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Cellular & Organismal Diversity:

⁃ Key Concepts:
⁃ the cells in your body take on diverse shapes & functions even though the
genetic material in each of them is the same
⁃ diversity in cellular & organismal phenotype across individuals of the same
species is due to differences in their genotypes that give rise to differences in
protein expression
⁃ How do we get diff
...
) some region of genomic sequence, corresponding to a unit of
inheritance, that is associated w/ regulatory regions, transcribed regions,
&/or other functional sequence regions
⁃ gene expression: the process of translating the info in DNA into functioning
molecules w/ in cell
⁃ diff
...
genes; not every cell expresses every gene that’s
encoded in the DNA
⁃ a cell decides which protein it needs based on signaling pathways that interpret
environmental (chemical) signals that interact w/ genetic regulation

Genes & Gene Regulation:

⁃ Mechanisms of Gene Regulation:
⁃ Differential gene expression is responsible for creating diff
...
cell types express diff
...
histone modifications &
contain diff
...


eukaryotic genes are turned on when specific regulatory proteins bind to enhancers &
promoter-proximal elements; the genes are turned off when regulatory proteins bind to
silencers or when chromatin remains condensed
⁃ this leads to certain proteins being produced only in certain types of cells
⁃ The Initiation Complex: two broad classes of proteins bind to regulatory sequences @
the start of transcription
⁃ Regulatory Transcription Factors: bind to enhancers, silencers, & promoterproximal elements, & are responsible for the expression of particular genes in
particular cell types & at particular stages of development (determine whether
gene is expressed or not)
⁃ basal transcription factors: interact w/ the promoter to recruit RNA polymerase
not restricted to particular cells; don’t regulate gene expression
⁃ Transcription Initiation in Eukaryotic Cells:
⁃ 1st: remodel chromatin @ site of chromosome where gene is going to be
expressed
⁃ regulatory proteins bind to enhancer sequences & the promoter-proximal
element
this assembles a complex that recruits basal transcription factors
⁃ basal transcription factors form complex w/ promoter for RNA polymerase to
initiate transcription





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