Lecture 1-18 Flashcards
Zygote definittion
Fertilized egg
Embryo definition
Developing organism from fertilization through the formation of differentiated tissues
What are the three tasks each embryo has during the early phase of development
- Increase the number of cells through cell division
- increase the number of cell types by differentiation
- generate polarity to allow establishment of the future body axis
What are the five stages of embryogenesis?
Fertilization, Cleavage, Gastrulation, Organogenesis and Histogenesis
What are the two poles of the egg called
animal and vegetal
What does fertilization trigger
Numerous metabolic interactions including change in CA+++ concentration, protein synthesis etc. – will influence the zygotes further development
What are the two genetic programs that organisms are regulated by
- Cytoplasmic determinants in the egg (eg. RNAS, enzymes etc)
- Genome of the zygote
The pattern of embryonic cleavage is determined by what two major factors
the amount of yolk in the egg cytoplasm and the distribution of yolk in the egg cytoplasm
The animal pole is closer to the ____ while the vegetal pole contains the ____
nucleus, yolk
T or F: by cleavage the majority of cells already have a predictable fate
T
What are the three major stages that cell fate goes thoguh
Specification, determination and differentiation
What happens during specification
cell has been instructed and will follow the instructions however fate is still reversible
What happens during determination
Cell’s fate is irriversible
What happens during differentiation
fate is absolutely irreversible, generation of specialized cell type
What is the difference between totipotent, pluripotent and multipotent
totipotent- can give rise to a complete individual
pluripotent- can form more structures than their original fate
multipotent- similar to pluripotent, but lesser number of structures
what is the difference between epithethilial and mesenchymal cells
Epithelial cells form sheets and are tightly compacted
Mesenchymal cells are loosely organized and attached, also can migrate as individual cells
what is indcution when it comes to cell actions
one cell or group of cells chnages the behaviour of another cell or group of cells
What is competence
ability of cells to respond to inductive signal
what is signal transduction
different pathways to obtain induction/competence capabilities
what is gastrulation
a series of complex morphogenic movements and activities proliferating cells migrate, rearragne sheets of cells bend, fold and spread forming gastrula
What are the three germ layers that gastrulation forms
Outermost ectoderm, innermost endoderm and the intermediate mesoderm
what does the ectoderm form
the outer layer of skin and nervous system
what does the endoderm form
the inner lining of the digestive tract and its appendages
what does the mesoderm from
form bone and other skeletal structure, muscle heart blood vessels, kidneys and reproductive organs
in organogenesis ectodermal cells form the ____ ____
neural plate
in organogeneis the endoderm forms the _______
arcenteron– gut rediment
what happens during histogenesis
cells specialize to perform particular functions, final cell differentiation
What is direct vs indirect development postembryo??
Direct is the development looks like a miniature adult, fetus, juvenile
Indirect is the larva going thorugh stages called metamorphasis. Ex. tadpoles and caterpillars
What is the axoneme
moajor portion of sperm- dynein- ATPases
What is an oocyte vs an ovum
oocyte is a developing egg while an ovum is a matured egg, reached stage in meiosis where it could get fertilized
Why is the sea urchin a good model organism in developmental biology
sexually mature throughout the year, and produces a considerable number of large, transparent eggs
What are the two important external layers in the sea urchin egg
the jelly layer and the vitelline envelope
What does the cortex of the sea urchin egg do at fertilization
high in globular actin which polymerize in mirofilaments which form microvilli which aid in sperm entry
the mammalian egg is surrounded by ____ which aids to
cumulus, aids to nurture the egg
what is the innermost layer of the cumulus
the corona
What is the zona pellucida
the mammalian analog of the vitelline envelope produced by the egg
What are the four major events in the process of fertilizaiton
- contact and recognition
- regulation of sperm entry into the egg
- activation of egg metabolism to start development
- fusion of genetic material
what attracts the sperm to the egg
chemoattraction by soluble moelcules and chemotaxis; ; sperm follow gradient of chemical secreted by the egg
What is the role of calcium in sea urchin fertilizaiton
ca+ from sea water gets into the cell and activates sperm flagellar dynein ATPase, energy for swimming
What are the two steps in acrosome reaciton in the sea urchin
- the fusion of the acrosomal vesicle within the sperm cell membrane
