Week 1 - Cells and Organelles Flashcards
What the 3 main feature of eukaryotic cells
They have sub-cellular compartments
These organelles are usually membrane bound apart from ribosomes
They are specialised for unique function
What is the nucleus enclosed by
The nuclear envelope with an inner and outer membrane containing pores
What is the nuclear lamina
Structural mesh that lays underneath the nuclear membrane and supports it
What is chromatin
DNA combined within other proteins mostly histones which form the chromosomes
What is the nucleolus
Site of ribosomal RNA and RNA synthesis
Name 5 subunits you will find in the plasma membrane
phospholipid bilayer
cholesterol
carbohydrates
proteins
lipid/membrane rafts
How is the mitochondria composed (4)
Outer membrane
Inter-membrane space
Inner membrane (cristae)
Matrix
Two main roles of mitochondria
ATP production
Apoptosis
What happens when cytochrome c is localised to inner membrane
It can allow the production of energy
What happens when cytochrome c is released into the cytosol
It initiates apoptosis
4 main functions of RER
Protein synthesis
Protein folding
Protein modifications
2 main functions of SER
Lipid synthesis
Calcium storage
What is the role of the Golgi apparatus
Receives proteins from the ER and modifies proteins for their eventual location
What is the role of the lysosomes
To degrade unwanted molecules
What is the main role of peroxisomes
The breakdown of fatty acids
Why is compartmentalisation of organelles important in cells
To increase efficiency
To protect the cell
What does amphipathic mean
A molecule that has a polar and non-polar end
What are filopodia
Very small spikes of microfilament based protrusions of the plasma membrane involved in cell motility
What is a phospholipid
A lipid made up of a phosphate polar head group and two fatty acid chains (one saturated and one unsaturated)
What is lamellipodia
Microfilament-based membrane protrusions that help cells move
What are desmosomes
Desmosomes are intercellular junctions that provide anchorage between the intermediate filament cytoskeletons of cells. For example keratin based intermediate filaments
Multi-molecular complexes that join one cell to another
What are lipid rafts
Cholesterol-rich domains that compartmentalise function by concentrating molecules e.g by acting as. signalling platforms by concentrating signalling receptors
What are glycocalyx
A layer of carbohydrate that covers cells. They are involved in cell recognition . Found in cells that line the gut
Name two types of phospholipids
Phosphatidylcholine (outer later)
Phosphatidylserine (inner layer)
What role does cholesterol have within the membrane
Membrane fluidity (viscocity of lipid bilayer)
What does the outer membrane of the mitochondria provide
Selective permeability
What stage of respiration happens in the inner membrane
Electron transport chain
What happens in the matrix of mitochondria
citric acid cycle
What happens in the inter membrane space
electron transport chain and other enzymatic reactions
What are the 3 types of cytoskeleton
Microtubules
Microfilaments
Intermediate Filaments
Which of the 3 types of cytoskeleton are dynamic
Microtubules
Microfilaments
Which of the 3 types of cytoskeleton are static
Intermediate filaments
What are the 2 roles of the intermediate filaments
Proving structure
Providing mechanical strength
Which type of intermediate filament is found in epithelial cells
Keratin family
Which type of intermediate filament is found in fibroplasts of the dermis
Vimentin
Which type of intermediate filament is found in the nuclei of all eukaryotic cells
Lamins which make up the nuclear lamina
3 examples of the uses of lamin intermediate filaments
Nuclear organisation
Nuclear membrane support
Chromatin organisation
Describe 3 uses of microtubules
Cell movement (flagella+cilia)
Intracellular transport of organelles
Mitotic spindle
What are microtubules made of
They are polymers of alpha and beta tubulin
Which motor protein moves cargo away from the centrosome along the microtubules
Kinesins
Which motor proteins move cargo towards the centrosome along the microtubules
Dyneins
What is the cytoskeletal component of cilia and flagella
Axonemes
What are cilia/flagella primary composed of
Microtubules and dynein
What is an axoneme
Doublets of microtubules arranged around a central microtubule doublet
What allow the bending of cilia and flagella
The sliding of microtubules against eachother through the motor protein dynein
What are microfilaments polymers of
Actin
What can microfilaments provide
Cell structure
Cell appendages such as microvilli so MOTILITY
Cell shape change
What do microtubules provide
intracellular transport
mitosis
locomotory structures (protein moving along microtubule)
What is responsible for cellular aggregation
Cell junctions
Why is cellular aggregation important
Because cells rarely function in isolation
How would you describe cellular protein complexes
Transmembrane protein complexes
What do cellular junctions attach the plasma membranes to (3)
Adjacent cells
Basement membrane
The cytoskeleton
What do anchoring junctions do
They connect cells to cells
Actin implies
Microfilament
Tubulin implies
Microtubulin
What does an adherens cell to cell junction connect to
Actin
What do desmosomes cell to cell junctions connect to
Intermediate filaments
What do focal adhesion cell-ECM junctions connect to
Actin
What do hemidesmosomes connect to
intermediate filaments
C-C and ECM-Cell junctions connecting to actin imply what about their strength
Dynamic structures as a result
C-C and ECM-Cell junction connecting to intermediate filaments imply what about their strength
Strong and stable tissue formed as a result
Name the 4 types of cell junction
Cell-Cell
ECM-Cell
Tight junctions
Gap junctions
What are the 2 functions of the tight junctions
Gate and fence
Describe what is meant by the gate function of the tight junction
The regulation of paracellular permeability (what can be passed through the intercellular space between cells)
Where is the gate tight junction found
Apical side of the cell (top)
Describe what is meant by the fence function of the
Stops the parts of the top of the cell from mixing with the bottom - maintaining the polarity of the cell.
What is meant by apical domain
the top part of the cell
What is meant by basolateral domain
bottom/below part of cell
What is meant by the gate function of the cell
Stops the apical parts of the cells from mixing with the basolateral parts of the cells
What is an example of a polarised cell
Epithelial cells
What is a gap junction
A channel between cells
What size of molecules/ions can pass through a gap junction
Only very small ones
What are the channels formed out of
A group of proteins called connexins (arranged in hexagonal clusters)
What is the role of cholesterol in the cell membrane
It strengthens the plasma membrane and prevents certain molecules from passing through
What are the functions of cell surface carbohydrates (3)
Cell to cell regcognition
ABO blood grouping
Sorting cells during embryogenesis
What are the 2 roles of integral proteins
Can act as pumps, carriers and channels
Can act as receptors to ligands to bring about a cascade of signals within the cell
What is the function of the nuclear pores in the nuclear envelope
To allow movement in/out of the cell
Where does glycolysis occur
Cytosol
Where does citric acid cycle occur
The matrix of the mitochondria
Where does the electron transport chain occur
Cristae
What are endosomes
Vesicles responsible for the transfer of molecules from plasma membrane to lysosome following endocytosis. They then fuse with lysosome to deliver their content
What are the 4 proteins which make up intermediate filaments
Keratin
Vimentin
Desmin
Lamins
Which types of tubulin make up the microtubules
Alpha and beta tubulin
Name 4 proteins which make up intermediate filaments
Keratin
Vimentin
Desmin
Lamins
