Cell ultrastructure (rest look at Callum ESA 1)

Question 1

Why are electron microscopes capable of finer resolution than light microscopes?

Answer 1

Limit of resolution is proportional to wavelength, resolution improves as wavelength decreases.
Electrons have a smaller wavelength than light (though the wavelength of electrons depends on the velocity they are accelerated to)

Question 2

How is the low pH of lysosomes maintained (pH5)?

Answer 2

Active pumping of H+ across the membrane (requires ATP) from the cytosol

Question 3

What is distinctive about mitochrondia in steroidogenic cells?

Answer 3

The mitochondrial cristae are typically tubular (or finger-like)

Question 4

What happens to mitochondria during cell division?

Answer 4

They also undergo mitosis

Question 5

What is the theory (endosymbiosis theory) of the origin of mitochrondria in eukaryocytes?

Answer 5

An ancestral eukaryote phagocytosed an ancestral prokaryote and instead of digesting it, maintained it within the cell as a symbiot. This is why it contains its own DNA (mtDNA). Its DNA, ribosomes and division are similar to bacteria

Question 6

Intermediate filaments are common in which type of cell?

Answer 6

Epithelial cells - form a tough supporting meshwork

Question 7

What type of filament helps form the nuclear lamina (found just underneath the inner nuclear membrane)?

Answer 7

Intermediate filaments

Question 8

What is the name of the protein structure found at the base of cillia?

Answer 8

Basal body

Question 9

What arrangement of microtubules occurs in cillia or flagella?

Answer 9

9 + 2 - nine on the outside arranged in a ring. 2 on the inside