates and inverts
- protochordates have dorsal neural tube and notochord but no real "head"
neural crest cells
68
responsible for the development of face, skull and branchial arches
cranial NC
69
allows for more efficient predation with sensory structures adjacent to the prey-capturing jaws
cephalization
70
one gene specify neuron or antero-posterior axis in larval stage
co-option
71
ex of co-option
1. enzyme in liver or crystalin protein in lens
2. wings - different forearms with new or diff. functions (flippers, arms)
