Cells and Cells transport

Question 1

Electron vs light microscope

Answer 1

Radiation source:
Electron vs Light

Wavelenght:
About 0.005nm vs 400-700nm

Max resolution:
0.05nm vs 200nm

Max magnification:
Over a million vs 1500

Lenses:
Electromagnets vs Glass

Speciment:
Dead, dehydraded, small and thin vs Living or dead

Image:
Black and white vs Coloured

Question 2

Advantages and disadvantage of electron microscope?

Answer 2

Adv:

Higher magnification

Higher resolution(due to shorter wavelenght)

Dis:

Vaccum so dead specimens

Difficult process and produce artefacts

Expensive and training required to use

Black and white image only

Question 3

Transmission electron microscope?

Answer 3

A beam of e- transmitted through specimen

Specimen stained by heavy metal

Substances deflect e- but pattter remaining e- produce create image

Adv: Higher resolution, internal structure observed

Dis: Very thin specimen, not 3D, specimen deteriorates

Question 4

Scanning electron microscope?

Answer 4

Specimen is coated with thin film of heavy metal

e- beam is scann specimen

e- reflected from surface are collected and produce image

Adv: Surface structure shown, 3D image, thick section examined

Dis:Lower resolution, only surface can be viewed

Question 5

What is required for a homegenic solution?

Answer 5

Ice cold, isotonic and buffer solution

Ice cold - so enzymes dont damage organelles

Isotonic - so no osmosis which causes burst or shiver

Buffer - so no damage to enzymes or organelles

Question 6

Describe homogenisation and centrifugation?

Answer 6

Break open tissue in homogenous solution using a blender

Filter to remove debris

Put it into tube and centrifuge at low speed

Cell debris e.g. cell wall would form pellets at bottom

Supernatant would be removed and spun at higher speed

Heavier organelles would form sediment e.g. nuclei

Continue process until desired organelle obtained, as continue density decrease

Usually, order is nuclei, chloroplasts, mitochondria, ER, and ribosomes

Question 7

List organelles found in eukaryotic?

Answer 7

Nucleus, centrioles, mitochondria, golgi body, lysosomes, RER, SER, chloroplasts, ribosome

Question 8

Nucleus?

Answer 8

Contain DNA

Nuclear envelope has nuclear pole that allows mRNA to communicate with cytoplasm

Nucleoplasm contains chromatin and nucleoli

In dividing cell chromatin is chromosomes

Controls cell process e.g. division, protein synthesis and ribosome synthesis

Question 9

Centrioles?

Answer 9

Produce spindle fibre for chromosome separation in mitosis and meiosis

Hollow cylinder contains 9 triplets of microtubules