Endomemebrane System Flashcards
What system do cells use to bulk transport things into the cell?
Endomemebrane system
What does the endomembrane consist of
-Nuclear envelope
-Endoplasmic reticulum (smooth & rough ER)
-Golgi apparatus
-vesicles
-lysosomes
-Vacuoles
-Plasma membrane
Two Regions of endoplasmic Reticulum
Smooth ER, Rough ER
The Functions of the
Smooth Endoplasmic Reticulum (sER)
-Metabolism of carbohydrates
-Lipid synthesis for membranes
-Detoxification of drugs and poisons
-Storage of calcium ions (cell signaling)
-Extensive sER in cells active in these processes
-Can increase or decrease in amount of sER to meet demand
Functions of the
Rough Endoplasmic Reticulum (rER)
-Rough appearance due to ribosomes
-Involved in protein synthesis
-Secreted and membrane-bound proteins enter the lumen
(interior) of the rER…
-Are processed by the rER and the rest of the
endomembrane system for release from the cell or retention on
the cell membrane
Ribosomes are…
Molecular machines that synthesize proteins
Composed of ribosomal RNA (rRNA) and proteins
Found free in the cytoplasm or attached to the rough ER
Present in both prokaryotic and eukaryotic cells
Functions & Properties of the Golgi Complex
-Series of membrane sacs and associated vesicles
-Receives, modifies, sorts and ships proteins arriving from the rER
-Has polarity:
-Vesicles from endoplasmic reticulum arrive at the cis face
-Processed vesicles leave at the trans face
Glycosylation In the Golgi complex is..
-Addition (or modification) of carbohydrates to proteins
-Important for secreted or cell surface proteins
Purpose of Sorting protiens in Golgi complex are to…
Add molecular markers to direct proteins to the correct vesicles before “budding” from the trans face. ‘Guides protiens to correct dock analogy’
Directing Vesicle Trafficking in Golgi complex ..
-Adds molecular “tags” to vesicles leaving the trans face to direct them to the correct targets
-Such tags are often short proteins exposed on the vesicle surface
-Tags direct vesicles to lysosomes, or secretory pathways, or to
plasma membrane to add membrane proteins
-Act as docking sites when they reach their target
Some Types of Vesicles
-Transport vesicles
(Moveproteins and lipids between organelles within the cell.)
-Secretory vesicles
Carry molecules to the cell membrane for exocytosis (release outside the cell).
-Vacuoles
tore materials like nutrients, water, and waste; in plants, the central vacuole helps maintain structure.
Artificial vesicles (liposomes) can be used for..
Drugs and vaccines (To trick body into letting things in cell)
The amount of sER in a cell is fixed (True or False)
False
(if they couldn’t adapt would be prety useless)
sER stores calcium ions (True or False)
True
(used as a signal in the cell)
Processed vesicles leave from the ‘cis’ face of the Golgi
complex
False
(Trans face Ships processed vesicles to their destination)
What is bulk transport across the plasma membrane?
Movement of large molecules or large amounts of substances via vesicles.
In Bulk transport across Plasma membrane Endocytosis is the _____ of materials (e.g., phagocytosis, pinocytosis, receptor-mediated endocytosis).
Intake
(Requires energy/active transport).
In Bulk transport across Plasma membrane Exocytosisis the ______ of materials (e.g., secretion of hormones, neurotransmitters).
Release
(Requires energy/active transport)
What are the differences between pinocytosis and phagocytosis?
Pinocytosis (“cell drinking”)
Uptake of extracellular fluid with solutes (e.g., proteins, sugars).
Vesicle formation aided by coat proteins.
Non-selective process.
Phagocytosis (“cell eating”):
Uptake of large “food” particles.
Forms a phagocytic vacuole, which is digested by lysosomes.
In humans, occurs in macrophages (immune cells).
In phagocytosis, “food” refers to..
Large Particles that a cell engulfs
This can include:
Microorganisms (e.g., bacteria)
Cell debris (dead or damaged cells)
Other large particles (e.g., dust in the lungs)
What is receptor-mediated endocytosis?
-Specialized form of pinocytosis. “Cell drinking”
-Allows the cell to take up bulk quantities of specific substances, even if they are present in low concentrations in the extracellular fluid.
-Receptor proteins on the cell surface selectively capture the required solutes.
-This process is highly selective compared to regular pinocytosis.
What are lysosomes and their functions?
Structure: Membrane-bound organelles made by the rough ER (rER) and Golgi body.
Function: Contain hydrolytic enzymes that break down proteins, lipids, carbohydrates, and nucleic acids.
The interior of a lysosome is acidic, which is necessary for the enzymes to be active.
They degrade cellular waste and release breakdown products into the cell for reuse.
What are the functions of lysosomes in cellular processes?
Autophagy: Lysosomes digest and recycle unwanted cellular materials, which is important for cell health.
Programmed cell death: Lysosomal digestion is involved in apoptosis (the intentional death of cells).
Lysosomal storage diseases: Defects in lysosomal enzymes can lead to these diseases, where undigested material builds up in cells.
What are vacuoles and their functions?
Large vesicles derived from the rough ER and Golgi.
Food vacuoles: Involved in phagocytosis and can perform lysosome-like functions.
Central vacuole (in plant cells): Absorbs water, allowing plant cells to grow without a significant increase in cytoplasm.
Plant cell: The largest compartment in the cell, typically containing the central vacuole.
In animal cells, they help with:
Storage of nutrients, waste, and ions.
Isolating harmful substances to protect the cell.
Maintaining internal pressure and balance.
Aiding in endocytosis and exocytosis.
