A&p Lec02-A Membrane Proteins And Transport

Front 1

What are 4 types of movement through the plasma membrane?

Back 1

-Simple Diffusion

-Carrier Proteins

-Channel Proteins

-Vesicular/Bulk transport

Front 2

What is commonly moved by Simple Diffusion?

Back 2

Fat soluable and small, uncharged molecules

Front 3

In what direction does Simple Diffusion work?

Back 3

Direction is always from higher to lower concentration, down the the concentration gradient

Front 4

What is commonly moved by Carrier Proteins?

Back 4

Small, water soluble molecules

Front 5

How do Carrier proteins work?

Back 5

Selective carrier molecules undergo conformational changes.

Front 6

Do carrier proteins require energy?

Back 6

Yes and No
Facilitated Diffusion - no energy needed.

Active Transport - energy required

Front 7

What is commonly moved by Channel Proteins?

Back 7

Small, water soluble molecules moving through hydrophillic channels

- no confromational changes like Carrier Proteins, just a channel for molecules to move down.

Front 8

What is commonly moved by Vesicular/Bulk transport?

Back 8

Large molecules or particles.

Front 9

What are the 3 types of Vesicular/Bulk tranport?

Back 9

-Endocytosis: brings material into the cell

-Exocytosis: moves material out of cell

-Transytosis: moves material across the cell - can include both endo and exo cytosis

Front 10

Vesicular/Bulk transport:

-often includes receptors

-energy/ATP is required

Back 10

Vesicular/Bulk transport:

-often includes receptors

-energy/ATP is required

Front 11

How does Endocytosis bring material into the cell?

Back 11

Involves formation and budding of vesicles from the plasma membrane

---Some of the internalized plasma membrane is often recycled---

Front 12

What are the 3 main types of Endocytosis?

Back 12

Pinocytosis (cellular drinking)

Receptor-mediated endocytosis

Phagocytosis (cellular eating)

Front 13

Describe 3 points about Pinocytosis?

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-
-

Back 13

-Extracellular fluid and its solutes are taken up by cell.

-non-selective uptake

-Most eukaryotic cells continually perform pinocytosis

Front 14

Describe 3 points about Receptor-mediated endocytosis?

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-
-

Back 14

-Receptors on the cell bind a ligand and take ligand into a cell.

-Selective uptake - allows specific molecules to be taken up.

-Allows concentration of dilute molecules

Front 15

What is a ligand?

Back 15

A substance that forms a complex with a biomolecule to serve a biological purpose.

In a narrower sense, it is a signal triggering molecule, binding to a site on a target protein.

Front 16

What is the key component of Receptor-mediated endocytosis?

Back 16

It depends on the transmembrane receptor proteins.

Front 17

What happens when the ligand binds with the receptor in receptor-mediated endocytosis?

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-

Back 17

-Receptors cluster in clathrin-coated pits

-After uncoating, vesicles fuse with sorting endosome

Front 18

What causes the ligand to release form the receptor in receptor-mediated endocytosis?

Back 18

Change in pH.

-receptors often sorted and recycled

-fate of ligand varies--degradation, release into cytoplasm.

Front 19

What causes Phagocytosis to occur?

Back 19

triggered by activation of receptors for complement or antibody

Front 20

What happens to the Phagosome after the material has been ingested?

Back 20

-Lysosomes fuse with phagosome forming phagolysosome (secondary lysosome).

-Enzymes degrade ingested material.

---Lysosomal enzymes work best in acid pH.

---Any undigested material becomes residual body.

Front 21

How are receptor-mediated endocytosis and phagocytosis different?

Back 21

-RME forms a coated pit with the receptors and then tranports the coated vesicle into the cell.

-In phagocytosis the plasma membrane slowly encloses material.

Front 22

Are the vesicles processed in Transytosis?

Back 22

NO!, they are just moved from one surface to another using both endo- and exo- cytosis.

-Basal or basolateral to Apical

Front 23

What does Apical mean?

Back 23

Lumen facing

Front 24

What does basolateral mean?

Back 24

Tissue facing

Front 25

Secretion is a type of Exocytosis. What are the 2 types of Secretion?

Back 25

-Constitutive secretion - Product leaves the cell immediately after synthesis

-Regulated secretion - product accumulates before release, for example:
---Peptide hormones
---Pancreatic enzymes

Front 26

What are some membrane proteins that are moved to the surface?

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-

Back 26

-Receptors

-Major histocompatibility (MHC) molecules