Microscopy Flashcards
What are the dark stains in a nucleus in electron microscopy?
Heterochromatin - the tight solenoid structure 30nm fibre
What are the light stains in nuclear DNA in a light microscopy?
Euchromatin - beads on a string.
In which form is the DNA when genes are being expressed?
A. Euchromatin
B. Heterochromatin
Euchromatin (beads on a string)
What is the limit of resolution?
The minimum distance at which two objects can be distinguished.
What is the limit of resolution proportional to?
It is proportional to the wavelength.
The smaller the wavelength the smaller the limit of resolution. (Therefore you can see more with a transmission electron microscope)
What type of electron microscope would you use if you were looking at the surface of something?
A scanning electron micrograph
Rather than a transmission electron microscopy.
What are the functions of the plasma membrane?
Selective permeability Transport of materials along cell surface Endocytosis Exocytosis Intercellular adhesion Intercellular recognition Signal transduction
What is the pH of a lysosome?
5
What type of enzymes do lysosomes have?
Nucleases Proteases Glycosidases Lipases Phosphatases Sulfatases Phsopholipases
Why don’t the enzymes broken down inside a lysosome break down the membrane?
The inside of the membrane has lots of sugar molecules that prevent the membrane breaking down.
Mitochondria have two membranes. True or false?
True.
In a mitochondrion which membrane is more permeable?
The outer membrane.
What is the mitochondria’s primary function?
Generation of potential energy (ATP) by oxidative phosphorylation.
Are intermediate filaments bigger than actin filaments. And where would you commonly find them?
Yes- they’re approx 10nm in diameter.
Often found in epithelial cells.
They form a tough supporting mesh work in the cytoplasm.
What are microtubules?
Where are they found?
Long hollow cylinders made of the protein tubulin. Found at sites where structures are moved e.g. Nerve fibres, the mitotic spindle, cilia and flagella.
