Lecture 5 - Endomembrane System and Bulk Transport Processes Flashcards

1
Q

What is the endomembrane system?

A

a membrane system interconnected by direct physical contact or transfer by vesicles.

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2
Q

What organelles make up the endomembrane system?

A
  • nuclear envelope
  • endoplasmic reticulum (smooth & rough)
  • Golgi apparatus
  • vesicles
  • lysosomes
  • vacuoles
  • plasma membrane
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3
Q

Where does synthesis occur in the endomembrane system?

A

Endoplasmic reticulum

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4
Q

What is responsible for the delivery of proteins?

A

Vesicles

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5
Q

What “tags and packages” proteins?

A

The golgi apparatus

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6
Q

What are the functions of the sER?

A
  • Metabolism of carbohydrates
  • Lipid synthesis for membranes
  • Detoxification of drugs and poisons
  • Storage of calcium ions (used as a signal in the cell)
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7
Q

T of F

The amount of sER in a cell is fixed

A

False

The amount of sER can be increased or decreased to meet demand

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8
Q

What are the functions of the rER?

A

Protein synthesis

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9
Q

What are the functions of the golgi apparatus?

A

Receives, modifies, sorts and ships proteins arriving from the rER

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10
Q

T or F

Processed vesicles leave from the
cis face of the Golgi complex

A

False

Processed vesicles leave at
the trans face while they arrive in the cis face

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11
Q

What is Glycosylation?

A

Addition (or modification) of
carbohydrates to proteins

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12
Q

T or F

sER stores calcium ions

A

True

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13
Q

Which one of the following statements concerning the endomembrane system is
INCORRECT?

(A) The Golgi apparatus glycosylates proteins destined for secretion.
(B) Lysosomes contain multiple protein synthesising enzymes.
(C) The rough endoplasmic reticulum is responsible for the synthesis of secretory
proteins.
(D) Exocytosis delivers both proteins and phospholipids to the plasma membrane.

A

(B) Lysosomes contain multiple protein synthesising enzymes.

Protein synthesis primarily occurs in the rough endoplasmic reticulum (ER) and cytoplasm (free ribosomes).

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14
Q

Which one of the following statements concerning the Golgi complex is INCORRECT?

(A) Proteins passing through the Golgi complex are sorted into specific vesicles.
(B) Vesicles leaving the trans face of the Golgi complex are ʺtaggedʺ for specific
targets.
(C) Endocytosis delivers vesicles directly to the cis face of the Golgi complex.
(D) The Golgi complex glycosylates some proteins destined to be embedded within the plasma membrane.

A

(C) Endocytosis delivers vesicles directly to the cis face of the Golgi complex.

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15
Q

The process of a cell taking up bulk quantities of specific substances which may be present at only low concentrations in the extracellular fluid is

(A) Receptor-mediated endocytosis (B) Constitutive exocytosis
(C) Phagocytosis
(D) Pinocytosis

A

(A) Receptor-mediated endocytosis

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16
Q

What are vesicles?

A
17
Q

What are three types of vesicles?

A

Transport vesicles, secretory vesicles and vacoules

18
Q

Pinocytosis involves:

A. uptake of extracellular fluid containing solutes such as proteins and sugars
B. release of hormones
C. uptake of ‘food’ particles
D. release of glycoproteins

A

A. uptake of extracellular fluid containing solutes such as proteins and sugars

Pinocytosis - CELL DRINKING

19
Q

What is Phagocytosis?

A

CELL EATING - Uptake of food particles

20
Q

What are the three types of endocytosis?

A

Pinocytosis, Phagocytosis and Receptor-mediated endocytosis

21
Q

What is endocytosis?

A

The cell takes in molecules and particulate matter at the plasma membrane

22
Q

What are two types of exocytosis?

A

Regulated and Constitutive

23
Q

What is regulated exocytosis?

A

Releases hormones and neurotransmitters

24
Q

What is constitutive exocytosis?

A

Releases extracellular matrix proteins

25
Q

What are liposomes?

A

Artificial vesicles

26
Q

What are lysosomes?

A

Membrane-bound organelles made by the rER and Golgi body containing hydrolytic enzymes

27
Q

What are vacuoles?

A

Large vesicles derived from the rER and Golgi

28
Q

What are the structural and functional differences of sER and rER?

A

The rER has ribosomes embedded to its surface while the sER is completely smooth. Functionally, the rER is involved in protein synthesis while the sER is generally used for the creation/storage of lipids and steroids

29
Q

Why is the inside of a lysosome acidic?

A

The inside of a lysosome is acidic because acid is required to make an enzyme active

30
Q

What is the purpose of tagging vesicles that leave the Golgi complex?

A

To direct them to the correct location

31
Q

What is the CORRECT order that a secreted protein moves through the endomembrane
system?

(A) rough ER –> vesicle -> Golgi –> vesicle –> lysosome
(B) Golgi –> rough ER –> food vacuole –> plasma membrane
(C) Golgi –> vesicle –> rough ER –> vesicle –> plasma membrane
(D) rough ER –> vesicle –> Golgi –> vesicle –> plasma membrane

A

(D) rough ER –> vesicle –> Golgi –> vesicle –> plasma membrane

32
Q

The main function of the endomembrane system is:

(A) building and modifying lipids, secretory and membrane-bound proteins.
(B) isolating DNA from toxic substances.
(C) secreting extracellular matrix onto the cell surface.
(D) producing ATP by aerobic respiration

A

(A) building and modifying lipids, secretory and membrane-bound proteins.

33
Q

Select the BEST answer. Receptor-mediated endocytosis allows a cell to:

(A) internalise water-soluble molecules from the extracellular environment.
(B) limit the uptake of water-soluble molecules that are present in the extracellular
environment at high concentrations.
(C) take up specific water-soluble molecules that are present at low concentrations in the
extracellular environment.
(D) avoid the need for energy expenditure in the transport of water-soluble molecules against
their concentration gradient.

A

(C) take up specific water-soluble molecules that are present at low concentrations in the
extracellular environment.