Cell ultrastructure

Question 0

What is the relationship between resolution and wavelength

Answer 0

-Indirectly proportional -> the lower the wavelength the higher the resolution

Question 1

Define limit of resolution

Answer 1

The minimum distance at which two objects can be distinguished

Question 2

Why do electron microscopes have a higher resolution then light microscopes and which kind has the highest?

Answer 2

• EMs have a shorter wavelength as they use electrons whose wavelength depends on the accelerating voltage used
• Transmission EM have a higher resolution then Scanning EM as they have a shorter wavelength

Question 3

Why do prokaryotes not exhibit compartmentalisation?

Answer 3

-They have an external membrane but no internal membranes, i.e. all the biochemical processes occur in the same compartment

Question 4

What is the structure and function of cell membranes?

Answer 4

• Phospholipid bilayer with free mobile proteins as well as proteins anchored to the cytoskeleton
• Contains cholesterol
• Is amphipathic (hydrophillic and hydrophobic)
• Impermeable selective barrier
• adherence and recognition
• signal transduction
• has a glycocalyx for biochemical specificity

Question 5

In what cells is the nucleus not present?

Answer 5

• RBCs
• Stratum Corneum
• Lens fibre cells

Question 6

How is heterochromatin packaged?

Answer 6

-selenoids

Question 7

How is euchromatin packaged?

Answer 7

-Nucleosomes

Question 8

What is the function of the nucleolus?

Answer 8

-RNA synthesis and ribosomal assembly

Question 9

What are the functions of the cytoskeleton?

Answer 9

• Cell morphology and movement (within the cell)
• Structural support
• To enable locomotion (Cilia)

Question 10

Describe microfilaments of cytoskeleton and give an example of where they are found

Answer 10

• actin fibres twisted together
• contractile
• dymanic (assemble/deassemble)
• intestinal microvilli

Question 11

Describe intermediate filaments of the cytoskeleton and give an example of where they are found

Answer 11

• Non-dynamic
• Supporting meshwork in cytoplasm
• nerve, neuroglia and keratin

Question 12

Describe microtubules of cytoskeleton and give an example of where they are found

Answer 12

• Polymers of tubulin
• Hollow
• Motile
• Mitotic spindle/cilia

Question 13

What is the function of the sER in the liver and mammory glands?

Answer 13

-Lipid synthesis

Question 14

What is the function of the sER in the ovarys, testes and adrenal glands?

Answer 14

-Steroidogenesis

Question 15

Name some hydrolytic enzymes found in lysosomes?

Answer 15

• Protease
• Nuclease
• Lipase

Question 16

What are residual bodies?

Answer 16

-Lysosomes which have digested cellular contents but contain undigestible remnants

Question 17

Why are lysosomes not broken down by the hydrolytic enzymes they contain?

Answer 17

-Lysosome membrane is heavily glycosylated for protection

Question 18

Why does the golgi exhibit polarity?

Answer 18

-To cause proteins in vesicles to migrate from the convex face to the concave face of the golgi

Question 19

Which two organelles are self-replicating and which contains its own genome?

Answer 19

• Peroxisome - doesn’t have genome

- mitochondria - has genome

Question 20

Where are there high amounts of peroxisome and why?

Answer 20

-Kidney tubules and parenchymal cells of liver for detoxification

Question 21

Of what lineage is mitochondria?

Answer 21

-maternal