• Developmental Genetics => Transforming info stored in linear DNA => into 3D organism.
• Characteristics of animal development:
o Multi-cellular characteristic
o Differentiation of cells => carry out a different function
§ Single celled zygote => decisions => complex multicellular organism w/
specialized & differentiated cells.
• Determination: predetermines cell’s fate
o Mechanism involved in regulating the choice of developmental fate a cell will eventually
o Normal cells => turns into a migratory cell => determination-changed cell's fate from
stationary to migratory
o Determination does not execute process of causing cell to differentiate yet => all it does
is predetermine what the cell will eventually become.
• Differentiation: executes cell’s fate
o Mechanism to bring about decided fate made by determination mechanism.
o Differentiation turns stationary cells into a migratory cell.
o Ex. Segmentation in fly => cells all look the same => but each cell already knows its fate
& what it will differentiate into => determination causes cells to know their fate => once
cells differentiate into a specialized cell => process of differentiation => cells know a lot
about their fate early on in development.
o THM: cells exhibit differentiation due to differential gene expression , which causes them
to turn into specialized cells.
o Give rise to pattern of expression => if genes show gaps or if the genes are showing a
pair-rule pattern => pre-pattern of future segmentation => or how the segmentation
would look like.
• Gene expression:
o Cells w/ exactly the same DNA genotype => exhibit distinct phenotypes from each other
=> via differential gene regulation & gene expression.
o Development => all about differential expression of genetic informa tion => development
is a problem of gene expression.
o Developmental information is passed along a developmental pathway => coordinated
• Levels of gene expression:
o DNA => primary mRNA => mature mRNA => inactive protein => active protein
§ DNA => primary mRNA via txn
§ Primary mRNA => mature mRNA via splicing
§ Mature mRNA => inactive protein via tsn
§ Inactive protein => active protein via protein modification & mutations.
• Four examples of loss of negative control:
o LacZ gene => gf allele (Oc MT) => level of regulation @ txn
o Transformer gene => gf allele (ms-site) => level of regulation @ splicing
o Hunchback gene => gf allele (NRE) => level of regulation @ translation
o RAS => gf allele (GTPase) => level of regulation @ protein modification
• Regulation of splicing during drosophila sex determination:
o Transformer gene is regulated @ level of splicing => male & female mRNA are distinct
from one another => spliced differently . o Sxl protein is only present in females => Sxl protein binds to ORF of primary mRNA &
blocks splicing machinery from splicing out intron 2 => full length ORF is present
(nothing spliced out) => functional Tra protein => maintains female sex.
o Males do not produce Sxl protein => nothing to block splicin g site => splicing occurs but