Lecture #8

Question 1

The ER, Golgi complex, endosomes, lysosomes, and vacuoles form an __________ system that act as a coordinated unit

Answer 1

endomembrane

Question 2

In __________, a transport vesicle fuses with the plasma membrane. Its content is released into the extracellular space, while the vesicle membrane becomes continuous with the plasma membrane.

Answer 2

exocytosis

Question 3

In __________, a plasma membrane patch is internalized, forming a transport vesicle. Its content derives from the extracellular space

Answer 3

endocytosis

Question 4

_________ pathway: Proteins are synthesized in the ER, modified at the Golgi complex, and transported to various destinations

Answer 4

Biosynthetic

Question 5

_________ pathway: Proteins synthesized in the ER are discharged from the cell

Answer 5

Secretory

Question 6

__________ pathway, materials move from the outer surface of the cell to compartments, such as endosomes and lysosomes

Answer 6

Endocytic

Question 7

____________ secretion: Materials are transported in secretory vesicles and discharged in a continual manner

Answer 7

Constitutive

Question 8

_________ secretion: Materials are stored in vesicles and discharged in response to a stimulus

Answer 8

Regulated

Question 9

_______ secretion occurs in endocrine cells (hormones), pancreatic acinar cells (digestive enzymes), and nerve cells (neurotransmitters)

Answer 9

Regulated

Question 10

Secreted materials can be stored in large, densely packed, membrane-bound _______ ______ (specific type of vesicle)

Answer 10

secretory granules

Question 11

Difference between a vesicle and a secretory granule is how ?

Answer 11

they look when using an electron microscope

Question 12

The various types of cargo are routed to their appropriate cellular destinations by _______ ________ encoded in the amino acid sequence of the proteins or in the attached oligosaccharides

Answer 12

sorting signals

Question 13

____________ visualizes biochemical processes by radioactively labeling molecules

Answer 13

Autoradiography

Question 14

Autoradiography showed the _________ _______ as the site where secretory protein synthesis occurred.

Answer 14

endoplasmic reticulum

Question 15

A “_____-_____” experiment was performed to determine the intracellular path of secretory proteins from their site of synthesis to their site of discharge

Answer 15

pulse-chase

Question 16

________ is enhanced by the use of a mutant viral protein that cannot leave the ER of infected cells that are grown at elevated temperatures (e.g., 40°C).

Answer 16

Synchrony

Question 17

Cell __________ fragments cytoplasmic membranes

Answer 17

homogenization

Question 18

Vesicles derived from the endomembrane system form similar sized vesicles referred to as _________

Answer 18

microsomes

Question 19

The ________ fraction can be fractionated into smooth and rough membrane fractions. Once isolated, the biochemical composition of various lipid and protein fractions can be determined.

Answer 19

microsomal

Question 20

__________ are vesicles whose surface consists of an artificial bilayer that is created from purified phospholipids.

Answer 20

Liposomes

Question 21

Large-scale studies of the genetic basis of vesicle movement have been carried out largely on ______ cells (Genetic screening). Screen for mutant cells that exhibit an abnormal distribution of cytoplasmic membranes reveals proteins that function in _________ . Strong evolutionary conservation of the process.

Answer 21

yeast, secretion

Question 22

RNA ________ (RNAi) is used to inhibit mRNA translation into proteins. By using siRNAs libraries, one can find genes involved in _______ steps of the secretory pathway.

Answer 22

interference, various

Question 23

The ________ ______ is a network of membranes that penetrates much of the cytoplasm and has a lumen separated from the cytosol by the ER membrane

Answer 23

Endoplasmic Reticulum

Question 24

_________ :
1. ribosomes bound to its cytosolic surface
2. flattened sacs (cisternae) connected to neighbors by helicoidal membranes
3. is continuous with the outer membrane of the nuclear envelope.

Answer 24

RER (Rough ER)

Question 25

_________:
1. lacks ribosomes
2. membranes are highly curved and present as a tubular network.
3. is continuous with the RER.

Answer 25

SER (Smooth ER)

Question 26

SER functions include:

1. _______ hormone synthesis in endocrine cells of the gonad and adrenal cortex.
2. ________ of organic compounds in the liver via oxygenases including the cytochrome P450 family.
3. Calcium ion _________ and regulated release.

Answer 26

Steroid, Detoxification, sequestration

Question 27

The _______ is the starting point of the biosynthetic pathway for secretory proteins

Answer 27

RER

Question 28

About one-third of the proteins are synthesized at the ____ and released into the ER lumen in a process called co‐translational translocation

Answer 28

RER

Question 29

In ________ cells, the nucleus and RER are near the ______ surface, facing the blood supply while the granules are facing the lumen of the duct

Answer 29

secretory, basal,

Question 30

The site of protein synthesis is determined by the sequence of amino acids in the _______ portion of the polypeptide

Answer 30

N-terminal

Question 31

Secretory proteins contain a _____ sequence at their N-terminus that directs the emerging polypeptide and ribosome to the ___ __________. The polypeptide moves into the _______ space of the ER through a protein-lined, aqueous channel in the ER membrane, as it is being _________ (co-translationally).

Answer 31

signal, ER membrane, cisternal, synthesized

Question 32

Proteins contain built-in “address codes” for protein ________ pathways throughout the cell. (Signal hypothesis)

Answer 32

trafficking

Question 33

Co-translational translocation deposits protein into the ER ______

Answer 33

lumen

Question 34

Signal sequence recognized by ? (SRP). SRP binds polypeptide and the ribosome, arresting ________.

Answer 34

signal recognition particle, synthesis

Question 35

The ribosome is handed off to the ________, a protein channel embedded in the ER membrane. Upon attachment, the signal sequence is recognized, the polypeptide is inserted into the translocon ________

Answer 35

translocon, channel

Question 36

Several of the steps involved in the synthesis and trafficking of secretory proteins are regulated by the binding or hydrolysis of ____

Answer 36

GTP

Question 37

SRP and the SRP receptor are __-______ that interact with one another in their GTP-bound states; GTP hydrolysis triggers the release of the signal sequence by the ____

Answer 37

G proteins, SRP

Question 38

The signal peptide is removed from most nascent polypeptides by _______ _______, while carbohydrates are added by _________________. Both enzymes are integral membrane proteins associated with the translocon

Answer 38

signal peptidase, oligosaccharyltransferase

Question 39

The ER membrane provides a large _____ _____ for ribosomes to attach, and the lumen gives a specialized local environment that favors protein processing

Answer 39

surface area