Brainscape's Knowledge GenomeTM

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


See full index

Cytology > Lesson 2: Cytoplasmic organelles and vesicle trafficking > Flashcards

Lesson 2: Cytoplasmic organelles and vesicle trafficking Flashcards

1
Q

What are glycosaminoglycans, and where are they synthesized?

A

They are long polysaccharides synthesized in the Golgi apparatus.

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

How does the Golgi apparatus modify proteins?

A

Through processes like glycosylation, phosphorylation, and proteolysis.

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

What structural differences exist between the cis, medial, and trans cisternae of the Golgi?

A

They differ morphologically and biochemically.

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

What is the Endoplasmic Reticulum-Golgi Intermediate Compartment (ERGIC)?

A

A region where vesicles transition from the ER to the Golgi.

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

What is the structure of the Golgi apparatus?

A

It consists of membrane-covered, stacked, flattened sacs called cisternae, which are disk-like and slightly curved.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Who discovered the Golgi apparatus, and when?

A

Camillo Golgi in 1898; he originally called it the internal reticular apparatus.

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

What are the main functions of the Golgi apparatus?

A

Sorting and shipping proteins,

Modification of proteins and lipids by glycosylation,

Production of vesicles into which proteins/lipids are transported

Activation of peptides by proteolysis, phosphorylation,

glycosaminoglycan + mucin synthesis.

Selection of enzymes to be delivered to lysosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the cis and trans faces of the Golgi?

A

The cis face is ER-facing, while the trans face is plasma membrane-facing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Name two models explaining protein movement through the Golgi.

A

Vesicular transport model and cisternal maturation model.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does the vesicular transport model work?

A

Proteins are modified in stable cisternae by enzymes, with vesicles transporting them between compartments.

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

What is the cisternal maturation model?

A

Golgi cisternae move from the cis to the trans face, maturing over time while carrying proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What determines the number of Golgi cisternae in a cell?

A

The activity level of the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are destinations of proteins synthetized in the RER and passing through the golgi

A

1) They are transferred to the cell membrane
2) They go to the lysosomes
3) They are secreted out of the cell by exocytosis
4) They remain in the Golgi
5) They go back to the RER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the role of the KDEL sequence?

A

a sequence of AA (Lys-Asp-Glu-Leu)
It signals proteins to return to the RER.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which protein coats vesicles for transport to the Golgi?

A

COP II.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What protein coats vesicles for retrograde transport to the RER?

A

COP I.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How are vesicles directed to specific compartments?

A

By v-SNARE proteins on vesicles and t-SNARE proteins on target membranes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is mannose-6-phosphate (M6P)?

A

A marker for proteins destined for lysosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the two types of exocytosis pathways?

A

Constitutive secretion and regulated secretion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What role do clathrin-coated vesicles play in protein transport?

A

They mediate transport to the plasma membrane or endosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does COP stand for in vesicle transport?

A

Coat Protein Complex.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is retrograde transport in vesicle trafficking?

A

Movement of vesicles from the Golgi back to the RER.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the functions of the coating on coated vesicles?

A

1) favours the bending of the
membrane during the formation of the vesicle
2) allows the selection of the components that
have to be inserted and transported into the vesicle
3) gives direction and destination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is constitutive secretion?

A

*Vesicles are coated by coating proteins (COPs)
* Not dependent on specific stimulation
* The secretion products are produced and immediately secreted
* It is a continuous process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is regulated secretion?

A

*Vesicles are coated by clathrin-like proteins
* Secretion is under the control of specific stimulation (ex: release of
hormones, pancreatic enzymes, neurotransmitters)
* Proteins to be secreted are stored into vesicles that accumulate into
the cell (maturation of vesicles)
* Vesicles accumulate close to the plasma membrane and fuse with
the membrane after specific extracellular stimulation
*allows to stock up on more signals -> readiness for a faster and stronger signal

26
Q

What is endocytosis?

A

The process of internalizing extracellular material via vesicles.

27
Q

Name four types of endocytosis.

A

Receptor-mediated endocytosis, pinocytosis, phagocytosis, and autophagy.

28
Q

What is receptor-mediated endocytosis?

A

Selective internalization of molecules bound to membrane receptors.

29
Q

What forms the vesicle coat during clathrin-mediated endocytosis?

A

Clathrin proteins.

30
Q

What is the function of dynamin in endocytosis?

A

It forms a spiral collar to help vesicle detachment.

