Cells and Organelles Flashcards
What is the function of the Plasma membrane?
- encloses cell contents
- provides barrier between outside and inside of the cell
- all signals into or out of the cell are mediated by this
What is the function of the nucleus?
- stores genetic information
- DNA replication and gene expression occur here
What is the function of mitochondria?
- Used for ATP production
- Contains cytochrome C for the ETC, if this leaks out apoptosis can occur
What is the function of Rough endoplasmic reticulum?
Used for protein synthesis
What is the function of smooth endoplasmic reticulum?
Used for lipid synthesis/calcium storage
What is the function of the Golgi Apparatus?
Proteins sorted for final destination in the cell here
What is the function of lysosomes?
Used to degrade unwanted molecules
What is the function of Endosomes?
Vesicles that ensure delivery of molecules from plasma membrane to lysosomes.
What is the function of peroxisomes?
Contain oxidases, catalase, and are involved in many processes such as detoxification and fatty acid metabolism.
What is the function of integral plasma membrane proteins?
Allows transfer of small molecules across the membrane
What are the types of integral plasma membrane proteins?
Channels, pumps, carriers
Why do cells compartmentalize into organelles?
- To provide permissive environments for specific biochemical reactions.
- Localizes processes for specific functioning
How does the phospholipid bilayer help the plasma membrane to carry out its function?
It has an antipatic nature to help provide a barrier
How does cholesterol help the plasma membrane to function?
Allows the fluidity of the membrane
How do lipid rafts help the plasma membrane function?
They concentrate proteins involved in signalling
How do carbohydrates help the plasma membrane to function?
They are in the glycocalyx and allow the cell to be recognised
What is the function of the cytoskeleton?
- Maintains the shape of the cell
- Supports plasma membrane
- Allows cell to adpot certain behaviours
- Facilitates movement of organelles
What filaments make up the cytoskeleton?
- Microtubules
- Microfilaments
- Intermediate filaments
What are microtubules composed of?
Composed of tubulin (accompanied by motor proteins dynein and kinesin)
What is the function of microtubules?
- miotic/meiotic chromosomal movement
- intracellular vesicle transport (kinesins move cargo away, dynenins move cargo towards)
- Forms basis of motile structures
- Cilliary and flagellar motility (axonemes made of microtubules are cytoskeletal component of cilia and flagella)
What are microfilaments composed of?
Composed of actin (accompanied by motor protein myosin)
What is the function of microfilaments?
- Forms basis of cell projections
- Form network in cytoplasm
- Help push out membrane to facilitate movement (lamellipodia and filopodia)
- Forms contractile ring to seperate dividing cells during cytokinesis
What are intermediate filaments composed of?
Composed of multiple protiens eg.(keratin, vimentin, desmin, lamins)
What are the functions of intermediate filaments?
Gives structural integrity to cells that need alot of strength
What are cellular junctions?
These are transmembrane protein complexes that interact with similar proteins on adjacent cells, lines the cell and their cytoskeleton together.
What are the 3 types of cellular junctions?
Anchoring, tight, GAP
What are the functions of GAP junctions?
- Cell-cell contact
- Allows passage of small molecule by linking cytoplasm of adjacent cells
What do tight junctions do?
- Specialised cell-cell contact
- Forms barrier
- Prevents mixing of membrane proteins
- Prevents paracellular access
Describe the gate and fence function of tight junctions?
‘gate’- regulates paracellular permeability
‘fence’- prevents membrane components on apical surface from mixing with membrane compartments in basolateral membrane. Results in cell polarity.
What is the function of anchoring junctions?
Provides mechanical stability
What are examples of cell-cell anchoring junctions?
Adherens(actin)
Desmosomes(Intermediate filaments)
What are examples of cell-ecm anchoring junctions?
Focal adhesions(actin) Hemidesmosomes(intermediate filaments)
What can be a clinical consequence of defective lysosomes?
Tay-sachs disease: failure to degrade lipids, so they accumulate in neurons and thus cause progressive damage to nervous system.
What can be a clinical consequence of microtubule dysfunction?
Kartagener’s syndrome; result of mutation in dynein, can lead to male infertility and recurrent respiratory infections
What can be a clinical consequence of mitochondria dysfunction?
Can lead to many diseases , particularly in organs with high energy demands such as the brain and the muscles.
Cytochrome c can also leak ot from the mitochondria and cause apoptosis.
