IB Biology Topic B2.2.9 Structure and Function of Vesicles in Cells Revision Notes (HL)

IB Biology Topic B2.2.9 Structure and Function of Vesicles in Cells Revision Notes (HL) | RevisionDojo

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Vesicles: The Cell's Internal Delivery System

Definition

Vesicles

Vesicles are small, membrane-bound sacs composed of a phospholipid bilayer. They enclose a fluid-filled space and can carry various substances.

Vesicles are small, membrane-bound sacs enclosed by a single phospholipid bilayer.
1. Because their membrane has the same basic structure as the plasma membrane and organelle membranes, vesicles can fuse with these membranes, merging their contents and lipid bilayers.
2. This makes vesicles the cell's main tool for moving materials between compartments.
Vesicles are constantly formed, transported along the cytoskeleton, and fused with target membranes, so they are not permanent structures.
1. A single vesicle might exist for only seconds before delivering its cargo and merging with its destination.
2. This constant turnover lets cells respond quickly, scaling secretion or uptake up or down as needed.

How Vesicles Form: Budding and Pinching Off

Vesicle formation starts when a region of membrane begins to curve.
1. The membrane bulges inward (for endocytosis) or outward (for secretion from an organelle), enclosing the material to be transported.
2. As the bulge deepens, the neck narrows until the membrane pinches off, forming a sealed sac with cargo inside.
This process needs ATP and specialised coat proteins that help curve the membrane into shape.
1. Without these proteins, the membrane would not bend sharply enough to form a vesicle.

Clathrin: Scaffolding for Vesicle Formation

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Vesicles: The Cell's Internal Delivery System

Definition

Vesicles

Vesicles are small, membrane-bound sacs composed of a phospholipid bilayer. They enclose a fluid-filled space and can carry various substances.

Vesicles are small, membrane-bound sacs enclosed by a single phospholipid bilayer.
1. Because their membrane has the same basic structure as the plasma membrane and organelle membranes, vesicles can fuse with these membranes, merging their contents and lipid bilayers.
2. This makes vesicles the cell's main tool for moving materials between compartments.
Vesicles are constantly formed, transported along the cytoskeleton, and fused with target membranes, so they are not permanent structures.
1. A single vesicle might exist for only seconds before delivering its cargo and merging with its destination.
2. This constant turnover lets cells respond quickly, scaling secretion or uptake up or down as needed.

How Vesicles Form: Budding and Pinching Off

Vesicle formation starts when a region of membrane begins to curve.
1. The membrane bulges inward (for endocytosis) or outward (for secretion from an organelle), enclosing the material to be transported.
2. As the bulge deepens, the neck narrows until the membrane pinches off, forming a sealed sac with cargo inside.
This process needs ATP and specialised coat proteins that help curve the membrane into shape.
1. Without these proteins, the membrane would not bend sharply enough to form a vesicle.

Clathrin: Scaffolding for Vesicle Formation

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic B2.2.9: Structure and Function of Vesicles in Cells Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Vesicles: The Cell's Internal Delivery System

How Vesicles Form: Budding and Pinching Off

Clathrin: Scaffolding for Vesicle Formation

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Vesicles: The Cell's Internal Delivery System

How Vesicles Form: Budding and Pinching Off

Clathrin: Scaffolding for Vesicle Formation

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account