synthesis, secretion, exocytosis

Question 1

proteins are directed to specific locations by small clusters of amino acids called_________________

Answer 1

signal or localization sequences

Question 2

what amino acids are present in signal sequences for import/retention into the nucleus?

Answer 2

K, R

Question 3

for import into mitochondrion

Answer 3

an amphipathic α-helix at amino terminus

Question 4

for import into endoplasmic reticulum

Answer 4

a stretch of hydrophobic amino acids at or near amino terminus

Question 5

for return to/retention in endoplasmic reticulum

Answer 5

KDEL sequence at carboxy terminal

Question 6

for import into lysosomes

Answer 6

mannose 6-phosophate on N-glycosylated amino acid

Question 7

Hutchinson-Gilford progeria syndrome (HGPS)

Answer 7

-pre-mature aging syndrome
-disease onset 12-24 months
-life expectancy 10-15 years
-cardiovascular defects. atherosclerosis

Question 8

what is the cause of the Hutchinson-Gilford progeria syndrome

Answer 8

spontaneous point mutation in lamin A

Question 9

Zellweger Syndrome

Answer 9

-genetic defect in the process of importing proteins into peroxisomes
-empty peroxisomes
-patients die soon after birth with abnormalities in brain, liver, kidneys

Question 10

-single membrane, single lumen, 50% membrane of cell
-synthesis of proteins
-proteins folding and modification
-lipid and lipoprotein synthesis
-detoxification reactions

Answer 10

endoplasmic reticulum

Question 11

attached ribosomes, protein synthesis

Answer 11

rough ER

Question 12

lipid synthesis and modification, detoxification

Answer 12

smooth ER

Question 13

-modification and sorting of proteins and membrane components
-ordered stacks
-oligosaccharide processing

Answer 13

golgi apparatus

Question 14

-sites of intracellular catabolism
-acidic pH ~5

Answer 14

lysosomes

Question 15

lysosomal storage diseases

Answer 15

-genetic defect in one or more lysosomal hydrolases
-severe pathological consequences
-substrate of defective enzyme accumulates in lysosomes
-organomegaly, neurological problems

Question 16

inclusion cell disease (I-cell disease)

Answer 16

-undigested lysosomal enzyme substrates accumulate in lysosomes, forming inclusion bodies
-patients die at a very young age
-due to single gene defect; recessive
-all the hydrolases missing from lysosomes are found in bloodstream
-defect is in the enzyme that phosphorylates lysosomal hydrolase precursors

Question 17

protein folding

Answer 17

-occurs in cytoplasm and endoplasmic reticulum
-usually occurs during synthesis
-often assisted by chaperones
-include heat shock proteins

Question 18

what are examples of protein-folding diseases

Answer 18

-cystic fibrosis
-creutzfeldt-jacob disease
-cancer p53
-huntingtons disease
-parkinosns/alzheimer disease