endomembrane system

Question 1

what does the system contain

Answer 1

Golgi
ER
vesicles
Nuclear envelope 
cell membrane

Question 2

nuclear envelope/nuclear membrane consists of and can also be found in

Answer 2

lipid bilayer and contiguous with ER

Question 3

Nuclear pores complex

Answer 3

regulate movement of molecules in and out of nucleus

protein that has column subunits and nuclear baskets etc

Question 4

nuclear baskets

Answer 4

regulate size of molecules

Question 5

movement of molecules direction

Answer 5

bidirectional - goes in both direction

Question 6

molecules that can move into nucleus

Answer 6

building blocks for DNA and RNA synthesis

molecules for energy

Question 7

molecules moving out of nucleus

Answer 7

ribosomal subunit synthesised by nucleus

Question 8

Nuclear localisation signal (NLS)

Answer 8

amino acid sequence tags protein for entry into nucleus

Question 9

Nuclear export signal (NES)

Answer 9

amino acid sequence tags protein for exit from nucleus

Question 10

NPC function

Answer 10

allow small (5kda) molecules to move freely in and out of nucleus
larger molecules move slower (>60kda) barely enter by passive diffusion

Question 11

mitosis of nuclear envelope

Answer 11

breaks down during prophase

Question 12

ER - endoplasmic reticulum - amount and function for proteins

Answer 12

> 50% of total cellular membrane

stores protein in lumen as well as golgi or lysosomes and delivered within ER

Question 13

role of ER

Answer 13

protein and lipid synthesis

calcium store in cell used for signalling processes

Question 14

RER - rough

Answer 14

covered in ribosomes for protein synthesis

transporting proteins into the ER in lumen or membrane

Question 15

SER - smooth

Answer 15

lower proportion
for lipid synthesis
lipids bud off in vesicles and transported, fuse with membrane

Question 16

co-translational protein import into ER

Answer 16

ribosome finds start codon and starts reading polypeptide chain
ribosome binds to ER membrane by the signal peptide (N-terminal)
ribosome continues to translate
protein is embedded into membrane

Question 17

Post-translational translocation

Answer 17

polypeptide fully formed in cytoplasm
ribosome never binds to membrane
found in mitochondria, peroxisomes, chloroplast, nucleii

Question 18

Transmembrane protein

Answer 18

partially translocated across membrane
pores
regulates movement of molecules 
embedded proteins and receptors
peripheral proteins

Question 19

peripheral proteins

Answer 19

proteins bound to one side of membrane

Question 20

water-soluble protein

Answer 20

fully translocated across membrane
secreted by signal peptide and cleaved off
protein released into lumen of organelle

Question 21

co-translational translocation into ER lumen

Answer 21

translocator in closed stated
opens when in contact with signal peptide
allow rest of polypeptide to go through
when fully translated, signal paptidase cleaves signal peptide
mature protein released and translocator closed

Question 22

polysomes

Answer 22

single mRNA simultaneously bound by several ribosomes

moves along mRNA and translates to free up space for another ribosome to bind to make polypeptides

Question 23

sucrose gradient

Answer 23

experimental technique
separates mRNA with different number of attached ribosomes
occurs at different times

Question 24

glycosylation of protein in ER

Answer 24

ER have different glycosylate enzymes

glycosyl transferase within lumen of ER

Question 25

Glycosylate enzymes

Answer 25

transfer sugars from lipid donors onto polypeptide chains formed
sugar is trimmed in golgi
used to make different functions of protein