Study Questions 1-2 Flash Cards
Define Development
Growth in size and ability by differentiation, progressive change through growth and differentiation
Define Growth
increase in size by mass and or volume of either whole organism or its components
define differentiation
process by which an unspecialized cell becomes specialized into one of the many cell types that make up the body
define histogenesis
differentiation of undifferentiated zygotic cells into the germ layers
what is organogenesis
the formation of organs from specialized tissues from the germ layers
What is morphogenesis
the growth and development of the psycological structure of an organism
what is reporduction
the biological process by which new offspring individual organsms are produced by their parents
define tissue
an aggregate of cells in an organism that have similar structure and function
define organ
group of tissues working together to form a functional organ body
what is the difference between growth and differentiation
growth is an increase in the number of cells via mitotic division, while differentiation is the process by which one cell becomes specalized into a specific role or function
What are the two major questions that are addressed by the discipline of developmental biology
How does an adult organism develop from a sinlge fertilized parent cell?
How does an adult organism produce another organsism?
What is chemotaxis
attraction of cells (sperm) upward a chemical concentration gradient towards the source of the chemoattractant
What is resact
a small 14 AA peptide released by the egg jelly in sea urchins that reacts with sperm as a chemoattractant
What is agglutination
the process of binding the sperm and the egg by species specific proteins
what is capacitation
the activation/maturation of sperm cells within the female reproductive system
what is acrosome
vacuole formed as a germ cell differentiates into a sperm
what is bindin
protein represented on the external membrane of the sperm; lines the acrosomal filament and binds to egg membrane
what is the acrosomal filament
an anctin microfilament extension from the head of the sperm that grows where the acrosomal vesicle had previously erupted
what happens in the early stage of egg activation
begins by fusion of sperm and egg membrane, leads to +vely charged cell
what happens in the late stage of egg activation
calcium increase inhibits MAP kinase** leads to DNA protein synthesis including cyclin B and cdk1 which initiates cell division
what is the cortex
gel like shell just under the egg cell membrane and contains cortical granuels
what are cortical granules
structure homologous to the sperms acrosome, contains enzymes which prevent sperm entry after fertilization
what is the fertilization envelope
cavity formed, filled and fused between the vitelline envelope and the egg membrane, filled with enzymes and begins to grow at point of cell entry, NOT in mammals
what is the zona pellucida
the mammalian analog of veitelline envelope, thick matrix that the sperm must pass through to reach the egg emmbrane
what are some of the factors that will increase the probablity of a sperm egg intreaction
huge numbers of sperm, species specific events, behavioural modifications, mating calls and behaviours, external vs internal fertilization
What role does chemotazis play in bringing the sperm and egg together
attracts the sperm towards the egg as it follows the chemical gradient (species specific event 1)
What induces sperm activation in sea urchins
Chemoattraction- sperm has receptors for resact and follows it up a calcium gradient which leads to the activation of dynenin ATPase which gives the sperm energy to swim
What organelle is the acrosome derived from?
from the golgi apparatus and migrates to the head of the sperm
what is the purpose of the enzymes in the acrosome
used to break down the eggs extracellular matrix
How are the acrosome enzyme released in sea urchins
fusion of the vesicle membrane with the sperm membrane allowing for the degredation of the jelly layer to occur
If intact sperm were injected into a sea urchin egg would they be able to fertilize it? why or why not?
No, most likely be broken down or taken up by lysosomes, **
What are the two barriers that prevent the sperm of one spevies from fertilizing the egg form another species
1- chemotaxis- different specie sattracted to different chemoattractants
2- agglutination- contains surface protein bindin which has species specific reveptor on egg cell membrane
what is the role of calcium in fertilization
Acitvates dynin ATPase for sperm, In sea urchins calcium in sea water increases ATP generation, inhibits MAP kinase and cyclin to allow DNA replication
describe the origin and funcitons of the fertilization membrane in sea urchin eggs
granules contain a number of enzymes that cause the fromation of the envelope that prevents polyspermy
why is it important to prevent polyspermy?
to avoid incorrect number fo chromosomes and centrioles, uneven number of centrosomes and centromeres will cause death of the embryo, incorrect number of centrioles will result in additional cleavage and incorrect partitioning of the chromosome.
