Flashcards in MCBG - Basic Cell Structure Deck (33):
Which is larger - a transmission electron microscope or a light microscope?
A TEM is much larger than a light microscope.
What is the difference between the lens in a light microscope compared with a TEM?
In a light microscope it is glass, while in a TEM/SEM it is a circular electromagnet
Ina light microscope, light passes through four things before it is viewed. What are these four things?
(Emitted from light source) -> condenser lens -> specimen -> objective lens -> eyepiece lens -> (image seen by eye)
What is the difference between heterochromatin and euchromatin?
Heterochromatin appears dark in the nucleus, forms a solenoid 30nm fibre and its genes are not expressed. Euchromatin appears light, forms "beads on a string" and the genes are expressed.
What is the limit of resolution?
The minimum distance at which two objects can be distinguished.
What does it mean when two images are "resolved"?
They can be distinguished.
True or false - the resolution improves as the wavelength descreases?
True. Violet light has the shortest wavelength of visible light.
What are the theoretical limits of resolution for light and electron microscopes?
Light microscope - 0.2 micrometers
Electron microscope - 0.002 nanometres.
True or false - prokaryotes have internal membranes while eukaryotes do not.
False - it's the other way around.
What is the average width of a eukaryotic cell?
Around 15 micrometres.
What does amphipathic mean?
A molecule with both hydrophilic and hydrophobic parts, eg. Phospholipid molecules.
Why do alpha helix regions often anchor the proteins in the membrane?
They are hydrophobic.
What is the glycocalyx made up of?
Oligosaccharide and polysaccharide side chains on the outside of the plasma membranes.
Give some functions of the plasma membrane.
Selective permeability, transport of materials, endo/exocytosis, intercellular adhesion and recognition, signal transduction.
What is the difference between the SER and the RER?
The SER does not have ribosomes on its surface, while the RER does.
Where is abundant SER often found?
Liver, mammary gland, ovary, testis, adrenal gland.
What is the function of the RER?
Protein synthesis and secretion.
Where is SER usually abundant?
Cells that involve lots of lipid production.
What is the function of the Golgi apparatus?
Modifying, sorting, concentrating and packaging proteins synthesised on the RER.
What is the difference between a primary and a secondary lysosome?
A secondary lysosome has already fused with a bacterium and broken it down.
What are lysosomes generated by?
The Golgi apparatus.
What do lysosomes contain?
Acidic hydrolytic enzymes. ATP is required to pump H+ ions inside the cell.
What protects the cell from being digested by its own lysosomes?
They have a thick glycocalyx.
What do peroxisomes do?
In the liver and kidney, they detoxify (oxidise) a number of molecules eg. Alcohol, phenols, formic acid and formaldehyde.
What is produced as an intermediate when peroxisomes detoxify RH2?
What is the name given to the inner folds in a mitochondrion?
What is the function of the mitochondria?
Generation of ATP by oxidative phosphorylation.
What is the endosymbiosis theory related to mitochondria?
The belief that an ancestral eukaryote developed mitochondria through fusing with another cell.
What is the average diameter of a microfilament (actin filament)?
What do intermediate filaments do?
Form tough supporting meshwork in cytoplasm. Common in epithelial cells and just beneath nuclear membrane.
Where are microtubules mainly found?
Sites where structures are moved eg. Nerve fibres, mitosis spindle, cilia and flagella.
Which is larger - an intermediate filament or a microtubule?
Microtubule is larger (25nm compared to 10nm).