Cells-studying cells

Question 1

2 types of microscopes?

Answer 1

Light and Electron (transmission and scanning)

TEM and SEM

Question 2

Magnification?

Answer 2

how much larger the image size is compared to the actual size

Question 3

Which has higher magnification?

Answer 3

TEM > SEM > LM

Question 4

Formula for magnification?

Answer 4

magnification = image size/actual size

Question 5

Conversion?

Answer 5

1 mm = 1000 micrometre.

1 mm = 1,000,000 nanometre

Question 6

Resolution?

Answer 6

minimum distance at which 2 very close objects can be distinguished

Question 7

Which has higher resolution?

Answer 7

TEM > SEM > LM

Question 8

Why does electron microscopes have a higher resolution?

Answer 8

Electron microscope uses electrons which have a shorter

wavelength

Question 9

Advantage and Disadvantage of TEM?

Answer 9

 Advantage = highest magnification and highest resolution
 Disadvantage = works in a vacuum so can only observe dead specimens, specimen needs to be thin, black
and white image, 2D image, artefacts

Question 10

Advantage and Disadvantage of SEM?

Answer 10

 Advantage = produces 3D image

 Disadvantage = works in a vacuum so can only observe dead specimens, black and white image, artefacts

Question 11

Cell Fractionation?

Answer 11

Breakdown tissue into cells
 add cold/isotonic/buffer solution
 homogenate – breaks open cells releasing organelles
 filter = removes large debris and intact cells
 centrifuge – spin at low speed, largest organelle builds at bottom (nucleus), leaves supernatant, spin at
higher speed, next heaviest organelle forms at bottom
 organelle by size: nucleus, chloroplast, mitochondria, endoplasmic reticulum/golgi body/lysosomes,
ribosomes

Question 12

cold?

Answer 12

reduce enzyme activity

Question 13

isotonic?

Answer 13

maintains water potential so

organelle does not shrink or burst

Question 14

buffer?

Answer 14

maintains constant pH