Week 4: Introduction To Organelles Flashcards
What are organelles?
Functionally distinct membrane-bound compartments within eukaryotic cells
Organelles include the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, endosomes, and peroxisomes.
What is the primary function of the nucleus?
DNA and RNA synthesis
What is the role of mitochondria?
Energy production - ATP
What are the main functions of the endoplasmic reticulum (ER)?
Protein synthesis, lipid production, Ca²⁺ storage
The ER is divided into rough ER (with ribosomes) and smooth ER (without ribosomes).
What does the Golgi apparatus do?
Modifies proteins and lipids from the ER and transfers them to other organelles
What is the function of lysosomes?
Digestion of unwanted cell organelles and other substances
What are peroxisomes responsible for?
Oxidative reactions and breaking down toxins
What is the role of the plasma membrane?
Maintains cell integrity and has distinct proteins and lipids
Why do we have intracellular compartments?
To isolate distinct functions and chemistry, and allow for organization and sorting of materials
How do proteins get targeted to organelles?
Using sorting signals, which are amino acid sequences that indicate where a protein should go
What are the three types of transport for proteins between compartments?
- Gated
- Transmembrane
- Vesicular
What is gated transport?
Transport between nucleus and cytosol through nuclear pore complexes
What is transmembrane transport?
Transport of membrane-bound proteins from the cytosol across a membrane into the organelle
What is vesicular transport?
Membrane-enclosed transport of proteins from one organelle to another
What is co-translational import?
Import of proteins into the ER while they are still being synthesized in the cytosol
What is post-translational import?
Import of proteins into the ER after they have been fully synthesized in the cytosol
What is the function of signal recognition particle (SRP)?
Directs the mRNA/ribosome/protein complex to the rough ER membrane if a signaling motif is present
What is glycosylation in the context of protein synthesis?
The addition of N-linked oligosaccharides to proteins, resulting in glycoproteins
What is the importance of glycosylation?
Quality control and acting as ligands for certain receptors
What are the protein translocators in mitochondria?
- TOM complex (outer membrane)
- TIM complexes (inner membrane)
- OXA complex
What is the double membrane problem in mitochondria?
Proteins must cross one or both membranes to be imported into mitochondria
What is the common theme in membrane spanning proteins?
Different types of signal sequences are involved in their insertion into membranes
What is a stop-transfer sequence?
An internal sequence that stops the threading of a protein across a membrane
Fill in the blank: Cellular compartments are called ______.
[organelles]
True or False: All proteins destined for organelles are synthesized in the cytosol.
True
