TOB Session 3 - Cell Ultra-structure Flashcards
Define the limit of resolution
The minimum distance two objects can be distinguished at
What is limit of resolution proportional to?
Wavelength
What is the theoretical limit of resolution for a light microscope?
0.2 micrometres
What is the theoretical limit of resolution for an electron microscope?
0.002nm
What is A?
Bilipid membrane
What feature of the phospholipid bi layer structure makes it selective, and in what way?
Phospholipid molecules are ampipathic - Hydrophillic phosphate groups on outside, hydrophobic lipids on inside.
This means they are relatively impermeable to most water soluble molecules.
What feature of phospholipid bilayer allows it to mediate the majority of its functions?
Protein molecules dissolved within the membrane
What is H?
Golgi apparatus
What is the structure of the golgi?
Saucer shaped stacks of cisternae
How do vesicles get to golgi, and where do they fuse?
Bud off from Rough Endoplasmic reticulum and fuse with the convex cis face of the golgi body
What feature of golgi bodies allows proteins to move through it?
Its polarity
In which direction do protein migrate through golgi?
From convex cis phase to the the concave trans face of the stack
What are the four function of the golgi?
Modify, sort, concentrate and package proteins synthesised on rough endoplasmic reticulum
What two destinations do vesicles budding from the golgi have?
Either lysosome assembly or secretion
What is the glycocalyx, and what is their function?
The cell “coat made up of oligosaccharide and polysaccharide side chains on the outiside of the plasma membrane
Give the cell specificity
What are the 7 functions of the plasma membrane of a cell?
Selective permeability
Transport of materials along the cell surface
Endocytosis
Intracellular recognitio
Exocytosis
Signal transduction
Intercellular adhesion
What is F, and what are its two major functions?
Nucleus
1) Stores the cells DNA
2) It coordinates the cell’s activities, metaolism, growth, protein synthesis an mitosis
What does most of the nuclear material consist of, and what does it form during mitosis?
Chromatin, the unstructured for of the cell’s DNA. Organises to form chromosomes during mitosis.
What is G?
The nuclear envelope, a double layered membrane that sepaerates the contents of the nucleus from the cellular cytoplasm.
What is the function of nuclear pores withing the nuclear envelope?
They allows specific types and sizes of molecules to pass back and forth between the nucleus and cytoplasm.
What is the nuclear membrane attached to?
A series of tubules called the endoplasmic reticulum
What is E and what is its function?
Nucleolus, an organelle that synthesises protein producing macromolecular structure called ribosomes.
What is D and what is its function?
Ribosomes, site of translation and also the unit used for protein synthesis.
What is x, and what is it continuous with?
The rough endoplasmic reticulum, and is continuous with the nuclear envelope.
When does a ribosome bind to RER?
When it begins to synthesis a protein destined for the secretory pathway
Give two major functions of the RER
Lsosomal enzymes with a mannose-6-phosphate marker added in the cis-golgi network
Secreted proteins, either secreted constitutively or regulated
Initial glycosylation - N linked
What cells are smooth ER found in and what are their functions?
iver and mammary gland, and in the ovaries testes and adrenal glands
Assist in lipid and steroid synthesis
What is L?
Lysosome
What do lysosomes contain, and how do they protect themselves against their contents?
They contain acid hydrolysases at pH 5. Lysosomal membrane proteins are highly glycosylated for protection from these enzymes.
What do primary lysosomes fuse with?
Membrane bound vesicles, autophagosomes (defunct organelles) or with excess secretory product to form secondary lysosomes in which contents are degraded.
What do peroxisomes do?
Major site of oxygen utilisation and H202 production
What utilises H202 produced from peroxisomes, and to what effect?
Enzyme catalase utilises H202 to oxidise other substancs such as alcohol (half alcohol we drink oxidsed to acetaldehyde)
What is interesting about peroxisome reproduction?
Self replicating, but no genome of their own
Why are peroxisomes most present?
In kidney tubules and liver parenchymal cells, where they detoxify toxic molecules in blood stream
What is the structure of a mitochondrion?
Double membrane with innermembrane thrown into distincy folds called cistae which are usually lamellar
What is the primary function of mitochondria?
Generation of energy rich ATP molecules by oxidative phosphorylatoion
What are the main substrates of mitochondria?
Glucose and fatty acids
What does the matrix of mitochondria contain?
Enzymes involved in krebs and fatty acid cycles, DNA, RNA, ribosomes and calcium granules
How can mitochondria divide?
Have their own genetic material
Where do humans inherit mitochondria from?
Maternal line
Give four functions of a cell cytoskeleton
Structural support or the plasma membrane and cell organelles
Means of movement for organelles, plasma membrane and other cytosol constituents
Locomotor mechanisms for amoeboid movements (e.g lymphocytes) and for cilia and flagella
Contractability in cells of spcialised tissues (muscles)
Give four features of microfilaments
5nm diameter
Two strings of actin twisted together
Associated with ATP (contractile)
Cann assemble and dissociate (dynamic)
Give four features of intermediate filaments
Not dynamic
10-12 nm diamete
Common in nerve and neurological cells
Also common in epithelial cells that are made of cytokeratin. Form tough suporting meshworks in cytoplasm.
Give four features of microtubules
Thirteen alpha and beta subunits polymerise to form wall of the hollow microtubules
They originate from the centrosome
Found at sites where structures in cells are moved (mitotic spindle, for instance)
Attachment proteins can attach to organelles and move them along the microtubule
(movement of chromosomes along mitotic spindles - classic example)