- extension of the acrosomal process
What are the three species specific events sea urchins go through
- sperm attraction by chemotaxis
- sperm plasma membrane contains receptors for species specific polysaccharies from the egg jelly coat
- acrosomal process contains protein bindin which has the cresptor on the egg cell membrane, ERB1
What are the five events breifly of sea urchin egg and sperm entry
- chemoattraciton
- exocytosis of acrosomal vesicle
- digestion of jelly layer
- binding of sperm to extracellular envelope and passage through it
- fusion of sperm and egg emmbrnaes
WHat are the two things that are necessary for fertilization
- egg and/or cumulus cells have to be able to produce chemotaxic attractant molecule
- sperm capacitation
what is the 5 steps in sperm entry in mammals
- chemoattraction
- binding of sperm to zona pellucida
- exocytosis of acrosomal vesicle
- passage of sperm though the zona pellucida
- fusion of the sperm and egg membranes
What are the three major proteins hte zona pellucida is made up of
ZP1, ZP2 and ZP3
sea urchin only has acrosomal ______
process
in mammals sperm binds at the _____, not the ____
side, tip
how is the fast block of polyspermy achieved
achieved by changing the electrical potential of the egg cell membrane
What is the primary component of the sea urchin
the cortical granule reaction
What are the four steps in the slow black in sea urchins
- Serine protease digest the protein and clips off extra sperm
- Mucopolysacharieds create osmotic gradient causing water to enter
- Peroxide enzymes harden the envelope by cross-linking tyrosine residues
- Hyalin coating is formed around the egg
T or F: there is a fertilization envelope in mamals
F
Granule fusion is driven by an increase in intracellular ___ in both mammals and sea urchins
Ca2+
Egg activation can be broken into ____ and ___ phases
early and late
What does Ca2+ activate
NAD+ kinase which converts NAD to NADP+
What happens to Ca+ in early sea urchin egg activation
dependant on a transient increase in ca2+ following egg sperm fusion
what happens to ca2+ in early mammal egg activation
several waves of ca2+ released corresponding to aspects of egg acvitation
In both sea urchins and mammals what happens in the late phase of egg activation
increase of Ca 2+ inhibits MAP kinase so DNA replication can start
What is the difference between sea urchin fusion and mammal fusion
the time of DNA replication
what are the two major developmental processes that occur in succession
cleavage and gastrulation
what happens during cleavage
a period of rapid cell division
T or F: cell division is accompanied by cell growth
F
Where is the site of first clevage
determined by the point of sperm entry
What is the cleavage driven by
the Mitosis promoting factor
What are the two subunits in the mitosis promoting factor
CyclinB and cdc2
CyclnB is regulated by factors in the _____
cytopalsm
What is karokinesis
the mitotic division of the nucleus
What is cytokinesis
the physical division of the cell
The pattern of embryonic cleavage is determined by what two factors
the amount and distribution of yolk, and the factors in the egg cytoplasm that influence the angle of the mitotic spindle
How do cells and tissues know how to develop
thorugh mutual interactions- induction and competence
cell fate is determined by what four factors
1- Asymmetric cell divions
2- Cell to cell interactions
3. Cell cell communications
4. Position of the cell in an embryo
what is the difference from asymmetric and symmetric division
asymmetric- sister cells born different
symmetric- sister cells become different as a result of influences acting on them after their birth
what are tight junctions
create sheets of cells
what are anchoring junctions
connect the cytoskeletons of adjacent cells, or connect cells to matrix
what are communicating junctions
permit small molecules to pass between cells
what is induction
interaction between two or more cells with different histories and properties
what is the inducer
cell that produces or sends a signal (morphogen) that will change the cellular behaviour
what is the responder
the target cell
what is competence
the ability of a cell or tissue to respond to a specific inductive signal; can change with time
What is instructive vs permissive cell communication indcution
Instructive- initiates new gene expression
permissive- allows expression of those traits
T or F: an inducer is a morphogen
T
What are the three types of cell-cell communication
juxtacrine-adjacant direct contact
paracrine-effects neighboring cells
endocrine-hormones affect cells throughout body
WHat are the four signa transduction systems
1- receptor with enzymatic activity
2- receptor coupled to a heterotrimeric G prrotein
3-intracellular receptors
4- Linked receptors
what is a kinase cascade
a series of protein kinases that phosporylate each other in succession, amplifying the signal