31
Q

What is the primary function of pinocytosis?

A

Uptake of extracellular fluids and dissolved nutrients. (very tiny soluble molecules, “cellular drinking”)

32
Q

What type of cell specializes in phagocytosis?

A

Phagocytes: Macrophages and granulocytes
They derive from blood and are able to destroy bacteria, viruses, dead or damaged cells.

33
Q

What happens to ligands during receptor-mediated endocytosis?

A

They are released in acidic endosomes.

34
Q

What occurs after vesicles lose their clathrin coat?

A

They fuse with early endosomes.

35
Q

What is the main energy molecule driving dynamin activity?

A

GTP.

36
Q

What happens to LDL receptors during receptor-mediated endocytosis?

A

They are recycled back to the plasma membrane.

37
Q

What is pinocytosis?

A

Non specific introduction into the cell of very small liquid
droplets picked up from the extracellular environment by the formation of
pinocytosis vesicles

38
Q

What is phagocytosis?

A

Phagocytosis is the process by which cells engulf solid matter
such as bacteria, cells, cell fragments.
actin cytoskeleton-mediated internalization of large
particles

39
Q

Who discovered lysosomes, and how?

A

Christian de Duve in 1955 through enzyme studies involving cell freezing and centrifugation.

40
Q

What is the pH inside lysosomes, and why is it maintained?

A

pH 5.0, maintained by proton pumps for enzyme activity.

41
Q

Name key enzymes in lysosomes.

A

Nucleases, proteases, glycosidases, lipases, phosphatases.

42
Q

What are the functions of lysosomes?

A

Cellular digestion, recycling macromolecules, and destroying microorganisms.

43
Q

Name a clinical condition related to lysosomal dysfunction.

A

Tay-Sachs disease.

44
Q

Why are lysosomal enzymes inactive in the cytoplasm?

A

Cytoplasmic pH is neutral (7.2), while enzymes require an acidic pH.

45
Q

What happens to phagosomes upon fusion with lysosomes?

A

They form phagolysosomes for digestion.

46
Q

Name three macromolecules degraded by lysosomes.

A

Proteins, lipids, and nucleic acids.

47
Q

How do lysosomes contribute to cellular homeostasis?

A

By recycling macromolecules and breaking down waste.

48
Q

What is the size range of lysosomes?

A

0.2–0.5 µm in diameter.

49
Q

What is autophagy?

A

The process of degrading and recycling a cell’s own components.

50
Q

What are lysosomal storage diseases?

A

Genetic diseases that originate from an abnormal accumulation of substances inside lysosomes.
Due to defects in lysosomal enzymes
Children are affected: developmental delay, defects in many organs, movement disorders, dementia, early death.

51
Q

What is the typical size of a peroxisome?

A

0.6–0.7 µm.

52
Q

What toxic byproduct do peroxisomes neutralize?

A

Hydrogen peroxide (H2O2).
Catalase transforms H2O2 in water and molecular oxygen, avoiding the diffusion of toxic H2O2 in the cytoplasm

53
Q

What are reactive oxygen species (ROS), and how do peroxisomes handle them?

A

ROS are damaging free radicals; peroxisomes detoxify them using enzymes like catalase.

54
Q

Which cells have a high number of peroxisomes?

A

Hepatocytes and renal cells.

55
Q

How are peroxisomes formed?

A

Through fusion of microvesicles originating from the RER.

56
Q

How do vesicles contribute to membrane fluidity?

A

By recycling and integrating membrane components.

57
Q

What is autophagy’s primary cellular role?

A

Recycling damaged organelles and proteins to maintain homeostasis.

58
Q

Name three processes closely related to lysosomes.

A

Phagocytosis, endocytosis, and autophagy.

59
Q

What are peroxisomes?

A

Heterogeneous group of membrane enclosed organelles containing several enzymes acting in different metabolic activities

variable shape: ranging from spherical/oval to rod-shape

60
Q

What is a key feature of peroxisomes?

A

presence of the enzyme CATALASE, representing 40% of the total enzymes

61
Q

What are the functions of the peroxisomes?

A

fatty acids and aminoacid oxidation (=degradation)

inactivation of H2O2 by catalase

detoxification of dangerous substances penetrated into the
organism

removal of free radicals and reactive oxygen species (ROS), such as the superoxide radical, the hydroxyl radicals (OH-) that may damage cell DNA and proteins

Cytology (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions