Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

From Flashcardlet > Microanatomy: Endocytosis, Lysosomes, and Trafficking > Flashcards

Microanatomy: Endocytosis, Lysosomes, and Trafficking Flashcards

1
Q

Trafficking

A

The mechanisms by which materials are sorted and transferred between different cellular compartments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Pinocytosis (3)

A
  • Cell drinking
  • Non-specific mechanism for uptake of fluids and solutes
  • Does not involve receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Caveolae (2)

A
  • Plasma membrane invaginations that project into the cell

- Associated with micropinocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Caveolins (3)

A
  • Transmembrane proteins that function in vesicle formation
  • Especially numerous in endothelial cells of blood vessels and at plasma membranes of smooth muscle cells
  • Associated with micropinocytosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Phagocytosis

A
  • Cell eating
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Receptor-mediated endocytosis (3)

A
  • Specific binding of certain molecules (ligands) to specific receptors in plasma membrane
  • Uptake is selective
  • Fluid is taken up along with ligand
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Process of endocytosis by endosomes is associated with

A

An acidification of the vesicle’s interior by proton pumps in the membranes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Endosomes (3)

A
  • Consist of small vesicles or endosomal tubules and multivesicular bodies
  • Site at which cellular material to be delivered to lysosomes is transported to the lysosomes.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

LDL transport in cells

A
  • Type of receptor-mediated endocytosis
  • Ligand = LDL
  • Cholesterol circulates blood bound to protein in LDL
  • LDL binds to LDLR (LDL receptor) and a clustering of the ligand-receptor complex occurs in association with clathrin-coated regions of the plasma membrane called coated pits
  • Coated pits invaginate and become coated vesicles
  • Vesicle’s interior is acidified by an ATP-dependent proton pump that releases the ligand from the receptor
  • Ligand and receptor are sorted
    - Lysosomal enzymes hydrolyze the cholesteryl esters in LDL particles, freeing cholesterol to move into cytoplasm where it is then available to be incorporated into new membranes
    - LDLR is recycled back to the plasma membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Late endosomes (function)

A
  • Connect endocytic pathway with lysosomal system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Late endosomes (shape) (4)

A
  • Heterogenous with respect to their morphology

- Can assume a tubular or ovoid shape or spherical with small vesicles inside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Late Endosomes (location)

A
  • Located closer to Golgi than early endosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Late endosomes vs early endosomes

A
  • Materials being trafficked to late endosomes are acidified more
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Early endosomes

A
  • Complicated structures with numerous intermediates and sub-categories
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Options for receptors after ligand and receptor are sorted during receptor-mediated endocytosis (4)

A
  • Receptor can be:
    - Recycled back to plasma membrane
    - Degraded by targeting to lysosomes
    - Shifted to different domains of the plasma membrane (transcytosis)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Lysosomes

A
  • Membranous organelles with hydrolytic enzymes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Materials taken in by a cell and combined with lysosomes will undergo (2)

A
  • Degradation and digestion
17
Q

Membranes of primary lysosomes

A
  • Resistant to digestion because their proteins are highly glycosylated
18
Q

Primary lysosomes (4)

A
  • Derived from Golgi
  • Are membranous bags of hydrolytic enzymes
  • Function at acidic pH created within lysosome by ATP-driven proton pumps with membrane of the lysosome
19
Q

When primary lysosomes are combined with ___ they become ____

A

Combined with the contents of an endosome and then become secondary lysosomes

20
Q

Heterophagy

A
  • Digestion of substances imported into a cell from the external environment
21
Q

Autophagy

A
  • Digestion of organelles in an otherwise healthy cell
22
Q

Residual bodies

A
  • Indigestible residues of lysosomal activity associated with normal wear and tear and accumulate with advancing age in the form of lipofuscin pigment
23
Q

Lysosomal targeting (process)

