1 Cell theory & microscopy

Question 1

Size of typical cell?

Answer 1

2-200um in diameter.

Question 2

Cell theory states: point 1

Answer 2

1 All organsims composed of one or more cells

Question 3

Cell theory states: point 2

Answer 3

2 Cells are the smallest units of life, basis of ogansization of all living organsims.

Question 4

Cell theory states: point 3

Answer 4

3 Cells arise only by division of pre-existing cell.

Question 5

Cells are the ________ units of life.

Answer 5

Smallest

Question 6

What does microscopy do?

Answer 6

Produces enlarged image through magnification.

Question 7

Difference betwee magnification and resolution?

Answer 7

Magnification refers to the increase in size of an object.
Resolution refers to distinguish two points at seperate.

Question 8

What’s light microscopy?

Answer 8

Beam of light, focused by condensor.

Question 9

Light microscopy - resolution.

Answer 9

0.2um

Question 10

Light microscopy - magnification.

Answer 10

1000x

Question 11

Label a microscope

Answer 11

xxx

Question 12

5 types of light microscopy:

Answer 12

Bright field. Phase contrast. DIC. Fluorescene. Confocal.

Question 13

What’s Brightfield? (4 points)

Answer 13

Classic. Poor contast. Staining of killed cells often required. Cells are fixed.

Question 14

What’s Phase contast? (3 points)

Answer 14

Uses differences in RI of cell components to imprive contrast. Good for living cells. Cells are live and fixed.

Question 15

What’s DIC? (4 points)

Answer 15

Utilises rate of chnage in RI. Produces apparent 3D images. Can be thick & unstained. Cells are live and fixed.

Question 16

What’s Fluorescene microscopy? (4 points)

Answer 16

Specimen stained with fluorescent dye/protein and excite with UV light. Produces high contrast against dark background. GFP from jellyfish. Cells are alive and fixed.

Question 17

GFP

Answer 17

Green fluorescent protein.

Question 18

What’s Confocal scanning light microscopy?

Answer 18

Thick. No sectioned. 300um in depth. Laser beam scans planes with fluorescene. Constructed to 3D. Cells are alive.

Question 19

3 steps for preparing sections of specimen.

Answer 19

Thin slices (10um) by fixation, embedding, sectioning and staining.

Question 20

What can a light microscope see? (5 items)

Answer 20

Most animal & plant cells. Most bacteria. Nuclues. Mitochondria.

Question 21

What can an e- microscope see? (6 items)

Answer 21

Smallest bacteria. Viruses. Ribosomes. Proteins. Lipids. Small molecules.

Question 22

4 steps of Transmission e- microscope freeze fracture process.

Answer 22

1 Fracturing. 2 Etching. 3 Shadowing 4 Replicating. xxx

Question 23

Two types of e- microscopy.

Answer 23

Transmission and Scanning.

Question 24

What is e- microscopy?

Answer 24

Uses a beam of e-, not light.

Question 25

E- microscopy reolution is:

Answer 25

2-20nm.

Question 26

Transmission e- microscopy.

Answer 26

E- passes through thin specimens. Specimens: 1 fixed, sectioned, dehydrated and stained with heavy metals OR 2 cyrofixed and freeze fractures with heavy metals (to reveal internal cell surfaces).

Question 27

TEM magnification:

Answer 27

1,000,00x

Question 28

Scanning e- microscopy.

Answer 28

E- beam scanned over specimen and back scatter strikes a detector. Apparent 3D image. Samples fixed, dehydrated and coated with thin layer of gold.

Question 29

Magnification SEM:

Answer 29

150,000X

Question 30

Resolution SEM:

Answer 30

10nm.

Question 31

Cyro-e- microscopy.

Answer 31

Less harsh. Uses frozen molecules in solution. More gentle e- beams to determine biomolecule structure.

Question 32

Super-resolution microscopy.

Answer 32

Fluorescene based. Ovecoming light resolution limit. Resolution: 100nm.

Question 33

Atomic Force Microscopy.

Answer 33

Visulises surface at molecular scale. Fine pointed tip, linked to cantilever arm. Detects fine movement, reflected on laser beam.