Intro/Cells

Question 1

Define: cells

Answer 1

smallest unit of living matter capable of independent existence

Question 2

How many types of cells are there in the body

Answer 2

around 200

Question 3

Define: tissues

Answer 3

Groups of cells and their ground substances that act together to perform a particular function

Question 4

What is the difference between simple and compound tissues?

Answer 4

Simple tissues are made up of all the same type of cell where compound tissues are made of different cell types

Question 5

What are the main tissue types in the body?

Answer 5

Connective, epithelial, muscle, and nerve

Question 6

Define: organs

Answer 6

anatomically distinct groups of tissues, usually of several types, joined as structural unit to perform specific functions

Question 7

Define: systems

Answer 7

primarily groups of organs, which have similar or related functional roles

Question 8

When is brightfield microscopy suitable? What do the specimens tend to look like?

Answer 8

for observing the natural colours of a specimen or the observation of stained samples.
The specimen appears darker on a bright background

Question 9

When is phase contrast microscopy useful?

Answer 9

observing unstained specimens that lack a colour

Question 10

What is another type of microscopy used to visualized unstained samples?

Answer 10

Differential Interference Contrast microscopy

Question 11

How is Differential Interference Contrast microscopy (DIC) similar and different to phase contrast microscopy?

Answer 11

As with Phase Contrast, DIC transforms the phase shift of light, induced by the specimen refractive index, into detectable amplitude differences. However, because DIC utilizes optical path differences within the specimen to generate contrast the 3D appearance may not represent reality

Question 12

What are the two main groupings of dyes used to stain (mainly) colourless tissues?

Answer 12

1. Basic (cationic) dyes - blue

2. Acidic (anionic) dyes - red

Question 13

Name an example of a basic dye

Answer 13

hematoxylin

Question 14

Name an example of an acidic dye

Answer 14

eosin

Question 15

How do basic/acidic dyes work?

Answer 15

They have either positively or negatively charged colour radicals that will bing with either acidic groups (like phosphates in DNA/RNA) or basic groups (like basic proteins)

Question 16

Hematoxylin/eosin (H&E) staining stains the nucleus and ribosomes ___, the cytoplasm ___ and collagen ____

Answer 16

blue, red, pink

Question 17

define: magnification. How do you calculate it?

Answer 17

the number of times lager the image is compared to the true size

image size/actual size

Question 18

define: resolution

Answer 18

the ability to distinguish between two points

Question 19

in brightfield microscopy, what is resolution dependent on ?

Answer 19

Wavelength

Question 20

What things can you not resolve with brightfield microscopy? why?

Answer 20

Things less than ½ the wavelength of light

won’t interfere with the light beam, so you can’t resolve them

Question 21

Why do electron microscopes have a much higher resolution than brightfield microscopes?

Answer 21

because electron wavelengths are more than 10,000’s times shorter than light wavelengths

Question 22

What determines the limit of resolution of brightfield microscopes?

Answer 22

Numerical Aperture (NA), or the ability of the lens to collect the light

Question 23

in air, the NA will typically be..?

Answer 23

less than 1

Question 24

What must be done for lenses with an NA value over 1?

Answer 24

need to use oil

Question 25

what is the typical magnification of a light microscope and the theoretical maximal resolution?

Answer 25

Typical magnification of a light microscope, assuming visible range light, is ~1000x with a theoretical resolution limit of around 0.2uM

Question 26

What formula can you use to determine resolution for a light microscope?

Answer 26

R = 0.5λ/NA

Question 27

What are 4 advantages to light microscopes?

Answer 27

1. Can be done on live cells or dead cells
2. Can use coloured dyes and fluorescent antibody labeling to distinguish features
3. Inexpensive
4. Easy to use

Question 28

What are two limitations of light microscopy?

Answer 28

1. ~200 nm limit of resolution

2. ~1000x magnification limit

Question 29

What are two advantages to electron microscopy?

Answer 29

1. High Resolution Images to ~50pm

2. ~100,000x magnification

Question 30

What are 4 limitations to electron microscopy?

Answer 30

1. Samples must be fixed
2. No possibility of colour
3. Expensive
4. Difficult sample preparation