1.1 Intro to Developmental Biology Flashcards
(28 cards)
What is developmental biology?
Study of transient stages between egg and birth
How egg produces adult and how adult produces egg
What areas of science do developmental studies inform?
Birth defects research Role of genes in disease Cancer Stem cells Regeneration Evolution
How does developmental biology inform medicine?
Permits development of preventative regimes and treatments for pathological conditions
- experimental model = mouse
^Identify gene sonic hedgehog (shh)
^Shh requires cholesterol
^Cholesterol inhibitors: Alkaloids - plants
^Alkaloids in animal fodder = cyclopic lamb
What are the mechanisms driving embryonic development?
- Generation of cells - mitosis and growth
- Cell differentiation - totipotent = any cell type
Pluripotent = several cell types
Differentiated have a final character - Generation of tissues/organs/whole body - morphogenesis
Definition of morphogenesis
Creation of structure or form; two major forms during embryogenesis
What is the difference between mesenchymal and epithelial cells?
Mesenchyme = single or loosely linked cells of irregular shape
Epithelial = cells tightly attached to each other or a common membrane, regular shape
What is anatomical embryology?
How anatomy changes with and between embryos
- easier in larger animals
What is experimental embryology?
Mechanics of development
- easier in larger animals
What is genetic embryology?
How genes control development
- smaller animals, shorter gestation
What are the pros and cons of using fruit flies?
- short life span - both
- easy to handle large numbers - pro
- easily mutated and easy to make transgenics - pro
- ideal genetic model - pro
- not a vertebrate - con
What are the pros and cons of using zebrafish embryos? - Danio rerio
Small, cheap and easy to keep - pro
Develop external to mother - pro
Transparent, good for anatomical development - pro
Easy to mutate - transgenics - pro
small eggs but can perform experimental embryology - pro
Can generate large numbers easily and rapidly - pro
What are the pros and cons of using chick embryos? - Gallus gallus
Develop external to mother - pro large embryo - pro Easily experimentally manipulated - pro not good for genetics - con Closer to humans then Xenopus and zebrafish - pro
What are the pros and cons of using mouse embryos ?- Mus muscuelus
Mammalian - closest to human - pro
Same no. of genes in the same order - pro
Good for genetics: transgenics - knockouts - pro
Small, short, breeding cycle - pro
Poor for experimental embryology studies - cons
Develops inside mother - cons
What are the pros and cons of using frog embryos? - Xenopus laevis
Large eggs - pro
Develop external to mother - pro
Easily manipulated for experimental embryology - pro
Genetics difficult as they have 4 copies of each gene - con
Can generate large numbers easily and cheaply - pro
What is drosophila segmentation?
Relationship between adult anatomy and embryonic segmentation - obvious - head mandibular maxillary labial = 1 -thorax = 3 - abdominal segments = 10 14 segments in total
What is the Drosophila maternal effect gene?
Genes expressed in mothers ovaries
- mRNA’s diffuse into egg and are transplanted upon fertilisation
How do the anterior - posterior regions develop?
Anterior = bicoid + hunchback genes
Posterior = caudal + nanos genes
Both are maternal effect genes
What happens in the absence of bicoid?
All tail no head
What are the drosophila zygotic segmentation genes?
Divide early embryo into segments (primordia) along A-P axis - expressed sequentially syncytial blastoderm 1st = gap genes 2nd = pair-rule genes Cellularisation 3rd = segment polarity genes 4th = homeotic selector genes
What are the gap genes?
Divide embryo into 4 broad domains
1st genes that drosophila embryo expresses (zygotic genes)
Encode transcription factors (hunchback, giant, krüppel, knirps, tailless)
Controlled by maternal effect genes
Cross replication ensure discrete expression domains
What are pair-rule genes?
Group of transcription factors including; hairy, even-skipped, runt , fushi, tarazu, odd-skipped, paired
Expressed in stripes, dividing embryo into 4 subunits (parasegments)
Expression controlled by gap proteins
What are segment polarity genes?
Mainly signalling molecules e.g hedgehog (hh) and wingless (wnt)
divide each parasegment into anterior and posterior compartments
Expression controlled by pair-rule proteins - mutual repression
parasegments (early embryo) - segments (late embryo)
hh expressed in anterior of parasegment but in posterior of segment
How to make segments unique?
- homeosis - transformation of whole segment or structure into a related one
Drosophila homeotic mutants
identification of homeotic complex (hom-c)
What is the homeotic complex?
HOX genes
Homeobox - containing transcription factors
8 genes, 1 chromosome - expressed in specific segments
Controlled by gap and pair rule gene
Later repressed by adjacent homeotic genes