A
  • Lysosomal enzymes are given a marker (Mannose-6-PO4 groups are bound to Mannose-6-PO4R transmembrane proteins within the trans-Golgi.)
  • Mannose-6-PR complex helps to package lysosomal enzymes into specific clathrin-coated transport vesicles that bud from trans-Golgi network and fuse with a late endosome
  • Mannose-6-PR proteins are separated from the lysosomal enzymes by acidification of the interior so the receptors are sorted back to the Golgi and the enzymes are sorted to late endosomes and primary lysosomes
24
Q

Phagocytosis

A
  • Process whereby larger insoluble particles, microorganisms, or entire cells are ingested via large endocytic vesicles called phagosomes
25
Q

Phagocytosis (process)

A
  • Binding of ligand to the receptors on the cell’s surface assures that receptors are activated and they then transmit signals to the cell’s interior to extend pseudopods and engulf the particle
  • Can also occur without interaction with a cell’s receptors
27
Q

Diseases that result from congenital absence of one or more lysosomal enzymes (5)

A
  • Lysosomal storage diseases
    - Pompe’s disease
    - Gaucher’s disease
    - Tay-Sachs disease
    - Fabry’s disease
28
Q

Absence of a lysosomal enzyme causes

A
  • Accumulation of its corresponding substrate, resulting in disturbances of other functions of the cell
29
Q

Pompe’s disease (2)

A
  • Lysosomal enzyme is absent in liver cells, causing accumulation of glycogen
29
Q

____ is required for a protein to be directed properly to lysosomes

A

Special signaling and sorting

30
Q

I-cell disease (inclusion cell disease) (3)

A
  • Lack of gene coding for the phosphotransferase for mannose.
  • Mannose is not properly phosphorylated in Golgi
  • Lysosomal enzymes are synthesized, but they are secreted rather than directed to lysosomes
31
Q

Default pathway for lysosomes

A
  • Constitutive secretory pathway
32
Q

Albinism and immunity

A
  • Melanocytes in skin transfer melanin from melanosomes directly into keratinocytes
  • Cytotoxic T-lymphocytes and natural killer cells secrete lysosomes containing perforin
33
Q

Structure of pinocytotic vesicles

A
  • Not coated in a structurally identifiable way, but do have caveolin proteins associated with them
34
Q

Early Endosomes vs. Late Endosomes (Location)

A

Early: Located closer to cell surface
Late: Located closer to Golgi

35
Q

Early endosomes vs. late endosomes (function)

A

Early: site of initial acidification
Late: site of continued acidification

36
Q

Autophagosome formation

A

Membranes of ER envelop organelle and enclose it in an autophagosome, after which lysosomal enzymes fuse with it to degrade the contents in a structure known as an autophagolysosome

38
Q

Fates of components involved in receptor-mediated endocytosis (4)

A
  • Receptors can be recycled to cell membrane for reutilization or degraded by lysosomal enzymes
  • Vesicle membranes can be recycled
  • Clathrin is recycled for reutilization
38
Q

Lysosomal enzymes are phosphorylated in the

A

Mannose-6 position

39
Q

Overall process of receptor-mediated endocytosis (8)

A
  • Ligand binds to receptor –>
  • Lig/R clusters –> membrane invagination involving coated pit and clathrin –>
  • Coated pit –> Coated vesicle
  • Clathrin disassociates from coated vesicle –>
  • Vesicle interior is acidified as it progresses to a lysosome –>
  • Ligand is released from receptor and acted upon by lysosomal enzymes for utilization within the cell
41
Q

Manose-6-phosphorylation is added to lysosomal enzymes in the (2)

A

cis-Golgi and then it binds to a receptor in the trans-Glogi

42
Q

Manose-6-Phosphate-Receptor complex is (3)

A

The signal that directs enzymes to clathrin coated vesicles budding from trans-Golgi (“tells” enzymes that they’re going to be lysosomal enzymes) in a process known as regulated synthesis

From Flashcardlet (110 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions