Flashcards in ToB 5 Cell Ultrastructure Deck (68)
What are the 2 types of electron microscopy?
What is the difference between the 2 types of electron microscopy?
Scanning microscopy fires electrons which bounce off the specimen, hitting a detector, creating an image. Transmission microscopy creates an image when the electrons pass through the specimen and reach the fluorescent screen beneath
What type of environment is found inside an electron microscope?
When looking at a cell nucleus via transmission electron microscopy, why are there 2 colours generated?
Nucleus contains DNA in 2 forms: heterochromatin which is in the solenoid form and very dense, and the euchromatin, which is in the beads-on-a-string form, which is much less dense so produces a lighter colour.
What type of filaments give microvilli their shape?
Define 'limit of resolution':
The minimum distance at which 2 objects can be distinguished
What is the relationship between resolution and wavelength?
As wavelength decreases, resolution improves
Why are electron microscopes capable of much finer resolution than light microscopes?
Resolution is proportional to wavelength,
Electrons have a much smaller wavelength (0.004nm) compared to light microscopes (0.4um)
What extra process must a specimen go through to be seen via SEM, as opposed to TEM?
Specimen must be coated (with gold/platinum) to reflect electrons
Why must a specimen be coated with gold/platinum before being viewed via SEM?
To reflect the electrons to generate an image
List the membranes found in a bacterial/archaeal cell:
List the membranes found in a eukaryotic cell
Membrane-bounded organelles ie:
-Outer/inner mitochondrial membranes
What is a phospholipid made up of?
Contains both hydrophobic and hydrophilic components
What main constituent of a cell is amphipathic?
Phospholipid within membranes
Why do transmembrane proteins often have a alpha helical structure?
Amino acids with hydrophobic side chains are the most compatible with alpha helix formation.
What is a glycocalyx?
Cell coating made of sugar residues on membrane proteins
Why is it possible to distinguish the glycocalyx from the plasma membrane?
The sugars can be stained
List 7 functions of the plasma membrane:
3) Selective permeability
4) Transport of materials along cell surface
5) Intercellular adhesion
6) Intercellular communication
7) Signal transduction
What is the name given to the space between the cisternae in the rER?
What is the main visual difference between the sER and rER?
rER appears rough due to presence of ribosomes, which are not present on sER
Name 5 places where sER is found in cells:
3) Mammary glands
5) Adrenal glands
What is the main function of the sER in an adrenal gland cell?
What is the main function of the sER in a mammary gland cell?
What is important to remember when looking at the endoplasmic reticulum via histology slides?
It is in fact contiguous, not made up of separate cisternae
Which face of the Golgi faces the rER?
Which face of the Golgi faces the plasma membrane?
From which face of the Golgi will the protein leave for exocytosis?
To which face of the Golgi will a protein enter the Golgi?
What are the 4 main functions of the Golgi, involving proteins?
What are the 3 possible paths that a modified protein may follow after going through the Golgi?
1) Stay in cell (lysosome)
2) Leave via signal-mediated exocytosis (regulated secretion)
3) Leave via constitutive secretion
What is the difference between a primary and secondary lysosome?
A secondary lysosome is created when a primary lysosome fuses with a phagosome, and may release useful building block materials into the cytoplasm
Describe the internal environment of a lysosome:
Contains acid hydrolases
Where are lysosomes created?
What stops the enzymes within a lysosome breaking down the lysosome membrane?
What is an endosome?
A coated vesicle within a cell, which entered via endocytosis.
What 3 things in a cell may a lysosome engulf and degrade?
3) Late endosome
Vesicle containing part of the cells own cytoplasm (and organelles) which is destined for degradation via secondary lysosome formation
In which 2 organs are peroxisomes abundant in cells?
Why is it important for liver and kidney cells to contain peroxisomes?
These detoxify substances such as alcohol, phenols, formic acid and formaldehyde
What types of substances can peroxisomes detoxify?
Alcohol, formic acid, formaldehyde, phenols etc
What is the function of a peroxisome?
Detoxification via oxidation
What are the folds of the inner mitochondrial matrix named?
What is contained within the mitochondrial matrix?
Which mitochondrial membrane is impermeable to small ions?
Inner mitochondrial membrane
What is the pH of the mitochondrial intermembrane space?
pH ~ 7
What is the pH of the mitochondrial matrix?
pH ~ 8
Why are mitochondria abundant in muscle cells?
They produce energy for the cell, so more mitochondria are needed in a muscle cell
How are mitochondria different when in steroidogenic cells?
The cristae are tubulovesicular, rather than classically lamellar
By what method do mitochondria replicate?
What is the main function of mitochondria?
Generation of potential energy in the form of ATP via oxidative phosphorylation
Name 3 parts/processes of the mitochondria which are similar to bacteria:
Down which lineage is the mitochondrial DNA passed from one generation to the next?
Which 3 filaments make up the cell cytoskeleton?
1) Actin microfilaments
3) Intermediate filaments
What is the average diameter of an actin microfilament?
Describe the distribution of actin microfilaments in a cell:
Mainly cortical (around the edge) to maintain shape of cell
Describe the strings of molecules make up the actin microfilament coil?
2 strings coil to form an actin microfilament
Polymers of one type of protein (actin)
What is the average diameter of an intermediate filament?
What is the most common protein found in intermediate filaments?
Where are intermediate filaments found within a cell?
Throughout cytoplasm (meshwork)
Forms nuclear lamina beneath the nuclear membrane
What is the average diameter of a microtubule?
Describe a microtubule:
Long, hollow tube
Made of tubulin protein
25 nm diameter
Where are microtubules found in a cell?
Where do microtubules originate from within a cell?
What type of cytoskeleton tubules are mainly involved in motile cells?
What is the function of microtubules within a nerve cell?
The neurotransmitters travel down the microtubules
Describe the arrangement of microtubules within a cilium or flagellum:
9+2: 9 outer doublet microtubules form a ring around 2 central single microtubules