2.2 Cell Studies

Question 1

What is the advantage of electron microscopes?

Answer 1

Higher resolution

Question 2

Why do electron microscopes have a higher resolution?

Answer 2

Electrons have a shorter wavelength

Question 3

How do optical microscopes work?

Answer 3

Focus a beam of light through specimen

Question 4

How do electron microscopes work?

Answer 4

Focus a beam of electrons through specimen

Question 5

What is the advantage of optical microscopes?

Answer 5

Specimen can be alive

Question 6

What are the types of electron microscope?

Answer 6

Transmission Electron Microscope
Scanning Electron Microscope

Question 7

Describe the preparation of a slide for a TEM.

Answer 7

Thin so electrons can penetrate

Question 8

Which microscope can see specimens in colour?

Answer 8

Optical/light

Question 9

What is the disadvantage of TEM slide preparation?

Answer 9

Complex staining technique

Question 10

Which microscope allows smaller orgamelles to be seen?

Answer 10

TEM

Question 11

Why do samples for a light microscope need to be thin?

Answer 11

Light can pass through
Only one layer of cells can be seen

Question 12

What is an eyepiece graticule?

Answer 12

Apparatus that goes over eyepiece with a ruler

Question 13

Why do eyepiece graticules need to be calibrated?

Answer 13

Value of the units changes with each magnification

Question 14

How is a mounted sample prepared?

Answer 14

Very thin
Stain appropriately
Add drop of water
Place coverslip with mounted needle

Question 15

What is used to calibrate an eyepiece graticule?

Answer 15

Stage Micrometer

Question 16

How much is each unit on a stage micrometer worth?

Answer 16

10 micrometers

Question 17

What equation can be used to find the units of an eyepiece graticule?

Answer 17

(Stage micrometer units/eyepiece graticule units) x 10

Question 18

How can an eyepiece graticule be used to measure a cell?

Answer 18

Unit value calculated x units

Question 19

Why are samples kept ice cold in ultracentrifugation?

Answer 19

Slow/stop enzyme activity so organelles are not digested

Question 20

Why are samples kept in a buffer solution in ultracentrifugation?

Answer 20

Keep pH the same so enzymes are not denatured

Question 21

Why are samples kept in isotonic solution in ultracentrifugation?

Answer 21

So there is no movement of water in/out and causes lysis

Question 22

What does ultracentrifugation separate organelles based on?

Answer 22

Weight/mass

Question 23

What is used to spin samples in ultracentrifugation?

Answer 23

Centrifuge

Question 24

What speed is used first in ultracentrifugation?

Answer 24

Slower

Question 25

What are the organelles at the bottom of a centrifuge called?

Answer 25

Pellet

Question 26

What is the remaining liquid in a centrifuge called?

Answer 26

Supernatent

Question 27

What is the first organelle to be separated in a centrifuge?

Answer 27

Nucleus as its the heaviest

Question 28

What is the second organelle to be separated in a centrifuge?

Answer 28

Mitochondria