3.2.1.3 microscopes

Question 1

resolution

Answer 1

minimum distance between 2 objects where they can still be viewed as seperate

Question 2

magnification

Answer 2

how many times larger an object is to an image

Question 3

light microscope advantages and limitations

Answer 3

uses wavelenght of light.
-lower resolution due to longer wavelength of light
-lower magnification
-can be colour
-can be living specimens

Question 4

light microscope how it works

Answer 4

beam of light condensed by glass lens.

Question 5

what are the two types of electron microscope

Answer 5

transmittion electron microscope and scanning electron microscope

Question 6

how TEM works

Answer 6

electron gun shoots beam of electrons at very thin specimen. electrons pass through and areas that absorb appear darker. produces a 2D image

Question 7

how SEM works

Answer 7

beam of electrons onto surface of specimen. electrons are scattered in different ways to produce a 3D image

Question 8

advantages and limitations of TEM

Answer 8

-can see internal structures
-2D image
-must be thin

Question 9

advantages and limitations of SEM

Answer 9

• 3D image
  -cant see internal strcutures
  -dont have to be thin

Question 10

advantages and limitations of electron microscope

Answer 10

re condensed by electromagnets
-higher res due to shorter wavelength of electrons
-higher mag
black and white
-must be in vacuum so non-living

Question 11

equation for magnification

Answer 11

image size= actual x magnification

Question 12

how to get from mm to micrometers to nanometers

Answer 12

mm–>micrometers= x1000
micrometers–>nanometers= x1000

Question 13

what is cell fractionation

Answer 13

breaking open cells to release organelles that are then seperated.

Question 14

why do solutions have to be:
-cold
-isotonic
-buffered

Answer 14

cold: to reduce enzyme activity so organelles arent damaged
-isotonic: prevent osmosis so organelles dont burst
-buffered: keep pH the same to prevent damage to organelles

Question 15

what is homogenisation

Answer 15

cells are blended in blender to break open cells and release organelles. using cold, isotonic, buffered solution.
solution is filtered to remove any large cell debris

Question 16

what is ultracentrifugation

Answer 16

solution is spun in centrifugeat different speeds to seperate organelles based on density

Question 17

what is differential centrifugation

Answer 17

centrifuge is first spun at low speed. most dense organelle will form pellet at bottom of centrifuge. supernatant is collected and centrifuged at increasing speeds and process repeats until all organelles are seperated

Question 18

what is the order of densities

Answer 18

nucleus, chloroplast, mitochondria, lysosome, ER, ribosome