Development Overview
FILL IN THE BLANK:
________ restricts alternate fates.
There are two different types of stem cells: ______ stem cells and ____ stem cells.
__cell differentiation__ restricts alternate fates.
There are two different types of stem cells: __embryonic__ stem cells and _adult_ stem cells.
1) fertilization
2) cleavage
3) gastrulation
4) organogenesis
BONUS: is homeostasis the same as equilibrium? Why/why not?
Homeostasis: "maintaining relatively constant chemical + physical conditions in an animal's body"
--> achieved through conformation OR regulation
*homeostasis is NOT equilibrium!
What are hox genes?
Hox Genes: "RTFs that specify identity of body parts"
- important for GOF + LOF mutations
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Embryonic stem cells can be derived from the inner cell mass of the ____. They can become ANY cell in the body; therefore, they are ____.
Adult (aka, somatic) stem cells are a population of stem cells in the adult body with more ____ potential: they are _____.
Embryonic stem cells can be derived from the inner cell mass of the _blastocyte_. They can become ANY cell in the body; therefore, they are _pluripotent_.
Adult (aka, somatic) stem cells are a population of stem cells in the adult body with more _limited_ potential: they are _multipotent_.
Apoptosis: "programmed cell death"
--> used as a normal part of development, some cells are eliminated (NECESSARY for normal development)
-->ex: webbed feet in chickens --> chicken with webbed feet have defective apoptosis genes
Describe the details of fertilization
1) multiple sperm contact oocyte
2) sperm release enzymes to aid movement through the outer layers of oocyte
3) plasma membranes of the sperm + oocyte fuse with each other
4) the sperm's nucleus enters the egg's cytoplasm (sperm = "nucleus + propeller" ??)
5) pronuclei fuse
What is negative feedback? Positive feedback?
Negative feedback: thermostat
Positive feedback: birth
Hox genes organization, expression patterns, & function are _____ in animals.
Hox genes organization, expression patterns, & function are _conserved__ in animals.
Why do differentiating cells lose their "potential?" (i.e. explain 2 hypotheses + experiment + conclusion)
Hypothesis #1: gene regulation-- "unused" genes are turned off
Hypothesis #2: genome reduction-- "unused" genes are deleted
Nuclear Transfer Experiment:
1) inactivate nucleus of oocyte
2) obtain nucleus from an intestinal tadpole
3) inject nucleus from intestinal cell of tadpole into oocyte
4) result: injected oocyte develops to tadpole stage (only 10/716 times)
CONCLUSION: differentiated cells contain a complete genome --> aka hypothesis #1 = correct (gene regulation-- "unused" genes are turned off)
What are the 5 fundamental developmental processes common to ALL animals?
1) cell proliferation
2) cell movement
3) cell signaling
4) apoptosis
5) cell differentiation
Describe the cleavage stage of development-- what are cytoplasmic determinants/what is their purpose?
"rapid mitotic divisions WITHOUT gap phases & WITHOUT growth; cytoplasm becomes divided into smaller & smaller cells"
zygote --> morula
-during early cleavage stages, NO RNA TRANSCRIPTION occurs; transcription from zygotic genome begins LATER in development
-Cytoplasmic determinants: "maternal contribution of protein, RNA, etc. stored in oocyte"
**cytoplasmic determinants control INITIAL development**
What are the 2 functions of the kidneys in terrestrial vertebrates?
1) Osmoregulation: "maintains water/electrolyte balance in tissues to achieve homeostasis"
2) Removes nitrogenous wastes from blood (i.e. urea, which is a byproduct of protein metabolism)
What are the 4 major tissue types and what are their main functions?
1) epithelial tissue: covers outside of body, lines surface of organs
2) connective tissue: structural support
3) nervous tissue: integrates functioning of organs in body; processes sensory input
4) muscle tissue: movement
What type of bonding is fertilization?
Species-Specific binding: fertilization from the eggs of one species bind to sperm of its own species, but does NOT bind to sperm of different species
--> why a cat and dog cannot have a baby cat-dog
--> there are exceptions [hybrids]... ex: mule = male donkey + female horse
Distinguish between...
1) totipotent
2) pluripotent
3) multipotent
1) Totipotent: "will give rise to ALL cells"
2) Pluripotent: "will give rise to ALL cells of the EMBRYO"
3) Multipotent: "will give rise to DIFFERENT cell types, but CANNOT contribute to other germ layers"
Describe gastrulation
1) ectoderm: epidermis of skin
2) mesoderm: skeletal, circulatory, lymphatic, muscular, reproductive systems
3) endoderm: epithelial lining of... digestive, reproductive, urinary, respiratory tracts; also liver, pancreas, thyroid
FILL IN THE BLANK:
A ____ is an example of a ____ ____ gene (cytoplasmic determinant). These gene products are present in the egg _____ fertilization and direct _____ development.
_____ of embryo depends on genotype of ____ and is _______ of sperm or zygote genotype.
A _bicoid_ is an example of a _maternal_ _effect_ gene (cytoplasmic determinant). These gene products are present in the egg _before__ fertilization and direct _early__ development.
_phenotype__ of embryo depends on genotype of _mother_ and is ___independent__ of sperm or zygote genotype.
How do cells acquire information to specify their identity in the embryo? [hint: experiment...]
Experimental design: genetic screen for mutants in fruit flies with morphological defects in spatial organization in embryos
-find genes that are mutated
-correspondence between adult & larval body parts
-Bicoid Mutant: "two-tailed" mutant --> bicoid protein = RTF that activates genes required for building anterior structures
--> Bicoid = morphogen = "provides spatial information via a concentration gradient"
Organogenesis: "organs begin to form"
Cell Differentiation: "cells begin to produce proteins specific to a particular cell type"
ex: muscle cells vs. neurons
**ALL cells in body have SAME DNA (SAME genes), but express a DIFFERENT set of PROTEINS**