Topic B Flashcards
some plant cells have the ___ squished against the side of the cell by the central vacuole
nucleus
describe nuclear pores
are numerous (~3000 per mammalian nucleus) and large (120nm diameter)
how do nucleotides enter the nuclear pores?
through diffusion
what is a test of discovery experiment?
based upon observing a process
what is a test of necessity experiment?
observing if the process occurs when something is removed
what is a test of sufficiency experiment?
observing if the process occurs when something is added
NLS
nuclear localization signal
what is required for nuclear import?
nuclear localization signal (NLS) and importin proteins
what do importin proteins associate with?
associate with the nuclear localization signal (NLS) and nuclear pore
what is required for nuclear export?
nuclear export signal (NES) and exportin proteins
what do exportin proteins associate with?
associate with NES (or RNA directly) and nuclear pore
importin and exportin’s affinity for the nuclear pore is?
always high
importin’s affinity for cargo is?
high in cytosol, low in nucleus
exportin’s affinity for cargo is?
low in cytosol, high in nucleus
ran-GTP has an affinity for?
importins and exportins
where is ran-GDP found?
the cytosol
where is ran-GTP found?
the nucleus
ran ____ importins and _____ exportins in the nucleus (load or unload)
unloads…loads
chromatin
complex of DNA, histones and non-histones found in the nucleus of a euk cell. Material that makes up chromosomes
outer nuclear envelope
surrounds the inner nuclear membrane. Is continuous with the inner nuclear membrane and the membrane of the endoplasmic reticulum
nuclear lamina
fibrous meshwork of proteins on the inner surface of the inner nuclear membrane. Made of intermediate filaments formed from nuclear lamins
nuclear pore complex (NPC)
large multiprotein structure forming the nuclear pore through the nuclear envelope that allows selected molecules to move between nucleus and cytoplasm
what do enzymes in the ER synthesize?
phospholipids, glycolipids and cholesterol
what mechanism is used to deliver membrane lipids to the ER and nuclear envelope?
lateral diffusion
what mechanism is used to deliver phospholipids to the ER and nuclear envelope?
lateral diffusion
what mechanism is used to deliver phospholipids to the rest of the endomembrane system?
transport vesicles
what mechanism is used to deliver phospholipids to semi-autonomous organelles?
phospholipid exchange proteins
what mechanism is used to deliver phospholipids to the chloroplasts?
phospholipid exchange proteins (same as mitochondria)
where are proteins made?
some in free ribosomes, some in the ER
what mechanism is used to create proteins destined for the cytosol?
free ribosomes
what mechanisms are used to create and deliver proteins to the mitochondrion, peroxisomes and the nucleus?
free ribosomes and then import (has cell signals)
how are proteins exported?
ribosomes at ER and then vesicles
what mechanisms are used to create and deliver proteins to the nuclear envelope and ER?
ribosomes at ER and then lateral diffusion
what mechanisms are used to create and deliver proteins to the lysosomes, golgi and plasma membrane?
ribosomes at ER and then vesicles
what mechanisms are used to create and deliver proteins to the chloroplasts?
free ribosomes and then import (same as mitochondria)
what are the functions of a vesicle?
- move material within endomembrane system
- exocytosis
- endocytosis
receptor mediated endocytosis
importing whole proteins
how do vesicles form?
cargo receptors -> clathrin (and other coat proteins) -> adaptin ->dynamin -> remove coat proteins
how many heme groups does hemoglobin have?
four
where is iron located in humans?
hemoglobin (in red blood cells)
what is the iron delivery path?
iron goes to the intestine cell -> blood -> future red blood cells
transferrin proteins
synthesized in liver cells, carry iron in blood
how does transferrin carry iron into future RBCs?
receptor mediated endocytosis
how do vesicles move?
microtubules, kinesin, dynein
kinesin
plus-end directed microtubule protein
dynein
minus-end directed microtubule motor protein
exocytosis uses ____; endocytosis uses _____ (which MT motor protein)
kinesins…dyneins
ER -> Golgi uses____ (which MT motor protein)
dyneins
how do vesicles fuse with their target membrane?
when SNAREs pull together
which organelles do vesicles move between?
ER, golgi, plasma membrane, lysosomes (endomembrane system)
tSNARE
target SNARE (on plasma membrane)
vSNARE
vesicle SNARE
dynamin
involved in vesicle formation, binds to clathrin-coated vesicle in the process of budding from the membrane
cargo
membrane components and soluble molecules carried by transport vesicles
adaptin
connect clathrins to cargo receptors (regulated like Ran)
function of cis side of golgi apparatus
“receiving”
function of trans side of golgi apparatus
“shipping”
amount of golgi in an animal cell
single large stack
amount of golgi in a plant cell
many little stacks
golgi apparatus function
modify and distribute proteins and membrane lipids made in ER
constitutive exocytosis
default pathway (eg. goblet cells, cell growth)
regulated exocytosis
secretes products rapidly on demand (eg. export of insulin)
what signal is given to future lysosome enzymes in the golgi?
M6P signal
M6P Receptor’s affinity for cargo is?
high in Golgi (pH 6.5)
low in lysosome (pH <6.0)
vesicles formed by receptor mediated endocytosis and phagocytosis fuse with what?
lysosomes
how do endosomes become lysosomes?
when pH drops (pH 6.0 to 5.0), done by ATP powered proton pumps
