Microscopy

Question 1

development of microscopy

Answer 1

Robert Hooke (1665) constructed the first LM, observed dead cork tissue and other plant and animal tissue - introduced the term “cell” from monk cells

Question 2

magnification

Answer 2

• number of times an object is magnified
• how much smaller/larger is the image than the real specimen

Question 3

resolution

Answer 3

• the ability of a microscope to show two close objects separately
• depends on the wavelength of the rays that pass through the spectrum (e- have much shorter wavelength so EM has much higher resolution)

Question 4

LM vs EM
- what passes through specimen?
- FOV (field of view)?
- magnification?
- resolution?
- colors?
- type of specimen?

Answer 4

• beam of light/beam of electrons
• larger/smaller
• up to 500x/up to 500 000x
• 0.25 microm apart/0.25 nanom apart
• visible/black-white
• alive/dead

Question 5

• as magnification increases, FOV…

Answer 5

…decreases

Question 6

magnification =

Answer 6

image size/actual size

Question 7

scale bar

Answer 7

• a line added to the micrograph to show the actual size of the structure

Question 8

freeze-fracture EM

Answer 8

• physically breaking apart frozen biological sample through the weakest piint of the cell
• structural details exposed by the fracture plane is visualized by deposition of Pt-C to make a replica for examination in the EM

Question 9

cryogenic EM

Answer 9

• structures of proteins, nucleic acids and other biomolecules
• studying how they move around and change as they perform their functions (alive)

Question 10

cell theory

Answer 10

1) cells are the basic units of life (nothing smaller than the cell can survive independently)
2) all living things consist of cells
3) new cells come from pre-existing cells by the process of cell division

Question 11

1) cells are the basic units of life (nothing smaller than the cell can survive independently) - evidence

Answer 11

• sub-cellular components have never been seen to perform functions of life whereas full cells have

Question 12

2) all living things consist of cells - evidence

Answer 12

• biologists examined tissues from all kingdoms, each specimen had at least one cell

Question 13

3) new cells come from pre-existing cells by the process of cell division - evidence

Answer 13

• we have observed cells coming from other cells but never observed spontaneous generation

Question 14

discrepancies (exceptions) to the cell theory

Answer 14

1) Striated (skeletal) muscles
- more than 1 nucleus per cell
- long cells, around 30 mm
2) Giant algae, Actabularia
- single-celled organism but up to 20 cm long
3) Aseptate Funghi
- fungal hyphae (narrow thread-like structures) are made up of rows of cells usually separated with septa but some funghi lack this septa -> each hyphae is a continuous multinucleated tube-like structure

Question 15

unicellular organisms…
(example)

Answer 15

…carry out all functions of life. Amoeba

Question 16

functions of life

Answer 16

1) metabolism
2) response
3) nutrition
4) excretion
5) reproduction
6) growth
7) homeostasis
8) movement

Question 17

metabolism

Answer 17

all chemical reactions in a cell (catalyzed)

Question 18

response

Answer 18

ability to react to stimuli from the environment

Question 19

nutrition

Answer 19

obtaining food to get energy

Question 20

excretion

Answer 20

removal of waste products

Question 21

reproduction

Answer 21

production of offspring sexually or asexually

Question 22

growth

Answer 22

irreversible increase in size

Question 23

homeostasis

Answer 23

regulating internal conditions (keeping them within limits)

Question 24

all cells (prokaryotic and eukaryotic) have some basic features in common:

Answer 24

• plasma membrane
• cytoplasm
• DNA
• present ribosomes

Question 25

differences between euk. and pro.

Answer 25

- size (pro - 0.2-10 microm, euk - 10-100 microm) - complexity - eukaryotic cells are compartmentalized (many differences arise from this fact like type of cell division, DNA structure...)

Question 26

pro, eu, karyon

Answer 26

before, real, nucleus

Question 27

TEM and SEM

Answer 27

transmission electron microscope (for the interior) and scanning electron microscope (for the surface)

Question 28

structure of a cell seen from a microscope

Answer 28

ultrastructure of cells

Question 29

anucleate cells vs multinucleate cells

Answer 29

don't have a nucleus - cannot transcribe DNA to make mRNA and synthesized proteins - red blood cytes (erythrocytes) have multiple nuclei (more mRNA and proteins) - skeletal muscle/aseptate fungi