Unit 3 Chapter 1A (Microscopy & Intro to the Cell)

Question 1

Robert Hooke

Answer 1

First person to look at a plant through a microscope

Question 2

Cellulae

Answer 2

Tiny compartments

Question 3

Cell Theory

Answer 3

Living things are composed of cells and all cells come from other cells

Question 4

Light Microscope

Answer 4

Visible light passes through a sample and glass lens. Passes through the ocular lens and then objective lens.
- Light is bent to magnify image of the specimen
- Earliest type of microscope
- Image projected into eye or camera

Question 5

Magnification

Answer 5

The increase in an object’s image size

Question 6

Resolution

Answer 6

Measure of the clarity of an image
- The ability to distinguish 2 nearby objects as being separate

Question 7

Resolution of a human eye

Answer 7

0.1 - 0.2mm

Question 8

Resolution of a light microscope

Answer 8

0.2 microns
- Resolution will not improve after its been magnified about 1000x

Question 9

Electron Microscopes

Answer 9

Focuses beams of electrons through a specimen sample
- Electromagnets bend the electron path & magnify image
- Images are always black & white
- Use began in the 1950s

Question 10

Scanning EM (SEM)

Answer 10

Studying the detailed architecture of a cell
- Sample is usually coated with thin film of gold
- Electrons excite the gold atoms
- Electrons are scattered and detected by a device that prjects an image into a screen
- 3D Image

Question 11

Transmission EM (TEM)

Answer 11

Electron beam passed through a thin section of a specimen
- Stains with heavy metal coat certain types of cellular structures
- Electrons are scattered by the more densely stained parts
- Electrons are detected and an image is made

Question 12

Electron Microscopy Limitation

Answer 12

Can’t be use to look at living samples
- Due to the specimen having to be broken up

Question 13

Light Microscopy Limitation

Answer 13

Many parts of a cell and some full microorganisms are too small to see

Question 14

Minimum Size of a Cell

Answer 14

Large enough to store enough DNA, proteins, and structures to survive & reproduce

Question 15

Max. Size of a Cell

Answer 15

Influenced by geometry
- Enough surface area to service the full cell volume

Question 16

Surface to Volume Ratio

Answer 16

A large cell has more surface area than a small cell but lower surface-to-volume ratio

Question 17

Types of Cells

Answer 17

Prokaryotic Cells & Eukaryotic Cells

Question 18

Prokaryotic Cells

Answer 18

First cells to evolve and lived for about 1.5 billion years before eukaryotic cells evolved
- Bacteria & Archaea
- Small, simple cell structure

Question 19

Eukaryotic Cells

Answer 19

Evolved from prokaryotic cells about 1.8 billions years ago
- All higher forms of life like plants, animals, fungi
- Larger, more complex cells

Question 20

Plasma Membrane (Cell Membrane)

Answer 20

Membrane that surrounds the cell. A flexible boundary between the living cell and its surrounding environments.
- Very thin
- Phospholipid bilayer

Question 21

Characteristics of the Cell Membrane

Answer 21

• Proteins are embedded in the lipid bilayer
• Hydrophobic regions embedded in membrane
• Hydrophilic regions protrude into the aqueous solutions inside or out the membrane

Question 22

Plasma Membrane Function

Answer 22

Regulates flow of material in and out of cells

Question 23

What can pass through the Cell Membrane?

Answer 23

• Small non-polar molecules (O2, CO2)
• Polar Compounds (water, ions, etc)
• Large Molecules (polar and non-polar)

Question 24

Channel Proteins

Answer 24

Forms a tunnel through the cell membrane which helps polar compounds get through.

Question 25

Transport Proteins

Answer 25

Changes shape to push molecules through cell membrane which helps large molecules get through.

Question 26

Cytoplasm

Answer 26

Entire contents of the inside of the cells, excluding interior part of nucleus

Question 27

Ribosomes

Answer 27

Machinery for protein synthesis

Question 28

Cytosol

Answer 28

Aqueous solution the fills the cells

Question 29

DNA

Answer 29

1 or more chromosome
- Prokaryotic has 1 chromosome

Question 30

Prokaryotic Cells

Answer 30

Small and simple structure that’s about one tenth the size of a eukaryotic cell and has no internal membrane-bound structures

Question 31

Parts of a Prokaryotic Cell

Answer 31

1. Nucleiod
2. Ribosomes
3. Cell wall
4. Capsule
5. Flagella

Question 32

Nucleoid

Answer 32

Region of the cell where the chromosome is coiled

Question 33

Ribosome

Answer 33

Are smaller and have a slightly different structure than eukaryotes

Question 34

Cell wall

Answer 34

Rigid, chemically complex shell surrounding plasma membrane
- Protects the cell
- Maintains cell’s shape

Question 35

Capsule

Answer 35

Sticky outer coat around cell wall
- Glues the cells to surfaces or other cells
- Not in all prokaryotes

Question 36

Flagella

Answer 36

Long projection that propels a cell through its environment
- Not in all prokaryotes