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B03101 TEST1 - Coggle Diagram
B03101 TEST1
all animals develop through alike stages
zygote polarized along axis
upper hemi= animal hemi
lower hemi= vegi hemi
1st divisions= cleavage & produce blastomeres
blastocoel forms in cleavage
embryo goes through gastrulation
gastrulae's tissue layers= germ layers= ecto/endo/mesoderm
give rise to somatic bodies
germ layer identity conserved in animals
germ line gives rise to gametes
C. Elegans
soil nematode
1st multicellular genome sequenced
self-fertilizing hermaphrodte
genome= 100mB (humans 3.2 GB)
19,000 GENES
302 neurons
programmed cell death
live 2 weeks
mutation= change in organism's genome
may result in changes in protein it encodes
spontaneous/ experimentally induced
transgenesis: insertion of new gene into genome
knockout= removal/ inactivation of a gene- permanent, heritable
knockdown= lowering gene's activity
knock-in= insertion of DNA into location
loss of function= protein product of gene less active than wild type
C. ELegans
not maternally controlled
controlled by site the sperm enters the egg (posterior)
p4 becomes germline
lost cells not replaces
A-P polarity mediated by P4
1 HOX CLUSTER W 6 hox genes
only 3 have loss of function
developmental genetics: development controlled by genes
forward genetics: ID gene responsible for phenotype
reverse genetics: ID function of gene by changing DNA sequence
diploid animals have 2 alleles of each gene
most common allele = wild type
gene names &mRNA in italics, protein product in plain text
human genes= uppercase italics; proteins= uppercase
mouse genes & proteins= 1st letter capitalized
Drosophila= holometabolous= larvae diff to adult
4 chromosome pairs: 3 autosomes 1 sex
generation time= 2 weeks
genome= 13,000 genes
innate immunity= toll=like receptors
body axes & germline determined maternally
hox genes detrmine segment ID; segmentation genes determine segment borders
bilaterians= all animals except sponges& cnidarians
most bilaterally symmetrical
some non-bilaterians bilaterally symmetrical e.g. sea anemones
humans nearly bilaterally symmetrical-> asymmetric bilaterians
gradients= when inducing factor scereted from 1 cell sheet
generates polarity ( where to put head)
morphogenetic field= group of cells that can respond to a morphogen
generate diff structures based on diff conc. of morphogens
use antisence RNA probe that hybridizes with mRNA
in situ hybridization= to visualise mRNA in cells where they are transcribed
doesnt show location
indirect info about activity
Rna seq= based on complete sequencing of entire transcriptome
immunohistochemistry
to detect specific protein in situ
uses antibodies that bind to the protein
inducing factors= extracellular molecules that make cells respond
aka hormones/ growth factors-----change cell's ID
can act via signal transduction pathway
sea urchins
30,000 genes; genome= 800mB
hydractinia= no cancer, grow like plant
20k proteinn coding genes---- 400MB
differentiation: how to generate cellular diversity
mammals=200 cell types
dominant if mutated single allele causes defective genotype
bicoid gradient controls gap gene expression
gap genes control pair rule genes
pair rule genes generate pairs of segments and control segmentation genes
hox genes dtermine identity
AXIS FORMATION IN FLIES & WORMS
Drosophila
body axes determined maternally
embryo has no control over position of poles
all events up to 5000 cells are controlled by maternal mRNA
1 site for sperm entry: micropyle, at future dorsal anterior
fertilized egg undergoes superficial cleavage, resulting in synctial blastoderm
nuclei reach posterior pole after 8th division to become germ lines (pole cells)
cells form after 13 divisions
cellular blastoderm stage is single cell layer around central yolk mass
mRNAs of bicoid & nanos synthesized maternally
by nurse cells & transported to anterior & posterior of oocyte respectively
bicoid forms anterior-posterior gradient
bicoid= anterior development
mRNAS act as morphogens
nanos patterns posterior pole
nanos blocks hunchback
bicoid blocks caudal
gurken initiates dorsal-ventral axis polarity
diffuses to follicle cells in ovary
transforms them to dorsakl type cells
wont be able to activate spatzle protein
primary axs formation during oogenesis
gene dorsal
dorsal's mRNA conc is ubiquitous
dorsal protein activated at ventral side by spatzle/toll
spatzle activated by ventral follicle cells
dorsal follicle cells unable to activate spatxle due to gurken
activated spatxle results in gradient of activated dorsal protein
binding of spatzle to toll causes phosphorylation of cactus
releases dorsal to nucleus
morphogenesis: how to makes tissues & organs
normal development= normal course of animal without experimental manipulation
fate map= shows fate of each region of embryo in normal development