Lecture 1+2

Question 1

Resolution definition

Answer 1

the ability to clearly tell apart two points close together

Question 2

Antoine van Leeuwenhoek

Answer 2

first observed and recorded cells in the 1660s using an early version of a microscope (x275 magnification)

Question 3

Robert Hooke

Answer 3

examined thin slices of cork and discovered a network of tiny compartments

Question 4

Robert Brown

Answer 4

discovered a round structure inside the plant cell and named it the nucleus

Question 5

Two types of light microscope

Answer 5

Upright light microscope- looks at sample from above
Inverted light microscope- looks at sample from underneath

Question 6

Types of microscopes used in cell biology

Answer 6

Light microscopes
-brightfield
-optical contract microscopy
-fluorescence
Electron microscopes
-transmission
-scanning

Question 7

Phase contract microscopy

Answer 7

Phase shifts in the light waves are converted into brightness changes in the image to allow for better contrast
-two waves in phase make it bright
-two waves out of phase would be dim

Question 8

Phase contrast

Answer 8

light passes through a diaphragm which focuses a ring of light onto a sample causing a phase shift to alter light wave path and results in improvement of contrast

Question 9

Differential-inference-contrast (DIC) microscopy

Answer 9

based on interference between polarised light, objects appear in relief and seem to cast shadows (look 3D)

Question 10

Types of contrast in light microscopes

Answer 10

brightfield- not great contrast
optical contrast DIC- much better contrast looking 3D
optical contrast phase contrast- produces a white halo around the cell

Question 11

Immunocytochemistry

Answer 11

relies on labelled antibodies that recognise specific cellular molecules (antigens)
dyes or enzymes are bound to an antibody to locate complimentary antigens

Question 12

Electron microscopes

Answer 12

lenses focus an electron beam
resolution of up to 0.1nm (2000x better than light)
specimens have to be stained with heavy metals
samples have to be viewed in a vacuum

Question 13

SEMs

Answer 13

focus a beam of electrons onto the surface of specimen providing images that look 3D

Question 14

TEMs

Answer 14

focus a beam of electrons through a specimen used mainly to study the internal structure of a cell

Question 15

Eukaryotic cells

Answer 15

have internal membranes to compartmentalise functions of organelle

protists, fungi, animals and plants

larger than prokaryotic

Question 16

Eukaryotic cells have:

Answer 16

DNA in nucleus bound by a membranous nuclear envelope

membrane bound organelle

cytoplasm in the region between the plasma membrane and nucleus

Question 17

Basic features of all cells

Answer 17

plasma membrane
semi-fluid substance called cytosol
chromosomes/DNA
ribosomes

Question 18

Prokaryotic cells

Answer 18

only organisms of the bacteria and archaea domain consist of prokaryotic cells

Question 19

Prokaryotic cells are characterised by:

Answer 19

no nucleus
DNA in unbound region called the nucleoid
no membrane bound organelles
cytoplasm bound by the plasma membrane