organelles part 1 Flashcards
what is the purpose of centrifugation
to separate cellular components based on density or sediment coefficiant
what is the endosymbiont theory
theory that mitochondria arose from an aerobic prokaryotic cell bacterium being taken up by an anerobic pre-eukaryotic cell (explains why mitochondria is double membraned and has own set of DNA and replication cycles)
what is the interior space of most organelles made of
similar to the extracellular space
nucleus general characetristics
contains almost all of DNA in eukaryotic cell
site of DNA replication, RNA transcription, RNA processing and ribosome assembly
surrounded by nuclear envelope that is continuous with ER
histones and nucleosomes
“beads on a string”
compact DNA, help it fit in smaller space
nucleosome is bead
histone is string
DNA from smallest to largest
- DNA double helix
- nucleosomes (beads on a string)
- chromatin fiber
- looped domains
- heterochromatin
- chromosome
what is heterochromatin
tightly packed DNA, proteins less accessible and less likely to be expressed
euchromatin
lightly packed DNA, proteins more accessible and more likely to be expressed
what is epigenetic?
heritable traits but no genetic mutations
ex. you can’t inherit cancer but you can inherit predispositions that make cancer more likely
how does the nuclear pore complex affect permeability of the nucleus
small molecules can move freely in and out but larger molecules must be actively transported (gated transport)
nuclear transport: import cycle
- importin binds cargo
- importin/cargo exits through NPC
- GTP bound ran binds to importin
- cargo pops off into the nucleus
- GTP/ran/importin exits nucleus
- GAP hydrolyses GTP/Ran to GDP and leaves importin
nuclear transport: export cycle
- exportin binds Ran/GTP
- exportin/Ran/GTP binds to cargo
- exportin/ran/gtp/cargo exits nucleus
- GAP hydrolyses GTP/ran to GDP and cargo pops off into cytosol
when is Ran considered”on” and “off” ?
ON–> when bound to GTP
OFF–> when bound to GDP
converted by GAP
what is the nuclear lamina
gives nuclear envelope structure and shape
anchored to nuclear protein complex and integral membrane proteins
made up of nuclear lamins (intermediate filaments)
how does the nucleus know where to reform during mitosis?
it can sense the cloud of GTP bound ran surrounding the nucleus
DNA associates with GEF
general characteristics of ER
continuous with nucleus
important for intracellular Ca2 storage
production of transmembrane proteins/lipids
makes proteins destined for secretion
rough ER
contains ribosomes embedded in ER
site of protein production, modification and lipid synthesis
(proteins are able to be translocated as they are translated)
smooth ER
not associated with ribosomes
involved in lipid metabolism and detoxification of lipid soluble drugs
important for intracellular Ca2 storage
what are the ways proteins can be imported
co translational translocation
- protein built as it is being moved across ER
post translational translocation
- protein is built and then moved across membrane
general characteristics of Golgi body
series of separate flattened sacs
major site of carbohydrate synthesis
sorts and dispatches proteins from the ER
attaches carbohydrates to proteins and lipids
modifies proteins
important for tracking and directing
how does Golgi transport work
pinches off vesicles from Golgi in order to ensure protein is not exposed to hydrophilic cytosol and fuses with membrane to release contents
