Lecture 3

Question 0

Magnifications and types of light and electron microscopy (2)

Answer 0

1) light = X1000-1400

2) electron = X100,000 (no color)
I) Transmission electron microscopy (TEM)
- 2D
II) Scanning electron microscopy (SEM)
- covered with heavy metal coating

Question 1

Describe different techniques used to study cells (3)

Answer 1

1) unaided eye (10m - < 1mm)
2) light microscopy (5mm - < 1micro M)
3) electron microscopy (100 micro - 5nm)

Question 2

Define Cell

Answer 2

‘A collection of organelles in the cytosol surrounded by a plasma membrane - the minimum self-replicating unit of life.’

Question 3

Relative sizes of plant, animal & bacterium cells (3)

NB. 1µm = 10^-6m

Answer 3

1) Plant = (20x30µm)
2) Animal = (20µm)
3) Bacterium = (1x2µm)

Question 4

Relative sizes of cellular structures - bacterial ribosome, membrane, microtubule, microfilament & DNA helix (5)

Answer 4

1) ribosome (large & small) = 25nm
2) membrane = 7-8nm
3) microtubule = 25nm
4) microfilament = 7nm
5) DNA helix = 2nm

Question 5

What limits cell growth?

Answer 5

Surface area to volume ratio

Radius = n
Surface area = n^2
Volume = n^3

Question 6

Basic features of ALL cells (4) P.C.C.R

Answer 6

1) Plasma membrane
2) Chromosomes (carry genes)
3) Cytosol (semifluid substance)
4) Ribosomes (protein synthesis)

Question 7

Three fundamental DOMAINS of life

Answer 7

Prokaryotes - 1) Bacteria
(Microbes) 2) Archaea

Eukaryotes - 3) Eukarya

Question 8

Four KINGDOM classifications

Answer 8

1) Plantae
2) Animalia
3) Fungi
4) Protists

Question 9

Eukaryotes and Prokaryotes SIZES & general structure

Answer 9

Eukaryotes (10-100µm):

 - membrane enclosed nucleus 
 - membrane enclosed organelles 

Prokaryotes (microbes) - (<5µm):

 - NO membrane enclosed DNA (naked)
 - NO membrane enclosed organelles

Question 10

Outline & define germ theory (Louis Pasteur)

Answer 10

“Many diseases are caused by the presence and actions of specific microorganisms within the body”

Resulted in PASTEURISATION (75 degrees - kills microbes without damaging structure of substance), and led to the conclusion that SPONTANEOUS GENERATION is Incorrect.

Refer to flash straight and bent neck experiments

Question 11

Outline Louis Pasteur works (5)

Answer 11

1) germ theory (of infection)
2) infectious disease (disease causing germs)
3) pasteurisation (kills germs)/biotech
4) vaccines (Attenuation/weakening of microorganisms)
5) stress (cold) increases susceptibility to disease

Question 12

Outline the conditions to Koch’s postulates (4)

Answer 12

1) Microorganism or other pathogen must be PRESENT IN ALL CASES OF THE DISEASE
2) Pathogen can be isolated from the diseased host and GROWN IN PURE CULTURE
3) Pathogen CAUSES THE DISEASE WHEN INOCULATED INTO A HEALTHY, SUSCEPTIBLE LAB ANIMAL
4) Pathogen must be REISOLATED from the new host and SHOWN TO BE THE SAME as the ORIGINAL inoculated pathogen