ch 5 cell theory early giants/microscopy

Question 1

robert hooke’s contribution?

Answer 1

gave us the word “cell”

Question 2

leeuwenhoek’s contributions?

Answer 2

discovered the microbial world (“animalcules”).

Question 3

postulates of cell theory? who is to be credited for this?

Answer 3

1. Cell is smallest unit of life
2. All cells come from pre-existing cells
3. Organisms are made from at least 1 cell (organisms range from unicellular to complex multicellular organisms)
4. Cells are tiny
   thanks schleiden and schwann

Question 4

contributions of schleiden and schwann?

Answer 4

credited for the cell theory. proposed that all living things are made of cells

Question 5

what 3 features are common to all living cells?

Answer 5

1. Cell membrane: controls what enters/leaves)
2. DNA region (nucleus/nucleoid): information for making proteins
3. Cytoplasm: all contents inside the cell

Question 6

main differences between eukaryotic and prokaryotic cells?

Answer 6

E:
- have enveloped nucleus, large amount of DNA
- large complex cells with membranous organelles
- can specialize
- compartmentalized met pathways
P:
- have a nucleoid region with small, circular genome
- simple and very small. efficient. use it or lose it.
- evolve/replicate very quickly
- lack nuclear envelope
- no membrane bound organelles

Question 7

metric system units just in case? (cm, mm, um, nm)?

Answer 7

1 cm= 1/100 meter
1mm = 1/1000 meter
1 micrometer (um) = 1/1,000,000 meter
1 nanometer (nm) = 1/1,000,000,000 meter

Question 8

why are cells so small? why is a high surface area to volume ratio important?

Answer 8

Cells have a high surface area to volume ratio!! It is essential! (like water balloons)

High surface area to volume ratio ensures efficient exchange of wastes/nutrients in cells!

Question 9

define magnification and resolution?

Answer 9

Magnification= increases size of object
resolution= basically the clarity of magnified object.
Defined as ability to discriminate 2 points close to each other in space

Question 10

2 main types of microscopes? how does each type work in a nutshell?

Answer 10

compound light microscopes and electron microscopes
- compound light: use glass lenses and light. Your typical lab microscope
- electron: electromagnets focus on an electron beam

Question 11

3 types of light microscopes?

Answer 11

brightfield
fluorescent
confocal

Question 12

how does brightfield microscopy work? an issue with is ?

Answer 12

works like a typical light microscope.
issues:
- not useful for living cells bc they gotta be chemically fixed/stained
- cells are translucent, so we can’t see subcellular structures

Question 13

how does fluorescent microscopy work? pros/cons?

Answer 13

object itself fluoresces! emits light on its own
Pro: light doesn’t cause blurriness since it’s not coming from underneath. Allows us to significantly raise the magnification and maintain resolution
Pro: can be useful on living cells
con: only gives 2D representation

Question 14

how does confocal microscopy work? pros?

Answer 14

works pretty much like fluorescent microscopy except that it uses lasers to form 3D grid!
- Allows us to see object in 3D plane!

Question 15

main pro of electron microscopy?

Answer 15

Powerful in magnification

Question 16

main con of electron microscopy?

Answer 16

Issue: object has to be carefully chemically fixed to maintain structure (aka object is DEAD). can’t observe living processes!

Question 17

3 types of electron microscopy?

Answer 17

scanning (SEM)
transmission (TEM)
freeze fracture

Question 18

how does SEM work? pros/cons?

Answer 18

we coat an object with thin coating of platinum/gold; electron from electron beam bounce off of that layer and are rendered into a 3D image

pros: looking at what’s on the surface of object, 3D image
Issue: not so useful for living cells. Only gives us image of what’s on the surface of object

Question 19

how does TEM work? pros?

Answer 19

Electron beam goes all the way through the object!
pros: can start seeing subcellular components, structures of cell

Question 20

how does freeze fracture/cryo electron microscopy work?

Answer 20

take cells and cut them w diamond bladed knife, while cell is frozen (ex. can slice the phospholipid bilayer in half)
Issue: cell has to be dead