lec 2.docx

5 Pages
Unlock Document

University of California - Irvine
Biological Sciences
Peter A.Bowler

D104 Lecture 2 1/9/12 pg. 14-32 Fundemental aspects of embryonic development • Cleavage: cell division; egg doesn’t increase in mass; occurs throughout the life cycle • pattern formation: different regions become subdivided • morphogenesis: changing shape of the embryo; occurs during gastrulation, where the embryo undergoes infoldings to give rise to the final shape • cell differentiation: different cell types are being built; eyes cells different from arm cells • growth: increase in cell size (increase in total mass) Five fundamental aspects of embryonic development see slide Five cell behaviors essential for Development • cell proliferation: dividing • cell death • cell shape changes • cell movement • cell-cell communication It’s all about regulation of gene expression • every cell has the exact same genetic material • cells express different genes (they don’t contain different genes)—this is how cells differ • genes control other genes • different genes are necessary for different cell types to function Gene expression and protein synthesis • Within the chromosomes, you have genes • gene has a coding region (makes the gene product) and elements outside of the coding region (promoter and enhancer regions) • enhancers: to what level genes are expressed • transcription produces mRNA, processed, leaves nucleus and enters cytoplasm, associates with ribosomes, translated to protein, and modified to carbohydrates, etc. • regulation at transcriptional level controls development Gene expression is controlled by binding of proteins to the regulatory region • genes are regulated by enhancers or repressors to then code the gene Gene expressions can be linked by interdependent feedback loops • Positive feedback: activator turns on gene, transcribes region, makes protein—the two genes keep each other on • Negative feedback: activator turns on gene, transcribes region, makes protein, that protein represses initial gene to repress the feedback loop • critical for cells to make decisions to become one cell type or another Development is progressive • development is progressive (frog life cycle)—gradual process • specification: transplant green square cells to empty dish-they become brick cells (on their way to developing toward their origin cell type • determination: are they absolutely determined to do that or can they change?; whether cell state can be changed by its environment • differentiation: yellow cells become different from green cells • when transplant green cells (color them red) to the yellow cells, the cells change from square to honeycomb (those cells are not determined) • if you transplant the cells from the green square cells to the yellow honeycomb cells, however, and they stay as square cells, then those cells are determined • specification happens first, then determination • a cell state is determined if it will not change.A cell state is NOT determined because it can change to another cell state. • Acell can only be determined or not determined if it’s transplanted to another region.A cell state is specified if it is just transplanted into empty space. • how does the environment in the dish (empty region) change how the transplanted cell reacts/changes? • firs
More Less

Related notes for BIO SCI E182

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.