module 2 (development + transcription) - bio 3 final review

general transcription factors

bind to specific DNA promoter sequences and recruit RNA polymerase II to set the start site

regulatory TFs - activator proteins

bind to specific DNA sequences in enhancers; activators interact with the general TFs and RNA pol = higher levels of mRNA = cell expression

enhancer

where activators binding site; unlike the core promoter, enhancers can be downstream of the start site, in addition to upstream

repressor proteins

also repressor proteins that bind to specific sequences and keep genes OFF

housekeeping genes

certain genes expressed for basic functions needed by all cells

development steps (in order)

1. fertilization

2. cleavage

3. gastrulation

4. morphogenesis + organogenesis

fertilization

egg and Sperm fuse to form zygote

cleavage

cell divisions that divide the early embryo

gastrulation

organizing into three primary layers (ectoderm, mesoderm, endoderm); at least one of the major body axes is established in most animals (anterior-posterior, dorsasl-ventral)

morphogenesis and organogenesis

organization into functional tissues and organs

order of cell potency

totipotent, pluripotent, multipotent

stem cells def

are cells in multicellular organisms that can give rise to many more cells like themselves (ie stem cells) and also give rise to certain differentiated cell type

stem cell outcomes

self renewal (both daughters also stem cells), two diff fates (both w/ same fate as stem cell/og cell), self renewal + daughter cell with different fate

shoot apical meristems

forms leaves + shoots with specialized tissues + cell types; produces reproductive tissues containing germ cells; pluripotent (can produce many cell types)

root apical meristems

form root systems, lots of multipotent cells, can produce all cells that produce other root systems; pluripotent (can produce many cell types)

plant morphogenesis

cells grow and change shape the orientation of cell division positions daughters to create form

plant embryo development

special clusters of pluripotent stem cells are also set aside = become the shoot meristem and the root meristem

stem cells in niches outcomes

non-stem cell daughter cells move away = undergo mitosis to produce more cells;

daughter cells specified to go down a pathway but then only later do cells differentiate

stem cells in plants

= regeneration; plants can go “backwards” in development under certain conditions, cells de-differentiate and make new meristems or some can = totipotent → regenerate a whole plant