Compare/contrast fast and slow polyspermy block
Fast block- 1-3 seconds, resting potetntial swithces from -70 to +20 mv by influx of Na+ ions
SLow block- primary component is corticle granule reaction, contain enzymes which modify the extracellular space,
Difference- fast block sodium mediated and not in mammals, slow blcok calcium mediated and occurs in both mammals and others
define telolecithal
yolk at one end
define holoblastic cleavage
formation of complete and separate cells
define meroblastic cleavage
incompltel separation of cells
define superficial cleavage
clevage that does not penetrate yolk
what is discoidal cleavage
merobalstic clavage in which a disk of cell is formed at the vegetal end of the yolk
what is radial cleavage
equal sharing of cytoplasm, equatorial
define determinate cleavage
development of fate has been determined
waht is the blastomere
cell resulting from cleavage
define blastula
spherical structure composed of blastomeres
define micro, meso and megalecithal
microlecithal- small amount of yolk
mesolecithal- moderat yolk
mega- large amount of yolk
what is indeterminate cleavage
if each cell is separated, capability of develping into whole organisms is still possible (totipotent)
what is direct development
the fetus looks like a miature version of the adult
define indirect development
the fetus goes through different phases called metamorphasis
define protostome
develop mouth from first blastopore then the anus
define deuterostomes
develop anus first
T or F: archenteron and primitive gut are the same thing
T
define delamination
splitting of one cellular layer into two
define ectoderm
outer germ layers, give srise ot body coverngs and nervous systems
define mesoderm
middle germ layer that gives rise to skeleton, muscle and connective tissues and reproductive organs
define endoderm
inner germ layer that gives rise to digestive organs
Is protein synthesis essential during early cleavage? mRNA synthesis?
Protein synthesis is required to produce cyclin B for the Mitosis promoting factor
mRNA synthesis is not necessary because of the already available mRNA in the oocyte hat controls initial rate of cell division
How does the cell cycle which occurs during cleavage differ from the cell cycle of normal adult body cells
cleavage is NOT accompanied by sell growth, blastula get progressively smaller due to division, no change in size or growth but volume of blastula is decreasing, only cyclin B and cdc2 are used
What FOUR factors determine cell fate?
- Asymmetric cell divisions
- Cell-to-cell interactions
- Cell-cell communications
- Position of the cell in an embryo
Define induction
interaction at close range between two or more cells or tissues with different historie and properties
define competence
ability of the cell or tissue to respond to the signal
define intrsuctive vs permissive effects
instructive- gives instruction/signal to induce other cells
permissive- allowing a cell to develop on it own because the cell has already been specified
Define morphogen
a morphogen is a ligand which is a ligand; ion, hormone, protein or polypeptide growth factor
what are the types of cell-cell communications in respect to morphogen production and distribution
Juxtacrine- direct contact by adjacent cell
Paracrine- morphogen released has effect on neighbouring cells
Endocrine- hormones released from a cell affect other cell throughout the body
Autocrine- secretes morphogen and responds to it
What is signal transduction
the passing of a signal across the cell membrane and the events within the cell htat occur in response to a signal
what is the most common outcome of signal transduction
the change of gene expression
What is the relationship between signal transduction and cell differentiation
cell differentiation is activated by signal transduction; eg. MAP kinase activated by kinase cascade
What are the three modes of cell type specification
Autonomous- specification by acquisition of certain cytoplasmic molecules in the egg
Conditional- specification by interaction between cells
Syncytial- specification of body region by interaction between cytoplasmic region prior to the blastoderm
Example of autonomous specification
Sea urchins and c elegans
Example of conditional specification
frog and mammalian embryos
example of syncytial specification
Drosophillia
What kind of moleucles are P granules and what is their function
ribonucleoprotein complexes that are localized randomly in the cytoplasm, found in C. elegans responsible for specification of germ cells
